US1391767A - Fuel-burning method and furnace - Google Patents

Description

W. C. BRAKE.

FUEL BURNING METHOD AND FURNACE.

APPLICATION FILED .IULY I2. 19H3.

Patented sept.. 27,1921.

4 SHEE'IS-SHEEI I.

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INVENTOR www@ Q W. CUDRAKE. FUEL BURNING MEHOD AND FURNACE'.

4 SHEETS-SHEET 3.

f Patented sept. 27,1921.

APPLICATION-FILED JULY 12| 1918.

N wh .R t 4 ms .www Q Qt w A w. c. mmm. :YUEL BURNING METHD ANU FURNACE.

APFLICATG FILED JULY l2, 9l.

Patented Sept. 27, 1921,

4 SHEETS-SHEET 4. fm..

@M www ATTORNEYS or vffiirgin fr i, substantially .improve the eilicieny and corn- UNITED STATESA PATENT' oFFicE..

WARREN c. BRAKE orv INWooD; NEW YORK.

FUEL-BURNING :METHOD AND FURNACE.

T0 all 101mm it mrtg] concern.'

Bc it known that l, YVluiiuiN '(J. DiiAiiE, a citizen of the llnited States, residing at lnwood, in the county of Nassau and State ot' New York, have invented certain new and useful lmprovements in Fuel-Burning Methods and Furnaces, of which the following a specification, reference being had therein to the accompanying drawing.

This invention comprises a4` novel fuel burning method and furnace, and relates more particularly to apparatus and method whci'einthe coal 0r other fuel is systematically introduced at the feed or front side, a fuel bed being maintained within the fury nace, and the fuel being gradually advanced toward the rear or dumping point as it be-- comes consumed, air being suitably supplied., preferably by forced draft from beneath;l

tlie heatresiilting from the combustin being;l

utilizable for steam boilers, driei's, melting plants, or other uses to which a t* furnace may be put.

l The main object of the present invention is to afford a furnace and method which will plctei'iess of combustion, consequently increasing' the heat-ing results, while effectingv a savingof coal and minimizingr the production of smoke, as compared ,with prior furnaces. A secondary object is to make prac- 'i vtical and profitable the burning of fuels of low grade. bituminous coals, coals containing a' large percentage of ash and other refuse` coals liable to coke from their rich-` ness in volatile hydrocarbons, and the like. Further objects ai'e to, improve the method of burningthe fuel in itsl progress 4through the furnace. and the continuous regulation of the operation, to improve the operation of the fuel feed and travel andthe regula- 'tion thereof, and to improve the supplying of air and its distribution and regulation; also various matters of structure, operation and detail, s will be hereinafter more fully lexplained.

'lo the attainment ofthe above referred to objects, the present invention consists in the mechanical. furnace and the method of burning 4fuel hereinafter illustrated oidescribed, as well as the various fetaures of operation,V structure, combination and detail thereof.- 1 n ln` the accompanying drawings, Figure 1 55 is a sideelevatiom partly in section on the Specification of Letters Patent. Patented Sept, 27, 1921-.' Application filed July 12, i918. Serial No. 244,656. i l

p lane l-l of Figs. 2- or 3, of a furnace .Y

trating and embodying the present iiiveii-z tion, with certain well-known and other parts omitted for'clearncss of illustration. g Fig. 2 isa plan view thereof` partly broken away to show certain particulars 'I Fig. 3 is a front elevation, that is. looking toward the left-of Figs. l and 2, also partly; broken away to show details. i j Fig. 4 is a side elevation partly in section.- sliowing three lunits or links of the chain4 grate on an enlarged scale. Fig. 5 is atop, yiew' ofthe parts shown in Fig.' 4.4 Fig. .tig is a perspectiveof onel of the. links ofthe chain. Fig. 4' is a perspective of onel end; of one of the two types of grate bai-,andi Fig. Sis1 a similar. perspectiveof theeiidjQi one of the grate .bars of the other type sliow,n- I` in Figs. 4 and 5. 'y Looked at ijn one way, the prcsentinven. tion novelly combines certain principles heretofore separately known in. different, types of apparatus.-4 The infced of' coalto a,- fuifnace upwardly from a point Abeneathktlie., fuel bed was per se known. for e.\ainple in` the uiiderfeedl .Stoker patents oi 4Jroiiesl 470,052,0f March i, 1892, una Daley 644.664,13 of March 6.,'190() both expi i-d; aud I einl1 ploy as an element hei-ein a fuel underfeed. The carrying through the furnace of a--fiiel bed toward the dumping `point by a. sof..

'alled chain grate was per se known in such;

expired patents as Richards 527454, o'f .Ocio tober 16, 1894; and Iemploy as an element herein achain. grate. None of.. these pirior.

iwi

apparatuses, however, nor any others with4 which I am ac uainted, are capable ofthe mode of operation, the veconomical methodof burning, the etiiciency of results or the other advantages pertaining to the presentA invention. In one aspect I attain the-re.-y

sults hereof by .employing the principle of underfeed of fuel to a fuel bed which is progressively carried along upon a travelingj grate to the dumping point. In a more spe-u cific aspect this invention involves a particfuf-V lai` combination of the elements or features mentioned,characterized by manner of ar rangenent, and y furtherv features, making-- highly practical and advantageous thecos-` I believe that no appa-=- operative result;

ratuses ormethods heretofore known or at# lfeed part of the bed, that is, it follows in substantially uninterrupted succession, so that the fuel bedis unitarily maintained, that is, there is no intermediate avalanching such as would destroy the zones of combustion. The. bed may rest on a foregrate to Vwhich the underfeed' carries it before it passes the chain grade, and there maybe a certain mechanical asslstance or agitation at the point of transition to facilitate the advanceof the underfed fuel onto the chain grate. Forced ,draft acts not only upon the underfed portion of the bed, but also upon '.A the, rtionl on the chain grate, extending towarilo the bridge wall or dump. Less importent, features will hereinafter appear.`

