THE EDGE MOOR WATER TUBE BOILER HEAT-POWER 39 ntinecrifig Bell Uni> IASeMENT STORAGE El ^-3 Cornell University Library TJ 314.E23 The Edge Moor water tube boiler.Generar 3 1924 004 107 110 riAot. fHUT-PO«WJl|. Date Due ■' - 11^1*^ # prr 1^'^ Cornell University Library The original of tiiis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924004107110 s THE EDGE MOOR WATER TUBE BOILER GENERAL CATALOGUE NUIMBER SIXTY-THREE 1922 CopjTight, 1921, by EDGE MOOR IRON COAIPANY Edge Moor Iron Company Designers and Builders of '& Edge Moor Waste-heat Plants and the Edge Moor Water Tube Boiler SALES OFFICES Boston 79 Milk Street New York Ill Broadway PHILAUELPHrA TERRITORY EdQE MoOR, DeL. Pittsburgh, Pa 309 Oliver Building Chicago 10 S. La Salle Street St. Paul Robinson, Gary & Sands Co. Charlotte, N. C Thomas B. \Vhitted Codes Used: ABC, Business, Liebers and Telef,raph Cable Address- EDGEMOOR, WILMINGTOX, DELAWARE IVIain Office and Works Edge Moor, Delaware a. s o o a a bJD 3 a) -^ TS *^ o 2 0) J= -&a 1? T3 ■s - .S c o e: BO EDGE MOOR WATER TUBE BOILER Development and Theory 171 VERY highly developed art passes through two stages of progress -J and has its beginnings in some new conviction; as, for example, power for industrial purposes can be generated from steam. In the earlier stage efforts are necessarily concentrated on the discovery of means to realize this conviction, and the appliances found "to work" are generally more or less crude. In the later stage the efforts are shifted to the develo])ment of refinements to overcome objectionable results, to improve quality and to increase quantity. TIk^ construction of the modern high-pressure boiler has followed a similar line of develo]5ment. At first, efforts were concentrated principally on the development of the now typical arrangements of the heating surface together with those structural details that are necessary for safetj^ and maintenance. In recent years, the efforts have l:)een confined to those seemingly minor details that affect that very important result — the all-over cost of power. Since the boiler is an auxiliary to the steam engine, their historical development, as far as steam pressures are concerned, has been parallel. The first steam engine of the piston type actually constructed, the inven- tion of Newcomen and Cawley which seems to have been patented in 1705, did not make use of the "pushing power" of steam. The top of the piston was always open to the atmospliere while the cylinder space below was alternately filled with steam, at al)out atmospheric pressure, which was later condensed to "hft off" the back pressure, thus causing motion of the piston. This was really a vacuum engine. Later, in 1765, James Watt invented the separate condenser, put a cylinder head on the Newcomen engine, admitted the steam l^etween cylinder head and piston, and thus produced the first pressure engine. Incidentally, he laid the foundation for the pressure boiler. Forty years later, steam pressures had crawled from that of the atmosphere to about five pounds per square inch! It was a pressure (1) EDGE MOOR WATER TUBE BOILER even modestly less than this tliat constituted the motive power for the first voyage of a steamboat — the Clermont in 1807. Between 1850 and 1860, according to Thurston, the customary pressures for new engines was from 20 to 25 pounds. In 1876, at the Centennial Exhibition at Philadelphia, the fourteen boilers there exhibited, which represented the best practice at that time, were tested at 70 pounds. S9S»s»;;..._^ Jy;w^,. Note the header construction, the horizontal drums, the straight, inclined tubes, the elliptical handholes and the efficient cross baffling In 1900, 150 pounds pressure was considered high for land plants, while today the customary pressure for the larger plants is from 175 to 250 pounds per scjuare inch. But high pressure alone does not distinguish the modern boiler from its predecessors. The tremendous increase in manufacturing, and in the domestic and industrial uses of electric power has created an insistent LIBERATION OF STEAM FROM TUBES 3 flemaiul for those refinements which have to do with cost of production, certainty of service and economical use of property. Thus, the fact that a boiler gave good satisfaction twenty-five years ago argues nothing as to its suitability for the needs of the present day. The Edge Moor boiler was designed to meet modern conditions. The first one of this type was built in our shops in 1895 and proved highly satisfactory. Since then there have followed the natural improvements in structural details and in methods of manufacturing, but the original principle, which will he explained presently, has been adhered to. Reduced to its simplest form, a steam boiler is a plate of metal with hot gas on one side and cold water on the other, the terms hot and cold being merely relative. As is well known, when the temperature of the hot side of a plate remains constant, the amount of heat which will be con- ducted through the plate will vary with the temperature of the cold side. That is, by lowering the temperature of the cold side more heat will be transmitted, and vice versa. Now the temperature of the cold side of the plate is dependent on the conductivity of the substance in contact with that side; for, if the heat that passes through the plate is conducted away rapidly, the temperature of the cold side will be relatively low l)ut, on the other hand, if the heat is conducted away slowly the tem- perature of the cold side will be relatively high. Since water is a much better conductor of heat than steam, it follows that the rapid removal of steam from contact with the heating surface, where it is generated, and its replacement with water will increase the transmission of heat into the boiler; that is, the capacity, and therefore the eflficiency for a given output, will be increased. But increased capacity and efficiency are not the only desirable results obtained by keeping the heating surface wet. Since, as stated above, the temperature of the cold side of the plate will rise if the substance on that side is a poor conductor of heat, it follows that the average tem- perature of the plate will also rise at the same time — that is, the plate will be overheated, which accounts for blisters and burns during forced firing. Therefore, from the three standpoints of capacity, efficiency and cost of maintenance there must be a minimum of retardation to the escape of steam from the tubes. How is this accomplished in the Edge Moor boiler? It will be seen that the distinctive feature of this boiler is the extension of the headers, at full width, well above the tops of the drums so that, contrary to the usual construction, the drums with their full area enter the headers, giv- 4 EDGE MOOR WATER TUBE BOILER ing a much larger throat as shown in tlie accompanying illustration. The importance of this greatly increased throat area from a theoretical standpoint is easilj' seen. The principal distinguishing feature of the Edge Moor boiler is the unrestricted connection between header and drum Consider what happens between the injection of a particle of water by the feed pump and its subscciucnt removal in the form of steam. At some jilacc in the boiler this particle of water reaches the maximum temperatiu'e at which water can exist as a lic|uid in the same vessel with steam at a constant pressure. Sooner or later, it passes into one of the tubes, conies in contact with the hut surface and is transformed into steam. Now this transformation is accompanied by a very great increase in volume. At 135 pounds pressure one cubic inch of water expands into 1.50 cubic inches of steam; at higher pressure the ratio of volume is somewhat reduced liut is still very large. In consequence, the steam generated in the tube nuist leave the tulie at a very much faster rate than the water coming into it. Now the faster a fluid moves, the greater is the frictional resistance which retards its passage and, since the PROOF OF CORRECTNESS OF DESIGN 5 resistance to the flow of fluids varies as some power of the velocity, and since velocity must decrease as area increases, the rationality of makino; throat areas large to minimize the hindrance to the liberation of steam is very apparent. However, it is always well to check theory with practice. For this purpose, the results of authoritative tests are licre given. Since the true function of a boiler is to absorb heat from the gases produced in the combustion chamber, the index to the efficiency of a lioiler is the tem- perature of escaping gases when they contain a high percentage of carbon dioxide, which is proof that tlie temi)erature of gases is a conse- quence of absorption in the boiler and not of infiltration of cold air near the breeching. Table I shows that gas temperatures have Vieen obtained less than 00° at)ove the temperature of the saturate(l steam, which is conclusive proof of the correctness of the ])rinciples underlying Edge Moor design. . -fSO K 460 '63oRn 8:30 10:30 ir.soAM. z:30 4:30 e:Jo a:so /o:30 i2:30P/i. z:3o 4:30 6:30 Tempebatuke of Flue Gases for Fik.st 24 HoeRS of Te.st No. 8, 'tABLE I Table I — Showing Temperatures op P^scaping Ga.ses frosi Edge Moor Boilers Test No.i 2 10 127 113.4 101.. 5 101 5 Per ceil . of Combined '■^*'^':' efficiency capacity I Percent, developed 76.9 50. 9.5 78 . 58 51. 6 C0> at damper Per cent. 11.7 13.3 14.3 12.. 5: 13. 4J Pressure of steam I.lis. 128 117.6 179 14.5.6 Tempera- ture of saturated steani Deg. F. 355 349 379 364 Tempera- Gas tempera- ture of flue ture — steam gases Deg. F. temperature Deg. F. 476 = 121 412 63 439 60 421 57 1 See tabic on next page. 2 Note that flue temperature is relatively higher when CO2 is lower. 6 EDGE MOOR WATER TUBE BOILER Table II is intended to show, primarily, the efficiencies obtained with Edge Moor boilers in different sections of the country. The efficiencies given are the combined efficiencies of the boiler and firing equipment, exclu- Tablb II — Tests of Edge Mook Wateb Tube Boilers d 1 Date of test 1909 Name and location of plant p.%es^K-d of stoke. Kind of fuel B.T. u, per lb. dry fuel 1 United States Navy Yard, Philadelphia, Pa. Four Overfeed Semibitum. coal 14,790 2 1914 Milwaukee El. Ry. & Lt. Co., Milwaukee, Wis. Three Underfeed Bituminous coal 13,101 3 190S Lardner's Point Pump. Sta,, City of Philadelphia Four Overfeed Semiliitum. coal 14,770 4 1908 Lawrence Ave, Pump. Sta., City of Chicago Four Chain grate Bitmiiinous coal 11,557 5 1912 Dill & Collins, Philadelphia, Pa. Four Overfeed Semibitum. coal 14,458 6 1916 Central Park Ave. Pump, Sta,, City of Chicago Three Underfeed Bitiuuinous coal 11,962 1913 National Tulic Company, Kewancc, 111, Four Underfeed Bituminous coal 11,048 S' 1913 National Ttibe Company, Kewancc, 111. Four Underfeed Bituminous coal 11,094 9 1911 American Ice Company, Pliiladclphia, Pa. Three Overfeed Semibitum. coal 14,214 lo- 1912 United States Navy Yard, Mare Island, Cal. Four Oil burner California oil 18,790 ll 1915 Cons. Gas El, Lt, & Pr. Co., HaltuHorc, Md. Three Underfeed Semiliitum, coal 14,454 12 19111 Sanitary District of Chicago, Chicago, 111. Three Lfnderfeed Bitimtinous coal 10,024 13 1910 Sanitary District of Chicago, Chicago, 111. Three Underfeed Bituminous coal 11,600 14 1915 Hershey Chocolate Co,, Hcrshcy, Pa. Three Overfeed Semiliitimi, coal 14,084 15 1915 E, I,DuPc,ntdeN.&Co,, Hop,.wcll. \-a. Three Overfeed Semibitum, coal 14,032 10 1919 Maj^'air Pumping Station, City of Chicago Four Underfeetl Bituminous coal 12,660 17 1917 Union Ellectric Lt. & Pr, Co,, St. Louis, Mo. Three Underfeed Bitiuninous coal 12,771 ' .Journal A, S, M, E,, vol, 36, p, 220, - Engineering News, vol, 69, p, 1126, 1914; and Bull, .53, Edge Moor Iron Co. May 29, 1913. OFFICIAL BOILER TESTS 7 sive of the firing auxiliaries, as determined in practice and as defined in the Power Test Code of the American Society of Mechanical Engineers. The difference between combined efficiency and 100 per cent, includes, of Table II (Continued) — Tests of Edge Moou A\'ateu Tube Boilers Dura- tion Hrs. Temp, of feed water Deg. F. Pressure of steam Pounds gauge Super- heat Deg. F. Draft in furnace In. Draft before damper In. Temper- ature of flue gas Deg. F. CO2 at damper Per cent. Hated capacity H.P. Per cent.Co'bined of rated eflfi- rapacity ciency. devel'p'dPcr cent. 1 12 52.0 142.6 79.4 0.21 0.39 468 456 113.3 74.97 2 24 120.0 179.0 83.1 0.04 439 14.3 765 101.5 78.58 3 24 39.2 128.0 None 0.33 0.63 476 11.7 505 127.0 76.9 4 12 42.8 156.3 None 0.54 518 279 158.0 74.7 5 24 80.3 110.6 None 0,24 0.45 521 10.7 749 116.4 77.9 6 24 1.58.8 119.3 113.1 0.01 0.16 436 12.7 497 121.0 75.29 7 24 183.9 116.0 91.2 0.01 0.28 450 13.0 613 127.9 80.38 8 72 194.9 117.6 77.9 0.01 0.26 412 13.3 613 113.4 80 . 95 9 12 155.4 144.9 None 0.15 0.33 213 111.7 77.2 10 10 170.8 145.6 90.0 0.19 421 12. 5\ 13.4/ 458 101.5 81.6 11 12 63.9 1S3.4 113.8 0.05 0.14 417 13.2 1047 130.5 77.3 12 13 169.9 1.54.2 86 . 7 0.05 0.19 429 12.0 499 125.8 78.2 13 23 170.0 153.8 86.4 0.02 0.18 438 10.6 499 108.6 76.7 14 12 55.6 162 . 5 83 . 8 0.19 0.29 477 14.0 410 108.9 76.3 15 9 195.6 132.0 None 0.51 0.82 539 600 166.2 74.4 16 12 37.5 159.4 142.2 0.02 0.30 428 12.6 516 118.0 78.21 17 12 181.0 ' 199.0 136.0 0.04 i 0.48 512 13.6 55S 163.0 77.7 8 EDGE MOOR WATER TUBE BOILER course, not only the loss due to escaping carljon monoxide, the loss from excess air, the loss from combustible to the ash pit, etc., which are charge- able to the furnace, firing equii^ment and firing labor, but also the unavail- able heat such as the "hydrogen loss." By separate analysis of the per- formance of the Ijoiler alone, excluding the losses chargeable to firing and unavailable heat, the efficiency of the Edge Moor boiler has been found to be much in excess of the combined efficiency. As regards high overload capacity. Table III shows that tests have been made up to 328.6 jier cent, of rating based on ten square feet of water- heating surface per horsepower. Another feature of boiler performance which must not be overlooked is quality of steam. JNIany official tests of Edge Moor boilers have shown that unusually (hy steam is delivered — less than I per cent, of moisture Ijeing \'ery connnon. Table 111 — Capacity Tests of Edi;e Moor Boilers N;ime and l(,r;ttioii of [tlaiit Date of test Duration of test Hrs. Rated eapadty HP. developed Per cent, of rating developed Uiiioji Elcitiic Light & Power Co., 1910 4 518 1265 244.2 St. Louis, Ml.. Union Electric Light & Power Co., 1917 2 558 1834 328.6 SI. Louis. Mi>. Sanitary District of Chicago, 1916 4 499 971 194.5 Chicago, IlL Consohdated Gas, El. Lt. & I'r. Co., 1913 S 736 1829 248.5 Baltimore, Aid. Consolidated Gas, El. Lt. & Pr. Co., 1913 2 736 2340 317.9 Baltimore, Md, Consolidated Gas, El. Lt. & Pr. Co., 1915 12 1047 2472 236.1 Baltimore, Md. New York Steam Co., 1917 240 lOCO 2070 207 . Nc;w York Cit.v New York Steam Co., 1917 10 1000 2596 259.6 New York City Materials and Workmanship THE defects of an. incorrect design can never Ije com- pensated fori )yworlv- manship or structural features, however good. But when it is recognized that the principles of design permit a realization of the best results, it is next in order to look into the various provisions for safety — the primary re- quirement, for accessibility for cleaning — which affects the efficiency and labor cost, and for convenience's for fiuickly taking a boiler out of service and putting it back — which affects the labor cost and the fixed charges. Triple riveted, double butt strapped drum showing U-plates on the inside Every drum is tested at the works with water under pressure to assure tightness of riveting before shipment (9) 10 EDGE MOOR WATER TUBE BOILER a: ^^ ^ ^ ^ ^ ^ , a ^ 5 -. ^ ^ , a ~ =; ^ §s ^ ^ -^ ■C sa q: -^) ^ = = CI ~1^ 1 ^ "• ~- ■~ 0, 5b ^ 1 .-^ ^ i 1 _^ ii. _^ k; A cq ^ ^ OD >< ^ _liL iS_ A (Q Ct ^ -ST "Sf ~rr "^ "ST "^ "sr T "5^ ^ "sr "^ -^ ■^ ■^ Cm CM "-I ^ 'I- > > « "1 M- ''t c^ ^ •* ,^ f^ IT^ "^ «^ "> ") "~> "1 >^ ^ ^ "i ":) ^ ") »J "1 "i (luoqdioifj r^ (^ ? s c^ > VS iS txi "> r^ ?~^ ^, (.-^ M M <.-l ^-1 l,^ v^ Ci \~i VI ■^ Ni Si Si SJ SI Qq fn t^ c- <3~ <:^ (J~ ^^ c^ Q o v^ <3- CI- ^ ^ ^ ■ — ^ ~-^ — Cm ^ \ -^ ^ ^, ^. ^ ~^ E»JY|nuiauo )o V) ^ Ci > ■- — •^ 5m ^^ -Ci -s C~l 't V3 M- ~- ''^ ■o K <5 '^ 10 Q 'O Q o *<) V<1 ^<) "i ^ ^ "^ ^ V3 v^ >.^ ? 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Sj CO H Ss s - a «5 «-. ^ o a 3 T3 MATERIALS AND WORKMANSHIP 11 For safety, it is of the utmost importance that all materials shall be of homogeneous quality and of known strength and properties. The Edge Moor Iron Company requires tests of all plates and staybolt mate- rials, and subjects such materials to critical inspection at its works before fabrication. The Edge Moor boiler, exclusive of handhole plates, is strictly an all sleel boiler, for not a particle of any such uncertain metal as cast iron Every header is also tested at the works. Special testing equipment for both drums and headers are required for this purpose enters into its construction. Hantlhole plates, which are in compression, are furnished of cither cast iron or forged steel, as the purchaser desires. Two other primary structural factors are riveting and the staying of flat surfaces. With regard to riveting, it is a standard practice with the Edge Moor Iron Company to first punch guide holes for the drill, J inch smaller than the finished rivet holes, in only one i^late of a joint. The plates arc afterward bolted together, and the rivet holes are drilled through the lapped plates at one operation, assuring a perfect match of holes and thus eliminating the possible future use of the injurious drift pin. The plates are then taken apart, all Ixirrs and chips are scraped off (only those who have seen the accumulations on the dismantled plates will appreciate the importance of this step) and the plates are reassembled for riveting. 12 EDGE MOOR WATER TUBE BOILER All rivets are of standard soft steel, brought to the proper heat before riveting, driven by an hydraulic riv- eter wherever possildc, or by a pneumatic hammer, and held until black. The tight- ness of all joints is proved in the final shop tests. The accompanying en- gravings show clearly the manner of staying the head- ers. Just as for effective designs in building and bridge construction, it becomes necessary to make use of built-up girders instead of rolled Ijeams, so in boiler construction it is necessary to resort to stayed surfaces when the space limitations of small containers, cylin- drical and spherical walls, and the uncertainties attend- ing their construction, stand in the way of carrying out a design that will give added strength and efficiency. A calile built up of strands of small wire far stronger and more reli- able than a solid wire of the same cross-section, be- cause of the greater cer- tainty of the strength of all parts. The same is true for built-up boiler headers as against those cast or forged to a single piece. The statistics of the boiler insurance companies with regard to the causes of accidents fully substantiate this point. An example of high-class workmanship. The hydraulic riveter is used wherever possible THE .STAYING OF HEADERS 13 The bulges opposite tlie drums of Edge Moor boilers are effectively stayed by eight steel bolts, 2^- inches in diameter, anchored through steel U-plates riveted to the inside of tlie drum. The joint in the header plate is made ])ermanently tight l)y the use of an annealed copper cone-nut which is drawn into the con- ical hole in the plate by screwing up on the outside nut be- fore the staybolt is anchored. The other parts header are by bolts of cross-section follows : of the stayed proper installed a After the staybolt holes are drilled and the headcT plates are riveted together, the headers are set on edge, and opposite stayl)olt holes in both plates are first reamed and then tapped by the continuous travel of a special combined reamer and long tap which passes through the staybolt holes in both plates and thus threads the oppo- site plates as if they were in the same piece of metal, making it possible to screw in the staybolts without forcing. Staybolts cut to size and threaded throughout their length arc then screwed in place and the projecting ends are riveted o\'er and caulked to make the joints tight. Edge Moor headers are stayed in a most effective manner Hollow staybolts are used when the tubes are to be dusted from front or rear T The Handhole Plate 00 often, boilers are bought "by the horsepower." Considerations other than the price and the heating surface are given scant thought, Elliptical handholes make it possible to remove any cover without disturbing any otiier cover resulting in a saving of time and gaskets with the result that several times the additional cost of a superior boiler may be wasted annually for extra fuel and maintenance. A feature of Edge INIoor construction that affects maintenance, and one worthy of especial notice is the handhole plate. Every handhole is elliptical to make it possible to pass every cover through its own hand- (l-t) PARTS OF AN EDGE MOOR HEADER 15 hole, instead of from one hole to another, as in those boilers where, for the sake of cheapening the cost of construction, most of the holes have CBmnn Top Trough Handhole Plate Tube Plate Bottom Troubh PARTS OF AN EDGE MOOR HEADER Visitors at our shops are impressed with the workmanship that gives Edge Moor boilers distinction been made circular with an elliptical or heart-shaped hole here and there to enable the covers to be removed. Such cheapened construction requires, 16 EDGE MOOR WATER TUBE BOILER Punched Forged Machined Every handhole plate is fabricated in three stages FABRICATING A HANDHOLE PLATE 17 Elliptical holes are first punched in the blank plate by means of a combined punch and spacing mechanism The purchaser may use any factory gasket, provided it is mailc to fit the cover. Returning to tlie construction of the handhole plate, it will be seen that the edges of the holes are flanged inward. This is done by means (jf dies after guide holes have been punched in the plate and it has been heated to the proper temperature for flanging. After the flanging, tlie of course, much extra labor to open and close up a boiler during the inspec- tion and cleaning periods. It will be noticed that tlie covers bear again.st the inside of the header plate which makes their factor of safety independent of the strength of the studs or dogs. Should, by accident, a stud break when being set up while a boiler is unrler pressure, the joint will still remain tight, for the cover is held against the plate by the internal pres- sure. No special make of gasket is required with Edge jMoor boilers, satis- ssaMj^l Hi H ^^Hn r^^Bn -jpalH ^ The plate is then heated to a cherry red and the holes are forged to shape between multiple dies A multiple spindle machine faces the edges and automatically spaces and drills the holes for staybolts plate is sent to a si)ecially con- structed multiple spindle machine which faces the upturned edges to smooth, plane surfaces. The flanging greatly stiffens the plate to resist the internal pressure of the water and to prevent the springing of the faces of the handholes while the plates are being set up against the gaskets — a workmanlike construction, assuring tight joints. Miscellaneous Details ONE of the unique structural details of the Edge Moor boiler is the patented pipe connector. This takes the place of the commonly used reinforcing pad wherever there is not sufficient thickness of metal for PATENTED EDGE MOOR PIPE CONNECTOR 1. Pipe connector 2. Plate to be reinforced 3. Lock nut 4. Lock nut on connector 5. Connector in place before caulking 6. Connector after caulking, showing pipes in place the larger pipe connections. For attaching the feed-water, water-column and surface blow-off piping, these connectors arc ideal. They are made of steel, arc verj' simple in construction and present a workmanlike appearance. The method of installation is as follows: Referring to the engraving above, a straight circular hole 2 is first bored through the plate to be rein- forced. The connector 1 is then passed through this hole, as at o, and locked in place by the nut 3, as shown in 6. This nut is threaded for an easy fit, (18) PIPE CONNECTORS AND UPTAKE 19 tlilil.