US2601333A - Coke stoker with oscillatable clinker breaker - Google Patents

Description

June 24, 1952 c, SHAFFER 2,601,333

COKE STOKER WITH OSC ILLATABLE CLINKER BREAKER INVENTOR 0/5.: 75/? E-JHAFFEB4 his ATTORNEY.

4 Sheets-Sheet 2 June 24, 1952 c. E. SHAFFER COKE STOKER WITH OSCILLATABLE CLINKER BREAKER Filed Sept. 4, 1947 INVENTOR. CHESTER JHHFFEE. W%

his

ATTORNEY.

June 24, 1952 c. E. SHAFFER 2,601,333

COKE STOKER WITH OSCILLATABLE CLINKER BREAKER Filed Sept. 4, 1947 4 Sheets-Sheet 5 IN VEN TOR. O/fisrse I. SHHFFER.

(9 TTOR/VE Y.

June 24, 1952 c. E. SHAFFER COKE STOKER WITH OECILLATABLE CLINKER BREAKER 4 Sheets-Sheet 4 Filed Sept. 4, 1947 INVENTOR. 0153752 A. Jun/men. BY 4 Z 11;:

ATTORNEY.

Patented June 24, 1952 COKE STOKER WITH OSCILLATABLE CLINKER BREAKER 1 Chester E. Shaffer, Arlington, N. J., assignor to Koppel-s Company, Inc., Pittsburgh, Pa., a corporation of Delaware Application September 4, 1947, Serial No. 772,049

3 Claims. (Cl. 110-45) This invention relates to coke stokers. More" particularly the invention relates to an automatic stoker having means for breaking clinker in the fuel bed during feeding of coke to a heating furnace grate for automatically controlling.

the fuel feeding and ash removal from the grate in accordance with the demand for heat.

The present invention embodies several features of the coke stokers embodied and claimed in my Patent 2,388,294 granted November 6, 1945, and in my patent application Ser. No. 551,084 filed August 25, 1944, now Patent No.- 2,453,162 of November 9, 1948. The features of these patents, however, are embodied in the present invention in such a way that the coke feed to.

and ash removal from the grate are more positive and adaptable for different sizes of fuel. Further the furnace grate is kept freer of ash and clinker and the operation of the Stoker is more quiet and clean. v f

The primary object of the present invention is to provide a reciprocable stoker apparatus that stoker hereinafter described and particularly defined in the claims.

The various features of the invention are 1111.15!

' trated in the accompanying drawings in which Figure 1 is atop plan view with parts broken away of a stoker embodying the preferred form of the invention;

Figure 2 is a view in side elevation of the stoker shown in Fig. 1; I

Figure 3 is a view in side elevation with parts shown in section taken on the line IIIIII of Figure 2 showing the ash removal conveyor;

Figure 4 is a view in elevation with parts in section taken on the line IV-IV- of Figure 2 showing the supports for the coke bin elevator.

Figure 5 is a perspective view of the hydraulic drive mechanism and the connectionsbetween the hydraulic cylinder and the other moving parts of the stoker which are operated therefrom; i

Figure 6 is a detail view in elevation with parts in section of the feed tube pusher andits connection with the hydraulic drive cylinder;

Figure 7 is a fragmentary view with parts in sectional elevation showing the mounting of the grate and clinker breaker on the coke feed tube;

Figure 8 is a detail plan view of the grate supporting ring;

Figure 9 is a sectional view of the grate supporting ring taken on the line IXIX of Figure 8; and v Figure 10 is a sectional view of the valve for controlling the operation of the hydraulic cylinder with the ports of the valve diagrammatically illustrated.

The present invention is designed and adapted particularly for feeding fuel to and concurrently breaking of clinker while removing ash from and controlling the'combustion in a domestic house-heating furnace. The various parts and operation of the stoker may be briefly outlined as follows:

Referring more particularly to Figures 1, 2 and 3 coke is stored in a bin having a hopper bottom (not shown) with a feed bin conveyor In which extends under and forms the bottom of the hopper. The feed conveyor [0 advances coke from the bin to the opening of a stoker feed tube l2 (Figures 1 and 2) from which the coke is advanced to and pushed as an underfeed centrally up into the bottom of an annular upstanding grate M from below mounted in the firebox of a furnace or boiler [3. The continued reciprocable feed movement of the coke by a reciprocating pusher up into the grate centrally thereof from below providesan up and down motion of the fuel in the central portion of the fuel bed on the grate which acts to discharge ash outwardly and downwardly along the grate tofallinto the ashpit of the furnace below the grate. Simultaneously with the movement of the fuel a clinker breaker and ash removal ring 16. disposed around the central fuel feed at the lower periphery of the upstanding annular grate is operated to oscillate the same to grind the clinker in the fuel bed and to assist in discharging ash and ground clinker from the fuel bed into the ashpit of the furnace below. The ash discharged intothe rear of the ashpit is moved by a pusher i 8 to oppositesides of the ashpit into the path of an ash feedvconveyor consisting of horizontally mounted plates 20 which are reciprocated to carry the ash out of the :ash box and to discharge it into the path of an ash re moval elevator 22. The ash removal elevator discharges the ash through ahflexible tube 24 out into a receiving container 26 (FigureB).

If the fuel is pushed intothe grate faster than come in contact with a fuel bed level controller 28 (Figures 1 and 2). The controller 28 consists of a high temperature metal contact member 30 secured to a rod 32 which is pivotally mounted in the wall of the furnace I3. As the controlling member 28 moves up and down, it operatesan electric switch, 36 mounted at the side of the furnace to open and close an electric circuit for operating a motor 38 which'drives a hydraulic pump 40. When the hydraulic pump is operated the driving mechanism for the coke 'tinu'ous so long as the 'fuelinjthe grate i's'below a predetermined level.

The burning of fuel in the furnace iscontrolled by a thermostat 42 which is usually located in the house or room-being heated. This thermostat'in' turn operates'an electric switch toopen and -closenan electric circuit for operating a damper control motor "44."When the thermostat calls for heat,'.the motor isoperated to move an eccentric lever to pull cables .46 and .48 to I open a stack damper50 and draftdoors52, re-

spectively. When'the'thermostat is not demand- I ing additional'heat" the eccentric lever is moved back 'to' operate'athefcablesto closenthe stack damper andlthe draftdoors' at 'thefront' of the furnace. It will-be seen'that'the fuel 'bed level controller and the thermostat operate independentlyv of oneanother for controlling combustion but the operation o'f'the fuel'bed level control is ,dependentlupon the heat demandas determined by" the thermostat. V

l Detail description of the st'oker warts The fuel conveyor lfl isimade up of steel. sides I '54 (Figure .4) .that are mounted-on a stand 56.

At thewbottomof the sides 54 are angles 51. .upon

1 which azhardened steel plate :58 formingthe con- 1 veyor: is slidably: mounted. This conveyor plate 58textends into'andformsgthe bottomof a hopper :ingthe 'cokeabin. Thegplate ,58 (Figures. land. 4)

has a. plate BD'attached ,to the top ,thereoffrom which projects axpin..-62. The. pin 62 fitsinto .one end of axlever (it -(Figure-) whichis con- :.;nected =witha driving mechanism, as hereinafter described. .The'..convey or plate 58 is-rgiven a s1ow-- wreciprocatingmotion. Upon its backward stroke it. slides under the fuel or cokejandiupon: its

forward stroke the :coke moves forward .withithe .plate- The forwardendof the'plate'discharges :the coke upon adeflectormember 66 ;(Figures.1; I 2 .and' 3) forming ,:the rear end of .thetunderfeed stoker feed tube [2. .The forward tendrof the frame in which; the:.binf conveyor,- is:; mounted rests upon a plate 68 (Figures 2.and3) whichis :integralwith the rear end of the stoker-feedltube. The-plate 68- and the front' end. of the conveyor housing are circular: in form so thatLtheconveyor housing may be mountedinxan angular position i with reference to the feed tube to providefor different locations of the coke bin withreference to'the furnace.