I. will new describe in detail the selected embodiment or illustration of the present invention which is shown in the figures of the 4accompanying drawings. Above a suitable foundation is shown what may be termed the t5 front wall 10 of the furnace, located at the fuel feed or supply side, and opposite thereto, at the. rear, is shown a bridge wall 11, but such bridge wall may be. absent,depend ing on the type and purposes of the furnace end its setting or relation to the boiler or other thing to be heated. .At the front side of wall 10 is one or n plurality of'fhoppers 12, the same being in the, nature of.a chute, into which the supply of fuel is placed which is to be introduced into the furnace. Gravity carries the fuel down to the point where, as

`will be described, it is forcibly thrust or undcrfed into the furnace through a throat 13. The fuel bed or mass of coal .14.vwi'thin the furnace extends from thel throat at the front rearwardly tothe dumping point, and, as willbe explained, theucl in the bod is bumped up at an intermediate point., forming a peak orsummit 15. Roughly, and without any clear line of. demarcation, the fuel bed may be considered as consisting of substantially three zones.' The first zone"16 consists of the` green coal before it has taken any part in the combustion. 'In the second zone 17, beyond that, coking takes place, the coal being co'nverted by the intense heat above and ,hydiocarbon gases distilled off, which become heat constituents by mixture with the air of combustion and are usefully and completely burned within the furnace, forming an invisible, smokeless, gaseous product. The third Vor incandescent zone 18 forms the top layer of the fire bed, and is that in which thefoxidi'zation of the coal, or rather the coke, is completed, this action continuing progressively along the length of the fire bed, until lat the dumping point only ashes, small clinkers and other refuse remain to be discharged into the ash pit 19.

At this point it might be mentioned that an air seal Aabove the ash pit is' desirable, and a water-cooled air seal or gate 20 is illustrated as mounted on the bridge wall.v This is shown in a somewhat' lowered position, but the position maybe adjusted externally to accord with the quantity', and nature of the discharged material; A perforated pipe 21 provides for small sprays of water, or steam, or lother fluid, directed toward and serving continuously to cool the ashes and othermaterial,both"before and aften thesame enter the a pit. When the fires are banked, the gate 20 can be entirely raised to close the pening between it and the traveling :grate to prevent air leakage into the furnace, and the water spray turned off.

an air pipe 22, supplied by a blower, or otherwise,'and providing a forced air draft through the fuel. bed and furnace, although in some casos a'natural draft'might be sufficieut` for the purpose. Additionalnir may be admitted to .the furnace through passages 23 at the front, just above the fuel bed, the same su )plied by a distributing air box 24, the air fio through which may be regulated in any suitable.- manncr.

As indicated inthe plan view, F ig. 2, the entire furnace mechanism consists of a number of longitudinal divisions, which may be termed sections or units, that can be in-` Bcneath the front Aof the furnace is shownA creased in number to any extent, four boing shown. A fuel hopper 12 servesfor all the mentioned.v y

The underfeeding mechanism comprises a pusher guide or case.,27, exterior to. each throat 13 and beneath the hopper 12,.:1nd withlncach pusher caso 1s a pusher or ram '28, adaptedto vreciprocate toward and from the throat, so that on each reti-acting stroke coal falls from the hopper in front of the pusher, While on the advancing stroke the `coal is thrust through the throat to the under part'of the coal bed. As shown,tbe shape of each throat and pusher is comparatively low or fla-t, and of maximum width, so that the infeed of fuel takes place over the greatest possible extent ot the total width ot the front` of the furnace. The trough-like structure inward of each pusher, into which the successive charges are thrust, will be .s sequently described. For its actulation the pus-lier 28 is provided with' a rack 29, engaged by driving sector 30, mounted on a rock shalt' 3l. The toothed sector 30 is shown as extended downwardly below the rock shat't 31 to where itis connected by a shearing pin 32 to a pair of opposed rock arms 32a keyed on the rock sha'lt, the piirpose of this safety device beingthat, in case the pusher is blocked, the pin 32 may shear ott', rather than alloi a breakage in other parte of the ii'ieclianism. The rate. ot' fuel iiifeed may be regulated by altering the rate ot action of the. pusher, or its throw might be changed hy means of :i lli-:isc connection anali'igous to the device T2, 73, later described.

An engine or cylinder 38 is shown for actuating the pusher and other parts of. the furnace mechanism. The engine piston reciprocates a crosshead 34, and this-ii; con nected by a link 35 with an arni 3&5 onthe rock shaft 31, thus reciprocating the pusher as described. Instead ot a separate engine foreach pusher and grate section. a single engine and a single rock shaft may be lused for the entire system. The engine connections to other )arts ofthe furnace mechanism will be su sequently described.

Coming now to the grate systeirrwithin the furnace, this as a whole may he generally horizontal, and-comprises the four or `more similar grate sections, as already"explained, each of which ':onssts o't' different portions, will now 'oc described. What may he termed the t'oregrate system, or that extending from the furnace front rearwardly to where the. traveling grate system comincia-cs. provides a fuel bed support which docs not travel, but uponl which the t'iiel is iiiidcrfcd by the staking mechanism described. The foregrate system compri-ses laterally extending twyerplatcs or blocks 4t), which arc shown as overlapping and forming a fuel Support extending rearwardly from the lower wall of each throat oi" fuel entrance 13.