*:*:*^*^^ These connectors, for feed water and water column piping, are a decided improvement on the commonly used reinforcing pads SO it may be screwed up Ijy hand. Finally, the bevelled edge of the con- nector is fullered and caulked against the plate to make a tight joint. The fullering causes the connector to fit snug against the plate and is equivalent to screwing up the lock nut with consideralile force, so much so that the connector can only be removed by cutting the nut apart. Uptake and damper furnished when the gases are to pass out of the top of the setting Owing to the ease with which connectors may be installed, they are especially suitable for any additional connections that may be desired during or after erection. They are to be found only on Edge ]\Ioor boilers as the patent is the exclusive property of the Edge Moor Iron Company. 20 EDGE MOOR WATER TUBE BOILER o 3 9 a a W o 3 METHODS OF SUPPORTING BOILERS 21 ,«»••*"•—— .^ -A -A A -t standard method of suspending Edge Moor boilers Edge Moor boilers are either supportetl by columns or liung from overhead beams. The method selected for an installation will depend on the special conditions to be met. In all methods the columns terminate in cast iron base plates set in the foundations and are not connected to, nor do they rest on, the Ijrickwork of tlie setting. When boilers are supported or hung from the sides, the initial con- nection is a speciallj' constructed steel tee riveted to the side trough of the header. This is bolted to the connecting angles on the colunni sup- ports or, in the suspended tj-pc, to the steel sleeve through -which the hanger Ijolt passes. This bolt terminates at both ends in ball-faced nuts which fit into correspondingly recessed washers to facilitate readjustment when the boiler expands or contracts. The design of other details such as front castings, manhole doors, tube dusting frames an'; : rra:^ ■■A\ '.■■A'' A' .-A' Front View of Furnace with Fokoed-Draft, Center-Retort, Underfeed iStdker UNDEIiFEED AND CHAIN GRATE STOKERS 29 Forced-draft, front underfeed stoker and natural draft, chain grate stokers under Edge Moor boilers. Laclede Gas Light Co., St. Louis, Mo, 30 EDGE MOOR WATER TUBE BOILER It will be noticed in the following drawings that the baffling can be arranged so that gases may pass out at the front of the top of the setting, or at the rear of the top of the setting, or at the rear of the bottom of the setting. Three Cross-Pass Setting — Gases off at Front — Side Overfeed Stoker No manufacturer of boilers can give the best service to boiler users by limiting himself to one or two "standard" types of baffling, because a type of baffling that will give good results with one kind of fuel or stoker may give poor results when these are different. As an example, the com- bination arch shown in the upper part of page 28 will give excellent results with soft coal but will decrease both efficiency and capacity when the coal is anthracite. On the other hand, the baffling shown in the lower part of the same page will give excellent efficiency and smokeless combustion when the coal is anthracite but will be very inefficient and a smoke nuisance when the coal is soft bitummous. Hence the baffiing of a boiler must be carefully selected to fit each particular case. It is sometimes supposed that the floor space required by boilers is modified by the horizontal center-to-center spacing of the tubes. That FLOOR SPACE REQUIRED 31 this is not so when the fuel to })e burned rerjuires a grate is easily seen. A steam generator consists of two parts which have entirely different functions — the grate and furnace evolve tlie heat; the boiler absorbs it. It is therefore plain that the first step in the selection of a steam generator Three Cross-Pass Setting — Gases off at Rear — Chain Grate is to determine the size of grate necessary for the proper coml.)Ustion of the estimated amount of coal to be burned, and the second step is to choose a boiler that will fit that grate mechanically as well as thermally. As an example, suppose it is desiretl to select a boiler for the continuous delivery of steam equivalent to 250 boiler horsepower. Suppose, further, that the coal to be used will have a heat value of 14,200 B. T. U. per pound, and that the combined efficiency of the generator will be 72 per cent. Then the stoking device must be able to burn at least 250 H. P. X 34.5 l bs. X 970.4 B . T. U . 0.72 X 14^200 B. T. U or 81G.6 pounds of coal per hour. 32 EDGE MOOR WATER TUBE BOILER Now suppose that the type of stoking device to be used and the fur- nace draft (or ash-pit pressure) available will permit of the continuous combustion of 20 pounds of coal per square foot of grate surface per hour. Then the amount of grate surface required will be 818.6 h- 20 or 40.9 square feet. Thkke Cross-Pass Kevehsed Setting — G.-ises off .\t Front — Front Overfeed Stoker Since the length of the stoker or grate is determined by the design, or by the stoking conditions, and is independent of the boiler, it follows that as soon as the grate surface is determined the width of furnace is also deter- mined, and this width, from the foregoing reasoning, is independent of any arrangement of boiler tubes. If, in the above example, the length of grate is taken as 6 feet, the furnace width will l)e 40.9 h- 6 or 6.8 feet; and the proper l)oiler for this installation must hav'e an inside width of setting approximately equal to this. With the width of boiler fixed by the amount of coal to be burned and stoking device to be used, the advantage of one design of boiler over another as regards floor space, VARIABLE ORATE SURFACE 33 must depend on the length of setting. Fortunately, the design of the Edge Moor boiler tends to make the length of setting a minimum. It should not be supposed that for every Edge Moor boiler of a given rating there is but one arrangement of tu})es and but one furnace width. The table given below illustrates the latitude of arrangement of tubes that is applicalile to all ratings. It is seen that there are five sizes of boilers 1 i. i {'■ ■ I ^ '•"''^jj^W^ i x;^-is: i Vr-; ^^ . 1 V '^.. 1 vSL-'^'^yi. ,--•■;-*."<.:. ^^^^^E^ ij^., ';i II Si '^ ■^v---^^ ',i<- 1 -<-^m:^o ' ., ■ III .-. -1.-^ IHffft ^ - ; t-: :: • ^Ar ;l\;si^'«-'/a ■ ,' .^■>' y^,:.^,^^- •j,.. 1 \ ■■■; ^iM: Vs^Jf.Ai^^ ' ^i \x^ wx^ ^ '^fftM \ _^MM J i Edge Moor boilers with natural draft, front overfeed stokers Lardner's Point Pumping Station, City of Philadelphia Table Showing Five Standard Size.s of Edge Moor Boiler.s for a Nominal Rating of 400 Horsepower. Tubes Are IS ft. LoNti. Length of Grate Taken at 8 ft. Tubes high Tubes wide 10 13 15 14 14 15 13 16 12 17 Heating surfaee Sq. ft. 4008 4069 4074 4060 3988 Furnace width 8' 3" 8' lOA" 9' 61" 10' 2" 10' 91" Grate surface Ratio of H.S. to G.S. Floor space Sq. ft. Sh. ft. 66.0 60.7 231.6 71.2 57.1 244.5 76.3 53.4 258.7 81.4 49.9 271.7 86.4 46.2 284.7 34 EDGE MOOR WATER TUBE BOILER each of which has approximately 4000 square feet of heating surface but with varying grate areas ranging from (36 to 86.4 square feet, and floor areas from 231.6 to 284.7 square feet. Typical installation of superheater in connection with a four cross-pass boiler By having a variety of sizes for a given nominal rating it is possible to meet, efficiently, the different recjuirements of boiler users. The liest size is generally determined by the kind of fuel to be burned. Thus, if the fuel is to be anthracite coal the best boiler to \ise is the one with a wide grate becavise it is possible to Ijurn only a relatively small amount of this kind of coal per square foot of grate surface. On the other hand, if a higli-gradc seniibituminous coal is to be used a boiler with a narrower grate will give the best results. STANDARD SIZES OF BOILERS 35 Four Cross-Pass Boiler with Superheater and Front Underfeed Stoker Standard sizes of Edge Moor boilers have ratings from 75 to 1050 boiler horsepower. All tubes are four inches in diameter. The lengths of tubes most commonly used are 18 and 20 feet, but other lengths «ill be furnished when special conditions make this desirable. (36) Firing with Oil OIL has been frequently spoken of as "the ideal fuel." It has many advantages over coal: delivery and storage are greatly simplified; firing requires simple equipment and a minimum of labor; there are no ashes to remove; fuel waste is much more easily controlled and therefore greatly reduced; consumption of fuel during stand-by periods is unneces- sary; upkeep is lower than in stoker-fired plants when design and operation have been given proper attention; smoke nuisances are avoided; and the boiler room may be kept as clean as the engine room. Unfortunately, the demand for oil as compared with the supply is so great that this fuel is not available for general use. Even though oil costs considerably more than coal for the same number of heat imits the differ- ences in the costs of storing, firing, etc., may make oil the cheaper fuel in the end. For comparing the economic values of oil and coal, costs on a fuel basis alone are therefore misleading. A c(jmplete analysis is necessary, for which the following form is suggested. Summary of Costs for Oil Versos Coal Estimated costs on annual basis With oil I with coal Cost of fuel, delivered at the plant site, consumed for ])ro- duction $ Cost of fuel, delivered at the i)lant site, consumed during stand-l)y periods $ Cost of fuel loss from storage S Cost of unloading, storing and delivering fuel to the firing equipment S Cost of firing labor S Cost of ash removal • • Cost of re])lacements and repairs for fuel handling and fir- ing equipment, and for furnaces S Charges for investment in storage equipment, firing equip- ment, etc j S Total I S (37; 38 EDGE MOOR WATER TUBE BOILER From the tabulated data below an approximate comparison of fuel costs may be obtained. It will be noticed that in each case the average net efficiency specified (the percentage of the calorific value of the fuel which enters the feed water to make useful steam) is about 5 per cent, less than would be expected from results obtained in tests. Some such allow- ance must be made, of course, to cover the difference between test condi- tions and average operating conditions throughout the year. Fuel Required Per Hour Per Thousand Useful Boiler Horsepower Plfmt A: Oil-burning plant (average net boiler-room efficiency 7.5 per cent., 18,500 B. T. r. per lb. oil, S lb. per gal., 336 lb. per bbl.J . . 301 gal. or 7.2 bbl. Plant B: Oil-Kiurning plant (average net Ijoiler room efficiency 73 iicr cent., oil as aljove) 310 gal. or 7.4 bbl. Plant C: Coal-burning plant, stoker-fired (average net boiler room effi- ciency 70 per cent., i:i,.500 B. T. U. per ll.i. coal, 2,240 lb. per 'on) 1 .() tons. Plant D: C'()al-I)urning jilant, hand-fired (average net boiler room efficiency 60 per cent., coal as aliove) l.S tons. C'oMP,\H.\TivE Costs e(jr Plants B and C Oil at 2 cents |)er gallon is on a ])ar with coal at $3.90 per ton. " 3 " " " " 5.85 " 4 " " " " 7.80 5 " " " " 0.75 Oil at 75 cents ])er barrel is on a par with coal at $3.45 " " $1.00 " " " 4.60 1.50 " " " 0.90 " 2.00 " " " 9.25 As a rule, the calorific value of oils used for boiler firing, from whatever source, varies very little from 18,500 B. T. U. per pound. It is, of course, very different for coal. The calorific value of the coal commonly used may be anywhere between 10,000 and 14,500 B. T. IT. per pound, while in certain locaHties the value may be outside of these limits. Also, firing efficiency must be considered. A hand-fired coal-liurning plant is much less efficient than the average oil-fired plant, but a modern stoker-fired plant may have an all-over efficiency almost as good. The oil used for firing boilers is either the natural liquid, petroleum, as it is taken from sand or rock strata in widely scattered regions of the COMPOSITION OF PETROLEUM 39 earth, or it is the end-product of that liquid after certain components have Ix'cn removed. Petroleum is a complex mixture of many cUfferent hydro- carbons. These may be separated in the refinery and are commercially known as gasoline, benzine, kerosene, lubricating oils, grease, paraffin or asphalt, etc. Generally the mixture contains small quantities of water, sulphur and sand. Its specific gravity may be between 10° and 50° Beaume (1.000 to 0.785 as compared with water) ; its color may vary from a pale yellow to a reddish or blackish brown; its molality from that of a hght oil to that of grease. Reduction Table for Oil Fuel Degrees Beaum6 10 11 12 13 14 15 16 17 18 19 20 Lbs. per gal. 8.33 8.27 8.21 8.16 8.10 8.0.5 8.00 7.94 7.89 7.83 7.78 Lbs. per cu. ft. 62. 3 61.9 61.4 61.0 60,6 60.2 59.8 59.4 59.0 .58.6 58.2 Lbs. per bbl. 3.50 347 345 343 340 338 330 333 .331 329 327 One barrel = 42 LT. S. gallons. A petroleum may be so poor in the valuable hydrocarbons as not to warrant refining, antl is then sold for firing boilers, etc. On the other hand, some petroleums are so rich in the valuable hydrocarbons that refining is carried to a point where no residue remains suitable for fuel. An untreated petroleum is commonly designated "crude oil." When the lighter hydrocarbons are removed from a petroleum and the residue is suitable for fuel this residue is variously known as "residuum oil," "topped oil" or "treated oil." The term "fuel oil" is sometimes used to designate the distillates of petroleum between the lighter illuminating oils and the heavier lubricants. Its gravity may be between 25° and 30° Beaume. 'Fuel oil' is commonly used for firing metal treating furnaces. Some petroleums are asphalt base, some are paraffine base and some contain both asphalt and paraffine. The B. T. U. per pound may be between 17,500 and 22,000. But these variations need not be considered in ordinary boiler-room practice. Paraffine and asphalt base oils burn 40 EDGE MOOR WATER TUBE BOILER about equally well. The petroleums high in B. T. U. are generally least suited for boiler-room fuel on account of the low flash point and more valuable for refining. These are commonly reduced to a residuum oil of gravity between 14° and 15° Beaume, which is sold for steam generation. Residuum oils do not vary considerably from 18,500 B. T. U. per pound. This is also true of the crude oils sold for fuel. Hence for ordinary boiler- room calculations the estimator may assume 18, .500 B. T. U. per pound. Oil fired fronts of Edge Moor boilers. Miami Beach Electric Co., Miami, Florida. There are three substances in oil which may occur in such quantities as to cause considerable troul;)le. These are sulphur, water and "foreign matter." The sulphur content burns to sulphur dioxide whicli combines with moisture, forming a corrosive acid. Ordinarily the quantity of sulphur present is too small to produce harmful effects. The water content does not generally exceed 1 per cent, but in exceptional cases may run as high as 30 per cent, from seepage into the wells or into the storage reservoirs. The term "foreign matter" includes sand and other solids. The tables on the opposite page show average properties and compo- .sition of California crude oils. The yield from other fields in the United States is mostly lighter. The heaviest oils come from the Mexican fields, are of asphalt base and run as low as 10° Beaume. RESIDUUM AND CRUDE OILS 41 Residuum oils are generally better for fuel than crude oils because in the process of refining nearly all of the associated water passes off with the distillates and settling removes most of the foreig-n matter. The gross calorific values of both classes of oils are about the same while the effective values may be higher for the residuum oils liecause of a l(j\\-er hydrogen content. Heavy oils generally have a somewhat lower calorific Properties of California Crude Oils' Name of oil field Kern River Average of Composite Coalinga Average of Composite McKittrick Average of Composite Midway Average of Composite Sunset Average of Composite Speeific gravity .at 1.5° C. 40 samples sample^ . 62 samples sample . 26 samples sample . 29 samples sample . 2.5 samples sample . 9670 . 949S . 9.50.J . 9.566 . 9600 . 9.570 .9580 ,9701 . 9705 Degrees BauiiiC. at m° F. 15.16 H.7,s 17.52 17.29 16.37 15. S3 16. 16. 14. 14. 34 14 Heat value per lb. B. T. U. LS,.553 IS, .562 18,727 l.S,720 18,508 1,8,335 18,613 18,565 18,478 18,419 Weight per gallon Lbs. 8.03 8 . 06 7.91 7.92 8.01 8.00 7.97 8 . 08 S.(!!) Composition of California Crude Oils' Name of oil field Kern River comi)Osite Coalinga . . . . McKittrick . . . . Midway . . . . Sunset Speeific Kra\-itv at 15° C. 0.9070 . 9505 . 9600 . 9580 .9705 Hydrogen Per cent. 11.27 11.30 11.41 11.61 11.37 Carbon Nitrogen I t^ulpliur Per cent. Per cent. Per cent. 86.36 0.74 SO . 37 1.14 86.51 .58 86.. 58 .74 85-64 .84 0.89 .60 .74 .82 1.06 Undeter- mined Per eent. 0.74 .59 .76 .25 1.09 1 From Bulletin 19, 1911, Btu'eau of Mines. 2 A composite sample is a mi.xture of several samples as received. 42 EDGE MOOR WATER TUBE BOILER value per pound than light oils, though not always, but as there are more pounds in a gallon or barrel of heavy oil — the units by which oil is sold — the heavier oils generally have a higher B. T. U. value per gallon or per barrel. In all methods used at present for boiler-room firing the oil is passed through strainers to remove foreign matter and raised to a pressure and temperature best suited for atomization — that is, for discharging the oil into the furnace in finely divided particles. In the "mechanical system" atomization is produced by giving the oil a whirling motion in the burner tip and discharging it into the furnace through a small orifice, without the aid of any atomizing agent. In the "steam-atomizing sj^stem" and in the "air-atomizing system," which are essentially the same in principle, the oil is l)rokcn up by a continuous discharge of steam or air under pressure within the burner or at the tip outlet. For stationary plants air has been found to have no advantage over steam as an atomizing agent and has gone out of use except for firing small house-heating boilers or where water is scarce. The mechanical system has an advantage over the steam-atomizing system in that the steam required to operate the complete oil-burning system is several per cent, less, but the steam-atomizing system is con- sidered to be better suited for regulation under the variable load conditions which obtain in most stationary plants and has other advantages that tend to more than compensate for the steam used for atomization. As a consequence, most of the stationary plants are equipped with the steam- atomizing system. Both systems require certain auxiliaries besides the storage and suc- tion tanks. There should be a steam coil in the suction tank to heat the oil when it does not flow freely to the pumps ; a coarse-mesh strainer in the pump suction and a fine-mesh strainer in the discharge between heater and burners to remove foreign matter; two suitable pressure pumps (one for stand-by) to raise the oil to the required pressure; and one or more heaters to raise the oil to the required temperature. Except for small installations, it is generally preferable to heat the oil with live steam. The amount of live steam required for heating is very small and better tem- perature regulation is obtained, as a rule, with live steam than with exhaust steam. The speed of the pump should be controlled by an automatic governor to maintain a uniform pressure of oil irrespective of the demand; there should be a relief valve on the discharge to release excess oil; an air chamber to neutrahze the pulsations of the pump; and a pressure gauge DETAILS FOR OIL FIRING 43 and thermometer to indicate the pressure and temperature of the oil passing to the burner piping. In and near cities and towns the manner of installing tanks and firing equipment is prescribed by underwriters' rules and building laws to minimize danger front fire and accidents. Tlicre are some details in the installation of oil-l^urning equipment which are not infrequently overlooked. The steam for the burners should be taken from a point where the steam will contain the least amount of moisture anil the piping should be installed so as to avoid pockets where condensed steam may accumulate. It is preferalde to run a steam line direct to the burners from each boiler outlet (or superheater outlet, if the boiler has a superheater) with an auxiliary connection to a header, the auxiliary connection to be used for firing up the boiler, and the boiler- outlet connection for operation. All steam piping shoukl be lagged. On account of the tendency of oil and oil vapor to leak through pipe joints, the threads should be cut with great care and the joints made up either with shellac or freshly mixed litharge and glycerine. Screwed unions should be of the ground joint type with either brass to iron or lirass to brass seats. No. 1 canvas shellaced or coated with litharge and glycerine on both sides makes an excelknit gasket for flanged joints. Before installing the burners both steam and oil piping should be lightly rapped and thoroughly blown out with steam or air. This will eliminate most of the trouble from clogging of burners when the installation is put into service. The temperature to which the oil shoukl be heated is of great impor- tance. No specific information can be given on this point because the viscosity of different oils varies greatly. The temperature for steam- atomizing burners will usually be between 100° and 160° F. but the operat- ing temperature should be determined by trial with the oil supplied. If the oil is too hot, the burners will puff; if too cold, a dull smoky flame will indicate improper atomization. (Water in the steam or oil causes a sput- tering action.) A good way to determine the best temperature for the oil is to first heat up the furnace walls of a boiler and then gradually alter the steam supply to the heater until clear and steatly flames are produced by the burners assuming, of course, that the supply of air is ample. The temperature at which this takes place should be noted and maintained. For the guidance of the fireman a thermometer in the oil supply pip< , conveniently located in the fireroom, is indispensable. Certain of the Mexican oils require heating to between 80° and 90° F. in the suction tank to produce a free flow to the pump. 44 EDGE MOOR WATER TUBE BOILER The proper oil pressure at the pump discharge is principally dependent on the construction of the Ijurner used, but the maximum horsepower to be developed per burner, the restrictions in the heater and piping and the viscosity of the oil are modifying factors. 