The feed tube l2 -(Figure 2)-'has a conveyor slidably mounted'therein. 'The conveyor plate is shownmore particularly in' Figure 6. 'Iherear menu of the platemis connected with a pusher plate 12 Fig. 5 which, in turn, is pivotally connected with a clevis on the front end of a piston rod 14. The coke which is discharged from the end of the conveyor plate 58 upon the deflector plate 66 falls upon the pusher plate 12 (Figures 1, Sand 5). The plate 10 is given a slow reciproeating movement. On} the rear stroke of the plate the coke resting *on-the'plates l2 and 10 is held from movement with the plates by the deflector 66 but upon the forward movement of the plates-10;and-l2ithe coke is pushed forward. As

fthez-coke reaches the front end of the conveyor 10 it. falls over a ram 16 (Figures 2, 5 and 6) which'istslidablymmounted in the bottom of the feed-tube. "On-'fjthe forward movement of the conveyor platelfl' the ram 16 forces the coke .acrossa .curvedi:.face 18 of the feed tube l2 to projects inwardly toward the axis of the fuel forcethe coke through the. throat of the feed tube up" into the grate of the furnace centrally thereof from below. the coke is forced up into the grate' peri'odicallyby the forward stroke of" the reciprocable pusher l6, the'fuelmoves "up and then falls back-somewhat with the retractive-movementof the .ram 16. -A chord edge '80"('Figurel) -at the top or the feed tube throat feed tube and tends-to hold the coke in an arched position-in the-fuelbedso that only apart of the 1 cokemoves downwardly when the forward stroke ofitheram is retracte'd. The ram 16 moves the coke;upwardly througli=the centralportion of the feed tube andthe fuel in'the central portion of :"the feed tubethen 'movesdownwardly with the retractive' movement-of the ram. During'com- 'bustion there-is a shrinkage of the coke-at the gratefwalls and the ash and-impuritiesgradually travel down the *facejof" the grate to the clinker breaker. The fuel movement is thus an upward movement "through the central portion of the along the 'walls'of the grate.

:thefine ash'passes out through thespaces begrate and an outward and. downwardmovement In this -movement tween the vertical 'barsof the grate andcoarser impurities of ash "or ;clinker are broken up-or crushed by the ring [6 when they reach the lower 3 limits of the upstanding annular "grate. 1 The ring 16 jmay remove. fine ash aswell-as the .,coarser'ash"or clinker. It has been foundthat thejupward' and downward movement of the coke bed in the grate isinecessaryto getthefine. ash

- and clinker. to move fromthe centerfof'the' fuel bed iout .tdthe grate-and "then down toythe breaker. This movement of ,the coke in the fuel bed inupwardlyand. downwardly directionswith eachstroke of. .the. ram. tends to move. the.. ash

.from the ..fuel.bed out to the grate ,andthen ..down along the. same so. that the ash pmoves through the grate bars to be discharged into the -.ashpit. of .the furnace. and the: clinker is. ground at the base of the grate, whenceitfdischargesto the ashpit.

"Toessistin removingash andclinker from the fuel -:bed which .does not pass through the grate *barsp: an koscillatably mounted clinker-breaker and-.ash 'rem'over annulus is positioned below the 7 grate I 4 'between. its I lower; periphery; and. the

vIcentral'fuel feed. 'rxThe-cokebreaker consists of a ct ring 1 I 6 *having. a: series ofsteeth L82ILO1'1' the 5 upper .rsurfaceiithereoff:(Figures 1, 5sand: 'lTherring L forms .amportion of the: grate and thus-"supports part of the fuel bed. The ring [6 is supported-on the front 'end o'f thevfeed. tubeLlZ' onutop of a directly on top "of thevtube I 2. The" ring- 84 is isecuredi:tofthe tubeli l'2iwhileithe ring J5; is islidably mounted on the base ring 84. A pair of downwardly projecting lugs 86 are formed on opposite sides of the ring I6 which extend through openings 88 in the ring 84 (Figures '7 and 8). The lugs have pins fixed therein which project into holes in each arm of an oscillatable yoke 90 (Figure 5), which is positioned under the ring. The yoke 90 is pivotally mounted at its mid. portion in an arm 92 of a compound lever 94 which is pivotally mounted for oscillation between flanges 96 projecting outwardly from the front end of the feed tube (Figure 2) for oscillating the yoke 90 and hence the clinker ring I6. A transversely extending arm 98 (Figure 5) fixed on the compound lever 04 is connected with a reciprocable driving link I which is connected with the driving mechanism, as hereinafter described. The ring I6 loosely fits in the base ring 84 to leave a space IOI (Fig. 7) by which the ash and clinker ground up by the ring I6 may move around the outside of the ring I6 to be discharged into the ashpit. On top of the base ring 84 is fixed a grate bar supporting ring I02 by means of pins I03 (Figure '7). The ring I02 has a. slot in its upper surface which receives the lower end of the annular series of grate bars I5. The grate bars incline from the ring I02 upwardly and outwardly so that the upper ends of the grate bars rest against the firebox wall of the furnace.