The plates 40 may be corrugated, and the' overlapping arrangement precludes solid matters sifting downwardly, while the passages or twyers 4l admit air beneath this portion of the coal bcd. The longitudinal extentof the tori-grate should be sutlicient to afford thorough preliminary distillation and heating, so that the combustion of the fuell will surely he completed before the traveling grate system finally discharges the residues @om the ash pit.

At the front between each two sections the foregrate )lireferably comprises an upstanding grate portion 42,constitiitiug a protuberance -siibstaiitially'in line with the division wall between each two coal entrances or throats 13 and jiitting rearwardly into they fuel bed. These protuberant grate. poi-tions 42 tendto form troughs bet\veeii.tlie ni and to constrain the underted coal-to flow )ro 5- 70 shown, a constant upward motion or flowofthe fuel is produced toward the coleing `and yincandescent zones, according to the prinl' ciple of the underl'ecd and as 'indicated in4 Fir. l.

`he general nature. of the movementor flow-of the solid fuel through the furnace. may now be advantageously.described. Uni.. der certain. coiidi'tionsoic operationl it tends. to fori a high ).i'oiiitor peak aiiproxiinately'I over w. ere tlieii'orcgrate meets whatniay90 be called the rear grate or traveling grate i system, as indicated in lfig. l. The fin-cible iii-thrust ot-the underfed coal against the lower pai-t. of the inert mass causes the Ytiiel to lniountjor hump up toward the peak while advancing. Such fuel flowl niaiiitaiiisfthe. proper shape of tuel lied; while at tlie"siiiic time evcry partcli` ot t'iicl is caused to ,vtfrom the green coal zone to and tliro'ugh'the, coking zone, and `thence into the incai'ide. cent zone, although the loweiinost i'trata,'o'l'l Jfuel may not .arrive at this /,oiie u iitil lwell beyond the peak. Beyond thi` peak tlie'llii'cl",

bcd progressively dccrcascs iii height, div the speed a! which the travcling'grates cai it along, and to thc tact that/the coinl'iustion is further and further reducing it to ther torni of ashes` ctc. (lenen-ally, the direction of the fuel hed and travel maybe approximately lcvcl or horizontal, rather" thanl` 5110 steeply downwardly inclined, and' therefore the total operation is tiioc.y 4from "violence, through avalanching ot the coal orl otliorwise. The rearward advancing flow fof the-i" fuel is, of course, exceedingly slow scarcely perceptible, and therefore, altho' small steps, the operation is for allI practical purposes commuous and steady, with the atl-,V120 vantage 'that the ash discharge as well is subi portion 75 stantially and automatically v c 'ontiniioiis' without the disadvantages ot' iieriodic-dump ing actions.

The above substantially describes the teii'cd iam-'ement of ifuel through. each tion of the furnace with the exception off an. agitating action to bedescrihed, by which the bed is constantly shaken at the point Where the fuel pasfgeslfi'oin the underfed por?. 130

aiidfb fh'f the. iiiiderfeed pusher is reciprocating andy the, traveling gratos movel intermittently lby,

` determined.

4tion to the traveling portion of the grate, that is, substantially beneath the peak of the fuel bed. Additionally, as will appear, the rate at which the diferent4 sections of the fuel bed are carried by the respective. :trave ing grate sections varies or diflers under suitable control, as will be explained.

The air flow, as stated, is preferabl forced, and its general nature, under control, may be as follows. Above the air pipe 22 is a, passage 44, with damper'45, leading to the inclosure or chamber below the grate. A front compartment 46 is formed by a vertical -division wall 47, which com rises the supporting I-beam shown with p ates above and below it, so that the space beneath the foregrate system constitutes a single compartment 46. From the compartment 46 the air under pressure passes upwardly through the twyers 41 and 43 into the fuel bed. Beneath the rear or traveling grate System the space may be subdivided into two or more com partrnents, for example, 48 in the middle, and, at the extreme rear, 49, a division wall 5() separating them.'y From each vcompartment the air flows upwardly into the fuel bed at the corresponding point, `The general direction of the three air streams thus pro duced is indicated by the elongated arrows or direction lines 51, 52 and 53, respectively.

Control of the air flow may be afforded in the first place by varying the air pressure in the passage 22 through regulation of the blower. Iii-this way the pressure in the front compartment 46 and the air flow through the twyers in therforegrate system may be The pressure and air flow throuofh themiddle and rear compartments 48 ant 49, and thereby the relative air Supply to the front, middle and rear portions of the grateas va whole, may be regulated by a.,

v `dampcr.55 in the division wall 47, and a second damper 56 in the dlvlslon wall 50. F or purposes of illustration the damper 55 is shown openedv and the damper 56 closed, under which conditions only the front and middle compartments 46 and 48 will receive air. From the .damper 55 extends a control rod 57 to alconvenient oint in front of the furnace, and llikewise rom the damperd extends a rod 58 with external handle. This damper system gives the possibility of securinguniversal control as between the front, middle anda-ear portions of the grate, so that the pressure and supply may be differ entially regulated to suit the rate of fuel combustiong'and lother conditions; while at the same time the total air supply and that securin maximum eficiency in a furnace. Y

At t e polnt -where the advancing fuel' passes from the underfed foregrate to the traveling gra-te system, I prefer'to maintain rest and balance upon the fixed top edge of l the partition .47, and provided with transverse grate members or plates 6l, 62, with t-wyer openings 68 between them. By tipping or rocking the agitating member 6() about its described pivot, a slow jogging' or settling movement is given to the piled-up coal where it, leaves the foregrate system. thus assisting,r it to descend forwardly and take its place upon the traveling zgrate system; this action, although 'not always necessary, is beneficial .iu the general process of combos` tionof the fue] bed.