3ECT/0NAL f^LEVATION The 0\vf,\s SxEAM-ATOMrziNn Oil Burner — Patented Steam-atomizing liurners are classed as "inside-mixers" or "outside- mixcrs " dejiending on whether the steam and oil are brought together inside of the Inirner or just outside of the til). But this classification has a doubt- ful value in practice. In the selection of a burner it is important to know if the burner is of the "long-flame" or "short-flame" tj'pe. The discharge of a mixture of oil and steam has more or less momentum which depends on the burner design, other factors remaining the same. If the l.)urner makes a long flame and the furnace is relatively short the flame will strike the ojiposite furnace wall and be reflected to the tubes, producing a blow- pipe action on both wall and tubes which is highly destructive. Such a "misfit" of l)urncr to furnace is a common cause of the furnace and tube troul)les experienced in oil-fired plants. The discharge openings in the burner tip should Ije cut witli great care, both as to size and finish. As a rule, after two to three months' service the openings Ijecome worn too large for good atomization. The tip shoidd then be renewed. The illustration above shows a steam-atomizing oil burner of the short-flame type which has proved highly efficient and reliable. The oil enters through one of the connections and flows along the upper half of the l:)urner body. The steam enters through the other connection and flows along the lower half of tlie liody. At the end of the Ijody is a flat disc or baffle which contains a few holes for the discharge of oil and a larger OIL BCliNERS AND FURNACES 45 number for the discharge of steam. The streams of oil flow into the jets of steam issuing through the lower part of the baffle, the mixture is carried along a one-inch pipe (which may be of any length) and discharged through a slot in the tip cut to give a fan-shaped flame of the desired width. The retardation in the pipe-mixer produces a soft flame, several feet shorter than flames from l)urners in which the steam and oil come together inside of the tip or just beyond it; also, the temperature of the oil is raised c(m- siderably by the steam before passage through the tip. This atlditional heating facilitates the combustion of very heavy oils. The burner is rugged and simple in construction and the only part which requires renewal is the inexpensive tip. In the early development of oil firing undue attention was given to the burner details and too little attention was given to the furnace design. The function of the burner is to atomize the oil ])roperly and prod\ice a flame of the desired shape, width antl length. But a good l)urner will give unsatisfactory results if the furnace is not i)r(ji)erly i^roportioned. The furnace shovdd be of such length that the discharge from tlie burners wih not strike the opposite wall; tlie height should be such that the gases are well mixed and the temperature lowered by radiation l^efore the gases strike the boiler tubes. When oil burns in the presence of Ijut little excess air the temjierature is close to 3000° F. and if coml)Ustion takes place close to the boiler tubes blistering and burning will result. Since combvistion cannot be uniform in the furnace, the furnace volume should be ample for good tliffusion of the gases. On account of the high temperatures in an oil furnace the lining should be of first quality firebrick throughout. It has been fountl that firebrick arches and deflecting walls are unnecessary in a well designed furnace as an aid to combustion. Also, they are olijectionable Ijecause they will melt or burn down rapidly at the high temperatures developed. For steam-atomizing burners the air is admitted through ports in the furnace floor directly under the burner ilischarge. Tht' size and location (jf these ports is of very great importance. The arrangement of ports should follow a plan which has been carefully checked throughout the working range of the burners by gas analysis. The air ports not only affect the quality of combustion but also the shape of the burner flame. Firemen sometimes change the arrangement of the air ports because they have trouble in lighting the burners or in keeping them going due to the inrush of cold air! When this occurs the aii- supply should be decreased bj' manipulating the air admission doors. 46 EDGE MOOR WATER TUBE BOILER The two following illustrations show an oil-fired front and a side view of an Edge Moor boiler equipped with an oil furnace. The burners enter the furnace through small framed openings in the front. These openings are of ample size for lighting the burners and observing the flames, and are fitted with doors especially designed for the convenience of the operator. Oil Fired Front and Burner PipiNt; The steam manifold is aliove the burners and the oil manifold below. A globe valve controls the steam supply to each Ijurner and a stantlard needle valve controls the oil supply. In addition, lx)th steam and oil manifolds include master valves for shutting off and regulating the supply of steam and oil to all burners of a boiler. Both valves are of the standard globe pattern Ixit the master oil valve is fitted with a lever for making adjust- DETAILS OF OIL FURNACE 47 ments conveniently to produce an increase or decrease of the fire as desired. The steam piping is fitted with a drain and is especially designed to prevent accumulations of condensetl steam. Sectional Elevation of an EnciE Moor Boiler Fitted with an Oil Furnace The furnace includes an access door in one of the sidewalls. This is protected with loose firebrick laid up in the opening. A small inspection door is placed forward of the bridgewall for observing the ends of the flames. The front part of the furnace floor is supported by cast iron bars; the rear part by an earth fill.. The floor is of first quality firebrick and contains air admission openings laid out according to a plan determined experimentally for obtaining the most satisfactory mixtures for combustion. 48 EDGE MOOR WATER TUBE BOILER The air supply is regulated by a large door under each burner hinged at the bottom. An advantage of this type of door is that the air is deflected to the front air spaces when the door is only partly open. This produces more efficient combustion during light firing. The doors may be separately adjustable or connected to a common shaft for central control. ;y//////////////^/^//////^/'yy/////////^^^^ Edge Moor Boiler with Oil Furnace FOR A Low Setting The illustration above shows a modification of the furnace previously tlescriljcd which is especially suitaljlc for low settings, though it lacks some of the advantages of a high setting and a horizontal floor. For economical use of steam for atomization the master valve of the steam manifold should be opened just enough to pass the required amount of steam. Throttling through this ^-alve is desirable as lower steam press- ures at the liurners produce softer flames. The steam burner valves shoidd be opened just enough to produce good atomization. The fireman can waste considerable steam through the burners by neglecting these adjust- ments. To start a burner, open the damper if it is not already open, then open the burner steam valve about a quarter turn, insert, a lighted torch and open the oil valve just enough to produce a short flame. When starting a MANIPULATION OF OIL BURNERS 49 fire in a cold furnace the torch should be left in the furnace until the flame burns steadily. If a burner stops firing even when the furnace walls are very hot, the oil valve should Vje shut immediately and not re-opened until a lighted torch is inserted, unless other burners are in service. Bad flarebacks or even explosions of sufficient force to blow out part of the sidewalls not infrequently happen when the fireman disregards this pre- caution. A 1000 H.P. Edge Moor boiler equipped with oil burners. U.S. Navy Yard, Mare Island, California In a properly equipped plant, an attentive operator who fires "by eye" can maintain a very high boiler-room efficiency without the guidance of instruments other than a pressure gauge and a thermometer on the oil supply to the burners, though a differential draft gauge connected to each 50 EDGE MOOR. WATER TUBE BOILER furnace is very helpful. With oil the greatest waste results from excess air admitted into the furnace as a consequence of neglect to adjust the damper and air doors to correspond with the quantity of oil burned. This is clearly shown by the table on the opposite page. As an example, for 13 per cent. COo the excess air is 19 per cent, and the chimney loss, for a chimney temperature of 450° above external air temperature, is 9.50 per cent. For 8 per cent. CO2 the excess air is 89 per cent, and the chimney loss is 15.21 per cent. The heating of the unneces- sary air therefore represents a waste of 15.21 minus 9.50 or 5.71 per cent, of fuel. The operator should aim to maintain the CO2 between 13 and 14 per cent, at the boiler damper. Adjustments to obtain a higher CO2 are so delicate that the formation of considerable monoxide will probablj' result, which increases the chimney loss. It should be noted that a given per- centage of CO2 indicates a very different percentage of excess air if tlie fuel is coal, due to the lesser hydrogen content of coal. This is shown in the following table. Table Showing Relation Between CO2 and Excess Air for Average Coal and Oil Per cent. C< t- in dry gases by volume 18.7 18,0 17.0 16.0 15.0 1.5.0 14.0 1.3.0 Per cent, e.xcess air for aver- age eoal 4 10 17 24 33 43 ^vr cent, excess air for aver- age oil 4 11 19 The calculations for oil given above are based on a composition of 85 per cent, carbon, 12 per cent, available hydrogen (H- 0/8) and 1 per cent, sulphur; calorific value 18,500 B. T. U. per pound. The ratio of carbon to available hydrogen in average coal is about 80 per cent, carbon to 4 per cent, available hydrogen. One pound of oil as alDove requires 14.0 pounds of moisture-free air for complete combustion without excess oxygen. When the oil j^ressure, oil temperature and air spacing in the furnace floor are properly maintained it is possible to burn oil completely with but little excess air, firing "by eye." The color of the most efficient oil flame, as it approaches the boiler tubes, is an almost clear EFFECTS OF EXCESS AIR 51 orange. With such a flame a shght haze will be visible at the top of the chimney. A dazzling white flame indicates considerable excess air while a reddish smoky flame indicates too little air. Light starring in the fur- nace indicates the combustion of finely divided particles of carbon which Excess Air and Chimney Losses for Different Percentages of CO-. Per cent. C()2 in dry sasfs by volume 1.5.6 15.0 14.0 13.0 12.0 11.0 Excess air in per cent, of theoretical minimum 4 11 19 28 39 Weight of dry gas per lb. oil in lbs 13.9 14.4 15.4 10.5 17.8 19.4 ' Chimney loss per 100° F. in ]K'r cent, of the calorific value of the oil . . . 1.78 1.85 1.97 2.11 2.28 2.48 ' Chimney loss ])er 4.50° F. in per cent 8.01 8.. 32 8.86 9.. 50 10 . 20 11.16 Excess Air and Chimney Losses — Continued Per cent. CC»> in dry {iuscs by volume 10.0 9.0 8.0 7.0 0.0 6.0 Excess air in per cent, of theoretical minimum 53 69 89 115 150 199 Weight of dry gas per lb. oil in ll)s 21.3 23.6 26.4 30.1 34.9 41.8 ' Chimney loss per 100° F. in per cent, of the calorific value of the oil . . . 2.73 3.02 3.38 3.86 4.47 5.35 ' Chimney loss per 450° V. in per cent 12 . 28 13.59 15.21 17.37 20.11 24.08 ' Based on dry-gas weights and therefore do not include heat carried away by steam formed from combustion of hydrogen, by steam for aiomization and by moisture in air. 52 EDGE MOOR WATER TUBE BOILER does no harm if the particles are completely burned before they strike the brickwork or tubes. (Soot is deposited if they impinge on any solid sub- stance.) But heavy smoky sparks are large globules of oil, indicating imper- fect atomization If additional steam does not correct this it is likely that Battery of boilers in the plant of the Miami Beach Electric Co., Miami, Fla. the slot in the burner tip is poorly cut or badly worn. As stated above, water injected with the oil causes the flame to sputter. This may come from accumulations in the steam piping or from the settling chamber in the oil heater. The latter should be drained at regular intervals. CHIMNEYS FOR OIL 53 For oil fuel, chimneys much higher than necessary are very ol)jection- al)le. It is not desirable to throttle the boiler clampers too much as flare- backs may result. Hence with an excessively high chimney air regu- lation is much more difficult and the induction of excess air is greatly increased, resulting in a corresponding waste of fuel. The furnace draft required for the burner and furnaces illustrated above is considerably less than for natural-draft coal-burning installations but, in general, this will not be true for burners of the mechanical-atomizing type. Also, provision for excess air under abnormal conditions need be very little for oil. Chimneys suitable for natural-draft coal-burning installa- tions will, as a rule, be much too high for efficient combustion of oil (employ- ing steam-atomizing burners) but chimneys for forced-draft installations will, generally speaking, be satisfactory since, in the latter, the allowance for furnace draft and excess air is much reduced and also l)ecause the gas volume per 10,000 B. T. U. in the fuel is about the same for oil and coal, for equal percentages of excess air. (54) Factors in the Recovery of Waste Heat IN the manufacture of certain products, especially steel and cement, millions of dollars' worth of fuels are annually converted into gases which leave the manufacturing equipment at a temperature between 1000 and 1500 deg. F. and are dischargetl into the atmosphere. The possibility of recovering a large part of the heat thus wasted has long been realized but the development necessary for a high economic return has been reached only in recent years. As an example of what may be expectetl, the approximate recovery per hundred pounds of 13,500 B.T.U. coal, burned in an efficiently operated cement kiln employing the dry process, is here calculated. To simplify the problem it will be assumed that no carbon monoxide is present. The production of gas per hundred pounds of coal is about 1400 pounds. The gas leaves the kiln at about 1500 deg. F. An equipment which would reduce the temperature from 1500 to 350 deg. F., with an allowance of 40 per cent, air leakage and mean specific heat of gas at 0.26, would recover about 379,000 B.T.U. for each hundred pounds of coal burned. If this recovery is in the form of steam, generated from feed water at 200 deg. F. to a pressure of 200 lb. per sq. in. gauge and superheat of 100 deg. F., the intake of heat per pound of steam is 1091 B.T.U. There- fore, the heat recovery per hundred pounds of coal would yield 350 pounds of steam. If this is delivered to a turbine plant which consumes 17| pounds of steam per kilowatt-hour at the switchboard, the power yield would be 20 kilowatt-hours; that is, for each one hundred pounds of coal burned in the kiln 350 pounds of steam or 20 kilowatt-hours would be obtained with- out any expenditure for fuel whatever. In some industries the recovery is itself sufficient to generate all the steam and power required. The recovery of heat from kiln gas has sometimes been greatly under- estimated because the temperature was measured either in the kiln housings or in the stacks. In the average mill, the leakage of cold air into the hous- ings, around the kilns and through openings in the housings, may amount to from 200 to 300 per cent, of the weight of kiln gas. The mixing of this cold air with the kiln gas produces, of course, a much lower average tem- perature. With well constructed kiln seals and housings this leakage may be almost entirely prevented; hence for estimates for a waste-heat plant the temperature should be taken at a point where the gas is not affected (55) 56 EDGE MOOR WATER TUBE BOILER by air leakage. In practice it has been found desirable to measure the temperature and take samples of the gas inside of the kilns, two feet from the end at about the center. Ql!>^»*.^'<^ Kilns, kiln seals, and housings. Mill of the International Portland Cement Company at Sierras Bayas, Argentine Republic Generally speaking, with Edge Moor equipment the reduction in cost of product will pay for a waste-heat installation in from two to three years. In cement mills usually from 30 to 50 boiler horsepower is available from the kiln gas per 100-barrel capacity per day, and the credit will amount to from eight to twelve cents per barrel of cement made. The recovery from open-hearth furnaces is from four to six boiler horsepower per ton of ingots per heat; that is, a 50-ton furnace will average from 200 to 300 boiler horsepower. The credit given the open-hearth plant will vary from thirty to sixty cents per ton of ingots. In soaking pits and regenerative heating furnaces the recovery is usually about one boiler horsepower per ten jiounds of coal burned in the producers per hour; from a heating furnace of the non-regenerative type, about twice as much heat is recovered. In these latter instances, the cost of the installation is usually paid for in the first year's operation. The early installations of waste-heat boilers were very crude because certain laws of heat transmission were not understood and insufficient RKCOVKRY OF WASTE HEAT 57 attention was given to important details. The design of an efficient direct-fired boiler plant of the ordinary type and the design of an efficient waste-heat boiler plant are and should be very different. In the former, the gas approaches the boiler at a temperature which may Ije as high as 3000 deg. F. while in the latter the gas enters at a temjierature between 1500 and 1000 deg. F. As a result, the average heat transmission per square foot of boiler heating surface is much greater in th(> former than in the latter. If boilers of the same design, similarly baffled, are used for both plants, as has been done, the boilers for the waste-heat plant will have to be very much larger for the same horsepower to be developed. In earlier installations it was common practice to allow about 20 square feet of heating surface per boiler horsepower. As a result boilers were relatively very large, had relatively large settings which increased the associated losses, and consccjuently produced a small net gain. Since then the laws of heat transmission are better understood. It has been found that the heat transmitted per square foot of boiler surface can be greatly increased by increasing the gas velocity across the surface. Roughly speaking, if the velocity can be increased three times the heating surface can be reduced one-half. Also, by making the gas passage longer the amount of heat abstracted is likewise increased. Increasing the gas velocity as al)ove outlined increases the frictional resistance opposing the passage of the gas through the boiler. This makes it necessary to include an intluced draft fan as part of the erpiipment, the increased draft required being too great to be produced by a chimney. For a given volume of gas transmitted the frictional resistance varies considerably in boilers of different construction and arrangement of baffling. The Edge Moor boiler, with its wide tube spacing and parallel liaffles, offers minimum resistance to tlie flow of gas. This has a bearing on the over-all efficiency, since the greater the frictional resistance the greater will be the power consumed by the fan. A factor of primary importance which affects the over-all efficiency is the infiltration of cold air into the flues and settings. This is detrimental in four ways. First, air coming into contact with very hot, incompletely burned gas tends to produce explosions untler certain conditions. Second, the mixing of the air with the hot gas lowers the temperature of the gas and this lowers the rate of heat transfer into the boiler. Third, the fric- tional resistance in the gas passages is increased causing an increase in the power consumption of the fan. Fourth, heat is carried into the chimney which could otherwise be absorbed Ijy the boiler. 58 EDGE MOOR WATER TUBE BOILER Edge Moor waste heat boiler equipped with superheater. The passes are proportioned for a high gas velocity RECOVERY OF WASTE HEAT 59 The detrimental effects of air leakage are much greater in waste-heat plants than in direct-fired plants because much more air is drawn through cracks or openings of the same size, due to the higher internal draft. This leakage is not so much through the brickwork as it is through the joints and around the frames of access doors, and generally along the contact faces between the brickwork and metal parts. Consequently, casing the boilers in sheet steel is of little benefit. It is necessary to reduce the number of openings to a minimum and to have few surfaces of con- tact between the brickwork or filling and the metal parts. In this con- nection, the box-header construction of the Edge Moor boiler is a manifest advantage. A considerable amount of carbon monoxide, without excess air, is often present in the hot gases. When the temperature is above 1200 deg. F., the approximate ignition temperatur(> of carbon monoxide, and air is introduced, further combustion takes place and releases additional heat for absorption by the boiler. But with open-hearth furnaces, or others of the reversing, regenerative type, the suction of considerable air at cer- tain points promotes gas explosions whicli, while not of a serious character, strain the setting and increase the general leakage. In a plant i)oorly dcsig-ned or maintained the aggregate loss resulting from air l(>akage may almost if not entirelj' negative any economic benefit from the installation. Another important factor is the maintained cleanliness of the heating surface. In a waste-heat boiler the loss from fouled surface is two to three times as much as in a direct-fired boiler. In the former, if due to fouled heating surface the average flue-gas temperature is raised 7.5 to 100 deg. F. the loss in evaporation will amount to from 10 to 1.5 per cent. The quantity of tleposits on the exterior heating surface is reduced in boilers designed for a high gas velocitj'. Where the water forms con- siderable scale, the deposits on the interior surfaces may be reduced or eliminated by chemical treatment of the water, but this is seldom necessary in a waste-heat plant. Deposits which do acciunulate should be removed at regular intervals if the maximum return on the investment is desired. This brings into prominence the provisions in the design for both external and internal cleaning. Until recent years cement mills have offered a difficult problem on account of the high dust content of the kiln gas. As an example of how much dust is carried along with the gas, in one plant it was found that this amounted to 44 tons daily for a production of 2900 barrels 60 EDGE MOOR WATER TUBE BOILER of cement, or about 30 pounds of dust per barrel of clinker burned. The dust problem has been successfully solved in the Edge Moor System not only by special design of the boiler, superheater, economizer and fan, but also of the flues, which are of ecjual importance — to facilitate and permit removal of dust without interfering with the continuous operation of the plant. From what has been stated al)ove it will be inferred that the design of a successful waste-heat plant involves many complex problems. In this connection, the following formulie may be of interest : Specific Heat of Gases. — The general formula for the instantaneous specific heat of a gas at temperature T in degrees F. is C'p = a + bT + cr where a, b and c are empirical coefficients.