US2567837A - Stoker furnace - Google Patents

Description

Sept- 11, 1951 J. s. BENNETT 2,567,837

STOKER FURNACE Filed Nov. 2, 1946 v 5 Sheets-Sheet l Figi TTO/e/VE Y Sept. 11, 1951 J. s. BENNETT 2,567,837

sToKER FURNACE ATTORNEY Patented Sept. 11; V1951 UNITED STATES PATENT 4Ol'fllGE STOKER FURN'ACE .Joseph S; Bennett, Merian, Pa., assignor to Americany Engineering Company, Philadelphia, Pa., v

a corporationof Pennsylvania, Application November 2, 1946; Serial No. 707;425 f In order to obtain maximum capacities and?"v efficienciesin steam powervpl'ants, it is necessary that the entirel grate area of the furnace be elfectively utilized toburnl the fuel Asupplied thereto. One of the problems encountered in stokers-'employed in' thelarger installations is in effectively feeding and distributing fuel so'that the entireavailable grateV surfacewill be utilized effectively. Inmany'ofv the modern power plants the boilers installed are of considerable depth from front to rear of the furnace; VIny such furnaces it has been found that the vfuel feeding devices of the stokers heretofore employed were inadequate to feed and distribute the fuel" such a` manner that the-required capacities'and efficiencies thereof'could be obtained'. This has been found to be true regardless of 'the type of stokers employed' feeding fuel over relatively long distances ifi roduces "many problems both in connection with the AfuelA vfeeding and distributing mechanism'ernpl'oyed and dueto slag and clinker formations which greatlyimpair proper operation ofA theV furnace. Y

One object of the present invention is to provide novel furnace constructions which eliminate the various problems heretofore encountered and which; enable operation of the furnaceV at the maximum capacities 'and e'ciencies.

Another object is to provide a novel furnace wherein feeding' of the fueliis eifected'at' the sidev thereof rather 'than at the front or rear ofthe furnace asis usually the case.

A further object is .to provide anovel furnace furnaces of the character described water-cooled. screens between the Various stoker units, the

tubes of the .said water-cooled screens being, so arranged as to facilitate the passage of combustion gases therebetween;

VA still furtherk object/isto provide in .furnaces of the character described one `or more Stokerr units of the. traveling grate spreader type.

3 claims. V(cl. 122-235) 2 e Other andE further objects will become apparent asthe description. of; the. invention progresses.

Ofthe drawings:

Fig. l-fis. a' longitudinal sectional elevational View of thefurnac'e,fshowing the arrangement of? theavariouselements thereof.

Fig.- 2 is a 'transverse Asectional'-elevational, view taken substantially-along Vline 2'2. of Fig. 1.

Fig.- 3- is a-1planfview, partly' in section, takenY substantially-'along line 3--3 of Fig. 2'.

Figi Lllisea sectional view of the tubes of afpon-v tion of' one of 'the watencooled screens ltaken substantially'alongjlinelle-4 of Fig.. 1.

Fig.` 5I is a transverse sectionalelevational View of a furnace 'of an alternative construction.

` Fig. tiV is a plan view, partly in section-taken substantially along4 line 6-6 of Fig;` 5.

' Fig. 'Zis a sectionalviewfof the'tubes of a portion-of one ofthe water-cooledscre'ens takensubstantially along line 'I-'l of Fig. 5.

Referring' tothe drawings, fand 'more particularly to Figs. 1 to 3' thereof, themuneral I designates `generallya furnace comprising front and rearv walls 2 and 3f respectively and side walls 4- and 5'-,V Extendingf'between sidewalls 4 and 5 and forming'the"bottorn'wall ofthe combustion chamber 6# ofthe furnace are three units l, 8 and lStof Va Stoker 'indicated lgenerally 'at I'll.