To secure the agitating movement the roc-ker 60 maybe provided with a. :forwardly extending arm 64, shown connected by a link 65 with an arm 66, secured on a transverse rock shaft, which at a suitable point has a. second arm 67 whfich .is connected to an actuating rod 68, which extends forwardly and in turn is connected to a rocker arm 69 on the oscillating,r power shaft 3l. The described connections 64 to 69, inclusive, may be duplicated for each of the four sections of the grate. As will be described, each rod 68 is the same rod through which the corresponding traveling grate is advanced, so that the action of the agitator will be speeded up proportionately to the speed of the grate, as it properly should be.' Preferably' the bell-A crank arm 67 has a loose or yoke connection with the actuating rod 68,1therebeing av collar 71 below it, so that .the action, is to swing the bell-crank and raise the-agitator grate bars 61 and 62, which thereafter d'e.A scend by gravity upon the return movement ot the rod. At the forward end of the rod 68 are adjustingr -nuts 72 and 73, in front and rear of arm 69. Adjustment of nut 7 2- alters the extent of'up-and-down movement of the agitator, and subsequent adjustment of' the nut 73 determinesthe rate of travel of the grate 75.

, I will now describe the travelingr grate system from Fig..1, assisted by the top view Fig. 2, sectional front view Fig. 3, and the structural detail views in thel remaining figures. As seen in Figs. 2 and 3, there are four traveling grates 75, and in Fig. 2 two -of these are broken open to show the underneath construction. Instead of havingr the traveling grates in mutually contacting juxtaposition. T prefer to have 'them somewhatseparated, ith stationary grate members 76 between them, and betweenthe first and last of them and the side walls of the furnace. I prefer to have these intermediate grate portions substantially in line with the foregrate protuberances 42, between which the coal entrance troughs'- are formed-.and lap-refer further to arrange otherintermediam-grate. members' 'T7 at a corresponding position betweenthe respective agitator sectionsk'ly. By this arrangement each inf- =Wardly thrust coal stream passes into and through the'trough ofthe oreg'rate system, and thence over the agitator, and then the 4traveling grate, all of which are directly in line'. 7The.intermediate grate portions 76 andf''7l are relatively narrow, and the portionxlof the fuel bed thereon-will be suilicicntl'v carried along for the Vpurposes hereour.

^ off By 'arching the same, as indicated in l `ig.'3, -a'tendency isproduced for the fuel `thereon -to` bear laterally down upon the traveling gratas,y thus enhancing the advaheingfnrovement thereof." The intermedifite grate' portions 77 between the respec- 20 tive agitators may be' composed 'of over- 4l`appi1 1`,'f:r;-:plates similar to the agitators. thus Aproviding tw'yer openings '63 to supply air between them; and the longitudinal inter- I'rr'iediate grate portion 76, which stands between-each' 'pair of traveling| grates may be amply provided with ai'r pa'ssages7 af. TheA 'construction of eachtraveling graft?A 75"' is generallyl that an 'endlessds'eries o 'i Overlapping 4'transverse grate bars '11s*"carri'ed by an endless series "of links, `which travel along'guidles and around rockets, being; driven through the'shaft o "one of 'sprofckets.- Each traveling grate is wholly 'independent'of the others, sothat its speed" may 'be indepelid ently vllied i and proportioned" to the rate lof, combustion in that section of th 'furnace -Before describ- ,the details oft'eiich/gratdit will be con` Asshwn'in Fig.' 1, the forwardc driving or 'spr'clk'tjsliaft 81 is provided'wth a ratchet wlieel "182. Loose on the' same shaft is apaivlcarier', and to give greater ineness I off-adjustment', this-lis 'provided 'with two pivoted pawls 84,y .84.' The oscillation of th'ecar'rier causes thepawls to ride back and fxorth over the ratchet teetbQand each pawl ha'sfyazcoiinterweight maintaining fit in enga'fement with" the ratchetl so that the 0 'r atehetflis given a step-bystep. movementLas 'the 4 carrier oscllates. The, lower` end oi eachr` carrier is connectedto the rear end of the :itatorl rod A68,y already mentioned. An

opening'viisyprovided in` the division wall 47 to":`i fr"omr nodate these parts.' Instead of a direct frigid' connectionjvbetween carrier 83 and'rol ,'68, Iffprefer a vyielding connection,

s togive a resilient drive for' the purpose'of `preventing'brealmge upon lthe travel becoming jammed.` To this .purpose the rea'rnd therod is"surroiindmil b Y a 'coil spring S61 whichfin t n v'is surrounded by abarreljff ATheI flan" rcollar at'the rear end0f`t`a'e"od Bears ror'wardly" inthe 4spring when pulled by the engine, and the rsections to be retarded relatively the pawls to any desired extent.