^ The mean specific heat lietween temperatures Ti antl T2 is then, C = a + b - -,:; h C ;5 For carbon ilioxide (C'Oi), Cp = 0.1983 + 835 X IQ-'T - 16.7 X lO'-T^ For oxygen (O2), 0.2154 -\- 0.000019 T For nitrogen and carbon monoxide (N2 and CO), C'„ = 0.2343 + 0.000021 T For water vapor at atmosiilicric pressure, Cp = 0.465 Miscellaneous Formulae: — Let— S = heating surface of boiler in square feet. Ti = temperature of gases entering boiler in degrees F. Ti = temperature of gases leaving iDoiler in tiegrees F. Ta = temperature of the atmosphere in degrees F. t = temperature of saturated steam in degrees F. - The values given below are according to Holborn and Henning, Annalen der Physif, 1()()7, aiifl are now accepted in scientific work as authoritative. WASTE HEAT FORMULAE 61 W — weight of gases entc^ring boiler in pounds per iiour. aW = weigiit of air leakage throiigli setting in pounds per hour. « = per cent, air leakage through boiler seating. Ci = mean specific heat of gases between Ti and Tx. C-i = mean spcscific heat of gases between T2 and T^. Co = mean specific heat of gases between Ti and T^. D = distance l)etween boiler sidewalls in feet. e = base of Napcrian logarithms = 2.7183. E = heat absorlied by l)(jiler in B. T. U. per hour. L = length of tubes in feet. N = numl>er of gas passes in boiler. R - heat transfer rate in B. T. U. ]ier hour per sq. ft. of heating surface per degree F. difference in tt'mperature. The mean heat transfer rates for the mean temperature differences noteil between gas and tube surface for 4-inch staggered tubes in cross- pass boilers are, For mean tcmj). diff. = 1000° F,, R = 2.0 + 0.0038 ^ /)^ " " " " = 500° F., R = 2.0 -I- 0.0031 !' -^ " = 200° F., 7? = 2.0 + 0.0027 l'-^ The draft loss through the boiler in inches of water is, v2 Draft loss = 0.65 ( - ^--\ \ 1000 L dI Case I. — When leakage through setting is neglected- Heat absorbed by boiler. E = (T, - - T;) Ci W Equivalent horsepower ^- «■ P- - 3slo (Ti - To) Ci W 33480 Weight of gases passmg through boilet lY = ^ . 62 EDGE MOOR WATER TUBE BOILER Temperature of gases leaving boiler r, = < + (Ti - t) e wo, Heating surface of lioiler „ TFCi, /Ti- ^= -R ^"^^ (t. 2 - tj Heat transfer rate of boiler For taljles of Naperian logarithms (base e) see Kent's Handbook, page 156 (1906 ed.), Marks and Davis' Steam Tables, page 76 (1912 ed.j, or Smithso?iian Mathematieal Tables (1909), Table V, p. 263. For the values of the exponential functions see Smithsonian Tables, Table IV, p. 225. Case II. — When leakage through setting is considered. — Heat absorbed by boiler E = W [C'„(Ti - Ta) - (1 + a) C2 (T2 - Ta)l Equivalent horsepower J? _ ^ W [Co (T, - Ta) - (1 + a) C, (T, - T,)] 33480 33480 Weight of gases entering boiler W^ ^ Co (Ti - Ta) - (1 + a) G2 (T, - T.) Weight of gases leavmg boiler TT (1 + a) = TT^ + Wa Per cent, air leakage ^ TFCo (T, - T,) ^E _ " irc, (r, - Ta) Temperature of gases leaving lioiler .S'« + iraC. ^V' Sli + WaC, J ^' ^ ""^ Waste Heat Equipment for Metal and Cement Mills THE primary factors which enter into the construction and mainte- nance of a successful waste-heat installation, whether for smelters, steel mills or cement mills, have been discussed in the preceding pages. Propor- tions, flue construction, details and arrangement will vary, of course, according to local conditions but, in general, the principal components will be similar. In earlier waste-heat practice it was considered best to have a separate boiler for each furnace or kiln. Later analysis has shown that this is dis- advantageous in many ways. By having fewer and larger boilers the invest- ment is decreased, the floor space is decreased, the number of openings permitting air leakage is decreased and other desirable results are obtained. - A/LNS Typical Abbanqement of an Edge Moue Waste Heat Plant FOR A Cement Mill (63) 64 EDGE MOOR WATER TUBE BOILER The use of a single collecting flue, which receives the gas from all furnaces or kilns, and distributes it to the waste-heat units, is a distinctive feature of the Edge Moor System. The drawing on the preceding page shows a typical layout for a cement ixiill. The location of the main flue and waste-heat units is varied, of course, to suit the available space. The arrangement is such that any comliination of kilns may be used with airy or all of the waste-heat units by means of the dampers. Gas from dry-process kilns usually contains from 1 to 3 per cent, of carbon monoxide without any free oxygen. The temperature is usually a1)ove the ignition temperature of the monoxide, hence the air drawn in through the kiln seals produces further combustion and changes in tem- perature. The main collecting flue therefore acts as a chamber where the gas from the different kilns is thoroughly mixed. But its most important function is to assist in the removal of a large part of the dust from the gas, especially the heavier particles which cause incrustation, before the gas reaches the boilers. As is shown in the illustration on the opposite page, each small flue between a kiln liousing antl the main flue includes a throttled area to speed up the gas, as in a Venturi tube. The velocity changes cause a large part of the dust to drop to the bottom of the main flue. The floor of the latter is trough-shaped and sloped to carry the dust to a scries of spouts, through which it passes to a conveyor box and is carrietl away. For long life and maintained high efficiency special construction of the main flue is of primary importance. In the Edge Moor design there is an outer casing of concrete, or of sheet steel reinforcetl with stiffening angles. Next to the casing is a course of special brick which has a high heat- insulating value ; and next to this is the firebrick lining. Large flues having arclied roofs not infrecpiently fail due to the settling of the arch. This weakness has been entirely overcome in the Edge Moor design. Spaced along the top of the flue is a series of strongbacks built up of steel channels with knee bracing at the corners. Connected to these, and running lon- gitudmally, are I-beams which counteract the thrust of the arch and effectively prevent any settling. When sev(>ral kilns are connected to a single flue, velocity changes and friction along the flue will give different drafts at the kilns unless some equalizing means is provided. Also, in some plants kilns of different sizes may require different drafts. Regulating dampers may be used for these purposes but they produce objectionable effects on the kiln output which, for a maximum, requires a steady draft pull. AHUANGEMliNT OF FLUES 65 as o « 5 5 3 3 CL < 3 S Si a. e cm OQ 6G EDGE MOOR WATER TUBE BOILER o e B DETAILS OF WASTE HEAT EQUIPMENT 07 Foundation for waste heat equipment. Marquette Cement Mfg. Co., Oglesby, III. Far more satisfactory results are ol^tained in the Edge Moor design by introducing the restricted openings in the connection l)etwcen each kiln and the main flue previously referred to. These act to produce a uni- formity of draft in all the kilns, counteracting the effect of flue resistance much in the same way as cores in superheater tubes cause an equal dis- tribution of steam to all tubes. The dampers used in these flues are a distinctive part of the Edge Moor design and have proved very serviceable. In mills where, at times, it is desired to operate the kilns without the waste-heat equipment, the kiln stacks are retained and special stack shut- offs are provided. On account of the special problems and the interdependence of all parts for efficient performance, the Edge Moor System for waste-heat recovery embraces the complete installation, from the ends of the kilns to the fan outlets. Special designs have been developed to overcome the highly detrimental effects of air leakage and dust. Patents covering certain of these designs limit their use to the Edge Moor System. 68 EDGE MOOR WATER TUBE BOILER m a, 1 B ■ a f- ■o ' , m o s Jh r ■o B ' a a \. CQ J t^ V 1 • ■v o s o ■a s •a s ADVANTAGES FOR WASTE HEAT RECOVERY 69 From the main flue, the gas is distributed to the waste-heat units through short brick-Uned flues. Each unit includes — An Edge Moor waste-heat boiler. A superheater, if superheated steam is desired. An economizer, if maximum recovery is desired. A fan to produce the required draft, and a low chimney. The structural features of the Edge Moor boiler make it especially suitable for waste-heat recovery. Excepting certain necessary modifica- tions, the parts are of the same standard design as for the direct-fired Edge Moor boilers commonly used in power plants. The design differs for waste heat in that headers are built much higher and relatively narrower, and tubes are longer, to obtain by suitable baffles the high gas velocity an.d long gas path necessary for a high heat transfer. Headers are continuous throughout their entire height and width and therefore have no packed joints in their faces through which cold air may pass into the setting. The baffles are easily installed and kept tight to prevent short- circuiting of gas. Baffles are straight, almost vertical, and the bottom of each pass is a clear opening through which deposits drop or are forced by the high gas velocity to the deep pits below. Also, there are no ledges or pockets where deposits may accumulate. The setting is such that equipment for hand or mechanical blowing may be installed for maximum efficiency and conv(^nience of the operator. The provisions for internal cleaning are likewise favorable. Tubes straight throughout their entire length and handhole plates individually removable make internal cleaning convenient antl efficient. An important advantage of the general design of the Edge Moor boiler is that all parts may be readily inspected to see the actual condi- tion instead of "guessing" at it. This is highly important for proper maintenance of plant. The diagonal rows of tubes are parallel, wdth clear spaces between them ; hence the inspector may see all of the exterior heating surface. Also, he can conveniently see both sides of the baffles as well as the junctions between the baffles and the bridge and sidewalls. Unless baffles and junctions in a boiler are kept tight the gas will short-circuit through the boiler with consequent decrease in the steam production. The inner surface of the tubes is also easfly inspected. By having a fight at one end of a tube and looking through the other, all tubes being straight, the internal condition of the tubes may be positively known. 70 EDGE MOOR WATER TUBE BOILER Concrete main flue in the center. Plant of the International Portland Cement Company, Sierras Bayas, Argentine Republic Waste heat boilers in course of erection. Alpha Portland Cement Company, Alsen, N. Y. SUPERHEATER FOR WASTE HEAT RECOVERY 71 The dust in the gas has made it necessary to employ a superheater of special design. Superheater tubes are surrounded by cast iron rings of relatively large diameter which taper outward to an edge leaving deep V-shaped spaces between rings. The superheater is placed above the first and second passes of the boiler with the tubes at right angles to the boiler tubes so that the gas, coming out of the first pass at a high velocity, sweeps through the V-spaces and prevents the accumulation of any con- Showing dampers, in shut and open positions, between economizers and fans. Knickerbocker Portland Cement Company, Hudson, N. Y. siderable amount of dust. A large part of the ring surface is therefore kept clean even when dusting by a hand lance or mechanical blower is not more frequent than once every eight hours. In practice 80 to 100 deg. of superheat has been obtained continuouslj' under these conditions. The superheater headers are set in cast iron boxes built into the side- wall. The space between headers and boxes is packed with a suitable filler, and the boxes are closed on the outside by doors, making the con- struction air-tight. 72 EDOE MOOR WATER TUBE BOILER Typical arrangement of boiler, superheater and economizer. Marquette Cement Mfg. Co., Oglesby, 111. An economizer of the design used in direct-fired plants is unsuitable for the gas from cement kilns. With headers at the top and bottom the economizer would soon become choked with dust. Scrapers are unneces- sary and objectionable and the openings for the chains would permit the inflow of an excessive amount of cold air. The economizer used in the Edge Moor System is therefore also special. The tubes are horizontal and staggered, terminating in vertical headers. The sides of the headers are machined to form tight sidewalls when in place. The roof of the economizer is built up of two steel plates with an insulating filler between. For dusting the tubes, cast iron bushings are .set in the roof at proper intervals and closed by plugs, contact faces being machined. ECONOMIZER FOR WA.STE HEAT RECOVERY 73 Boilers and economizers, showing dusting plugs for economizer tubes. Kniclierbocker Portland Cement Company, Hudson, N. Y. Radiation from the exposed surfaces of the headers is reduced by removable side casings. Beneath the economizer are dust pits provided with tight fitting clean-out doors. An economizer of this design maj^ be set very close to the boiler, resulting in a very compact installation. To provide against, water hammers the connection between economizer and boiler consists of a large vertical riser which opens to both the steam and the water space of the boiler. Any air or steam in the economizer is therefore immediately freed to the top of the boiler. In cement plants a fan of the ordinary type will not give satis- factory results. In such a fan dust will accumulate so rapidly that it 74 EDGE MOOR WATER TUBE BOILER o Pi S • £ c CO OJ 3 n W FANS FOR WASTE HEAT RECOVERY 75 will be necessary to shut down the fan at frequent intervals for cleaning. Also, the erosion from the dust will soon wear away blades of the common designs. The fan used in the Edge Moor System has been devel- oped to overcome these difficulties. The blades are so shaped that prac- tically no dust accumulates. With this and other modifications fans may be kept in service continuously and at a high efficiency. Fans are driven either by small steam turbines or by electric motors. When the temperature of the available feed water is low, it is more eco- nomical to employ turbines exhausting to a feed water heater. But when the Turbine-driven fan with reduction gear. Alpha Portland Cement Company, Martins Creek, Pa. feed water can be heated to a temperature of about 200 deg. F. by the exhaust from other equipment the electric motor is preferable, unless the exhaust from fan turbines can be utiHzed in a mixed or low-pressure power turbine. It is sometimes supposed that waste-heat equipment will reduce the normal cement production of the mill. On the contrary, a properly designed waste-heat installation tends to increase it because, with fans, the kiln draft may be easily maintained to that required for maximum output of clinker. 76 EDGE MOOR WATER TUBE BOILER Summarizing, special design of the flues causes a large part of the dust to drop out of the gas before it reaches the boilers; the design of boilers, superheater, economizers and fans avoids construction which would permit heavy accumulations of dust at objectionable points. The cross-section of passes in boilers and economizers is such as to produce a high gas velocity, which tends to keep the heating surface clean. The small amount of dust which collects on the heating surface may be removed at regular intervals with a hand lance or mechanical soot-blower, but this is done more to prevent the dust from "building up" than to keep the surface entirely clean. The amount of dust which collects on the boiler, superheater and econmizer tubes in a day does not seriously interfere with the steam production. As evidence of this, the performance of one of the first Edge Moor installations is here gi\'en. The tubes were dusted with a hand lance only once in twenty-four hours. The results are the averages of observa- tions for eight days. Average steam production . 1666 boiler horsepower. Average steam pressure, gauge . . 160 II3. per sq. in. Average sujjerheat 69 deg. F. Average rise of water temperature in econo- mizers 85 deg. F. Average temperature of water entering econo- mizers 190 deg. F. In another mill the steam produced continuously by the waste-heat equipment was found to be sufficient to generate the total power required, which averaged 2200 kilowatts. Before this equipment was installed the average coal consumption per l^arrel of cement was 96 pounds in the kilns and 61 pounds in the power house; afterward, the average for the year following was 96 pounds in the kilns and 6 pounds in the power house, the latter for heating, fire pumps, etc., when the mill was shut down. The net saving, due to the waste heat equipment, is therefore 56 pounds of coal per barrel of cement manufactured. In wet-process mills, the water in the slurry makes the weight of kiln gas per barrel of cement manufactured very much greater than in dry- process mills. Also, the specific heat of the gas is higher. But, counter- acting these differences, th(> temperature of escaping gases in dry-process mills is generally several hundred degrees higher and the gas usually con- tains carl)on monoxide which yields additional heat. As a consequence, RECOVERY FROM WASTE HEAT 77 the reclamation of waste heat per barrel of cement manufactured should be about the same for both types of mills. f ' Mill of the International Portland Cement Company, at Sierras Bayas, Argentine Republic, where steam is generated with Edge Moor waste heat equipment The importance of waste-heat equipment in conserving fuel resources is indicated by the following calculation for a single cement mill of average size. The estimated net steam production from waste heat in a 4000-barrel mill is about 53,000 pounds per hour, from a feed water temperature of 200 deg. F. to a pressure of 200 lb. per scj. in., gauge, and 100 deg. of super- heat. This is exclusive of the steam consumed by the fans, and is therefore available for power. A modern stoker-fired boiler plant without economizers will consume about 115 pounds of 13,500 B.T.U. coal per 1000 pounds of steam generated, or 2.7 long tons per hour for an hourly net steam production of 53,000 pounds. Hence if the steam reciuired for power is generated from waste heat instead of by a modern stoker-fired boiler plant the saving of fuel for the 4000-barrel mill should be as follows : Estimated saving of coal per 24-hour day Saving per 300-day year .... 65 long tons 19,500 long tons It has been estimated that the cement industry in the United States consumes over two and one-half million tons of fuel for power purposes 78 EDGE MOOR WATER TUBE BOILER only. Since all or nearly all the power required by cement mills can be generated from the waste heat in the kiln gas, the two estimates given above show that extensive use of waste-heat equipment will go a long way toward solving problems of fuel shortage and conservation, besides pro- ducing a considerable reduction in the cost of the manufactured product. Flue from fans, in the low building, to a Cottrell dust separa tor. Alpha Portland Cement Company, Alsen, N. Y. Representative Installations T N every critical investigation of a product it is not alone sufficient J- to satisfy oneself that the design is theoreticallj' correct and practical, that the materials and workmanship are first class, and that the perfomi- ance in authoritative tests compares favorably with that of the best of other makes of the same kind of product. The most convincing tests are after all, represented by the questions: Who have bought this product? Candy Factories Page 97 Cement Plants " 89 Central Heating Plants " 85 Central Power Stations " 81 Chemical and Dye Works " 92 Department Stores " 98 Educational Institutions " 8(j Electric Railroads " 85 Fibre Mills " 93 Grain and Flour Mills " 97 Hospitals " 87 Hotels and Clubs "100 Ice Plants " 95 Iron and Steel Works " 90 Machine Shops and Foundries " 91 Mines and Smelters " 89 Miscellaneous Plants " 100 Municipal Plants " 87 Office Buildings " 98 Oil Pumping Plants and Refineries " 94 Packing Houses " 95 Paper Mills " 93 Powder Plants " 95 Rubber and Tire Factories " 94 Soajj and Starch Factories " 95 Steam Railroads " 86 Sugar Mills " 97 Tanneries and Glue Works " 95 Textile Mills " 92 ITnitod States Government Plants " 86 And have these purchasers shown their satisfaction by placing additional orders? The pages which follow give the answers to these questions. It will lie seen that almost all classes of industries are represented in this partial list of users of Edge Moor boilers and that the largest and most critical buyers are included. (79) 80 EDGE MOOR WATER TUBE BOILER r 0\ FIFF - ?T PF FF - ~ 1 , i£,SW' Commerce Street Station of the Milwaukee Electric Railway and Light Company Edge Moor boilers set with chain grate stokers. Fort Worth Power and Light Company, Fort Worth, Texas REPRESENTATIVE INSTALLATIONS 81 CENTRAL Arkaiisixs Valley Railway, Light & Power Company Pueblo, Col. POWER Beloit Water, Gas & Electric Company, four orders Beloit, Wis. STATIONS Burlington Light & Power Company Burhngt.on, Vt. Charleston Industrial Corporation Nitro, W. Va. Consolidated Gas, Electric Light & Power Company, seven orders. .Baltimore, Md. Desert Power & Water Company, three orders Kingman, Ariz. Dominion Power & Transmission Company, Ltd Hamilton, Ont., Can. Erection of one-thousand horsepower units for the Consolidated Gas, Electric Light and Power Company, Baltimore Edison Electiic Illuminating Company of Brockton, three orders E. Bridgewater, Mass. Fort Worth Power & Light Company, five orders Fort Worth, Tex. Interstate Light & Power Company, three orders Galena, 111. Iowa Railway & Light Company, seventeen orders Boone, Cedar Rapids, Iowa Falls, Marshallto^-n, and Perry, Iowa. Laclede Gas Light Company, three orders St. Louis, Mo. Logan County Light &■ Power Company, four orders Logan, W. Va. Metropolitan Edison Company, three orders Reading, Pa. Miami Beach Electric Company Miami, Fla. Milwaukee Elec. Ry. & Lt. Company, twenty-six orders Milwaukee and Racine, Wis. 82 EDGE MOOR WATER TUBE BOILER Northern States Power Company, seven orders St. Paul, Minn., Fargo, N. D., and Sioux Falls, S. D. Oshkosh Gas Light Company Oshkosh, Wis. Ottertail Power Company Fergus Falls, Minn. Penn Central Light & Power Company, six orders Altoona, Warrior Ridge, and Williamsburg, Pa. Pennsylvania Utilities Company, two orders Easton, Pa. Edge Moor boilers with forced-draft stokers United Electric Light Co., Springfield, Mass. Philadelphia Electric Company , cle\en orders, Chester, Philadelphia, andTacony, Pa. Public Service Electric Company, tlu'ee oi'dei's Burlington, Camden, and Cranford, X. J. Rockland Light e<; Power Company, two orders Hillljiurn, N. Y. Society for Establishing Useful Manufactui'es Paterson, N. J. Southern Power Company University, N. C. Turners Falls Power & Electric Company Chicopee Jet., jMass. Union Electric Light & Power Company, three orders St. Louis, Mo. United Electric Light Company Springfield, Mass. United Water, Gas & Electric Company Hutchinson, Kansas. Wichita Falls Electric Company, two orders Wichita Falls, Texas. Worcester Sulmrban Electric Company, three orders Uxl)ritlge, Mass. REPRESENTATl VE INSTALLATIONS 83 Plant of the Union Electric Light and Power Company, St. Louis Sixteen boilers in course of erection at the plant of the Metropolitan Edison Company, Reading, Pa. 84 EDGE MOOR WATER TUBE BOILER Generating Station at Batavia, III. Aurora, Elgin and Chicago Railroad One of the installations of the Wilmington and Philadelphia Traction Company, Wilmington, Del. REPRESENTATIVE INSTALLATIONS 85 CENTRAL Germantown Steam Company, two orders Germantown, Pa. Plants' ^°^^ ^'^'^^^ ^*^*'*"^ Company, three orders New York City. Overbrook Steam Heat Company, four orders Overbrook, Pa. ELECTRIC Aurora, Elgin & Chicago Railroad, six orders Batavia, 111. RAILROADS Bay State Street Railway Company Salem, Mass. Connecticut Company, The Hartford, Conn. Cortland County Traction Company, two orders Cortland, N. Y. Partial view — Consumers Light and Power Company, St. PauL and operated by H. M. Byllesby Company Owned LexingtiOn Utilities Corporation, two orders LexingtiOn, Ky. Lincoln Traction Company Lincoln, Neb. Philadelphia & West Chester