yMounted in any suitable'fmannerincombustion chamber 6is a boilerl l. Boiler Il may be of'anyfsuitableftype and, as illustrated, comprises. three steam drumslz, I-S-'and i4 and a mud drum l5. Banks of tubes I6, llandf I8, ofusual construction, extend #betweenand -are connected to steam drums-v l2, l`3l-a^nd'"Utrespectvely and nmud" drum'j l5l Vl'a'nksof"y tubes l5 and 12D' also connectf steam drums '-I'2 and I`4- tosteam drum-|`3. A lowerbaiile 21= andan upper baffle 2'la,extend ingresp'ectively from#y the l'rear and front ends lof the combustion cham-ber transversely over the stoker'sectonsdire'ct the flow of combustion gasesy from? the -stok'ei 'sections'fto and over! a common patlrftraversing thedr-ums and'itube's'of the' boiler.` Battles;4 21e; Zibiandf 2lu of: 'usuali construction, compelnthe furnace gases to follow the fdirection of the arrows inl'ig:l l'to` the" lower" "e'nd lof an economizer f'muntedf adjacent rearA Wall 3f and indicated generally byI numeral 25. The furnace gases nowupwardlyin econornzer '25 andfinto a duct 26 connect'edtothe inlet side of' an inducV tion fan Zlffrom'whichfthe gases arey conducted to the stack 28 of the furnacey by an outletk duct. 29; .Fan-121. and` duct 26k are. mounted on any suitable supporting structure 3l)` disposed a short distance {beneath- -the root lfrof. the .furnace I.

lower end of side wall 5. Branch ducts 36, 31

and 38 connect communicating duct 35 with plenum chambers 39, 4|) and 4| provided respectively beneath stoker units 1, 8 and 9.

The lower portion 43 of bale 2| is spaced a short distance from mud drum |5. As a result any cinders or fly ash settling on mud drum |5 will -pass between the tubes of bank I6 and onto a deflector plate 44. Deflector plate 44 conducts the cinders and y ash toa hopper 45 provided adjacent the lower .end of economiZer 25. A valve 46 isprovided. atthe lower end of hopper 45 through which the cindersand fly ash may pass to a second hopper 45a. disposed therebeneath. A second hopper 41 is connected to the lower end of economizer 25 for receiving any cinders or fly ash settling in the latter as the furnace gases flow therethrough;` A valve 48 is provided at the lower end of hopper 41 through which the cinders and fly ash collecting in said hopper may pass to a second hopper 41a. Hoppers 45a and 41a are connected to any suitable blower, indicated at 49, having a spout 498b connected to the discharge side thereof. The cinders and fly ash deliveredl to spout 492L by blower 49 are conducted thereby to any suitable place of disposal. A. sealing plate 44a extends between mud drum l5 yand the lower end of economizer 25 to prevent the ow of gases from the latter into hopper 45.

Each of the stoker units 1, 8 and 9 is similar in construction, and isgenerally similar to the stoker shown and described in the lpending application of June E. Beck and AErnst L. Midgette, Serial No. 644,580, led January 31, 1946, now PatentNo. 2,531,719, and to which reference may be had for a complete disclosure thereof. Inasmuch as the stoker unitsv1, 8 and 9'are similar in construction a description of one will suffice for all. For convenience, a description will be given of stoker unit 1, and upon reference to Figs. 1 and 2 it will be observed that said stoker unit comprises an endless traveling grate 50, which is mounted upon a lsupporting framework 5|. Traveling grate 50, as shown herein, is comprised of two sections 50a and 50h, disposed in side by side relation, although it is apparent that a greater or lesser number of such sections may be provided, if so desired, without departing from the invention.v Framework 5| comprises a series of I-beams 52 extending lengthwise of the grate 50 which in turn are mounted upon a series of transverse I-beams 53. The transverse I-beams 53 for stoker units 1 and 9 may be supported at the outer ends thereof on transverse I-beams 53e and 53b mounted adjacent front and rear walls 2 and 3 respectively and at their inner ends on supporting structures indicated generally at 53 and 53d. The transverse I-beams 53 for stoker unit 8 are supported at the opposite ends thereof on supporting structures indicated generally at 53e and 53f.