Since all these described elements to 87 are duplicateddor each grate section, the means is provided for independent speed adjustment of the several sections, as already stated. In part the importance of thisis due tofthe tendency in a furnace to burn',-

with irregular or varying intensity at different transverse areas. Thus,-near the'two side wallsv the tendency is to burn hotter and faster than in the center, with the r 'ult that, if-theentire width of 'grate wasradjusted to the vsamespeed to suit the rate of combustion in the middle sections, the combustion in the -extreme or side sections would be improper, being too rapid and intense in the 'rst/partof travel and the-conibu'stibn not extending entirely to the dumping point; their places in th'e bed would occur, and the air would rush in excess quantities through the same, disturbinfr the combustion over the whole surface. nder such conditions my invention permits the edge sections to .be Speeded up and the ,middle l l This complete control of the combustion enables .a constant and ,uniform fire bed to be maintained over the wholeinterior of the furnace. It'gives a gradual and positive, b ut `clifferential,=movement of the fuel' bed all the way to the ash pit, so vthat in each sectionof the furnace the combustion continues competely tothe r ar,V and is finished at `the dumping point. may require changes in the adjustment. The

described control may be accompanied by a ifferent fuel' conditions differential control of air 'ow through the front, middle and rear air compartments and fuel bed, as described. The` described' principle of forming a peak or high point in the fuel. bed bythe advantageous underfeed, and then gradually carrying the bed along beyond the peak by the carriers or traveling gratas under the described regulation",y gives a very advantageous shape of bed,v which can be controlled somewhat by relative regulation of underfeed and travelinggrate speed, while the greatest eiciency of combustion is attained, vno reliance 'on grayity for the advance'- is necessary, and the forward movement proceeds vthroughout t'h'e 'furnace Without 'violence of action.' This'E method of burning the coal has the further result of preventing waste because minimizing the amount of combustible remaining in the discharged ashes. At no art of the furnaceis the fuel required to e pre` niaturely dumped. The heretofore known underfed furnaces, relying on gravity for travel and resulting in a paddling action, are 'well known to possess tlie great disadvantage of forming largeclinkers, which is largely or wholly prevented by the present invention, which also permits a substantially steady and continual ash discharge, rather than the disadvantageous periodical dumping operations necessary in the prior ap aratuses.

ach tr'avelin grate17 5 is preferably the full width of t e longitudinal open space betweenmeacli two intermediate grate 'portions 7 6, and may be, for example, approximately '24 inches. Each .driving sprocket shaft 8l will be substantially this length, and its ends are supported'by bearings 89 held by the stationary vertical supporting Walls-of the intermediate grate portions 76,' as seen in Fig. .3. The-front pair of driving sprockets 90, 90, are keyed to thev shaft so as to be driven by it and to drive the chain grate. Atxthe rear end each grate is -enl gaged upon a lsimilar pair ofidle sprockets. 91, 91. A chain grate tightening device for taking up any slackdue to expansionor stretching of each chain may be rovided, for'example, as indicated in 'dotte lines in 1. This consists of bearing blocks 92 foiV the shaft 93 of each rear sprocket, said blocks being longitudinally adjustable in stationary boxes 94. Each block has a threaded stud 95 extendin r forwardly as indicated, and a threaded co lar or nut 96 en gages this rod andserves when turned -to thrust the sprocket shaft.rearwardlyv to take up slack. .I i To properly control vthe air flow against undue loss at the rear, I have shown a i'ear wall or partition 97. inside the grate structures .and approximately above the supporting I-beam 98. At the topv of. the wall 9 7 is shown a bent plate or shield 99, the horizontal portion of lwhich bears upwardl against the traveling links by a pressure at justable through the nut 100. An analogous bent plate 101 bears internally against the returnin" or lower portion of the traveling grate. third hentfplate 102 is secured on the I-beam 98, and-bears upwardly against the lower or exterior side opposite to the plate 101.

The grate itself is built up of two kinds or types of 'overlapping transverse grate bars 105 and`106, respectively, each corrugated in the manner indicated, so as to provide twyer openings between them. 'lhis endless series of grate bai's is supported on an endless series of grate links 107, which 65 are shownas being all the same 'm construcprojections of the sprocket wheels, as indicated. There are, of course, two opposite chains' of links for each `traveling grate, and the links and the grate bars carried thereby, as they travel rearwardly, are shown supported against sagging by reasonof a guide or flange 110, as more. especially seen' in Figs. 1 and 3. Each link stud 108 has a. roller 109 ruiming on this guide or flange.

The shape of each link 107 is shown in. perspective in-Fig. 6. It is wider at its rear end, having two ears 112, perforated for the receptionof the stud 108 and -two ears 113 at the other end spaced less far apart, so as to be capable of being engaged between the ears 112`of the next link, as sl1o\vn.gTlie lody of each link 107 'is hollow, and. near its teifi and 'fr ont ends, res ectively, has cross bars 114, 115, through w iicli tliegrate bars are secured to the links.

As previously explainech each link has connected .to it two grate bars, and the gen- C eral arrangement can'be perceived by examining on Fig. 1 the relative positions of the links and bals as they travel around the sprocket wheel. -The grate bar is ap- 95 plied first to the link, see Figs. 4 to 7 This type ofgrate bar` for this purpose has an underhanginglu r oi'liook 117, whic'lnwhen the grate is assenibled, reaches under the link cross bar 115, asclearly shown in Fig. 4. 10'0 The other type of grate bar 106 has an underhanging lug 118, which engages under the rear ci'oss bar 114 of the link. A recess- 119 is provided near the'end of each grate bar 105 to accommodate the hook 118 ofthe 105 overlying grate bar. Analogous'ly the edge of the grate lhar 106 is notched at 1.20 to' accominodate the liik cross bar 115. To secure the two grate bars rigidly to each other and to the link, a screw 121 is shown passing 110 through a hole 122 in the grate bar 10G, and engaged in the threaded hole 123 in the` grate bar 105. A

Each grate bar is corrugated, as explained, to provide twyei' openings between them, 115 and each has at its underside a"lon`gitudinal rib 124' for strengtheningpurposes: The links being all slightlyinclined to give the overlapping arrangement shown, each 'one may have an upstanding end lian e '125,giv- 120 ing a generally flat or even edge or the support of the inverted grate bars asthey return from the rear vto the front ofthe grate, these lflanges 125 bearing on and sliding alongalower guide plate 126, best shown l 5 in Figs., 1 and 3.