A second outwardly extending arm I04 (Figures 2 and 5) on the compound lever 94 has the scraper I8 attached thereto which extends downwardly from the lever to close proximity to the bottom of the ashpit but above and between the ash bars 20 for the purpose of moving the ash which falls from the grate between the bars 20 and into the path of the ash feed bar conveyors 20.

The hydraulically operated driving mechanism is illustrated more particularly in Figures 1, 2 and 5. The pump for placing the driving fluid under pressure is submerged in a driving fluid in chamber I05 which has a hydraulic liquid filling tube I06 and a cleaning tube I08. The pump draws fluid from the closed chamber and forces it through a valve mechanism IIO which is mounted within the chamber I05. The motive fluid flows from the valve IIO through a tube II2 or tube II4 to a hydraulic cyllnder- II6 in accordance with the position of the driving piston within the cylinder. When one of the tubes II2 or I I4 is used for driving the cylinder piston, the other tube is used for exhausting the fluid from the opposite side of the piston. The fluid returning from the cylinder to the valve is exhausted through the valve into the chamber.

The construction and arrangement of the valve H0 is illustrated in Figure 10. The valve consists of a block having cylindrical plungers H8 and I20 slidably mounted within the block. Each plunger is provided with three faces which are arranged to open and close ports in the block IIO to provide different paths of flow of the hydraulic fluid through the valve. The pump 40 is diagrammatically illustrated in Figure as opening into a port I22 under the plunger H8. The fluid entering the port I22 flows through a port I24 to the tube H4 and thence through the tube into the cylinder II6. While the fluid is forcing the plunger to move through the cylinder, fluid from the other side of the cylinder flows through the line II2 into a port I26 and thence through a port I28 and passage I30 in the block down into the storage chamber I05. At the same time oil flows from the port I24 through a pas- 6 sage I32 to a port I34 behind the end of the plunger I20, thus holding the plunger I20 to the right in the position shown in Figure 10. Also the oil from the pump flows through a passage I36 into a port I38 behind the plunger I20 and this oil also passes through a port I40, through passage I42 into a port I44 against the end of the plunger H8. The plunger H8 is held in its position by spring pressed detent I40 which rests against a central shoulder on the plunger. The pressure of the spring will hold the plunger II8 stationary under the ordinary operating pressure of the pump. However. when the piston reaches the end of its stroke the continuous operation of the pump 40 tends to build up the oil pressure and when this pressure rises above the usual or operating pressure, then the fluid flows from the port I40 through the passage I42 to the port I44 and moves the plunger I I8 to the left (viewing Figure 10). When the plunger II 8 moves to the left the port I22 is positioned on the right side of the central face of the plunger so that the fluid may flow through the port I26 and a passage I48 to a port I50 behind the plunger I20. The operation of the plungers III; and I20 is such that the plunger I I8 moves from one position to the other before the plunger I20 follows in this movement. With this operation the ports are all completely closed or completely open. When the plungers move to the left, ports I52 and I54 are open to passage I56 which permits the oil to flow into the sump. It will be understood that when the plungers are shifted to the left the pressure oil flows through the valve to the line II2 and oil exhausted from the cylinder flows from the line I I4 into the port I44 and thence through the passage I56 to the sump in the pressure chamber I05. Rubber bumpers I58 are mounted on the inner ends of the nuts I60 which .close the passages in which the plungers H8 and I20 are mounted so that the plungers strike against the bumpers and thus deaden the sound of the valve shifting. The valve arrangement which is described above is important in that the valves are reversed when excessive oil pressure develops in the feed lines. This arrangement acts as a safety measure so that if the driving mechanism is prevented from making a full stroke by some obstruction to the fuel feed or ash removal the driving mechanism will be reversed to relieve the pressure and therefore an excess pressure will not be exerted upon the driving mechanism. A locking pin I02 is mounted in the central portion of the valve block H0 and moves between the plungers IIO and I20. This detent prevents the plunger I20 from moving to the left (Figure 10) when oil is being forced into the cylinder through the tube II4. When the plunger II8 has been moved to the left the oil entering through the port I22 flows through the port I26 and passage I40 to the port I50. This oil moves the plunger I20 to the left. As the plunger I20 moves to the left the detent I62 is raised. The detent I62 thus insures that the plunger IIB will move in each direction in advance of the following movement of the plunger I20. The same fluid pressure tends to raise the detent I62 and also acts to raise the detent I46.