Sprocket wheels 54 and 55 are secured to shafts 56 and 51 respectively, which are mounted in any suitable'bearings providednear the outer ends of framework 5|. Chains (not shown). to which the grate bars 58 of grate 50 are pivotally attached, are trained over sprgcket wheels 54 and 55. Shaft 51 is actuated by any suitable operating mechanism, such as that shown in the pending application, Serial No. 644,580, previously referred to herein. v

The right hand end (Figi-2). of stoker unit 1 extends into an enclosure 60 mounted exteriorly of side wall 4. Suitable access doors 6| are provided in enclosure 60 to enable the operator to observe the fire and otherwise tend to the stoker. The lower end 62 of side wall 4 is spaced from grate50 to enable movement of the grate and the fuel or ashes thereon past said wall. In

- operation, shaft 51 is so operated as to cause the upper run 63 of grate 50 to move from left to right (Fig. 2). The ashes carried by grate 50 are dumped over the right hand end thereof (Fig. 2) and gravitate 'into an ash pocket 64 provided beneath the enclosure 60.`

In order to prevent separation of the grate bars 58 as they pass over sprocket wheel 55, retaining shoes 65 are provided. As shown in Fig. 2., each shoe 65` is rpivotally supported as the upper end of an arm 66 which in turn is rigidly connected to a rod 61 mounted in brackets 68 secured to thel front end 0f a skid ramp 69. The grate bars 58 are also held in Contact with each other as they pass over the inclined surface 1|) of skid ramp 69.

Air for combustion purposes is supplied to plenum chamber 39 from ducts 35 and 36, as previously described. The air in chamber 39 passes upwardly between the grate bars 58 and into the combustion chamber 6 in the usual fashion. In order to prevent the escape of air beyond the intermediate extremities of stoker unit 1, suitable sealing means is provided. As shown in Fig. 2, a vertical sealing plate 12 forms one end wall of chamber 39. Plate 12 is curved at the upper end thereof so as to extend part' around the left handfend of stoker unit 1. inclined plate 13 extends between the top of plate 12 and-the inner surface'14 of side wall 5. A sealing plate 15 interlockingly engages the upper end of plate 12 and'rests upon the upper surface of the grate bars 58. A second sealing plate 16 is provided beneath the grate bars 58 near the right hand end (Fig. 2) of stoker unit 1. A weighted lever 11 engages the underside of sealing plate 16 and resiliently retains the latter in engagement with the grate bars 58.

A hopper 18 is provided beneath stoker unit 1 for receiving the siftings passing between the grates 58 thereof. These siftings may be removed from time to time through a spout 8U connected to the lower end of hopper 18.

Fuel 'is .fed to and distributed over grate 56 by rotors 8|, 8|. Rotors 8|, 8| are rotatably mounted exteriorly of side wall 4 and propel the fuel through openings 82, 82 provided in said wall. Conveying mechanisms 83, 83 convey fuel from hoppers 84, 84 disposed thereabove to the rotors 8|, 8|, the said hoppers in turn receiving fuel from an overhead bunker 85 through communieating spouts 86, 86. Two fuel feeding and distributing rotors and associated apparatus are shown for each of the stoker units 1, 8 and 9. It is apparent, however, that a greater or lesser number of such rotors and associated apparatus may be provided for each stoker, if it is so desired, without departing from the invention.

The feeding and distributing rotors 8|, 8| may be of any suitable type, such, for example, as that shown and described in the'pending appliafnemer cationof Ernst L. :Midgette andfRobert'W". Reid, Serial No. 599,812, .nledJune 1'6,:19.45,now1?at ent No. 2,511,935. I

l,As shown more p-articularly in.FigS. V1 and 3, a water-cooled screen. 90 is provided between Stokerv units 1 and 8. Wa'tere'cooled screen '90. comprises a series of vertically disposed tubes 9| connected to and` extending upwardlyifrom a header 92 supported upon a resilient supporting member 93 provided between the lower end .of header 92 and a transverse supporting I-beam 94. The lower portions 95 of tubes 9| lie in substantially. Vthe same plane and have protective blocks 9B and 91 provided respectively atopposite sides thereof. In order to facilitate thepassage of furnace gases between stoker units 'I andx, alternately disposed tubesV Bla and '9|1) are bent slightly to the left andright (Fig. 1). respectively, as shown at 98 and 99. Thetubesthencontinue upwardly in substantially parallel relation,.and arethen bent forwardly and upwardly asshown at|| and |02. The tubes are then bent rearwardly and upwardlyasshown at |03 and '|04, and the'upper extremities |05 thereof then'continue in substantially the same plane and terminate at their upper ends insteam drum I2.. By providing a resilient support 93 for header 92, the water wall is free to expand and contract due to the changing temperature conditionsin the furnace.