The traveling grate construction described' provides. large cooling surfaces to all the lportions which bear the/fuel bed, and, moreover, every portion of the mechanism which contacts with the fuel is protected against overheating by direct ycontact with the in- "flmi'ing cool airff- The provision of rollers 1;()9 on the link'studs 108 minimizes friction and .resistance to the advance of the grate, end thereby prevents warping of the grate bars, which also are preventcdfrorn sagging lthe fact that the grate bars are not of excessive length, have the strengthening ribs ineentionechland are rigidly locked in place by their inter-engaging lugs.v 'The grate l bars are easily remo y"able, interchangeable "and replaceable when necessaryand the structure isZ such that replacement of the (frate "bars practically renews the furnace, iiice Vtllierlinks and other supporting parts y "protected from undue deterioration.

'i llfiileflvhave shown fourgrate sections, Iltis, obvious that'the principles hereof could beemployed with a 'greater or smaller num'- ,ber of sections, Thus, with three separately freglable' sections, the middle one could be "etardcd relatively to the edge ones; while j 'h n ve or more sections Va yet more thor- ,ugh proportioning of 'the speed tothe rate fcoin'bnstion at each part of the furnace be, attained. This multiple gra-te', comib'ined 'es described with the multiple undereed nieansgive s al .furnace with controlled vinfeedand discharge, so that intelligent regeii,th e lnfeed 'and discharge to he made to correspond with' thev ratio between the -totfl fuel and the incombustible portion thereof. Theunder'feed, consisting of a pluralitypf low, wide pnshers, gives a stream 'bfenterlngcoal which is as near as possible tothe'full widthof the furnace. The grate pr'otubcran'ces between the fuel entrances are ,.s'niall and narrow, and shaped to secure unilication or consolidation of the separate enrin "streams, so that substantially the full Qwidt, of the fuel bed flows rearward over the' fdrc'grate to where the travel is continued by meansof the endless grates. These important features of structure are renderedA even more eflicient by the introduction of air directly underneath the fuel lying over the -f ore, ,n'rate and 'protuberances` since the distillation and combustion of volatiles is ccmvinenced and carried on to a substantial exs 'tent before the fuel passes from the foregrate. The present method and machine require'no s uch disadvantageous expedients as have been found practicall necessary in heretofore used ,furnaces .hose furnaces wherein an underfeed was followed `by an nvalanching overt'eed down a steeply in 'clined grate. frequently required, n0t 0nly thevinfeed pnshers, but supplemental push v ers Iilecip'rocatingi; at -,various parts ofthe fuel bed ;v all of which resultedln the'puddling and avalanchingactioirs already, mentioned, "requiring a periodically" acting dumping 4eli grate at the end, and involving' the forma! i possibl e, permitting the ratio betion of large clinlccrs and consequent discharge troubles, beside high loss of conibustible matter. (.)rdinary chain grate furnaces have heretofore been fed 'by an overf' lt will thus be seen that l have describedl a novel fuel burning method and furnace embodying the principles and attamin r the p advantages or the present invention. .since many matters of procedure, operation, com lunation, arrangement. structure and detail may beraried without departing from the' underlying principles, no limitation to' such features is intended except so far as speci fied in the appended claims.

W'hattis claimed is:

-1` A fuel burning method comprising forcibly uniiler'feeding fuel into the front portion of the bed of burning fuel and consecutively therebeyond bodily carrying along the fuel bed rearward with substantially horizontal trzrcl toward the dischrge.

2.`A. fuel burningmethod comprising forcibly underfeeding fuel into the front portion of the' bed of burning fuel to form and maintain such bed, and thcrebeyon'd bodily carrying along the so formed bed rearward with substantially horizontal travel toward the discharge, while applying forced draft through both the undcrfed and bodily carried portions o'l the bed.

El. A fuel burning method comprising forcibly underfeeding fuel into the front portion of the bed of burning fuel. and consecutively therebeyond bodily carrying along thefnel bed rearward with substantially horizontal travel toward the discharge, while causing forced draft at both the underfed portion and the subsequent bodily carried portion of the fuel bed.

4. A fuel burning method comprising maintaining the forcbcd of burning fuel across the entire width of furnace by underfceding green fuel into the front side. thereof so as to cause rearward travel of the forebed, and consecutively beyond the area of the forcbed maintaining Iand bodily carrying rearwardly/fthe main portion of the fuel bed of substantially greater area than the underfed forebed, while subjecting the same to forced draft.

5. A fuel burning method comprising forcibly underfeedin and maintain suchmbed, andI consecutively therebeyond bodily carrying along .the ,so formed bed vrearward with substantially fuel into lthe `front .portion of the bed o burning fuel4 to forxn horizontal travel toward theflischargqenltlie underfeeding and bodily carrying operations being performed with substantial continuity transition-from the underfed portion to the.

bodily carried portion of the bed to assist such transition.

'l'. A fuel burning method comprising forcibly underfeeding fuel into the front portion of the bed of burning fuel, and consecutively therebeyond bodily carrying,

`along the fuel bed rearward with substan-` tially horizontal travel toward the discharge subject to forced draft, and maintaining va differentiation of speeds in different transvelse sections of the fuel bed, for exam le, the edges at fasteuspeeds than the middle,

whereby'to maintain substantially uniform the combustion in'all sections.