Traction C(im]5any, four orders Llanerch and Ridley- Creek, Pa. Shore Line Electric Railway Companj^ Norwich, Conn. Trenton & Mercer County Traction Corporation, two orders Trenton, N. J. Wilmington & Philadelphia Traction Company, six orders Wilmington, Del. Worcester Consolidated Street Railway Company Millbury, Mass. 86 EDGE MOOR WATER TUBE BOILER STEAM Boston & Maine Railroad Boston, Mass. RAILROADS Port Dodge, DesMoines & Southern Railroad Company, five orders Fraser, Iowa. Great Northern Railway Company, seven orders St. Paul, Minn., Allouez and West Superior, Wis. Minneapolis, St. Paul & Sault Ste. Marie Railway, five orders. . Minneapolis, Minn. New York Central & Hudson River Railroad Company, two orders Albany, N. Y. and Avis, Pa. Oregon Railroad & Navigation Company Portland, Oregon. Philadelphia & Reading Railway Company Philadelphia, Pa. Pennsylvania Railroad Company, five orders . Baltimore, Md. , and Wilmington, Del. Union Depot Company, two orders Columbus, Ohio. «;■■-... • . • . Passenger Station of the Great Northern Railway, Minneapolis EDUCATIONAL Drexel Institute, two orders Philadelphia, Pa. INSTITUTIONS Haveifor.l College Haverford, Pa. .lefferson Medical College Philadelpliia, Pa. West Chester State Normal School West Chester, Pa. U. S. GOV'T Naval Aircraft Factory, two orders, League Island, Philadelphia, Pa. PLANTS United States Naval Operating Base Hampton Roads, Va. United States Navy Yard Brookljm, New York. United States Na^-^- Yard, three orders League Island, Philadelpliia, Pa. United States Navj^ Yard, two orders Mare Island, Cal. United States Navy Yard, two orders Norfolk, Va. United States Soldiers' Home, two orders Wasliington, D. C. REPRESENTATIVE INSTALLATIONS 87 MUNICIPAL Baltimore, City of, two orders PLANTS High Pressure Pumping Station, Baltimore, Md. Chicago, City of, eight orders. . .Lawrence Ave.; 95th St.; Roseland; Central Park Ave.; 39th St.; Mayfair; Springfield Ave.; and Lakeview Pumping Stations. Holyoke, City of Holyoke, Muss. Minneapolis, City of. Northeast Pumping Station Minneapolis, Minn. Montclair Water Company Little Falls, N. J. The Roseland Pumping Station, City of Chicago Philadelphia, City of, Water Department, tliree orders Lardner's Point and Roxboro Stations, Philadelphia, Pa. Railway Water Works, two orders Railway, N.J. Sumter, City of, two orders Sumter, S. C. Wilmington Water Department, two orders Wibningt.on, Del. HOSPITALS Cook County Hospital Chicago, 111. Eastern Shore Hospital Cambridge, Md. Hahnemann Hospital, two orders Philadelpliia, Pa. Sheppard & Enoch Pratt Hospital Towson, Md. Springfield State Hospital, two orders Sykes^-ille, Md. St. Luke's Hospital Chicago, 111. State Asj'lum for the Chronic Insane Wernersville, Pa. EDGE MOOR WATER TUBE BOILER REPRESENTATIVE INSTALLATIONS 89 MINES AND Blackwocid Coal & Coke Company Pardee, Wise County, Va. SMELTERS Charleston Mining & Manufacturing Company , . . Fort Meade, Fla. Elkhorn Piney Coal Mining Company Weeksbury, Ky. Florida Phosphate Mining Corporation Royster, Fla. Homestake Mining Company Lead, S. D. New Jersey Zinc Company Hazard, Pa. Newport Mining Company Bessemer, Mich. Phosphor Bronze Smelting Company, two orders Pliiladelphia, Pa. Southern Phosphate Corporation Tancrede, Fla. Susquehanna Collieries Company, two orders. . . Lykens, Pa., and Shamokin, Pa. United States Metals Refining Company East Chicago, Ind. An Arizona installation. Desert Power and Water Company, Kingman, Ariz. tEMENT Alpha Portland Cement Company, four orders PLANTS Alsen, N. Y.; Manheim, West Va.; and Martins Creek, Pa. Asano Portland Cement Company two plants, Tokyo, Japan. Clinchfield Portland Cement Company Kingsport, Tenn. Crescent Portland Cement Company Wampum, Pa. Dewey Portland Cement Company Dewey, Oklahoma. Dexter Portland Cement Company Nazareth, Pa. Hokoku Cement Company Kobe, Japan. Huron Portland Cement Company Alpena, Mich. 90 EDGE MOOR WATER TUBE BOILER International Portland Cement Company Sierras Bayas, Argentine. Knickerbocker Portland Cement Company Hudson, New York. Lehigh Portland Cement Company Oglesby, 111. Ma)-([uette Cement Manufacturing Company Oglesby, 111. Northwestern States Portland Cement Company Mason City, Iowa. Petoskey Portland Cement Company Petoskej^, Mich. Trinity Portland Cement Company Eagle Ford, Texas. Western States Portland Cement Company Independence, Kansas. At the Kewanee Works of the Walworth Manufacturing Company, Kewanee, 111. IRON AND American Steel & Wire Company Worcester, Mass. STEEL WORKS Bethlehem Steel Company, three orders S. Bethlehem, Pa. Birdsboi'o Steel Foundry & Machine Company, three orders Birdsboro, Pa. Eastern Car Company, Limited, two orders New Glasgow, N. S. International Harvester Company, ten orders. .Chicago, 111., and Milwaukee, Wis.*^' Jones & Laughlin Pittsburgh, Pa. Lobdell Car Wheel Company, two orders Wilmington, Del. Meadville Malleable Iron Company Meadville, Pa. Mesabi Iron Company Babbitt, Minn. Oliver Chilled Plow Company South Bend, Ind. Walworth Manufacturing Company Kewanee, 111. Wisconsin Steel Company Chicago, 111. Worth Steel Company, two orders Claymont, Del. REPRESENTATIVE INSTALLATIONS 91 / Cedar Rapids plant of the Iowa Railway and Light Company MACHINE SHOPS Allis Chalmers Company, five orders W. AUis, Wis. AND FOUNDRIES American Pulley Company, two orders. . . .Philadelphia, Pa. Camden Forp;e Company, two orders Camden, N. J. Landis Tool Company Geiser, Pa. Lan.ston Monotype Machine Company Philadelphia, Pa. Pusey & Jones Company, two orders Wilmington, Del. Sellers & Company, Wm., Inc., two orders Philadelphia, Pa. 92 EDGE MOOR WATER TUBE BOILER TEXTILE Aberfoyle Manufacturing Company, three orders Chester, Pa. MILLS American Printing Company, tlrree orders Fall River, Mass. American Thread Company Fall River, Mass. Bancroft & Sons Company, Joseph, four orders Wilmington, Del. Dobson, Jolm & James, Inc., two orders Philadelphia, Pa. Erlanger Underwear Manufacturing Company Baltimore, Md. Fleisher, S. B. & B. W., Inc., four orders Philadelphia, Pa. Franklinsville Manufacturing Company Franklinsville, N. C. Gera Mills, two orders Passaic, N. J. Harmony Mills Cohoes, N. Y. Highland Worsted Mills Camden, N. J. Lewiston Bleachery & Bye Works Lewiston, Maine. "1 Riverside and Dan River Cotton Mills, Danville, Va. Ludlow Manufacturing Associates, two orders . . Calcutta, India, and Ludlow, Mass. Maverick ^Mills East Boston, Mass. National Knitting Company Milwaukee, Wis. Riverside & Dan River Cotton Mills, five orders Danville, Va. Viscose Company, six orders. . . .Roanoke, Va.; Marcus Hook and Lewisto^m, Pa. Wolstenholme & Son, Inc., Alfred, two orders Philadelphia, Pa. Wolstenholme & Sons Company, Thomas Pliiladelphia, Pa. CHEMICAL American Agricultural Chemical Company Pierce, Fla. AND Crescent Chemical Manufacturing Company, three orders DYE WORKS ■ Brookljm, N. Y. Curtis Bay Chemical Company, two ordei's Curtis Bay, Md. Krebs Pigment & Chemical Company Newport, Del. Liquid Carbonic Company Chicago, 111. Monsanto Chemical Works St. Louis, Mo. Nichols Copper Company, two orders Laurel Hill, N. Y. Perth Amboy Chemical Works, two orders Perth Amboy, N. J. Philadelphia Dye Works Philadelphia, Pa. REPRESENTA 77 VE INSTALLA TIONS 93 PAPER American Writing Paper Company Holyoke, Mass. MILLS Bird & Son, F. W East Walpole, Mass. Dill & Collins Company, four orders Philadelphia, Pa. Glatfelter Company, P. H., two orders Spring Grove, Pa. Great Northern Paper Company E. Millinoeket, Maine. Hanmiermill Paper Company, two orders Erie, Pa. Boilers in course of erection.at the Covington, Va., plant of the West Virginia Pulp and Paper Company Kimberly Clark Company Kimberly, Wis. Lawless Bros. Company East Rochester, K. Y. Megargee Paper Mills, three orders Modena, Pa. New York & Pennsjdvania Company Willsboro, N. Y., and Johnsonburg, Pa. Port Huron Sulphite & Paper Company, two orders Port Huron, Mich. Sorg Paper Company, Paul A., two orders MiddletoT\ii, 0. St. LawTence Pulp & Lumber Corporation, two orders. . . .Chandler, (Quebec, Can. Warren Manufactuiin g Company, five orders Milford, Warren and Hughesville, N. J. West Virginia Pulp & Paper Company, fourteen orders Mechanicsville, N. Y.; Tyrone, Pa.; Covington, Va.; and Piedmont, W. Va. FIBRE MILLS Continental Filire Company, four orders Newark, Del. Diamond State Fibre Company, two orders Bridgeport, Pa. 94 EDGE MOOR WATER TUBE BOILER OIL PUMPING American Cotton Oil Company Guttenberg, N. J. PLANTS AND Associated Pipe Line Company, two orders. .San Fratiicisco, Cal. REFINERIES Beacon Oil Company Everett, Mass. Crew-Le-\ack Company, Seaboard Oil Plant Chester, Pa. International Oil & Gas Corporation Shreveport, La. Sinclair Refining Companj', two orders Coffey vUle and Kansas City, Kansas. Edge Moor boilers with forced draft, underfeed stokers. Light Company, Worcester, Mass. Worcester Electric RUBBER Electric Hose & Rubber Company, two orders Wilmington, Del. AND TIRE Essex Rubber Company, two orders Trenton, N. J. FACTORIES pjgj. Rubi^er Company', two orders Chicopee Falls, Mass. Hood Rubber Company, two orders E. Waterto-mi, Mass. Quaker City Rubber Company Philadelphia, Pa. Revere Rublser Companjr, two orders Providence, R. I. REPRESENTATIVE INSTALLATIONS 95 ICE PLANTS American Ice Company, four orders, three plants, Philadelphia, Pa. Bee Hive Hygienic Ice Company Brooklyn, N. Y. Delaware Storage & Freezing Company Philadelphia, Pa. New York Ice Company New York City. Terminal Freezing & Heating Company Baltimore, Md. PACKING Armour Packing Company Kansas City, Mo. HOUSES Oobel, Adolf Brooklyn," N. Y. Morris & Company, fourteen orders Chicago, 111.; East St. Louis, 111.; Kansas City, Kan.; St. Joseph, Mo.; Oklahoma City, Okla.; Montevideo, S. A. North Packing & Provision Company, two orders Somerville, Mass. Richardson & Robbins Dover, Del. Plant of A. E. Staley Manufacturing Company, Decatur, III. TANNERIES Foerderer Company, Robert H., three orders AND GLUE Bridesburg and Frankford .Junction, Pa. FACTORIES pfister & Vogel Leather Company, nine orders tliree plants, Milwaukee, Wis. Trostel & Sons Company, .Albert, two orders ^Milwaukee, Wis. United States Glue Company, six orders Carrolh-ille, Wis. SOAP AND Pels & Company, two orders Philadelphia, Pa. STARCH Larkin Company Buffalo, N. Y. FACTORIES Lgver Bros Cambridge, Mass. National Starch Company Oswego, N. Y. Staley Manufacturing Company, A. E., four orders Decatur, 111. POWDER E. I. duPont de Nemours Powder Company Barkesdalc, Wis.; PLANTS Wilmington, Del.; Repauno, N. J.; Carney's Point, N, ,J.; Hopewell, Va. Hercules Powder Company, two orders San Diego, Cal. 96 EDGE MOOR WATEH TUBE BOILER Hfc^^ ^'z^'i j 1 ^m ■H \ "*'^', ..■i.wSwisBtWx**"''" ,«,«»»««*««««*''■'-■■ V ^; .-^ . Sfi: .1 iJ T / r / / f f / Edge Moor boilers set with bagasse furnaces. Central Agramonte, Camaguey, Cuba REPRESENTA TI VE INSTALLA TIONS 97 GRAIN AND Commercial Milling Company Detroit, Mich. FLOUR MILLS Gambrill Manufacturing Company, C. A EUicott City, Md. Millbourne Mills Company, two orders Philadelphia, Pa. Philadelphia Grain Elevator Company Philadelphia, Pa. Washburn-Crosby Company Buffalo, N. Y. Commercial Milling Company, Detroit, Mich. SUGAR MILLS E. Atkins & Company, three orders Central Florida, Camaguey, Cuba; and Central Soledad, Cienfuegos, Cuba. Cape Cruz Company Esenada de Mora, Cuba. Central Santa Ana Auza, Oriente, Cuba. Compania Azucarera Vertientes, three orders Centrals Agramonte and Vertientes, Camaguey, Cuba. Cuba Cane Sugar Corporation Central Stewart, Cuba. Czarnikow Rionda Company Central Francisco, Cuba. Hershey Corporation, two orders Central Hershey, Bainoa, Cuba. Honolulu Iron Works Central Fe, Cuba. Manati Sugar Company Central Manati, Oriente, Cuba. Miranda Sugar Company Central Miranda, Oriente, Cuba. United Frait Company Bocas del Toro, Panama. CANDY American Chicle Company Long Island City, N. Y. FACTORIES Hershey Chocolate Company, four orders Hershey, Pa. Wilbur & Son, H. 0., two orders Philadelphia, Pa. 98 EDGE MOOR WATER TUBE BOILER DEPARTMENT Baltimore Bargain House, thi-ee orders Baltimore, Md. STORES AND Filene Sons Company, Wm., two orders Boston, Mass. WAREHOUSES Qi^^gi Brothers Philadelphia, Pa. Mandel Brothers, two orders Chicago, 111. Montgomery Ward & Company, four orders. . . .Chicago, 111., and St. Paul, Minn. Rhodes Brothers Department Store Tacoma, Wash. Rice Stix Dry Goods Company, two orders St. Louis, Mo. Rosenburg Brothers & Company Rochester, N. Y. Zangerle & Peterson Chicago, 111. Filene's — Boston's finest department store OFFICE Chicago Title & Trust Company Chicago, 111. BUILDINGS Cincinnati & Suliurban Bell Telephone Building Chicinnati, 0. Drexel Building, two orders Philadelphia, Pa. DuPont Building, four orders Wilmingt-on, Del. Fidelity Building Baltimore, Md. Fire Association Building Philadelphia, Pa. First National — Soo Line Building Minneapolis, Minn. Girard Buildmg, two orders Philadelphia, Pa. Hudson BuikUng New York City. Merchants' National Bank Building. . St. Paul, Minn. REPRESENTATIVE INSTALLATIONS 99 Minahan Building Green Bay, Wis. New York Life Building, two orders Chicago, 111. North American Building Chicago, 111. r '- ~ y'-':":-" "^ - ■? ■ Just below Independence Hall, Philadelphia, is the Drexel Building equipped with five Edge Moor boilers North American Building PhUadelphia, Pa. Otis Building Chicago, 111. Pacific Electric Building Lns Angeles, Cal. Public Service Building Milwaukee, Wis. 100 EDGE MOOR WATER TUBE BOILER HOTELS Belvidere Hotel Baltimore, Md. AND Illinois Athletic Club Chicago, lU. CLUBS Manufacturer's Club, two orders Philadelphia, Pa. Morrison Hotel Chicago, 111. Rennert Hotel Baltimore, Md. Union League Club, two orders Philadelphia, Pa. At United States Soldiers' Home, Washington, D. C. The U. S. Government has also purchased Edge Moor boilers for the Brooklyn, Mare Island, Norfolk and Philadelphia Navy Yards MISCELLANEOUS Auto Car Company Ardmore, Pa. Cleveland Sarnia Saw Mills Company, Ltd., two orders Sarnia, Ont., Can. Clinton Wire Cloth Company Clinton, Mass. Columljia Box Company St. Louis, Mo. Corning Glass Works Corning, N. Y. Delaware River Cordage Company, two ordeis Philadelphia, Pa. Destructor Company, The, four orders Brooklyn, N. Y.; Atlanta, Ga.; Paterson, N. .1.; Havana, Cuba. Farr & Bailey Manufacturing Company Camden, N. J. H. H. Franklin Manufacturing Company, two orders Syracuse, N. Y. liamiltou Browii Shoe Company St. Louis, Mo. MacAndrews & Forbes, four orders Camden, N. J. REPRESENTA TI VE IN ST ALL A TIONS 101 One of the many office buildings equipped with Edge Moor boilers North American Building, Chicago New York Consolidated Card Company, The Long Island City, N. Y. Remington Salt Company Ithaca, Xew York. Townsend Grace Company Baltimore, Md. Victor Talking Machine Company, seven orders two plants, Camden, N. J. Waldorf Box Board Company, two orders St. Paul Minn. 102 EDGE MOOR WATER TV BE BOILER OJ g T3 s o o ENGINEERING DATA Fuel THE manj' kinds of fuel used for the generation of steam maj- be divided into three classes: natural fuels, prepared fuels, and the by-products and end-products from industries. To the first class belong wood, coal, crude petroleum and natural gas; to the second powdered coal and briquettes; and to the third bagasse, tan bark, blast-furnace gas, coke-oven gas, waste gases from cement kilns, open-hearth furnaces, etc. Of these fuels, the most widely distributed, and therefore most commonly used, is coal. Classification of Coal. — The very great variation in the composition of coal found in different localities has made it desirable, for technical pur- poses, to classify coal into various grades based on some relation between the volatile matter and either the fixed carbon or total combustible present. In the language of the chemist, that part of coal, moisture excepteil, which is driven off when a sample is subjected to a temperature up to about 1750° F. is the "volatile matter"; the solid carbon is the "fixed carbon"; the sum of volatile matter and fixed carl ion is the "total combustible"; and the part that does not burn is "ash". Classification of American Coals^ Class Volatile matter Per cent, nf combustible Oxygen in combustible Per rent. 1 to 4 B. T. r. per lb. combustible I. Anthracite Less than 10 14,S0O to 15,400 II. Semi-anthracite .... 10 to 1.5 1 to 5 15,400 to 15,.500 III. Semi-bituminous 1.5 to 30 1 to 6 15,400 to 16,0.50 IV. Eastern cannel .... 4.5 to 60 5 to S 15,700 to 16,200 V. Bituminou.s, high grade 30 to 4o 5 to 14 14,800 to 15,600 VI. Bituminous, medium grade 32 to .50 6 to 14 13,800 to 15,100 VII. Bituminous, low grade . 32 to 50 7 to 14 12,400 to 14,600 VIII. Sub-bituminous and lignite 27 to 60 10 to 33 9,600 to 13,2.50 From table by WiUiam Kent in Journal A. S. M. E., vol. 36, p. 437, 1914. ( 103 ) 104 EDGE MOOR WATER TUBE BOILER Sizes of Coal. — Coal as taken from the mine varies in size from large lumps to a fine dust. In general, the smaller the size the greater is the amoimt of impurities ])resent, the heat value is lower, more coal sifts through the grate, and other objectionaljle results are increased. As a consequence, the larger sizes usually command higher prices, especially for anthracite. Coal is graded into sizes by screening through standard openings which, however, tliffer somewhat both as to size and shape in different localities. The jireliminary report of the Committee on Power Tests of the American Society of Mechanical Engineers (1912) recommends the grading of coal as follows : Sizes of Anthracite Coal Size Diameter of opening through or over which coal will pass, inches Through 4| Over Broken 3i Egg 3} 2 A Stove . 2A If Chestnut . .,„,-..,... If 7 8 Pea . . 7 8 9 16 No. 1 Buck\A heat .......... 9 16 A No. 2 Buek\\ lieat A A No. 3 Buckw beat ,1 16 .3_ 3 2 SIZES OF BITUMINOUS COAL EASTERN STATES Run of mine coal — The unscreened coal taken from the mine. Lump coal — That which jjasses over a bar-screen with openings Ij inches wide. N^ut coal — That winch passes through a liar-screen with Ij-inch openings and over one with f-inch openings. Slack coal — That which passes through a l.iar-screen with |-inch openings. SIZES OF BITUMINOUS COAL WESTERN STATES Run of mine coal — The unscreened coal taken from mine. Luntp coal — Divided into 6-ineh, 3-inch and IJ-inch lump according to the cUameter of the circular openings over which the respective grades PROPERTIES OF FUELS 105 pass; also into 6 x 3 lump and 3 x \\ lump accordinp; as the coal passes through a circular opening of the larger diameter and over cue of the smaller diameter. Nut cnal — Divided into 3-inch steam nut, which passes through a 3-inch circular opening and over a l|-inch; Ij-inch nut, which passes through a Ij-inch circular opening and over a f-inch; and f-inch nut, which passes through a f-inch circular opening and over a f-inch. Screenings — That which passes through a Ij-inch opening. Variation in Calorific Value. — The calorific value of the principal fuels per jiound as received varies about as follows: Air-dried wood ......... 6,000 to 7,500 B. T, U. Air-dried peat Lignite .... Siib-bituminous coal . Bituminous coal . Semi-bituminous coal Anthracite coal California crude oil . Pcnn. heavy crude oil 6,000 to 7,500 B, about 7,500 5,200 to 7,500 5,.500 to 11,500 10,000 to 14,.500 13,500 to 14,000 11,000 to 13,800 17,000 to 19,300 about 20,700 Composition and Calorific Values of Fuel Gases^ Vapor Pounds per 1000 cu. ft. B. T. U. per 1000 cu. ft. Producer gas Natural pas Coal gas Water gas .\nthra. Bltuniin. 0.50 6.0 45 . 27.0 27.0 2.18 46.0 45 12.0 12.0 92.6 40.0 2.0 12 2.5 0.31 4.0 0.4 0.26 0.5 4 2.5 2.5 3.61 1.5 2.0 57.0 .56.2 0.34 0.5 1.5 0.5 1,5 0.3 0.3 45 . 6 32.0 45.6 65.6 65.9 1,100,000 735,000 322,000 137,455 1.56,917 W. J. Taylor, Trans. A. S. M. E,, vol. xviii, p. 205. Properties of American Coals. — The data in the six pages following were selected from Professional Paper 48, 190G, Bureau of Mines; BuUetm 85, 1914, Bureau of Mines; and The Chemical and Heat-Producing Proper- ties of Maryland Coal, 1905, by W. B. D. Pemiunan and Arthur L. Browne, Maryland Geological Survey. 106 EDGE MOOR WATER TUBE BOILER a > o H 0^ CO O O o s H rj-j H K Pi H « O cc H « H PL, O K CM k P. ■ ffi O CO 00 CI o:! OC' o ^ t^ ci CI O CD >— I f- X' O O QC' 00 CI t-- ci ^ o o <:d CO ^ C: ^ -n t^ CI t^ CO CI ^ O "* i-H Ol LO ^' ':^^ C: CO 00 CO CO c: Oi '-' -^ C' -t CO CO CO 'f CO CO i-H CO lO -t^ O CI -^ CO Cj CO CI CO O '—I I CO CD CO lO »-0 -t C-. ^ C'J X I_Q 1- -t- ■ -t ^ ^ ^ ■ ^ C-- to I- o -r o x CO -f cr. .-H CO 'C -"-I r::^ O CI -H '-^ LO »o >-( 1- cr. o CO CO C-- c: s c; cr lo ci e o i-H t^ ^ 1-- c; CO 1-- -Xj ^ lO t-O CI Cl t^ t^ CO CO C: Cl ':t^ CO X I- O -f o Cl O O CO -t^ O CO 1-^ 1^ CO »-0 -t lO C^ ':t^ CO i-H Ci -^ oo O I G — CO t^ c/: c: CI ■ CI ■X a: ci o o CD Ic -t CO Cl CO CI CI -t^ '~5 zt '^ ^ "^ '^^ P CO CO CO lO uo -Tt^ ^ ■ -t- ■ ■ C- ffi -^ -t^ i-O ■ -t^ - LO p^ 3 '5 CO lO ^r CO C] CO CO LO (/ Gi to -f C -H "^1 Cl T-l CO Cl o o CO Cl CO CO Cl CO CO 1 — 1 Cl LO X 1- CO Ol C (~ — « o -t^ o o ■-H -f- -1- lO o CO lO ^ oo ,_, .— ^ -Tfl ^ r-^ CO CM CO _:! --I CO ^ ^ 2 hu I>-J -C'-^ u^ ^ >. c c El Paso Count > Gunnison Coun Las Animas Co Montozunui Co <: ^ < c :3 d . o CD o 5 X U o 'Ji ^ be - : Matanuska n o S O Boise County Cassia County Fremont Coun -t^ -T- A J l-I -1^ ft . e -2: 'O r-T -:- ' o" ci' T-T (— - _' eq ^ - ^ ^ ^ I— ( 1 1 >— t (— 1 ■" --H rt i-H ■ CO Ci o CVJ CO O CO' CO CO -3 tD CO Ol o Tf^ -H CO -— I to LO -:3 5 Cl ■ Oi c. >o " ■-H 1— I - lO ■ 'O -t^ 'X -f CO I-- 01 CO 01 o ■ Oi -t' 01 -t CO -f^ O ."tn ■ 1— t I-H 1—1 .— 1 rH 1— 1 >— 1 1— ( I— 1 1 c c ■ (- ■ CO -fH O O Ol -t- LO 1- t^ o X; CO CO CO Ol 1- LO O Ol CO u, p3 - Ol ■ CO t^ Ol I— < O CO d iO CO CO t-^ CO LO CO CO CO' ■^ ■ o _, i-~ o CO' — CO O CO O CO .^ iQ CO CO - . ..o . ■ *o CO lO »0 LO LO LO LO t-O 0^ 13 .~ a O '2 C/D' ».0 O CO t OI o o rr CO CO G-- lO O £- r-' "ft CO CO 1^ CO C: CTi l~ O CO >o -/J -t^ CO CO CO ^ Ol .-H -f ^ CO -f CO -f CO -t 01 CO O: OG CO CO "O >0 CO -+ CO m r- n-j -tH -H o o t^ CO — ' o -^ O t^ LO O CD o i^ C: o CO -H I- O LO GO t^ < 'O o o ^ ^ 1- o lO o Ol CTj Ol o CO C: Ol O 1- O Ol ■ 1—1 .—1 ■"* ■"" I—I '"' '"' ""* QJ ~ c r-H rM O TtH lO O!' c:- T-H -tS o ^ CO CO o Ol O t-O CO CO CO a oS c-i c O 00 1- CO r-H O O' c^ CO 1- x LO CO -t< cr. CO OC' ^t; eg OC' r- T-H ^ 'X: o o cr - 'O o: Ol O CO 'O CO o ,2 co -+ -t^ -t^ -iH lO CO rt^ -t^ ^ I-O ^ CO CO LO -V CO -H -+ lO ■^ = _o I, ^ m: [- Ol Oi »0 C: O c: CO ,_, -t •o 'X' CO ^ 01 o l- .O CO ^ •o o CO i-O o -t CO LO »0 '^ 1- Ol -t o ■o 3 O i-C 1^ CO --1 -t -r -t' CO CO o »-0 to .^ CO CO CO CO CO CO CO coco CO CO CO CO CO CO Cli CO CO CO CO o £ O -f ^^^ Ol CO LO Cr. I'-l ^ -t CO — ,„ — ,_ CO o -r CO O CO CO lO O CO CO 1- jC vi: X ■— 1 o t- CO Cl C^ CI 01 CO 00 t^ CO CO G: t^ co CO -t X -t i-H 01 CO OS ^ r-^ c 3 o O O ■51 "SO UU jO:3 O r so '-' __ c :; ! ^ J_ d c ■ 3 o ^^ <5 S ffi h^ V c ■.too W J O OJ S: 2 1^ B 108 EDGE MOOR WATER TUBE BOILER o O a s o w O o < S w -^ W to H Ph O « H o M Ph Heat value per lb. . T. U. CO -1^' CO -t cc '-f co" '-f CO CO c-r -t^" lO ^ O C-1 GO CI 'iH ^ CO LO Oi -p o en ^ rt' ^' c' o' of 9,135 6,021 5,830 O C5 H •a OD C; ^ LO t^ lO »o »o >o »o CO 01 >o lO -* O) GO ^H CTi CO to t^ Ol O I- O O CO Tt< ^ lO O lO I^ r-H t^ -t^ P3 £ H -= ^ -5 O ^ ..O -H O O -r CT- ° CO o ^ o -5 - H PROPERTIES OF AMERICAN COALS 109 CQ O CO O CO O CO O CO (X' CO CI I- o j: o CO Cl l~ -f^ lO CO o c-i CD lO CO CI -r CO I- O -ti »0 t^ "^ 01 03 1-1 -rfi Tf O .— ici-^cocooco-^t-* ajoiioi'-.'-HCit^o-f ^_^^-^_^^^^_^ Cl QC -t^ .-I ^O -^ - o O o c U ,.