A second water-cooled screen |01 is provided between Stoker units 8 and 9. Water-cooled screen |01 is generally similar in construction to water-cooled screen 90 and also comprises v a series of vertically disposed tubes |08 extending upwardly from a header |09. Header |09 is mounted upon a resilientsupport |10, rextending between the bottom ofsaid header and a transverse supporting I-beam `I The opposite sides of the lower portions l2 of tubes |08 are provided with protective blocks. |I|3 and ||4 as Shown in Figs. 1 and 3. The alternately disposed tubes |08a and |081) of water-cooled screen`|01 are 'ben-t tothe left and to the right as shown .at .I I5 'and IIE, and then extend vertically in Vsubstantially parallel relation. The alternately vdisposed tubes |08a and |081) are then bent upwardly and for-l wardly as shown at |1 and I8, and thenfare bent upwardly so as .to extend in substantially .the same plane as shown at ||9 and |-20,\.and terminate .at their upper ends in steam `drum 12. By separating the alternately disposed tubes in this manner movement ofthe furnace gases between the said tubes is facilitated.

.A water wall |23 is provided adjacentthe in. terior of front wall .2. Water wall |23 comprises a series of vertically disposed and parallelly arranged tubes v|24, which areconnected at their, lower ends to a header |25. Header .|25 is mounted upon a resilient supportingmember |126l which in turn is mounted upon a transverse supporting I-beam |21. The upper ends of tubes |24 are bent rearwardly as shown at |28, and terminate at their upwardly and rearwardly-disu posed ends in steam drum l2.

A water wall |is also provided adjacent rear wall v3. Water wall |30 comprises a seriesof verl-Y tically disposed and parallelly arranged fluid con ducting tubes |3|, which .are connected ,at their lower ends to a header |32. lHeaderY |32 is mounted upon a resilient supporting member |33 disposed between the lower end -of said .header and a-transVerse supporting I-beam |134. f The upper ends of tubes |3`| are-bent `forwardlyfand slightly upwardly as shown vat |35, at!!'slfthen,ared

bent upwardly and.- rearwardly as shown .at 'l 3E.' and terminate at their v upper ends in mud drum- |32, frontl and rear'water walls |23 and |30 are also free to expand and contract due yto the changing temperature conditions in thefurnace. During operation of the furnace, the furnace gases flow in the direction of the arrows-shown in Fig. 1 and pass between the'tubes of watercooled screens 9|)l and |01., andfthence :iiow through the boiler Il around bailles;2|,.2|s, 2|1) and 2|, and then enter the lower end of: economizer 25. through economizer A25 andA into duct 26, thence through induction fan 21,*outlet duct 29 and4 into stack 28.

lBy arranging water-cooled screensand |01: in the manner shown, a considerable quantity of the heat generated in the furnace is absorbedthereby, since they are disposed in the combustion chamber and lie in the hottest portions of the furnace.

Water walls |23 and V|30 also absorb a'considerable quantity of the heat generated and add materially to thesteam generated in the system.V

Thewater-cooled screens 90 and |01 and water walls |23 and |30, together with the banks 'of tubes I6, |1 and I8 ofboiler Il, constitute an eicient steam generating system, which operates atL maximum efficiencies under all conditions of Operation.