8. A fuel burning furnace includinv in combination, means for forcibly imderfe'eeding fuel into the front portion of the o'edI of burning fuel, a noxvtraveling fore ,rate upon which the underfed fuel is force and supported, and consecutively to the rear thereof a traveling grate adapted tobodily and steadily carry along the fuel bed rearward toward the discharge.

9. A fuel burning furnace, includin in combination, means for forcibly under eeding` fuel into the front portion of the bed of burning fuel,a non-traveling foregrate upon which the underfed fuel is forced and supported, and consecutively to the rear thereof a traveling grate adapted to bodily and steadily carry along the fuel bed rearward toward the discharge; said traveling grate positioned at substantially the level of the underfed foregrate so as to directly receive and substantially horizontally continue the advance ofthe fuel bed without disrupting 'its character..

10. A fuel burning furnace, includingl in combination a. non-traveling fore ate of the full width of the fuel bed but ess than half the length of the fuel bed, means for forcibly underfeeding fuel upon the entire width of the foregratc, and a traveling grate located directly td therear of and `at substantially the leyel 'of the underfed foregrat'e, adapted toreceive'and steadily carry along rearwardlythe fuel bed.

11'. A fuel burning furnace', includin in combination.v means for forcibly. under .eeding fuel into the front portion of the bed of burning fuel, a non-traveling foregrate upon which the underfed fuel is forced and supported, and to the rear thereof a traveL ing grate adapted to bodily and steadily carry along the fuel bed rearward toward the discharge, and means for causing forced underfeeding) fuel a traveling endless grate adapted to odilycarr and continue vthe travel of the fuel bed rearward in a substantially horizontal direction from Qthe inf' feed toward the. discharge.

13.l A fuel burning furnace, including-in combination, IlIneens for forciblfy underfeeding fuel rearwardly into the ront portion of the lbed of burning fuel so as to form 'the be'd into afpeak' rearward'of the fuel en trancc, and a traveling endless rate adapted to 'carry along vthe fuel ed rearward ipx a subbtantiallyhorizontal direction' from t e fuelv eaktoward the discharge. ,s

14. A el' burnin furnace, includin in` combination, means or forciblyu'nder ing fuel rearwardly, into the front portion of the bed of burnin'gffuelsoasto form the bed into a peakgrearward -of the fuel enf trance, and a. trggeling endless grate a dapted izobodily carry' alongl the fuel bed rear! ward in a substantially orizontaldirection from the fuel peak toward the.' discharge,

with air assa beneath the fuel bd provided bot- .in t. e underfeed portion and the traveling grate' portion, and forced draft passages thereto.

15. A fuel burning furnace, includingin combinati-on, means for forcibly underfeedin fuel rearwardly into the frontportion of the bed of burning fuel S0 as to form the bed intov a peak rearward of the fuel en trance, a traveling endlessrete adapted to bodil carry along the'lfuel d rearward in a su stantially horizontal direction from the fuel peak toward the discharge, -andv means for methodicall agitating the fuel. beneath the peak to assist the continued fuel flow between the underfeed and the traveling grate.`

16. A fuel burning furnace, including in combination, means for forcibly underfeeding fuel into the front portion of the bed of burning fuel, an air-supplied non-traveling foregrate of substantial extent upon which the underfed fuel is forced and supported, and consecutively to the rear thereof an airsupplied traveling grate arranged to bodily and steadily carry alon the fuel bed from the foregrate rearwar toward" the discharge.

17. A, fuel burning furnace, includin in combination, means for'forcibly, under ceding fuel into the front portion of the bed of I the underfed fuel is forced and supported,

1,391,7er g theunderfed fuel is forced and su ported,

and consecutively to the rear thereo an airsupplied traveling grate arrangd [tobodily and steadily carry along the fuel bed from the. foregrate yrearward toward the discharge, together with mechanism for substantially continuously operating said nnderfeed and'travelinggrate whereby a 'rearward fuel' flow from the underfe'ed to the discharge is steadily', maintained, with a substantially continuous discharge of ashes.

19. A fuel-burning furnace. including in combinatiomtheiront and side ywalls, of thev combustion chamber, a bridge wallu-atthe rear thereof, means at the front wall for forcibly underfeeding fuel into the front portion of the lied of burning fuel, 'a nontraveling foregrate upon which the underfed fue] is forced and supported, and be-- tween said foregrate and bridge wall a trav-` eling grate adapted to bodily and steadily carry along the' fuel bed rearward from the underfeed to the discharge.

20. A fuel burning furnace, including in combination with the front, bridge and side walls of the combustion chamber, means for 'underfcedin rlfuel'to the front portion of the f uel bed. and a plurality -of separate traveling gratesarranged in side by side alinement at substantially the level of the.

j undcrfeed between the' front and bridge walls for bodil carrying' the fuel rearward, the length of t ie several traveling grates being greater than the distance' from the frontwall to the grates, and means for supplying forced draft to the; fuel Abed on the travelin g grates.

21.-A fuel burning `furnace, including 1n combination with ythe walls of the combustion chamber, means for underfeeding fue] to the front portion of the'fuel bed, and ya plurality of cri-extensive traveling grates arranged side by side at substantially the level of the underfeed for bodily carrying the fuel rearward therefrom to the discharge.

22. A fuel burning furnace, includirg in combination with'the walls of the :combustion chamber, means for underfeeding fuel to the front portion of the fuel bed, a'n d a plurality of separate Vtraveling grates 'ar- "combination,- nieans for-infe'edmg fuel to the ranged side by side' vfor bodily carrying the fuel rearward therefrom, said underfeeding means comprising a plurality of fuel pushers, each in line with and acting in the direction of travel of' one ol said traveling gratos, a .protuberance on the frontwall between each two pushers, and a non-traveling longitudinal grate portion in linefivith each protuberance and extending between each twmtra'veling gra tes.