^ H C -1^ az-M ^ ^ W O 2; ^ ,— 1 t^ rr) CO r- h- CO in GTi I/J CO . -r CO CI CO C-0 o CI CJ '"' '"' ■"" ■"• ■"^ ^ ■"■ ^ ^ ci CO CO lO o ^ CI LO CO 00 CO -f^ 'rt< 'TtH ..o CLJ o rjj -+^ CO O CI -t 1 ,^ o m CO o ^ '— ' oo t- C/D -tH lO oo O '-1 < ^ ^ C/1 LO oo CD CO CO lO ^ CO CO CO a CJ ^ 1- »o CO c/:^ ^—i or I'"! ,_, ,r-. r'^ c: CD CO >-0 -1H lO o o o oo m o CO r/-' CO -H Ol CA lO ~v CD >o CO ■"^ c ^ t- 'O 1- oc c/: -t^ --D /-r> ■^ 9^ ,— 1 o z CO o CO -+■ ^, Oj "5 2 ,_( »o m -t t^ r- ,— 1 lO ,— 1 rr rr. S ;> c CO CO OJ CJ CO CO 01 CO CO CO o fi. r/> I^ CD CD 00 LO .-H 1~ ^^ CI CO ,_^ CO CO CO CO »-0 Ol 'V o C: o CO -t^ CO -^ CI -f o CO t- c/: '~ cr. -1^ o i^ o iQ cC' c/: O' o '^' ^ ^ ^H CO ci O c <: O - o ^ ~ "^ ■- ^ l^ -i ^ " £c ^ '" o'-S _c O O o s w x W H o to a pj H CM o PL, U^ »^ (N fN r/-) CO -f^ »o -t Ol n* o r- lO r~ CD ^__, »o O CO cr, o (TO I/) C) m r/) c ; ■lO ^ iC o rr- Ci CO -r> O". -t r_^ CO l^ t-- cyj o o CI CO CO cc CO CO -— 1 I^ lO C: OJ -t^ r-H Ci ■" -t^ CO Ol CO -V CO -t CO CO CO iC zo CO -t- CI -"1 '^l o CO -f CO cq •^^ 1— H ""* ■"* ""^ '"' '"' 1—1 ""^ ""• ""^ ""• '"' d -t in t^ o CO f-) ~ r rr. [^ rJl CI X cr. -^ r-. CO CI bO CC o y. o Ol CI 01 X X CI 1- o ^— < y. lO l^ c*o M CO fO UO CO CO CO CO ,_, CO -t< CO r^ 'O CO CO o '"' -t ""■ CI . 1-H LO 1 LOiOClCl-ti-f-tO'-O'O CO o . CI "J .-H 'O CO Ol o LO ■— ' C' '— ' i-O -— ' o lO ,__, o CO r-i CO c-. cr: I- l>- CO t-- CO 1^ QK t-~ CO 01 -r _ Ol I-- l~- o i-O' X C-. CO 01 lO -V o uo '-0 -r 'O i-O g?^^! CO X O O r-^ -— lO o-i 'O CI CI 1.03 1 . ss 1 . 43 -r C-- i~ CO CO CO CO C-- t^ -t »o X a « 01 i-H '-' '-1 r-H T-H CO "^ ^ o CO CO i-O o o uO CO o O' CO 'O CO CI CO o Ol CO X o CI o t-- CO < 1-- QCi ^ •o CC' - t- LO Gl c s X o lO -f LO LO -f CS-. LO O — c ? CO lO CI C) o CO -1^ -f* CO CO o »0 LO ll o 1^ I- CO LO CO CO LO 00 8 CI o t- c X CO CI X Ol CI X o CO O C: CO CO CO CI o LO lO O) lO CO o CO lO CO CI CJ "O CO OJ CI CO s -t CI CO CO 1 CO -f -t s o ''o CO ~v - o CO s C-- oc Cr. CO co- CD CD t-- Ol 'o ■"^ CI CO 01 '"' '"' ""^ -rr^ CI CI -+ CO '"' CO ""• t^ CO CO ol CI CO 1 .d S i^' s ^ rr -T3 it; j^ S^ a C ^ ^ 3 O M ^ H- h-i Oi ^ w Ph go c >> O o "S >> > X" Or^.O ? P T^ o Z o s ■ o B D o c «ts PROPERTIES OF AMERICAX COALS 111 ffl D— . •— I o cc) ■*+ CO >-o -t^ -^ o CI iro c: I- 1^ a: o ci i^ CD 00 c-t GO CO g:> o CI 1-1 o CD 1— ( c-i c/: CO o 1-- ■:/: c/: -r lo c; lo ci 1-- o J.- »o o oc Lo i- ic o a: --H i-^ c; Cj r^ o o oC' ci CI O LO 1-1 o O lO t^ 'M Ci G Cl lO t~ CT. CO ^ I-/* ^ ,— r.-^ r -t l~/^ r ^ CI M '— " Ol o CO Ci '—' o LO ■— ' ■— ' w 1- lO' c- l-~ LO' CO lO >< TAi CD CI CO lO CO -f -t Oi rr lO »(-. c^. (--i rr -r CO C r— 1 '"' □ <-~. Cl >-0 -f CO (- 1- -r ■-/- 1^ i-^ ^1 V C" V ,_, ,_( c: O lO 'O CD -f F— ( T— < -+ L^' LO LO o .■t; ^ ,__, ^ ^ ^ ^ r-H ^ ^ ,__, , , , 1 , , ^ , ,, ^ '^ c ^1 o 1^ CI CO O r~ o: --^^ -t i-i rr ^ xj C-. C/j '-' o o -v t- ryj CD 1- CD CI o CD LO ri rr> LO CO -fH G: '^ 1- o I- ~v -t^ cn ry 1- ,_, in CO CO u iO t- l^ 'y^' I- f^J l^ X I^ l- j: V. 1- t^ oo C/L 'X 1^ CO Cl C/C' m -f^ _ ,„ ^ .. Cl -f 1- ^ r^ 1- .„ -f -a l^ t^ CI c: X lO CO CI CO CI ^ 00 l^ l; c:-' l^ CD LO LO -t" -f ~v -f -v LO »o -+ -t* LO -H -t^ -r -f -t^ W =5 OC rr.- CD or l'~l r/ ai' t^ n-i CO ^' V ^jT c- CO rM 00 CI 'O O 'O r- CD CD O 1- 1- C: "O LJ -H Gl 3 o .— 1 ,__, ,__, CI ,_, K CO CO C I CO CO CD CI CD -t »0 o o m (~. c: oo -+ CO O' ■^ "^ "— ' '"' I- CO rr en rr. -t^ o -+ o t^ in ,_, Cn OO' -i- to CD »o CD ,^ -, f- CO ?1 CJ cr.' CO' • o o CD LO CD LO o m rr o o o: CD lO CO -H -f r/-. LO -t OO CI >o Oi ■^ 10' -f -f v: CD CI t^ CO T— ' 'X LO OO^ CO -f l- C". c/: --t- TtH -t< oo ^ or ^o ^— ■ n| -f^ CO ^__i -)H 1 CI cr 1- 1- o CO CD CO CD -tH ^ s CO >— ' o C' rJi c/j ^' -t C/j c>: l— cr- '^ 1^ ■"^ '^ 'Ci t m r-> m rr. n-i CO CI CO -r ^1 CI CI CD' 1- »o CD cr. LO O I^ CO vo LO CD l^ 1^ CD L-- LO LO t- I- O Cl.^ 1-- l^ 1.^ O L- ^ ^ CO co ^ rr> rr> ^ CI o cO CI rr. 1—1 I^ r^ , CO CO 'D ^ 'O CO CD -t^ O r-- CO o GO' Oi -+ -f -t^ O LO CO I~ o o O: »o t^ "1 2 , 'O in cn CO in CO 1^ rr CO (Tj t^ T- c/: I- CO Cl nj rjr >s CO CD CO CO CI CO CO ""* ""* CI CI " '"' ^ CO »o -v c/: n^^ r- r-1 •^1 rr lO o CO ^ CO o CO lO 1- Cl ^ r-~ or h- or -t^ a: o lO o: T-H CO o; CD CD CD -f cr:> -t ^—' 1^ c--' '—' -f LO '— ' CD h- ^__l -f '^1 rr> m '^1 CI ni CI CO CO ,_, ,_, -t C) CI CI 1- CO CD Cl LO Ci (^ C § 3 ^ 3 O O o g 3 M hJ Ph CO ^ o t: U c 3 O O > P ■ :4 o o bj: ^ - - c ^ 3 3 X ^ O _9 o '-fi o '^ fSfS s la .- g 2 X rs z S S t; o ^ 112 EDGE MOOR WATER TUBE BOILER PHOPEHTIES OF BAGASSE 113 Fuel Value of Bagasse. The refuse of sugar cane, known as bagasse, when burned in properly constructed furnaces is capable of generating most if not all of the steam required 1 1 f i -r> Ash axd Calorific Value' by a modern sugar factory. Bag- asse consists of woody fibre, sucrose, glucose, very small quantities of other solids including ash and con- siderable moisture. Proportions depend not only on the processes employed in milling but also on the quality of the cane as deter- mined by the locality where the cane is grown and its age at the time of cutting. Wet bagasse contains from 30 to 50 per cent, of fibre (to which most of the heat of combustion is due) and less than 10 per cent, of sucrose, glucose and other organic solids. The amount of moisture varies from about 40 to 60 per cent. As a rule, the ash in dry bagasse does not exceed I5 per cent. On account of the high moisture content of bagasse a much smaller proportion of the gross calorific value is available for the generation of steam than when the fuel is coal or oil. The practical fuel value is best determined by calculating the various losses and subtracting these from the gross calorific value. Assuming 80° F. as the temperature of bagasse as received, the same temperature for the air supplied for combustion, 500° F. as the temperature of escaping gases and .237 as the specific heat of dry gases, the heat carried away per lb. of dry gases is .237 (500-80), or 99.5 B. T. U. The loss of heat per pound of moisture, for .47 as the specific heat of steam, is 1237.8 B. T. U. as shown below. Sourre Per cent, ash in dry bagasse 1.19 Gross B. T . U. per lb. dry bagasse- Louisiana 8396 *' 1.26 8431 u l.U 8427 " 1.21 8340 a .96 83.50 i( 1.40 8283 it 1.44 8357 a .86 8318 i( .85 8409 Cuba .75 8431 u .76 8400 *' .83 8435 a .87 8650 " .78 8300 " .76 8380 Heating water to 212° requires 212-80, or 1.32.0B. T. U. Evaporating water into steam at 212° requires .... 970.4 Superheating steam from 212° to 500° requires .47 (500-212), or 135.4 Total heat loss per lb. moisture 1237.8 ' Prof. E. W. Kerr, Louisiana Bulletin No. 117, Agricultural Experiment Stations. '' By calorimeter. 114 EDGE MOOR WATER TUBE BOILER Assuming dry bagasse composed of 44.5 per cent, carbon, 6 per cent, hydrogen, 48 per cent, oxygen and 1.5 per cent, ash, the gases to the chimney for different percentages of excess air, assuming complete combustion, will be as follows: Table Showing Weicht of Gases pee Lb. Dry Bagasse Per cent, excess air 1.63 1b. .00 " 3.94 " 50 100 Carbon dioxide Free oxygen Nitrogen 1.63 lb. .59 " 5. 91 " 1.63 1b. 1.19 " 7.88 " Total dry gases \A'ater of formation from hydrogen 5.571b. .54 " 8.13 lb. .54 " 10 , 70 lb. .54 " Total gases per lb. dry liagas.se .... 6.111b. 8.67 lb. 11.241b. For the above conditions, 50 per cent, excess air and a gross calorific value of 8350 B. T. U. per lb. of chy bagasse the net heat convertible into steam per lb. of bagasse containing 50 per cent, moisture is determined by the following calculations. B. T. u. Gross calorific value per lb. wet Ijagasse equals 50 X 8350, or 4175 Dry gases per lb. wet bagasse equals .50 X 8.13, or 4.06 lb. Heat carried away by dry gases equals 4.06 X 99.5, or . 404 Moisture of formation from hydrogen cciuals .50 X .54, or 27 111. Free moisture in bagasse ...... .50 " Total moisture jier lb. bagasse 77 ll>. Heat carried away l:>y moisture equals .77 X 1237.8, or 953 Heat lost from radiation, conil>ustible in ash and incom- plete combustion of gases (assimred as 10 per cent, of the gross calorific value) , , 418 Total losses . . . , , 1775 Heat remaining for absorption by boiler ... 2400 Per cent. 100.0 9.7 22.8 10.0 42.5 57.5 FUEL VALUE OF BAGASSE 115 The results in the following tables were obtained by similar calcu- lations and by converting the heat remaining for absorption Ijy the boiler into pounds of equivalent evaporation and pounds of bagasse per boiler horsepower. For large boilers and efficient furnaces the loss of heat from radia- tion and incomplete combustion may be as low as 5 per cent, of the gross calorific value instead of 10 per cent, as allowed, but the latter more nearly represents this loss for average operating conditions. The ])er- centage of excess air will vary from 50 to 100 per cent, when furnaces are properly designed and given reasonably good attention. Equiv.vlicnt Evapou.vtion and Bagasse per Boiler Hoksei'ower for .50 Per Cent. P]xces.s Aih Per cent, moisture in bafj::isse 25 30 35 3.60 9.6 40 3.23 10.7 45 2.8.5 12.1 50 55 2 . 09 16.. 5 60 Kqiiiv. cvap. from and at 212° jior 111. wot bagasse, in llis. Wet Ijagasse per boiler horsejiower, in lbs. 4.3.5 7.9 3.97 8.7 2.47 14.0 1.72 20.1 Equivalent Evapor.'Vtion and Bag.-v.sse per Boiler Horkepower for 100 Per Cent. Excess Air Per cent, moisture in bagasse 25 30 35 40 45 50 ' 55 60 Equiv. evap. from and at 212° per lb. wet bagasse, in lbs Wet bagasse per l^oiler horsepower, in lbs 4.16 8.3 3.79 9.1 3.43 3.07 10.1|11.2 2.70 12.8 2.34 14.7 1.97 17.5 1.01 21.4 116 EDGE MOOR WATER TUBE BOILER Edge Moor boilers in the plant of the Society for Establishing Useful Manufactures, Paterson, N. J. Combustion ACCORDING to a well-established law of ehemistrj', there is a fixed and definite relation between the weight of a combustible and the weight of oxygen with which it unites during combustion. Composition of Air. — In boiler practice the oxygen recjuired for com- bustion is taken from the air. Besides those negligible substances such as ammonia, oxides of nitrogen, etc., there are present in air varying amounts, usually small, of car])on dioxide and water vajior. In the eastern states where the humidity often exceeds 75 per cent, at summer tem- peratures the percentage of water vapor may he as high as two per cent. Average proportions of oxygen and nitrogen in pure air free from moisture, as commonly given, are 20.91 parts oxygen to 79.09 parts nitrogen by volume, and 23.15 parts oxygen and 76.85 parts nitrogen by weight. The latter is erjuivalent to one pound of oxygen in 4.32 pounds of moisture-free air. Air Required for Combustion. — The only elementary combustibles in fuels that need be considered in boiler practice are carbon, hydrogen and sulphur. The oxj^gen antl air reciuired for their coml)ustion is given in the following table: Oxygen and Air Theoretically Required for Co.mplete Combustion Conibustil)le Profluct of ' ""S'R"! r''|iHr''il Moisture-free air combustion : P" P"U„;[ of per pound of combustible combustible Carbon ......... Carbon dioxide Plydrogen .......[ A\'ater Snlplmr ....... I Sulphur dioxide Air for Different Fuels. — If X represents the minimum weight of oxygen recjuired for combustion in pounds per pound of fuel then 2.G6-I- lbs. 11.5 lbs. s . on .34.(3 " 1 (Id 4.3 " X |c + s(h-^)+.s where C, H, and S represent the respective weights of carbon, hj'drogen, oxygen and sulphur in a pound of fuel. The accompanying weight of nitrogen will be 3.32 A'; and the weight of air, allowing 1 per cent, of water vapor, will be 4.36 A'. (117) 118 EDGE MOOR WATER TUBE BOILER The proportions of these elementarjr comljustiljles in the common fuels vary consicleraljly. Some analyses are given Ijelow. Variable Composition of Common Fuels Composition — moisture includec Moisture B. T. U. Fuel per lb. fuel per lb. as received Carbon Hydrogen Oxygon Sulphur Ash, elf. Nortli Dakota lignite 0.394 0.068 . 438 0.007 , 093 0.362 6,700 Colorado lignite . . .578 .060 .310 .004 .048 .207 9,941 Illinois bituniinoiis .(i09 .058 . 192 .037 .104 .127 10,989 Ohio liituniiiious . . 70.5 .0.54 .112 .029 .100 .052 12,733 Ppnns\'lvania bitinninous . 757 .0.54 . 103 .012 .t)74 . 035 13,700 Pennsylvania semi-bituminons . .807 . 043 .032 .014 .104 .012 14,096 West Virginia semi-bituminons . .843 .047 .052 .007 .051 .031 14,688 Pcnns\'lvania anthracite . . 752 .028 .041 . 008 .171 .021 12,472 California crutle oil .S(i6 .116 .000 .008 .010 .000 18,565 By means of the formula and air ratio given aliove the air for each of these fuels was calculated, as follows: Minimum Weioht or Air Required for Different Fuels Fuel North Dakota lignite Colorado lignite Illinois bituniinovis . . . . Ohio bituminous Pennsylvania bituniinovis Pennsylvania semi-bituminous . West Virginia semi-bituminous Pennsylvania anthracite California crude oil . . . . ,, , , Air per lb. -Air per 10,000 Air per lb. fuel co,„l',„stible B. T. U. in fuel Lbs. 5.0 7.5 8.4 9.7 10.3 10.8 11.2 9.6 14.1 Lbs. 9.2 7.54 9.9 7.. 53 10.8 7.66 11.2 7.63 11.3 7. 50 12.0 7 .65 12.1 7.65 11.9 7.06 14.2 7.59 It is seen that there is a wide variation in the air required per pound of fuel. The air per pound of comliustible is more uniform and the air per 10, (too B. T. U. is almost the same throughout. HEAT OF COMBUSTION 119 Heat of Combustion. — According to another law of chemical actic.in, a definite amount of heat is evolved when a unit weight of combustiljle undergoes oxidation, that is, is burned. This heat of combustion, usually called "calorific value" varies somewhat under (hfferent physical condi- tions, which accounts for the variations in the values obtained by different investigators and given in the text-l)Ooks. Approximate Calorific Values oy the Common Combustibles Combustible Carbon (C) . . . . Carbon (C) . Hydrogen (H) Sulphur (S) . . . . Carbon monoxide (CO) Ethylene {C^Hi) . . . Methane (CH4) . . . Product of ( [ibustii Carbon monoxide (CO) Carbon dioxiile (CO2) .... Water (H.>0) Sulphur dio.xide (SO2) .... Carbon dioxide (CO2) .... CaTbf>n dioxide (CO2) and water (HoO) Carbon dioxide (CO2) and water (H2O) Heat evolved per pound of eonibusfible 4,4.50 B. 14,.540 i)2,iy.il) 4,0,50 4,. 300 21,500 2.3,.5.50 T. U, Calculating Calorific Values. — It has been cstablishetl (see Technical Paper 70, 1914, Bureau of INIincs, p. 43) that the calorific value of anthra- cite, semibituminous and l)ituniinous coals can be calculated from an ultimate analysis to an accuracy of about \\ per cent, by means of Dulong's formula, as follows: B. T. V. per poimd = 14,.540 C -|- 62,0.30 [// — -) + 4050 S where C, H, and .S are, as before, the weights of carbon, hydrogen, oxygen and sulphur in a pound of fuel. The constants used in tlic above formula are equivalent to those recommended by a committee of the American Chemical Society {Jour. Am. Chem. Soc, vol. "21, p. 1130). The accuracy mentioned aljove is with reference to the calorific value obtained with a boml) calori- meter. This formula will not give such accurate results when applied to fuels rich in volatile matter as peat, lignite and crude oil. Importance of Ignition Temperatures. — Xo matter how much oxygen is brought in contact with a comlnistible it will not "catch fire" unless it is at or above a certain temperature. This temperature of ignition varies for different substances and, to a lesser extent, for the same substance under different physical conditions. This accounts for the variation in 120 EDGE MOOR WATER TUBE BOILER ignition temperatures given in different text-books. The following are the Fahrenheit equivalents of those given in Fiiel, by J. S. S. Brame. Combustible Temperature of ignition Hydrogen 1070 to 1090 degrees F. Carbon monoxide 1191 to 1216 " Methane 1200 to 1240 " Acetylene 760 to 825 " Bituminous coal 750 to SCO " Anthracite coal Appr. 925 " Every experienced fireman is aware of the difficulty of trying "to make steam" when the furnace walls are cold or when the fuel bed is in such bad condition that a large amount of excess air enters the furnace and chills the fire. The object of keeping the furnace hot is, of course, to keep the temperature well alcove the ignition temperatures of the solid fuel and volatiles. If carbon monoxide is not burned before the temperature falls below about 1200° F. then further combustion will not take place no matter how much excess air is present. The result is "the loss due to carbon monoxide." Reducing Fuel to Equivalent Gases. — In boiler and chimney calcula- tions it is often desiralilc to determine the weight and volume of gases involved. Practically, the true combustibles in the bituminous, semi-bitu- minous anil anthracite coals are total carbon, available hydrogen (H — ^) and sulphur. The proportion of available hydrogen to total carbon in coal is somewhere near one part available hydrogen to twenty parts carbon. On the assumptions that this proportion will be representative for the average coal, that the sulphur can ])c neglected, and that all carbon is burned to COo, the data in the next following table were calculated. Weight and Volume of Gas per Horsepower.^The weight of gas per boiler horsepower can lie determined approximately Ijy the formula 33480 w W = 10000 E where W is the weight of gas in pounds per hour per boiler horsepower, w is the weight of gas corresjjonding to an assumed CO2 from the table following and E is the efficiency of lioiler and furnace. The total water vapor in the gases, including moisture in coal and air and that formed from the combustion of hydrogen, amounts to only a few per cent, of the total weight except in extreme cases, and therefore may be neglected. CHIMNEY LOSSES AND PER CENT. COi 121 Weight of Gas and Chimney Losses for Different Percentages of CO2 Per cent. CO2 in dry gases by volume 18.7 18.0 17.0 16.0 15.0 14.0 13.0 12.0 Excess air in per cent, of theoretical minimum 4 10 17 24 33 43 54 Weip;ht of dry gas ])er 10,000 B. T. U. in the coal in lbs. 7.8 8.1 8.6 9,1 9.6 10.3 11.0 11.9 Chimney loss per 100° F. in per cent, of the cal- orific value of the coal 1.85 1 . 92 2.04 2.16 2.28 2.44 2.61 2.82 Chimney loss per 500° F. in per cent. , 9.25 O.f.O 10.20 10.80 11.40 12.20 13.05 14.10 Weight of Gas and Chimney Losses — Continued Per cent. CO2 in dry gases by volume 11.0 10.0 9.0 8.0 7.0 0.0 5.0 Excess air in per cent, of theoretical minimum 68 85 105 130 162 206 267 Weight of dry gas per 10,000 B. T. U. in the coal in llis. . 12.9 14.2 15.7 17.6 20.0 23.3 27.8 Chimney loss per 100° F. in per cent, of the cal- orific value of the coal 3.06 3.37 3.72 4.17 4.74 5 . 52 6.59 Chimney loss per 500° F. in per cent. . 15.30 16 . 85 18.60 20.85 23.70 27.60 32.95 The volume may be calculated from tlie formula 6.73 (t + 459.6) 1,000,000 W where Q is the volume of gas in cubic feet per second per boiler horse- power, t is the temperature of the gases in degrees Fah. and TT' is the weight of gases in pounds per hour per boiler horsepower. 122 EDGE MOOR WATER TUBE BOILER Effect of Excess Air on Boiler Efficiency. — Referring to the percentages of chimney losses given in tlie tiil)k> above it is seen that the loss per 500 degrees for 13 per cent. CO2, which may be taken as representative of good furnace conditions, is 13.05 per cent., while for 7 per cent. COo it is 23.7 per cent., or a decrease in efficiency of 10.65 per cent. Actually, the decrease is greater because, in general, the flue temperature rises when the excess air in the fimiace is increased, the rate of steaming remaining the same. Another detrimental effect of excess air is reduction of available draft liecause of the increased volume of gas passing through fuel bed, boiler, breeching, and chimney. The Three Factors of Efficiency. — Figuratively, the boiler is that part of the power jilant where money is burned to make power. From an economic standpoint it is therefore the place where the greatest saving can be effected and where the greatest waste is possible. The efficiency of the Ijoiler room may be represented l.iy the formula E = S X B XO where E is the all-over efficiency of the boiler room; S is the stoker effi- ciency including grate, stoker proper and furnace, and adaptability of the stoker to the fuel Ijurned; B is the l)oiler efficiency including boiler and setting; and is the operating efficiency including both firing and mainten- ance labor. If any one of these factors is low the all-over efficiency must be correspondingly l(jw. A high all-over efficiency requires high individual efficiencies for each of the three factors involved. Water and Steam WHERE heat is to Ije evolved in one place, transported and used in another, as in the steam plant, some carrier for the heat must be employed, since heat is transportable only when associated with matter. Of the substances that have been tried for this purpose water has proved to be preeminent because of its thermal properties, its fluidity, its abun- dance, and its low chemical activity. But water is not found in nature in the pure state, hence arise those complications for eliminating or neutral- izing the impurities which come under "feed water treatment". Effects of Impurities. — The oljjectionalile effects of impurities depend on the relative amounts of each present, on the aggregate of all impuri- ties and on the chemical or physical effects that one impurity has on another under the conditions that exist within a boiler. Impurities are usually reported in "grains per gallon", or "parts per million" l)y weight. Corrosion. — The term "corrosion" as used in boiler practice means the eating away of metal liy chemical action. When the metal is attacked only in spots, it is said to be pitted, when the action is the result of moisture in contact with exterior parts of the boiler, the metal is said to be " ru.sted". The most common causes of internal corrosion arc acids, dissolved carbon dioxide, air in solution or sucked in l)y the feed pump, chloride and sulphate of magnesium, sea water, grease, and sewage. Priming. — Since steam is generated in the midst of water, there is a tendency for ijarticlcs of water to cling to the bubbles of steam. The carrying over of water with steam is called "priming". In properly de- signed boilers using fairlj- good feed water the amount of water carried over with the steam will ordinarily not exceed one and one-half parts in a hundred by weight, or (roughly) one part in aljout 10,000 by volume. The steam is then said to be "dr}-". When the percentage of moisture by weight exceeds two or three per cent, the steam is said to be "wet" and the boiler is said to "prime". The water may go over as a spray, in "slugs", or in a continuous stream. When there are sudden fluctuations of the water level in the gauge glass, indicating violent disturbances of the surface of the water, "foaming" is said to take place. Usually, foaming is accomj^anied liy heavy priming. When the design of the boiler is not at fault, priming alone results from high concentrations of the readily solulile salts such as sodium chloride (common salt), sodium carbonate (soda a.sh), and sodium sulphate. Foaming is caused by accumulations of scummy matter at the water level, usually either from grease, sewage and other "(1133) 124 EDGE MOOR WATER TUBE BOILER organic matter, or through the cementing action of the carbonates of cal- cium and magnesium on the soUd particles in the water. Incrustation. — The impurities in water are either dissolved or held in suspension. When ordinar}' water passes into a boiler, the pure water is driven off and removed as steam, while the impurities, both dissolved and suspended, are left behind. Since there is a limit to the solubility of every substance, the excess of the soluble matter will be thrown down as "precipitates" which, together with the solid matter in suspension, will accumulate in different parts of the boiler as "incrustations". Certain substances, like the readily soluble salts are deposited as a sludge; others, like calcium carbonate, form a soft porous scale; while others, like the sulphate of calcium alone or in admixture with mud, oxide of silica, etc., bake on the boiler surface into a flinty scale which is very