By dividing thesto-ker l0 into units 1), 8 and 9,

l ing from the invention. y

Figs. 5 and 6 disclose an Valternate constructionv wherein ring of the boiler is effected from both of the side walls ofthe furnace. As shown therein numeral |42 designates a furnace comprising front and rear walls |43 and |44 respectively and side walls.|45 and |46. A Stoker |41 comprising` units |481), |481), |4911, |491) and |5021, |501) is provided in the furnace and constitutes `the bottom wall ofthe combustion chamber 15| thereof. The pairs of stoker units |489, |481), |491), '|491' and |502),A |501) are disposed in end to end relation; and all the units are generally similar in construction. The said Stoker units are also generally. similar in construction to the stoker unitsvfl. 8 and 9 previously described. Accordingly, because of the similarity ofthe Stoker units shown in Figs. 5 and 6, a 'description of one pair of such units will suffice for all, and for convenience a brief description will -now be .given of Stoker units' Stoker unit |48a comprises a traveling grate |52, consistingof aseries ofgratebars |53 mounted upon a supporting framework |54. Sprocket 7,5 wheels |55-and 156,mounted respectively` In View of the resilient supports provided for headers |25 Vand- The gases then flow upwardly shafts |51 and |58'journalled in bearings providednear the opposite ends of framework |54, have trained thereover vchains (not shown) to which the grate bars |53 are Apivotally attached. The front end of Stoker unit |48aextends into an enclosure |60 disposed exteriorly of Side wall |45. Shaft |58 is operatively connected to any suitable operating mechanism, such, for example, as that shown and described in the previously referred to pending application, Serial No. 599,812, and to which reference may be had for a full disclosure thereof. y

. Upon operation of shaft |58, the upper run |59 of grate |52 is caused to move from left to right (Fig. causing the ashes carried thereby to be dumped over the right hand end of the Stoker. The ashes so dumped gravitate into an ash pocket |62 disposed beneath enclosure |60, from which they may be removed from time to time by any suitable means.

The Siftings Ipassing between the grate bars |53 of Stoker unit |48a gravitate into a hopper |63 disposed beneath said Stoker. A spout |64 is connected to the lower end of hopper |63, which conducts the siftings to any suitable place of disposal. Air for combustion purposes is supplied to the Stoker unit |88a by any suitable fan or blower mechanism (not shown), the said air being conducted to a plenum chamber |66, disposed beneath saidstoker unit by means of a communicating duct |65 and a branch duct |61.

The left hand end (Fig. 5) of the plenum chamber |66 is bounded by an end plate |68, which is curved at the upper end thereof. as shown at |69, so as to extend around a portion of the left hand end of Stoker unit |488.

A sealing plate |12 engages the upper end of end plate |68 and rests upon the grate bars |53 of traveling grate |52. Sealing plate |12 extends transversely of the Stoker unit |88a and may be attached to end plate |68 in any suitable manner. A Secondv sealing plate |13 is provided beneath the grate |52, near the right hand end (Fig. 5) of Stoker unit |483, and a weighted lever |14 retains the plate |13 in engagement with the Said grate.

Fuel is fed and distributed over the grate |52 of the Stoker unit |48EL through a pair of openings |15, |15 provided in side wall |45 by feeding rotors |16, |18. Fuel from hoppers |11, |11 is conducted to rotors |16, |16 by any Suitable conveyor mechanisms |18, |18. Hoppers |11, |11 may be Supplied with fuel from any suitable Yoverhead bunkers (not Shown) through spouts Stoker unit |481El is similar in construction to Stoker unit |488, and also comprises a traveling y grate |82 consisting of a Series of grate bars |83 mounted upon a supporting framework |84. Sprocket wheels |85 and |86 mounted on shafts |81 and |88, journalled in any Suitable bearings provided respectively near the opposite ends of framework |84, have chains (not shown) trained thereover, to which the grate bars |83 are pivotal- 1y attached. Shaft |88 is connected to any Suitable operating mechanism (not shown), Such as that disclosed in the previously referred to pending application, Serial No. 644,580.