23. A `fuel burning furnace. including in combination, means for forcibly underfeeding fuel into the front portion of the bed of burning fuel, an air-supplied non-traveling foregrate of substantial extent upon which the underfed fuel is forced and supported, and to the rear thereof an air-snpplied traveling grate adapted to bodily carry along the fuel bed rearward toward the discharge, together with mechanism for substantially continuously operating saidunf der feed and traveling grate whereby a rearward fuel-flow is steadily maintained and terial.

24. A fuel burning furnace, including in combination, means forA forcibly underfeeding fuel into the front portion of the bed of 4burning fuel, an air-supplied noli-traveling `foregrate of substantial extent upon which the underfed fuel is Jforced and supported. and to the rear thereof an air-supplied travcling grate adapted to bodily and steadily carry along the fuel bed rearward toward the discharge; and means for relative] y regulating the air supplied to the foregrate and traveling grate, respectively.

25. A fuel burning furnace, including :in combination, means for underfeeding luel 1e the 'front portion of the fuel bed. a non-trav cling foregrate upon which the underJ fuel is directly received and supported, ani a pluralityof separate traveling gratos arranged at substantially the underfeed level for bodily and steadily carrying the fuel' Arearward from the foregrate. 1l`0 2G. A fuel burning furnace, including,T in combination, means for underfeeding fuel to the front portion of the fuel bed, and a plu- .rality of separate traveling endless .grates front portion .of the fuel bed, a plurality no of separate traveling endless grates arranged side by sideat substantially thevlevel of the underfeed for bodily carrying the fuel rearward therefrom toward the discharge, and mechanism for adjusting the operation in different sections of the furnace to secure different relations respectively between in- Afeed and discharge.`

29. A fuel' burning furnace, including in combination, means for infeeding fuel to the front portion of the fuel bed, a plurality of separate traveling endless grates arranged side by side at substantially the level of the underfeea; for bodily carrying the fuelreur-4 ward therefrom toward the discharge, and

mechanism for advancing such endless gratesat different speeds, and differently adjusting their speeds to'coperate with ratejof combustion at different parts of furnace.

30. A fuel burning furnace, including in combination, means for underfeeding fuelto the front portion of the fuel bed, a nontraveling foregrate upon which the underfed fuel is directly received and su ported, a plurality of separate traveling en less gratas arranged side by side for bodily carrying the fuel rearward therefrom, and means for regulating the relative s eedsof travel of different ates whereby t e edge of the fuel bed may e caused to advance faster thanV of different grates whereby't e edge of the fuel bed may be caused to advance than its middle. 4

32. A fuel burning. furnace, including in combination, means for underfeeding fuel to the front portion of the fuel bed, and'aJ plurality of separate traveling grates arranged side by side for bodil carrying the fuel rearward therefrom, sai underfeeding means comprising a plurality of fuel pushers, each in line witli' and acting in the direction of travel of one of said traveling grates.

A33. A fuel burning furnace, includingr in combination,` means for underfeeding fuel to the front portion of the fuel bed, a nontraveling foregrate upon which the underfed fuel is directly received and supported,

faster 4and a plurality of separate traveling grates arranged for bodily carrying the ,fuel rearward therefrom, Asaid underfeeding means comprising a plurality of fuel pushers, each in line with and acting in the direction "of traveling foregrate upon which the underreceived and supported,

fed fuel is direct-l and a plurality ofy separate traveling grates arrangedl for bodily carrying the fuel rearward therefrom; said foregrate comprising an agitator device receding each traveling' grate; and means or-regulating independently the speed of travel of different grates and correspondingly the action of each agitator.

35.. A fuel burning furnace, including in combination, means for underfeeding fuel to the front portion of the fuel bed, a nontravling foregrate upon which the underfed fuel is directl received and supported, and a plurality o separate traveling gra-tes arranged for bodily carrying the fuel rearward therefrom; means dividing the beneath-grate space into transverse compart- `entrance portion, followed by agitating means, followed by an endlessl grate, means for forcibly underfeeding fuel into cach entrance, means for advancing the endless grates, and means for relatively regulating the infeeding and advancing means.

37. A fuel burning furnace, including in combination, a sectional grate comprising aplurality of side by side grate sections,

veach section'coniprising a fuel underfeed entrance v portion, followed by agitatingl means, followed by an endless grate, means for forcibly underfeeding fuel into each entrance, means for iulvancing'the endless grates, and means for relatively regulating the speeds of different endless grates.

38. fuel burning furnace, including in combination, a sectional grate comprising a plurality of side by side grate sections` each section comprising a fuel undcrfccd entrance portion, and an endless grate, a pusher for underfceding fuel into cach en- 'ments from which air may pass up through i trance, an engine or motor, connectionsfrom thcI engine for reciprocating all the pusliers, and connections from the cuginil for coperatively causing the advance of all the endless grates, said last named' connections having means for adjusting the speeds 'of different grates relatively tofeacli other and to the pusher operation. Y

39. A fue] burning furnace, including in combination, means for undeyeeding fuel to the fuel bed, and a grate system comprismg an endless grate consisting of a plurality of endless chains o links, and an endless series of grate bars arranged t0 overlap with air passages between, euch link having secured to it lapping bars, and A` a plurality o such over ur on each link being bai' on `another link. Wliereoi` I have affixed my WARREN C. BRAKE.

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