difficult and expensive to remove. Tube Failures. — Tubes sometimes fail from pitting or general corro- sion, but most often from overheating. The grades of steel used in the man- ufacture of tubes are excellent conductors of heat, but when these l:)ecome coated with substances that offer a high resistance to the passage of heat, such as hard scale or oil, the cooling effect of the water and steam on the inside of the tubes is grcatljr fliininished and the metal fjecomes overheated. This results in two kinds of destructive action: (1) The outside surface of the tube is attacked and eaten away by the steam and free oxygen in the gases of combustion; the result is a "burn" or "scab". (2) The metal becomes more ductile and is stretched ])y the internal pressure; the result is a "Itag" or "blister". When either kind of action is allowed to go far enough, the weakened metal will burst open, often with very serious results. This action usually takes place in portions of the two bottom rows of tubes nearest the fire, and nearly always in spots on account of the uneven distribution of the scale or oil. It is. therefore of prune importance not to allow more than a very little scale to accumulate in the tubes in these rows, and everj' effort should l)c made to keep oil and grease out of alioiler, because a very little is apt to cause serious trouble. If it is known or sus- pected that the tubes arc heavilj' coated with scale, or that oil has entered the boiler, the fire should be kept as low as possible until the boiler can be taken out of service. Treatment of Feed Water. — The various methods of treating feed water are classified as follows: (f) Filtration with or without the aid of some coagulant like alum for removing visible impurities. (2) Chemical METHODS FOR FURIFYJXG WATER 125 treatment within or witliout the boiler which precipitates or neutrahzcs the harmful impurities in sohition. (3) Heating of water, as in exhaust or live-steam heaters, which makes use of the precipitating effects of higher temperatures on the carl)onate and sulphate of calcium. (4) The use of sul:)stances like petroleum or graphite which form a thin coating on the metallic surface and prevent scale from adhering to it. (5) Combi- nations of two or more of the aljove, as in water-softening plants. There is no single remedy or "compound" that is effective for all boiler waters. In every case the remedy must be chosen with especial regard to the impurities in the particular water to be treated. Where the water is Ijad and the method of treatment is not satisfactory, the prol^lem should Ije submitted to a competent chemist or engineer wlio has had experience in tliis field. Use of Caustic Lime and Soda Ash — The substances most commonly used for treating feed water are caustic lime (CaO) and sodium carbonate (NaaCOs). Crude caustic lime is the same as "builders' lime". Impure carbonate of soda is known as "soda ash" or "crude soda". Caustic lime is much used for the precijiitation of the liicarbonates Ijefore the water is pumped to the Ijoiler. A typical reaction is as follows: C'ulciuni bicarbonate + Caustic lime = C'alciain carbonate + Water CaH.CCO.,).. + CaO = 2CaC03 + HoO The soluble ljicar))onate is reduced to the insoluble carljonate which is precipitated and can be removed liy filtration. Sodium carl)onate (soda ash) is used to precipitate certain sulphates, thus : Calcium sulphate + .Sodium carlionatc = Sodium sulphate + Calcium carbonate CaS()4 + Na,CO:, = NaoSOj + CaCOj The calcium sulphate, which will l)ake into a very hard scale if precipi- tated within the boiler, is chemically replaced l)y sodium sulphate which is very soluble and does not form scale. The calcium carbonate formed is precipitated and may be removed by filtration if the treatment is ex- ternal, or if the treatment is internal, as when soda ash is fed to the boiler direct, the calcium carbonate may be removed in part Ijy Ijlowing off. The residue will form a soft scale which is much less oljjectionable than that from calcium sulphate. Both cau.stic lime and soda ash are much used to neutralize acids; 126 EDGE MOOR WATER TUBE BOILER also, soda ash is very effective for removing oil from within a boiler. There is a limit to the amount of sotla ash that can be injected into a boiler without causing priming. Testing for Sea Water. — The objectionaljle effects of sea water are well known. In plants equipiDed with surface condensers and using sea water for condensing, it is common practice to check the tightness of the condensers once every hour or oftener bj' treating a sample of the condensate with a test solution of nitrate of silver, which can be bought at a drug store. Plants situated near the sea coast, and using river water for the boilers, sometimes get salty water during the dry season. When this occurs precautions should be taken to guard against priming and foaming cspeciall)'. To keep down the concentration of salt, the blow- off should be used frequently, once every four hours or oftener, when the amount of salt in the water has reached about 600 grains joer gallon. The blow-off should he opened quickly when piping conditions permit and should be left open only a few seconds at a time. The most practical way to determine the concentration is with the instrument used to deter- mine the specific gra^'ity of liquitls — the hydrometer. 600 grains per gallon corresponds to a specific gravity of about 1.01, or to about 1.5 degrees Baume. Boilers using salty water should not be forced, as objec- tionable results are increased thereby. Where to Sample Water. — It is oljvious that the ciualitj' of water within a boiler may lie very different from the water delivered to it l)y the feed iiumji on account of continuous concentration and the chemical effects which take place at the higher temperatures. Hence, to deter- mine the cause of troublesome results from feed water, the sample must be representative of the water in circulation within the boiler. It is recom- mended that samples of water from Edge ^Nloor boilers be drawn through the lower water-column pipe, the mouth of which is in the active part of the drum, either liy means of a special connection, or through the water-cohnnn drain. The water column should be blown out thoroughly immediately Ijcfore taking a sample. The sample should be taken while the boiler is in active service, when the impurities will be distributed throughout the water. Steam Calorimeters. — The percentage of moisture in steam, if any, is determined by means of a steam calorimeter. The throttling type is used when the percentage of moisture will not exceed about 4 per cent. Ijy weight for pressures of 100 pounds and over. For moisture in excess of this the separating calorimeter must be used. Since steam MOISTURE IN STEAM 127 containing more than 4 per cent, of moisture would hardly be tolerated in a modern plant the throttling calorimeter alone is ordinarily sufficient for testing purposes. Both construction and theorj' of the throttling calorimeter are very simple. It is merely an orifice with provision for determining temijera- ture or pressure of the steam, or both, before and after passage through the orifice, and it is constructed mechanically to minimize the loss of heat by radiation and conduction. By the law of conservation of energy, the heat on both sides of the orifice must be the same (assuming no loss); hence the formula H - U - k it - Q X = 100 H where x is the percentage of moisture in the steam by weight, H the total heat above 32° F. of one pound of saturated steam at the initial pressure, U the total heat above 32° F. of one pound of saturated steam at the final pressure, k the specific heat of superheated steam at the final pressure, t the observed temperature of the steam discharged from the calorimeter in degrees F., t„ the temperature in degrees F. corresponding to saturated steam at the final pressure, and h the heat of the water above 32° F. at the initial pressure. If the discharge is into the atmosphere at a pressure of 14.7 His. per sq. in., [/ = 1150.4, k = 0.47 appr., and <„ = 212. The formula is then H - 1150.4 - 0.47 (t - 212) .^100 --^- H and h. maj' be taken directly from Marks and Davis steam tables. Determining the Source of Priming. — Because wet steam is received at an engine, it docs not necessarily follow that the moisture originates at the boiler. In several investigations made by our engineering depart- ment where there was unmistakable evidence of very wet steam, the cause was traced to defective drainage of the steam piping and the "priming" stopped as soon as the drainage was corrected. The proper instrument for determining moisture is, of course, the throttling calorimeter but such an instrument, or several of them, is not always available. In lieu of this an ordinary J in. air cock can be used. To illustrate, suppose very wet steam is received at the throttle of an engine and it is desired to find where the moisture originates. The first 128 EDGE MOOR WATER TUBE BOILER suspicion would probably be directed to the boiler. Therefore tap a hori- zontal section of the steam pipe near the boiler nozzle at the sides or top, but not at the bottom, and install a j in. air cock. With the boiler in service open the cock until a jet of steam flows freely and observe the character uf the discharge. If the steam within a pipe does not contain more than a few per cent, of moisture, the discharge into the atmosphere will become superheated on account of the reduced pressure. Now suiDerheated steam is almost colorless and feels cool and drj^ when the hand is passed through it, but wet steam will burn the hand and, of course, looks wet. To observe this, install the cock where steam is knowai to be practically dry or superheated but interpose a piece of j in. pipe about 18 inches long between the steam pipe and cock. Wrap some lagging around the J in. pipe, open the jiet cock and let the steam flow until the pij^e is thoroughly heated. The discharge should he as described above for superheated steam. Then remove the lagging and pour cold water on the j in. pipe to chill the steam inside. The change in the nature of the discharge will be uuniistakulile. Returning to the assumed case, if the steam at the boiler is found tt) Lie dry then install one or more cocks along the steam line, and try each until the source of the trouble is found. A "dip" in the piping is a frequent cause of wet steam. Properties of Saturated and Superheated Steam' Miirk.s and Davi.s Temperature in degrees Fahrenheit T Temperature Fahrenheit absolute T +459.6° Specifie vokime in cubic feet per pouml V Total heat per pouml above 32° in B. T. U H Press. Gauge .bs. Abs. 85.3 100 90.3 105 95 . 3 110 100.3 115 105.3 120 110.3 125 115.3 130 120.3 135 I T 327 . 8 0.02 298 . 3 331.4 0.02 302 . 334 . 8 0.02 305 . 5 338.1 0.02 309 . 341.3 0.02 Sat. Stoan Supt^rheated .Steam — Degrees of Superheat 70° 80° i 90° 100° : 110° I 120° 130° 327. S 377.8 387.8 397.8 407 . s 417.8 427.. s 4.43 4.79 4.80, 4.93 5.00 5.07 5.14 1 180 .3 1213 .8,1219 . 1 1224 . 3,1229 . 5 1234 . C 1239 . 7 331.4 381. 4J 391. 4I 401.4' 411.4 421.4 431.4 4.23 4.58 4.05 4.71 4.78 4.84 4.91 1187.2 1214.9 1220.2 1225.4 1230.0 1235.7 1240. s 437 . 8 5.21 1244.7 447 . -x 5 , 27 1249 . 7 441.4 451.4 461.4 4.97 5.04| 5.10 1245.9 1250.9 1255.9 457 . 8 5 . 34 1254.7 334 . 8 4.05 1188.0 338 . 1 3 . 88 1188.8 341.3 384.8 394. s 404.81 414. s 424.8 434 , s 4.38| 4.45, 4.5l| 4.57 4.04 4.70 1215.9 1221.2 1220.5 1231.7 I23U.9 1242.0 388. 1' 398.1 1 408. r 41,s.l 428.1 43S,1 4.20| 4.27! 4.33 4.39 4.45 4.51 1216.9,1222.3 1227.6 1232. s 1237.9 1243.1 444.8 4 . 7(5 1247.1 448 . 1 4.57 124N.2 454 . 8 4 . S3 1252.1 45N.1 4 . 03 1253.2 464.8 4.89 1257.1 468 . 1 4 , 69 1258.2 391.3 401.3] 411.3' 421.3 431.3 3.73' 4.04 4.10 4.10 4.22 4.28 441.3 4.33 H 312.3 1189.6 1217.9 1223.3 1228.6 1233.8 1238.9 1244.1 344.4 0.02 315.5 125.3 140 r 347 . 4 130.3 135.3 0.02 318.6 350.3 0.02 321.7 451.3 4 . 39 1249.2 4111.3 4 , 45 1254.2 471.3 4 . 50 12.59.3 T V H 353.1 0.02 324 . 6 T V H 355 . 8 0.02 327.4 145 150,T,3.5S.5 V, 0.02 :Hi.330.2 344.4' 394.4 404,4' 414.4 424. 4j 434.4 444.4 3.5sS 3.88| 3.94! 4.00] 4.061 4.11' 4.17 1190.3 1218.8 1224.2 1229 .54234 .s 1240.0 1245.1 347.4' 397.4 407.4 417.4 427.4 437.4' 447.4 3.45] 3.74 3. .SO 3..S5 3.91 3,96 4,02 1191.0 1219.7 1225.1 1230.4 1235,7 1240.9 1246.1 350.3 400.3! 410 3' 420.3! 430,3 440, 3| 4.50,3 3,. 33 3,01 3.07 3.72 3,77 3.. 83: 3.,SS 1191.01220.6 1226.1 1231.4 1230.6 1241.8 1247.0 353.1 403.1 413.1 423.1 433.1 443. ij 4.53.1 3.22' 3.49 3,54 3.00 3.65 3.70 3.75 1192 2 1221 4 1226.8 1232.2 1237.5 1242.8 124s, I'll .355. Sl 405.8 415.8 425.8 435.8 445.8' 455. s 3.12 3.38' 3.43 3.48 3.53 3.58 3.03 1192 8 1222.2 1227.7 1233.1 1238.4 1243,6 124S.S 358. 5| 408.5 418.5 428.5, 438.5 3.01' 3.27 3.32 3.371 3.42 1193.4 1223.0,1228.5 12.33.9 1239 .2 448.5 45s, 5 3.46' 3.51 1244.4 1249.6 454.4 4.22 12.50.2 457.4 4.07 1251.2 1 460.3: 3,93' 1252.1 463 , 1 3 , 80 1253.1 465.8: 3.68! 1254.0, 468.5 3.56| 1254.8 464 . 4 4.2s| 12.55.3 467 . 4 4, 13 1256.3 i 470,3 3 , 98 1257,2 473,1 3 , S5 125.S.2 I 475 . 8 3.72 1259.1 47s . 5 3.61 1259.9 474.4 4.33 1260.4 477.4 4,18 1261.4 480 . 3 4 , 03 1262,3 483 . 1 3.90 1263,3 485 , 8 3.77 1264,2 488 , 5 3.66 1265.0 ' Ab.-stracted by permission from "Steam Tables and Diagrams" (copyright) by Marks and Davis. Publrshed by Longmans, Green & Co. (129) 130 EDGE MOOR WATER TUBE BOILER Prras. Lbs. Gauge Abt 140 . 3 lo.5 T 361.0 V| 0.02 H 332.9 150.3 Sat. Steam 301. 411. 0| 421.0 2.92 3.171 3.22 .Superheated Steam — Degrees of Superheat 431.0, 441.0 3.27 3.31 451.0 461.0 471.0, 481.0, 491.0 3.361 3.41 3.46 3.5ol 3.55 1194. 04223. 6jl229. 2 12.34. 7|1240.0 1245.2 1250.5 1255.7 1260. S 1265.9 145.3 160 t'363.6 303.6 413.1): 423.6, 433.6 443.0 453.6 463.6 473.6 4.S3.6, 493.6 Vj 0.02 2.b3i 3.07| 3.12| 3.17| 3.2l| 3.26' 3.3o| 3.35| 3.40, 3.44 Ih 335.6 1194.5 1224.5 1230.0 1235.5 1240. s 1246.1 1251.3 1256.5 1201.6 1206.7 105 T 306.0 306.0 416.0 426.0 430.0 440.0 456.0 466.0 470.o'4,s6.0 496.0 V: 0.02, 2.75, 2.99, 3.04 3.0,s, 3.12 3.17 3,21 3.26 3.30 3.35 !h'33S. 2, 1195.0 1225.2 1230.7 1236.1 1241.5 1246. ,s 1252.0 1257.2 1202.3 1267.4 155.3 170, T 308.51 368.5 418. 5| 428.5 438.5 V, 0.02' 2.08 2.91 2.95 3.00 448.5' 458.5 468.5 47N.5 488.5 498.5 3.04 3.08 3.12 3.17 3.2l' 3.25 'h 340.7 1195.4 1225.9 1231.5 1237. 04242. 3'l247. 1252. s 125N.0 1203.1 1268.2 ! ' ! I I ' 160.3 175 T 370.. s 370.8 420. .s 430.8 440. 8j 450.8 460.8 470.8 480.8 490.8, 500.8 \\ 0.62 2.(i0 2. .83 2.87 2.91^ 2.96, 3.0o' 3.04,' 3.08,1 3.12' 3.16 ,H 343.2 1195.9 1226.0 1232.2 1237.7 1243.0 1248.3 1253.6 1258.8 1263.9 1269.0 165.3 I.SO T 373.1 373.1 423.1 433.1 443.1 453.1 463.1 473.1 4.s,3 . 1 493.1 503.1 \\ 0.02 2.53 2.75' 2. .so 2,84; 2.88 2.921 2.90! 3.0U 3.04' 3.08 H345.(i 1190.4 1227.2 1232.8 1238.4 1243.8 1249. 11254.3 1259.5 1264.0 1269.7 1.85 T 375. 4 375,4' 425.4 435,4 445,4 455,4 465,4 475.4 485.4 495,4 505,4 A", 0,02 2.47| 2.68| 2.72, 2.76 2.81, 2..S5, 2,89 2.93 2.97, 3.01 H 348.0 1190.8 1227.9 1233.5 1239.0 1244.4 1249.7 1255,0 1200.2 1205.3 1270.5 ! I J I ' i I > I I 175,3 190X377,6 377,6 427,0 437,6 447. 0| 457,6 4()7.6 477,6 487.6 497.0 507.6 V 0.02 2,41 2,02 2,110 2.70| 2.74 2,78 2.81 2,85 2,89 2.93 ;H 350.4 1197.3 122s. 1234.3,1239.8 1245.1 1250.4 1255.7 1200.9 1200.1 1271.2 180.3 195 T 379, s^ 379. 8| 429 , s 439.. s 449.8 459. 8| 469,8 479.8, 489,8 499 , s 509.8 "\', 0.02J 2.35' 2 55 2,59 2.63 2,07 2.71 2,75 2.78 2.82 2.86 H352.7|1197.7J1229,2 1234,9 1240.4 1245, s 1251.1 1250.4 1261.6 1266.7 1271.9 185,3 190, 200T381,9 3.sl,9 431.9 441,9 451,9 461,9 471,9 481.9 491,9 501,9 511,9 V 0.02 2,29 2,49 2,53 2,57 2,01 2,64 2.08' 2,72 2.76 2.79 |H354.9,119S.1 1229, s 1235,5 1241.1 1246.5 1251, ,s 1257.1 1202.3 1207.4 1272.5 III' ' I ! 205T3.S4,II 3,s4,(i 4:il,0 444.6 454.0 464,(1 474, o' 4,S4,(1 494.0 504.0 514.0 |V 0.02 2,24| 2,44 2,47i 2,51 2.55 2,58, 2,02 2,60! 2,09 2,73 j H 357.1 119.S.5 1230,4 1236, 1 1241,7 1247. 1 1252,4 1257.7 1262.9 1268.0 1273.2 195.3 210X380,(1 386,0 430.0 440(1 450(1 400,0 476,0 4.86.0; 496.0 500.0 510.0 V| 0,(J2 2.19 2,38 2,42 2.45 2,49, 2,53 2.56, 2.601 2.63 2.67 !h 359.2 119S..S 1231.0 1236. 7;1242, 3 1247.7'l253 . 1 1258.4 1263,6 1268.7 1273.8 200 . 3 205 . 3 215'X3SS.0 3SS,0' 43S.0 448,0 45s , 40s, 47s, 488,0 49,s,0 508,0 518.0 V 0,02 2,14 2,33 2,36 2,40 2,43 2,47 2,51 2 . .54 2,57 2,61 ;'H 361,4 1199,2 1231,6 1237.3 1242.9 1248,3 1253,7 1259,0 1264.2 1269.3,1274.5 220X3.S9,9 3S9,9 439,9 449,9 459,9 469,9 479,9 489,9 499,9 509,9 519,9 V 0,02 2,09 2,2s 2,31 2,35 2,3s 2,42 2,45 2.49' 2.52 2 , .55 |H3(.i3,4 1199,0 1232,2 1237,9 1243,5 1248,9 12.54,3 12.59,6 1204.8,1269.9,1275,1 PROI'ERriES OF STEAM 131 Press. Lbs. Gauge Abs. Water Sat. Steam 210.3 225 T391.9 391.9 V H Superheated Steam — Degrees of Superheat 50° 60° 70° j 80° 90° 4S1.9 100° 110° 120° 1.50° 441.9 451.9 461.9 471.9 491,9 501.9 1 511.9' 521.9 0.02 2.05 2.23' 2.20 2.30 2.33 2.37 2.40 2.43 2.47 2.50 305.5 1199.9 1232.7 1238.5 1244.1 1249.5 1254.9 1200.2 1205.4 1270.5 1275.7 215.3,230 220.3 235 225.3 ;30.3 235 . 3 240.3 245 . 3 240 245 250 200 ' I ' I 393.8, 393.8 443.8 453.8 463.8, 473.8! 4S3.8 493. S 503.8 513.8 523.8 O.O2I 2.00 2.18| 2.22I 2,251 2.28 2.32! 2.35. 2.38! 2.42 2.45 367.5,1200.2 1233.2 1239.0 1244.7 1250. 1 1255.4 1260.7 1260.0 1271.1 1276.3 I 1 I i , 395.0 395.6 445.6 O.O2I 1.90,' 2.14 369.4 1200.0 1233.8 455.0, 465.0 475.6' 4S5.6; 495. 61 505.6 515.6 525.6 2.171 2.21' 2.24' 2.27, 2.30' 2.34 2.37 2.40 1239.6 1245.2 1250.7 1250.1 1261.4 I20().0 1271.7 1276.9 I 397.4' 397.4 447.4 457. 4' 467. 4| 477.4 O.O2I 1.92 2.09 2.13! 2.10! 2.20 487.4 497.4 507.4 517. 4| 527.4 „.„„ _„„ , ...„, _.^„, 2.23' 2.20 2.29i 2.32! 2.35 371.4 1200.9,1234.3 1240.1 1245.8 1251.3 1256.6 1201.9 1267.1 1272.3 1277.5 449.3' 459.3 469.3' 479.3' 489.3 499.3; 509.3 519.3; 529.3 399.3 399.3 0.02 1.89 373 2.05 2.09 2.12 2.18 2.22 2.25 2.28 2.31 1^ J. . oy *i . \J'J\ ^ . yjzf ^.iw .^.i<_»| w.i'-' ^.^^1 ^ . ^-j j-i . j^'j}\ j^ . •jx. 3 1201.2 1234.8 1240.7 1240.3 1251.8 1257.2 1202.5 1207.7 1272.8 1278.0 401.0 451.0 401.0; 471.0 481.0 1.85| 2.02 2.05 2.08 2.11 401.0 0.02 .... _.„ .,_, ..__, _ 375.2 1201.5 1235.4 1241.3 1246.9 1252.3 1257.7 T|402.8 402.8 452.8 V| 0.02 1.81 1.98 H377.1 1201.8 1235.9 .'404.5' 404.5 454.5 0.02 1.78| 1.94 462 . 8 2.01 1241.8 491.0, 501.0, 511.0 521.0! 531.0 2.17| 2.21J 2.24| 2.27 1263.0 1208.2 1273.4 1278.0 2.14 472.8 482.8! 492.8 2.04I 2.07I 2.11 502.8 512.8 522.8 532.8 , I 2.14 2.17t 2.20I 2.23 1247 . 4 1252 . 9 1258 . 3 ' 1203 . (i 1208 . 8 1273 . 9 1279 . 1 464.5! 474.5 484.5, 494.5 504.5 514.5 524.5! 534.5 2.00' 2.04 2.07 2,10 2,13 2,10' 2.19 H378 9 1202.1 1230.4 1242.3 1247.9 1253.4 1258.8 1204.1 1209.3 1274.5,1279.6 1.97 250.3 205 T !V ! H 400.2 0.02 400.2 1.75 456.2 466.2 476.2 486.2' 490.2 506.2 516.2 526.2 5.36.2 I.91I 1.94! 1.97 2.00 2.03 2.00 2.09| 2.12 2.15 380.7 1202.3 1230.9 1242.8 1248.4 1253.9 1259.3 1204.0 1269.8 1275.0 1280.1 Factor of evaporation H — h 970.4 where H is the total heat as given m the table.s and h is the heat in the feed- water entering the boiler, h is almost equal to the temperature of the water, in degrees Fah.. minus 32. Proportioning Flues and Chimneys IN 1884 William Kent published a simple formula for proportioning chimnej'S for coal burning plants, together with a table of chimney capacities calculated therefrom (Trans. A. S. JNI. E., vol. vi, p. 81). When this table was published, and for manj- j-ears afterward, coal was almost universally hand fired with natural draft and boilers were not operated Chimxey Sizes by Kent's Formula 30 33 36 39 42 48 54 15.90 427 60 19.64 536 6(i 23 . 76 72 2S.27 7S 33 . 18 84 38.48 90 44.18 96 50 . 27 102 56 . 75 108 63.62 114 70.88 120 78 . 54 132 95.03 144 113.10 100 4.91 113 5.94 141 7.07 173 8.30 208 9.62 245 12.57 330 119 149 182 219 258 348 449 565 694 835 Height in feet. 110 ' 125 1 1.50 17.5 I 200 250 I 300 156 191 229 271 365 472 593 728 876 1038 1214 ^ Comnierci;il boiler horsepower 204 245 268 289 316 342 389 426 .460 .503 551 595 632 692 748 776 849 918 934 1023 1105 1107 1212 1310 1294 1418 1531 1496 1639 1770 1712 1876 2027 1944 2130 2300 2090 2399 2592 2685 2900 2986 3226 3637 3929 4352 4701 492 636 800 981 1181 1400 1637 1893 2167 2459 2771 3100 3448 4200 5026 6(5 848 4455 5331 894 2008 I 2116 2298 j 2423 2609 2750 2939 3098 1040 1097 i 1201 1253 I 1320 I 1447 1485 , 1565 1715 1736 ! 1830 2005 2318 2654 3012 3393 3288 3466 3797 3657 3855 ' 4223 4696 5144 5618 6155 *Bascd on five pounds of coal Inirncd per hour per Bl. H.P. For limitations see Kent's Handbook. ( 132 ) PERFORMANCE OF CHIMXEYS 133 at much above rated capacity. For this practice, with medium grade bituminous coal and short direct flues, chimneys according to Kent's table have generally given satisfactory results. Later developments in boiler plant practice have introduced complex factors which vary greatly for the same boiler horsepower developed. Fuels other than coal have come into extensive use; the hand firing of coal has been largely superseded by mechanical stokers with both natural and forced draft; boilers of different types, and the same boiler differ- ently baffled, have friction losses which are far from uniform for the same volume of gases passing through the setting; and maximum rates of steam generation per square foot of heating surface have increased from two to three times the customary rate when Kent's formula was deduced. As a consecjuence other methods have been suggested for determining the size of a chimney. For the general case, because of the great variation in the factors involved, there can be no simple relation between the size of a chimney and either the maximum amount of fuel which can be burned through its draft producing power or the maximum amount of steam which the boilers connected to it can generate. Since a chimney is analogous to an induced draft fan, which sucks gas through a series of complex conduits and discharges it into the atmosphere, methotls have been suggested for proportioning a chimney based on the laws conunonly used for the trans- mission of fluids. Because the density of the hot gases within a chimney is less than the density of the surrounding air a chimney produces a suction, or draft, which induces gas to flow into it. Di-aft is the same as pressure difference and may be expressed in any unit of i^ressure. The common unit is the inch of water column and the common instrument for measuring it is the draft gauge, which is made in various forms. Maximum Draft of a Chimney.— If a draft gauge is connected to a chimney just above the point where the gases enter, the draft indicated is the effective draft of the chimney. If the flow of gases could be gradu- ally reduced without altering the temperature of the gases, so as to dim- inish the loss by friction in the chimney, the draft indicated would increase and become a maximum when the flow is zero. This maximum draft of the chimney depends primarily on the tem- perature of the external air, the temperature of the gases entering the chimney, the height of the chimney and the altitude of location. Wind, humidity, variation of the barometric pressure from the normal, varia- 134 EDGE MOOR WATER TUBE BOILER tion in tlic composition of gases and cooling of gases in the chimney also affect the maximimi draft, but generally to a minor extent. In practice it is customary to determine the maximum draft from temperature of air, temperature of chimney gases, altitude and height. This may be obtained from the accompanying curves (taken from Trans. A. S. M. E., vol. 37, pp. 1075, 1076). c 1000 900 C-) 800 700 o 60O Q) L -3 -4- 500 r> L 400 5= l, / / ( o 7 y y / 1 ^/ [few r-y h / / / / w ^/ " / V ' / 1 / /^/ / / / / / / / / / f r / / y ' / / / / / / r <. /> / 1 / / / / / /, / / / / / / / / / / / y / / / / / / / / / / < K / / / / y y 'A y /' ^ y y A y^ ^ f^ ^ y y' y ^ y ^ 200 0.10 0.20 030 O40 050 0.60 070 O.