The left hand end (Fig. 5) of Stoker unit |48b extends into an enclosure |89 disposed exteriorly of side wall |46. Shaft |88 is so operated by the operating mechanism that the upper run |92 of grate |82 is caused to move from right to left (Fig. 5) of the furnace, causing the ashes carried thereby to be dumped over the left hand end of the Stoker unit and into an ash pocket |93 dis- 8fposed beneath the enclosure |89. Anysiftlngs passing between the grate bars |83 of the grate |82 gravitate into a hopper |94 disposed beneath Stoker unit |48b. A spout |95 connected to the lower end of hopper |94 conducts the siftings collecting in hopper |94 to any suitable place ofv disposal.

Air for combustion is conducted to a plenum chamber |96, disposed beneath the Stoker unit |48b, by any fan or blower mechanism (not shown). As shown more particularly in Fig. 5, the air from the Said fan or blower is conducted to plenum chamber |96 through a communicating duct |91 and a branch duct |98. Plenum chamber |96 is closed at one end thereof by an end plate |99, having a curved portion 202 at the upper end thereof, which partly Surrounds the right hand end (Fig. 5) of Stoker unit |481.

A Sealing plate 203, extending transversely of Stoker unit |48b, rests upon the grate bars |83 as they pass around sprocket wheel |85. Sealing plate 203 may be attached to the upper end of plate |99 by any suitable means. A second sealing plate 204 is provided beneath the grate bars |83 of Stoker unit |48b, near the right hand end thereof, and is held in engagement with the said grate bars by means of a weighted lever 205.

Fuel is fed to and distributed over the grate |82 of Stoker unit |48b through openings 206, 206

provided in Side wall |46 by feeding and dis-v tributing rotors 201, 201. Fuel from hoppers 208, 208 is conveyed to rotors 201, '201 by means of any Suitable conveyor mechanisms, Shown generally at 209, 209. Fuel is supplied to the hoppers 208, 208 from overhead bunkers (not shown) through the spouts 2|2, 2|2.

The upper ends of end plates |68 and |99 have extending upwardly and inwardly thereof plates 2|3 and 2|4, which have air openings 2|5 and 2|6 provided therein through which secondary air may enter the combustion chamber |5| above Stoker units |48EL and |48b. As shown more particularly in Fig. 5, end plates |63 and |99 are spaced apart to form a duct 2|1, which communicates with the communicating duct |91. Accordingly, a portion of the air from communicating duct |91 will flow upwardly into duct 2|1 and then emerge into combustion chamber |5| through openings 215 and 2|6 provided in plates 2|3 and 2|4 respectively.

A water-cooled Screen 220 is provided between Stoker units |488, |48b and |499', |498. cooled screen 220 comprises two rows of vertically disposed uid conducting tubes 22| and 222. The lower ends of tubes 22| and 222 are connected to headers (not shown) mounted in any suitable manner Ibeneath Stoker |41. The lower portions of the opposite sides respectively of tubes 22| and 222 are covered by protective blocks 223 and 224-, as Shown in Figs. 5 and 6. 'Ihe intermediate portions of alternately diS- posed tubes 22| and 222 are bent outwardly, as shown in Fig. 7, so as to facilitate the passage of furnace gases therebetween. The said tubes 22| and 222 then continue upwardly through combustion chamber |5| similarly to tubes 9| of water-cooled screen 90, previously described, and terminate at their upper ends in one of the steam drums of a boiler (not Shown).

A second water-cooled screen 226 is disposed between Stoker units |49, |49 and-|50-, |501. Water-cooled screen 226 is similar in construction to water-cooled screen 220, and also com- Waterare connected at their lower ends to headers (not shown) disposed beneath Stoker |41. The opposite sides of the lower portions of tubes 221 and 228 have provided thereon protective blocks 229 and 232 respectively. The tubes 221 and 228 extend upwardly through the combustion chamber similarly to tubes ||2 of water wall |93, and the portions disposed above the protective blocks 229 and 232 are bent outwardly similarly to the tubes 22| and 222, as shown in Fig. '1, so as to facilitate the passage of furnace gases therebetween. The tubes then continue upwardly similarly to the tubes |I2 of water wall H38 and terminate at their upper ends in one of the steam drums of the boiler (not shown).

Front wall |43 also has provided interiorly thereof a water wall 233. Water wall '233 comprises a series of vertically disposed, parallelly arranged fluid conducting tubes 234, which are connected at their lower ends to a header (not shownl, disposed beneath the Stoker |41. The tubes 234 extend upwardly along wall |43 similarly to the tubes |24 of water wall |23, and are then bent inwardly, and also terminate in one of the steam drums of the boiler (not shown).

Rear wall |44 has also mounted interiorly thereof a water wall 236, consisting of a series of vertically disposed and parallelly arranged uid conducting tubes 231, which are connected at their lower ends to a header (not shown) disposed beneath stoker |41. Water wall 236 is similar to the water wall shown in Fig. 1 and the tubes thereof extend upwardly along the rear wall and are then bent forwardly and terminate at their upper ends in the mud drum of the boiler (not shown).

Water-cooled screens 220 and 226, as shown, are comprised of two rows of fluid conducting tubes. It is apparent, however, that water-cooled screens consisting of a greater or lesser number of rows of tubes may be provided, if it is so desired, without departing from the invention.

From the Vforegoing description it is seen that novel and highly efficient Stoker furnaces have been provided, which are capable of operating at the highest eiciencies under all conditions of operation. The stoker furnaces herein shown and described are particularly adapted for use in connection with the larger boiler units; although they may be employed with equal efi'iciency in smaller units. By arranging the units as herein shown and described, the entire grate area of the furnace may be effectively utilized, and as a result the furnace may be operated efficiently at the highest capacities. l

It is apparent that the constructions herein shown and described may be modified to meet the requirements of the different types of furnaces and boiler installations without departing from the invention. Accordingly, while the embodiments of the invention herein shown and described are admirably adapted to fulfill the objects primarily stated, it is to be understood that it is not intended to limit the invention thereto, since it may be embodied in other forms,

all coming within the Scope of the claims which follow.

What is claimed is:

1. In a boiler furnace having front and rear end and side walls defining a combustion chamber, boiler drums extending transversely between said side walls, and boiler tubes in transverse banks connected to said drums and forming with the latter a boiler assembly above Said chamber.

Stoker means forming the bottom wall of said combustion chamber and comprising a plurality of individual sections each extending endwise be tween said Side walls and in side-by-side relation so that the fuel and ash move across the furnace, a fluid cooled screen in the form of an upwardly extending transversely disposed bank of fluid conducting tubes located between each adjoining pair of said Stoker sections and connected to said drums, means for feeding fuel to each of said Stoker sections through a side wall of the furnace, and means for directing the flow of combustion gases from the said Stoker sections laterally through Said screens to and over a common path traversing the drums and tubes of the Said boiler.

2. A boiler furnace according to claim 1 wherein the boiler comprises upper and lower drums, and wherein further the said combustion gas directing means includes upper and lower baffles extending respectively from the front and rear ends of the combustion chamber transversely over the Stoker sections to the said upper and lower drums and forming in effect the top wall of said chamber.

3. A boiler furnace according to claim 2 wherein the upper and lower baiiies extend over the upper and under the lower drums respectively and in spaced relation to the latter, the said lower baffle comprising a portion inclined downwardly and rearwardly from the boiler and terminating at'the lower end thereof in an ash receiving hopper.

JOSEPH S. BENNETT.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 772,435 Sewell Oct. 18, 1904 1,106,453 Jacobus Aug. 11, 1914 1,931,948 Armacost Oct. 24, 1933 1,939,535 Badenhausen Dec. 12, 1933 2,057,622 Webster et al. Oct. 13, 1936 2,110,452 Moyer Mar. 8, 1938 2,111,605 Bennett Mar. 22, 1938 2,139,348 Badenhausen Dec. 6, 1938 2,167,545 Duram rJuly 25, 1939 2,182,782 Barnes Dec. 12, 1939 2,182,783 Barnes Dec. 12, 1939 2,305,611 Frisch Dec. 22, 1942 2,416,053 Grossman Feb. 18, 1947 FOREIGN PATENTS Number Country Date 538,008 Great Britain July 16, 1941

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