&O 0.30 1.00 1.10 1.20 Draft In In of Wcifer M.txiMUM Draft at Sea Level per 100 Ft. of Chimney Height Corresponding TO the Air TE.MPEK.ATrifES XOTED ON THE CuRA'E.S For any other heiiiht // in ft. niultipl.v by 0.01 // For any otlier altitude, multiply by the corresponding factor of correction from the cur^'e below. Elevation above Sea Level inft- 900 1,800 2.B0O 3,600 4.600 BOO 7.0Q0 g.tOO 9.400 IQ.tiOQ Za Z7 -26 25 24- 23 22 Barometric Pressure in in. of Mercury Factors of Correction for Maximum Draft Above Sea Ije-^-el CONSUMPTION OF MAXIMUM DRAFT 135 For example, the maximum draft per 100 ft. of heiglit at sea level for an air temperature of 80° F. and gases at 550° F. is 0.63 in. from the draft curves. A chimney 200 ft. high would therefore produce a maximum draft of 2 X 0.63 or 1.26 in. For an elevation of 5900 ft. above sea level the factor of correction is 0.8 and the chimney would therefore produce a maximum draft of 1.26 X 0.8 or 1.01 in. The consumption of the maximum draft produced by a chimnej^ is illustrated in the drawing which follows. PT^" i iff — w\^ — R ,. B Typical Aeranuement of a Boiler Plant Showing Draft Losses The gauge / indicates the draft in the furnace, which is equal to the draft loss from the boiler room to the furnace irrespective of whether air for combustion is supplied by natural or forced draft. The difference between the readings of gauges d and/ indicates the draft loss through the boiler, the difference between gauges z and d indicates the draft loss through the Ijoiler damper frame, R represents the draft loss in the flues and C the draft loss in the chimney. The effective height of the chimney, H, is shown as the height above the boiler damper since vertical components of the flue may be considered a part of the chimney on account of their 13G EDGE MOOR WATER TUBE BOILER draft producing power. The structural height of the chimney may be higher by twenty feet or more but this extension has no draft producing power. Effective Draft and its Utilization.— The effective draft of a chimney is its maximum draft less the draft loss in the chimney. This effective draft is consumed in furnaces, boilers and flues, to accelerate the gases to the ultimate velocity of discharge, to overcome all friction Ijetween gases and contact surfaces and to overcome the loss of pressure from eddies in the gas stream. In practice, the effective draft of a chimney must ecjual the sum of the following: (a) The draft in the furnace. (b) The draft loss from furnace to boiler damper ("draft loss through the l.)oilcr"). (c) The draft loss through the boiler damper frame. id) The draft loss through the economizer, if any. (e) The draft loss in the flues between boiler damper and chimnej^. The sum of these is the draft required at the entrance to the chimney. Where more than one boiler is served by a single chimney only one path- way from a boiler to the chimney need be considered but the boiler selected should be the one which reciuires the highest draft at its outlet or is situated furthest from the chimnej^. The other boilers may have too much draft but this can be overcome by partly closing the dampers. Allowances for Operating Conditions.— The data for proportioning a chimney should be based on the least favorable conditions for generating the required amount of steam continuously with reasonable upkeep of equipment. The average drafts and draft losses observed in boiler tests should be increased by an amount sufhcient to allow for poorer fuel and less efficient firing, which may be expected at times. But if the allowances are too liberal the corresponding size of chimney not only involves a waste of investment but may also cause a waste of fuel as a consequence of excessive draft. This is especially true when the fuel is oil. Draft Required in the Furnace.— This is the draft required to produce or to assist in producing the desired combustion. For boilers fired with steam atomizing oil liurners furnace drafts for 150, 200 and 250 per cent, of rating may l^e assumed at .10 in., .15 in. and .25 in., respectively. For most of the forced draft underfeed stokers a furnace draft of .10 in. is ample for all rates. For natural draft stokers and hand fired grates there is a wide variation for different ratios of heating surface to grate surface, for different sizes of openings in the grates and for tliffcrent grades of DRAFT LOS.SES 137 coal; hence the furnace draft to be allowed should be obtained from the builder of the firing equipment. Draft Loss through the Boiler.— For the same volume of gases from the furnace the draft loss through a boiler varies principally with the size and arrangement of tubes and the number of passes. The allowances in the following tables will ordinarily be ample for Edge Moor boilers with a superheater above the first and second passes. The actual losses observed during efficient operation will be less than the tabulated allowances, since the latter arc for abnormal percentages of excess air. With oil, the air entering the furnace is easily controlled, and hence the allowances may be less than for coal. Draft Loss Allowances for Three-pass Edge Moor Boilers WITH 18 Ft. Tubes and Superheater Maximum perccntaf^e of ratini; to be developed. 125 130 200 250 Draft loss allowance for coal, in, of water column Draft loss allowance for oil, in. of water column .35 .20 .4.5 .2.5 .65 .45 .80 .65 Draft Loss Allowances for Four-pass Edge Moor Boilers WITH 20 Ft. Tubes and Superheater Maximum percentage of rating to be developed. 125 150 200 260 Draft loss allowance for coal, in. of water column Draft loss allowance for oil, in. of water column . .50 .25 .65 .40 .85 .65 1.00 .85 Draft Loss through the Boiler Damper Frame. — For maximum evapo- ration the damper is, of course, assumed to be wide open. As a rule, the 138 EDGE MOOR WATER TUBE BOILER damper frame is of such liberal proportions that the draft loss through it is negligiljle, but this may not always be the case. Draft Loss through the Economizer. — In general, when economizers are installed an induced draft fan must be included, because the total draft required cannot be produced by a chimney of desirable height on account of the low temperature of the escaping gases. But for moderate overloads and firing equipment which requires a low furnace draft a chimney may be used. For such cases the draft loss through the economizer should be obtained from the builder. Draft Loss in Flues and Area of Cross Section. — The total draft loss should include the loss from friction in the straight parts and the loss from turns, including the turn into the chimney. When the gases are discharged from a flue into a chimney of much smaller cross section a considerable loss of draft will result from accelerating the gases into the latter. When the cross section of the flue is 20 per cent, greater than the cross section of the chimney this loss theoretically amounts to about .05 in. of water column. Flues are generally proportioned so that the loss in the straight parts will be al)Out .10 in. per 100 ft. of length. Other conditions remaining the same the draft loss varies with the weight of gases transmitted. For coal burning plants an allowance of 80 11). of gas per horsepower developed should ordinarilj- be ample for 150 per cent, of rating and 60 lb. of gas per horsepower developed for 200 per cent, of rating. Both assumptions reduce to 120 lb. of gas per rated horsepower. From the published formulce for draft losses in flues and from these gas weights the cross-sectional areas of unlined steel flues can be determmed. These areas, allowing a draft loss of .10 in. per 100 ft. of length, are given in the following table, together wth the losses from turns. Size of Flues and Draft Losses for Ratings up to 200 Per Cent. For Coal Ratoil II. P. of l)oilers. Area of vitilincd sti>el flue in sq. ft Draft loss per 00° (urn, in, of water column .... Draft loss per 4.5° turn, in. of water column 250 ! 500 10. (i .05 IS. !.5.6 .00 I .07 .01 I .02 .02 1000 1500 2000 .3000 4000 32 2 44.6 .3(1 . 1 77. G 97.7 .08 .10 .11 .13 .15 .02 .03 .03 .04 .04 DRAFT LOSS IN FLUES 139 For 250 per cent, of rating the tabulated areas should he multiplied bj' 1.12. When the fuel is to be oil the tabulated areas may be multiplied by .8 for 150 per cent, of rating, by .9 for 200 per cent, of rating and taken the same as the tabulated areas for 250 per cent, of rating. If a flue is to be of brick or concrete the area for an unlined steel flue should be multiplied by 1.13. For these larger areas the draft loss from turns will be approx- imately eight-tenths of the tabulated losses. The draft loss in a rectangular flue with sides in the ratio of I5 to 1 will be only 2 per cent, greater than in a square flue of the same area. For sides in the ratio of 1 to 2 the loss will be G per cent, greater and for sides as 1 to 3 th(! loss will be 16 per cent, greater. This refers only to the draft loss in the straight parts — the draft losses from turns are theoretically the same. Hence areas as above may be of such shape as to best meet local requirements, but for a given area a square flue will be cheaper than a rectangular flue with uneciual sides. Example: An installation is to consist of four 500 H.P. boilers, set side by side, to operate at a maximum of 200 per cent, of rating with coal. An unlined steel flue is to run directly above the boiler uptakes and chscharge into the chinnu'y at an angle of 45°. The length of flue, from the center line of the end boiler to the chimney, is to be 70 ft. Starting with the end boiler, the cross section of the flue just beyond the first uptake should have an area of 18.5 scp ft. The area should increase gradually to just beyond the last uptake where it should be 56.1 sq. ft. From here to the chimney the area should remain the same. The draft losses to be allowed will be as follows: Loss due to length of flue = .7 X .10 in. or 07 in. Loss from 90 " turn, uptake to flue 06 in. Loss from two 4.5° turns into eliinmey 06 in. Acceleration loss if cross sectional areas of flue and chinniey are to be about equal 00 m. Total draft loss due to flue 19 in. General Formula for Diameter and Height of Chimney.— The general formula for the diameter of an unlined circular steel chimney at sea level is J0000172 T (H.P.)' ir- d = 140 EDGE MOOR WATER TUBE BOILER where d is the inside diameter of the chimney in in., T is the absolute temperature of tlie cliimney gases (equals temperature in deg. F. + 460), H.P. is the maximum boiler horsepower to be developed, W is the weight of gases passing through the chimney in lbs. per hr. per H.P. developed, and p is the draft loss per 100 ft. of height in in. of water column. To obtain the diameter of a circular brick or brick-lined chimney, d should be multiplied l)y 1.06. Calculations by this formula are easily made hy means of logarithms. The formula for height is 100 R H = P - p where H is the effective height of the chimnej^ in ft., R is the draft required just above the entrance to the chimney, P is the maximum draft of the chimney per 100 ft. of height and p, as before, is the draft loss in the chinmey per 100 ft. of height. Hy assuming different values of p for a fixed set of conditions these two formulie will give different sizes of chim- neys having the same capacitj^ Simplified Formulse for Ordinary Installations.— It is customary to assume that a chimney will be well proportioned when the draft loss in the chimney is two-tenths of its maximum draft. With this assump- tion, allowing for coal 80 \h. of gas per hr. per H.P. developed for 150 per cent, of rating, 60 lb. of gas per hr. per H.P. for 200 per cent, of rating, 55 lb. of gas per hr. per H.P. for 250 per cent, of rating, and assuming the same air and gas temperatures as for the subsequent formulae for height, the formula for diameter of an unlined steel chimnej- becomes — d = v'yiO (II. P.)- for 1.50 per cent, of rating. d = \/ 490 (H.P.)' for 200 per cent, of rating. d = "v/tlO (H.P.y for 2.50 per cent, of rating. where d, as before, is the inside diameter of the chimney in in. and H.P. is the maximum horsepower to be developed. Diameters for 150 and 200 per cent, of rating by the above formuliE but expressed in terms of rated horsepower are practically the same, hence a single curve answers for both rates. This curve is given on the opposite page and may be used instead of the formula. Diameters for 250 per cent, of rating should be 5 per cent, larger. When the fuel is to SIZE OF CHIMNEY 141 4000 3800 3600 3400 3Z00 3000 2800 E600 ^1400 ^ 2200 e indicated on account of the pressure or suction produced by velocity. Thermometers and Pyrometers. — With mercury instruments errors are apt to result because of incomplete exposure of the stem. Mercury pyrometers for taking gas temperatures should not Ije inserted through brick walls because a considerable part of the stem will be exposed to a THERMOMETERS AND PYROMETERS 147 cokler temperature, resulting in low readings. For boiler testing, electric l)yronieters are much more convenient and usually more accurate tlian mercury instruments. It is important that the thermocouple, or bulb and stem, Ije placed in the active path of the gas passage and not in a "dead" space as Ijehind a partially opened damper. Also, care should be taken to keep the exposed part of the instrument as far as possible from the relatively cold heating surface of the boiler on account of the chilling effect due to radiation. When taking temperatures within a bank of tubes with an electric pj'rom- etcr the actual temperature of the gases in contact with the tul)es is somewhat higher than indicated even when care is taken to adjust the couple for minimum radiation effect, which should always be done by mov- ing the couple in and out, about a halt-inch at a tune, until the highest temperature is indicated for a steady rate of firing. Miscellaneous Information THE closing pages have been devoted to information suggested by experience as useful in the management and design of steam-boiler installations. Calculating Horsepower from Fuel Consumption. — It is sometimes desirable to determine, approximately, the horsepower developed bj^ a boiler without going to the expense of making a regular test. In such a case the method outlined below has lieen found useful. Weigh the fuel fired during several hours, the longer the better, and calculate the fuel burned per hour. If the fuel is coal, it should be fired so there will be al>out as much on the grate at the end as at the beginning of the run. From a knowledge of the fuel, Ijoiler, stoker and firing condi- tions assume a calorific value for the fuel as fired and a reasonable combined efficiency, and calculate the horsepower by the formula IF XH XE H.P. 33480 Where IF is the weight of fuel burned per hour in pounds, H is the assumed calorific value of the fuel in B. T. U. per pound, E is the combined effi- ciency of the steam generator and 33480 is the heat equivalent of one boiler horsepower. Example: An average of 500 pounds of coal was burned per hour, the estimated B. T. U. in the coal was 14,000 and the estimated efficiency was 70 per cent. What is the horsepower developed? Ans. : 500 X 14,000 X 0.70 , ,,. ^ ^ 33480 = ^^"^ ^•^- The horsepower calculated in this way will represent, of course, only the average developed and may lie considerably less than the maximum. If a damper regulator is used there may be wide variations in the horse- power developed 1 >}' the Ijoiler even though the demand for steam is fairly constant. Hence hand regulation of the damper should be employed and adjustments made slowly when making a run as indicated above. Provision for Replacing Tubes. — We give below the minimum linear distances which should l)e allowed, either at the front or rear of boilers, for replacing tubes. While in some plants it has not been ( 148 ) MISCELLANEOUS INFORMATION 149 necessary to replace a single tube in many years of service, yet there is always a possibility that a tube will give waj' due to scale, corrosion, or other causes; and it is therefore wise to provide for this. In general, it is better not to install any coal-handling apparatus in such location that it will have to be taken down to replace a tube, not only because of the extra labor required but also liecause of the extra time required, as the failure of a tube may occur just when a shut-down can be least afforded. For 16 ft. tubes, A shmld not he lexx than ]-5 ft. in. " 18 " " " " 17 ft. in. " 20 " " " " If) ft. in. Of course, it is not necessary to have the clear space for replacing tubes entirely in the boiler room. Windows or doors of the proper size may be placed opposite the tulx' sheets of either header, through which the tubes can be passed, provided pilasters and columns are set so they will not interfere. Flow of Steam through Open Pipes. — For the flow of steam into the atmosphere Napier's formula has been found to give results which agree closely with those obtained experimentally. If w is the weight of steam discharged into the air through an orifice in pounds per second, p the initial 150 EDGE MOOR WATER TUBE BOILER absolute pressure in pounds per sq. in., and a the area of the orifice in sq. in., then, according t(j Napier, J) a w = ">. " 70 Modified l)y the nitroduction of a coefficient fO.96 and 0.925 are two vahies given), this fomuila is used to calculate the discharge capacities of the safetjf valves used in boiler practice. The very great amount of steam that is discharged through drains and open pipes for heating is indicated in the table below. The outflow v\'as calculated bj' Napier's formula, uncorrected, and reduced to Ijoiler horsepower Ijy dividing l>y 30. Boiler Hobsepowbh Discharged into the Air through Open Pipes Initial prL'SSurc Lbs. trau^c N, minal sizf o f extra lira\- y pipe. Inchr-s 13 J. i 1 li li 345 2 100 45 84 140 2.50 577 150 19 65 120 200 359 495 828 200 25 85 156 261 468 645 1080 2.50 31 105 193 1:122 577 795 1330 Leakage of Air. — The tabular values below are for the ideal case of zero friction and contraction and must be multiplied by a coefficient C to obtain the actual leakage. For the eciuivalent of an orifice m a thin plate, C = 0.6 appr. For a short cylindrical pipe with inner corners not rounded, C = 0.75 appr. Theoretical Le.vkage op Air at 70 Degree.^ Fahrenheit Leakut^e in pounds per hr, per sq. in. of opening 153 177 197 216 234 Kffcctive draft in inches of water Leakat^e in pounds per hr. per sq. in. of opening Effective draf in iuclies of water 0.2 56 1.5 0.4 79 2.0 0.6 97 2.5 0.8 112 3.0 1.0 125 3.5 Four-inch Boiler Tubes. 1.047 sq. ft. -The external surface per foot of length is No. 10 B. W. G.: Tliickness = 0.134 in. Nominal weight per ft. = 5,62 lb No. 9B. W. G.: " =0.148 in. " " " =6.09 lb. No. 8B. W. G.: " =0.165 in. " " " =6.78 lb. MISCELLANEOUS INFORMATION 151 Brickwork and Foundations. — The sizes of red and fire brick and the quality of the materials used in brickwork and foundations vary considerably; hence the following information is approximate and intended for preliminary estimates only. Size of standard firebrick is 9 in. x 4^ in. x 2 J in. Weight about 7 pounds. Size of standard red brick is 81 in. x 4 in. x 2 in. Weight about 4§ pounds. One barrel of Portland cement equals 3.8 cu. ft. and weighs about .380 pounds. Quick lime weighs from .50 to 7.5 pounds per cu. ft. Dry sand weighs from 90 to 110 pounds per cu. ft. Weight of brickwork, red or firebrick, is about 120 pounds per cu. ft. Weight of cinder concrete is about 112 pounds per cu. ft. Weight of concrete made with gravel, limestone, sandstone, etc., is about 150 lbs. per cu. ft. Number of rod brick usually allowed per srj. ft. of 4 |-mch wall . . . 7.0 Number of firebrick per sq. ft. of 4|-inch wall, no bonding . . . . G.O Number of firebrick per sq. ft. of 42-inch wall, bonding every sixth course 7.0 Number of firebrick per sq. ft. of 45-inch wall, bonding every fifth course 7.2 It is important that sub-foundations for boilers shall be built with due regard to the character of the soil beneath, as settling will cause bad cracks in the brickwork. Allowable Be.vrinc; Cip/Vcities of V.-vrious Kinds of Soils Kind of material Rock (the hardest) in thick layers, in native bed Rock equal to best ashlar masonry . Rock equal to best brick masonry Rock equal to poor brick masonry . Clay on thick beds, always drj' . Clay on thick beds, modcratelj' dry . Clay, soft Gravel and coarse sand, well cemented . Sand, compact, and well cemented . Sand, clean drj' ....... Quicksand, alluvial soils, etc. Bearing power Tons per sq. ft. r^lininiuni Maximum 200 25 30 15 20 5 10 4 6 2 4 1 2 8 10 4 6 2 4 0. 5 1 1 From Ira O. Baker's Treatise on Masonry Construction. 152 EDGE MOOR WATER TUBE BOILER Equivalents and Constants: — 1 inch of water at 112° F. = 0,03609 lb. per sq. in = 0.5774 oz. per sq. in. = 5.196 lbs. per sq. ft. = 0.0736 in. of mercury at 62° F. 1 U. S. gallon = 231 cu. in. = 0.1337 cu. ft. = 8.33 lb. of water at 70° F. 1 B. T. U. is the heat required to raise one pound of pure water 1° F. at or near the temperature of maximum density (39.1° F.). 1 kilogramme-calorie is the heat required to raise one kilogramme of pure water 1° C. at or near the temperature of maximum density. 1 pound-calorii' is the lieat required to raise one poimd of pure water 1° C at or near the temperature of maximum density. 1 B. T. U. = 77S.1 ft.-!b. = 0.252 kg.-cal. = 0.000393 hp.-hr. 1 kilogramme-calorie = 3.96S B. T. U. 1 povmd-ealorie = l.S B. T. U. 1 boiler horsejiower = 34.5 lb. X 970.4 B. T. U. or . 33,478.8 B. T. U. per kr 1 engine or motor horsepower equals 2,.544.7 " " 1 kilowatt eqvials 3,412.4 " " 1 kilowatt = 1.341 engine horsepower. 1 horsepower = 0.746 kilowatt. Volume of one pound of air at 62° F. 13.1 cu. ft Volume of one pound of flue gases at 500° F. 23.2 " Volume of one poimd of fine gases at any temperature is T' = 0.0242 (( + 4.59.6) where T is volume in en. ft. per pound, and ( is the temperature of the gas in degrees F.' Specific heat of flue gases, approximately . 237 Degrees Fahrenheit = 1.8 X degrees Centigrade -|- 32. Degrees Fahrenheit absolute = degrees Fahrenheit + 459.6. Coefficient of linear expansion of brass per 100 (leg. F., a,npr. . , . 0.001 Coefficient of linear exi)ansion of steel per 100 deg. F., appr. . . 0.00065 Coeflfieient of lineai expansion of brick per 100 deg. F., appr. . . . 0.000306 g = 32.2 ft. per see. ])cr see. = OSl cm. i)er ,sec. per sec. JT = 3.1410. TT -^ 4 = 0.78,54. Vtt = 1.7724. Tr^ = 9.8696, INDEX Am, composition of Excess in cliimney gases Lealvage of ... . Retiuired for eoml)iistion Bagasse Boilers, Edge Moor: Baffling . . . Escaping gases from Four-pass Front and rear views Handliolc plate Header Installations . Materials and workmanship Shipment of . Shop tests Sizes of Staying of Supjjorts . Tests of . . Three-pass ITptake . . Waste heat . Brickwork 50,51 11^ Calorie . Calorific value, of coinbus Of fuels . . . Calorimeters, steam Chimneys, losses in Proportioning of Coal, classification of Properties of Sizes of Combustion Concrete Constants . Corrosion Draft gauges . Dulong's formula 12, tuples P.\GE 117 , 121 150 , 118 113 27 5 34 22, 23 14 13, 15 79 9 25 9, 11 33,35 13 20 6 2 19 5S 151 152 119 105 126 1, 121 132 103 10(3 104 117 151 152 123 146 119 Efficiency of boiler plant Effect of excess air on. Expansion, linear . 122 122 152 Factor of evaporation Flues, size of Foundations, bearing capacities for Fuel Variation in calorific value Variable composition Gase.s, fuel Formula for weight of . Formula; for volume of Specific heat of . . . . HoR.SEPowER, calculation of Ignition temperatures Incrustation .... Installations .... Napier's formula . Oil fuel: Burners for Calif