A piston mounted in the cylinder H6 is connected with a pusher plate I2 by the piston rod I4 (see Figures 1 and 5). The movement of the cylinder piston which drives the feed tube conveyor furnishes the power for operating all of the stoker mechanism. To protect the plunger analyses and its packing fr'om'the ash and :dust of the coke a *fie'xible corrugated" protector- I64 is mounte'd around the plunger and 1 connected between the end i of the cylinder I I6 and the plunger 14.

To drive the coke 'bi nconveyor a crossbar I66 (Figures 1 and-) is-attached to the bottom of the-conveyorplate m so asto move with the con'-' veyor plate. A connecting rod 168 is. pivotally connected to the righthandend oi the =-bar I66 (viewing Figure 5)' andthe other end'of the link is connected with a lever I I'll which is secured to an ash conveyor quadrant cut-out plate 112 The ash conveying quadrantcut-out fplateand lever I16 are pivotally' mountedon the-bott'om of the feed tube frame I14 -'-(Figure 2) by means of a plate- I 16' and pinflB (Figuresl,i2 and 5):. An upwardly extendingpin -ISOI is mountedin'the rod- 'I681to receive a-islotted end I62 of.a:link I 84 The :link 1 8k is; connected with. a lever 186 whichis fixed-on a pin l88 (Figurebl pivoted in a bearing I 96 -WhlCh is attached to I the side of the-feed tube; A lever 'IBZFisI secured-to the upper" end of:- the :pin: I 88 so was-atobe movable therewith The lever I92 iswpivotally:connected with the link-64' so thatthe movement imparted to the link |'84, levers II 86" and l 92' are-imparted to thelinkifi i for giving the reciprocating movement to'=the.coke bin-conveyor plate 58.. The slot l86in thelink I34 is provided .with a thread- :edbolt I94 'by whichsthe:amplitudewof, or the extent of themovement of the coke bin conveyor may be varied.- Itv has been; found in practice 7 that the stroke :of the coke =bin'conveyor should be shorter thanathestrokeioftherfeed tube conveyor in order to properly allocate :the desired amount of coke being .ied :to the :fuel bed.

To operate the-annular.clinker breaker and :ash remover, the r-linkhlflfl which is connected with the compound lever :94 base pin. and slot connection withthexlett 'handL endJof the bar I66 (viewing Figure 5). The link I66 has. a.slot and pin COIHIECtlOl'l'TWith a pinzl96 mountedcin. the rod I66 by whichrthe .7 length of: .stroke' of. the crusher may :be varied.

The coke feed :tube-has la circular cross section. at the frontaside .of the-.igrate so thatash whichfalls inlthe vicinity of therfeedttube flows down to the floor of the ashpit. The ash scraper 13 moves the ash whichafalls at the back-ofthe grate to the-sides ofithe 'ashpit in the path of movementeof vthe ash -feedconveyor. The ash feed conveyorvconsists of two reciprocating bars or plates 20 whichare slidably mountedin guides 266 positioned-under thefeed tube Figure 2).

The front end'of the bars or plates 26 are connected with pins .262 that are mountedin the face of the ashconveyor quadrant cut-out plate H2. The movement-cf the :link I68 .-andlever I76 oscillates the plate I12 to give a reciprocating motion to the ash conveyor .bars or plates. 20. The plates 26 are spaced from each'other :on opposite sides of the feed tube: and. move in .opposite directions The slow reciprocating motion of the plates-ZH -carriesthe ash from the ashpit-of the furnaceforwardly to the conveyor quadrantcut-outplate I I2. The conveyor quadrantrcut-out plate has a cut-out 'quadrantsection' 264 which'acts to move the ash into elevator cups 266 of the ash removal elevator 22-. Thenposition of theflelevator cups .with referencetotthe quadrant 284 of: plate .I'I'Zis shown inFigures .1 and.2. Each oscillating stroke of therconveyor plate I12 acts tomove-ash from one of the bars or plates: 20 tothe elevator: cups 206.:

The construction of: the:ash: removal "elevator is illustrated-more .particularlyzin Figures 1,12 and 3. A boot 2U$constructedto ":receive :the lower end of a frame'2 1.0 for housingzthe ashtre-' moval elevator is zattached to thetframe'ofithe feeds-tube immediately under :the .front end. of the :coke bin conveyor- The; ash :preceivenboot 208 :is constructed and :arranged so that it may be attached to: either side'of the feed" tube frame in order to permit; the. elevator :to .be alocatedi in any desired arrangement of. the housing for the heating furnace. The elevator consists: of a chain.2 I2 which :runsbetween sprockets: 2 I4 and '2 I36 that. are :rotatably ,mcuntedon saxlesr2 I-8 and 226,vrespectively: The .axle 21 8 ,issmountedrxin hearings in the boot 268 :and' the :axle. 2261s mounted in bearings; inxthe irame 2l 0 The-axle 220isthedrivingraxle'zfor the-elevators To drive the: elevator. a cable 222' '(Figurel'5) 1 connected withthe left hand end of the 'bar.:I66 (Fig-ure 5) and extends to a pulley 224 pivotally.,-mounted in'the boot 2.08. The. cable-V:passes-overnthe pulley 224 and: is connected .withira chain. 226 which passes around a clutchzpulley .228 onrthe axle 228.- Upon-the forward stroke -,of the=feed tube conveyor the cable 222 operates the clutch 228 to-drive the elevatorr'for a predetermined distance; Upon the return-stroke ofthe feed conveyor the cable andiclutchhidle as they are moved inla rearwardly direction-by1a:coiled.spring 239 which is connected to the .chain 226 =and the elevator frame 2 H1. Accordingly {the elevator :is given :an intermittent motionzwhich corresponds to the feed stroke of-the feed tube conveyon: A series-ofcups 2G6 mounted-omthechainrZ I2 move into the path of.v the ash, advanced by the; ash conveyor plate I E2 and carry the ash out to the discharge tube 24 and-receivers.

With the construction outlined above, it will be seen that all of thestokerparts areimounted on frames which rest on the floorlevelv Of'lthB furnace. The coke bin conveyor may be s adjusted to angular positions to, permit different locationsof the coke bin with: reference to the furnace. The ash elevator :may 'be-mountedron either;side of the coke feed tube. Twotash'receivers 26 are positioned onlthefioorat theside of the ash conveyors An .emptyreceiverthus may be readily placed'under-.-the tube--24 when one container has been filled. z

The movement of the coke tothe furnaceigrate and the removal-ofashand clinker fromthe-ashpit are "carriedouteby flatreciprocating plates. Such awconveyor has a distinct advantage .over screw conveyors or continuously operating belts .because such: conveyors a do not? :become clogged with the different kinds vofematerial; being ,,ccnveyed;

The hydraulic drive'is positive zanduquiet and still will automatically ;change the. :stroke torreverse itself if the drivingpartebecomeclogged.

Thepreferred; form of thewginvention having been thus describedwhat is 'claimed as' new is:-

'l.. Awstoker for supplyingzfuerto :and removin ash-from aheatingifurnacecomprisingt, anannu- ;lar upstanding fora-minous grate arranged. for

passage :01?- =ash*therethrough: and adapted lto.:fit within the flIBbQX of a: furnace-inaa stationary position, ae fuel feed 'tube with a: discharge z-portionmounted-atthe central-portion-of and below the grateto deliver ofuel up throughzthe J grate centrally: thereof from below a the ;grate,-: a fuel conveyor pusher within the afuelf eed: tube torfeed :fuel' through :the feed. tube 'for ;deliv,ery;to :the

grate. an annular zclinker ---breakerl-mountedaafor oscillation .below' the rgrateaand extending inside the lower peripheral portion of the grate in position to engage clinker in the bottom of a fuel bed in the grate, means for operating the fuel conveyor pusher, an oscillatable driving member connected with the clinker breaker, and means to oscillate the driving member to impart an oscillating motion thereto to oscillate the annular clinker breaker.

2. The combination defined in claim 1, and in which the annular upstanding grate is supported on the fuel feed tube and is inclined upwardly and outwardly 3. The combination defined in claim 1 and in which the annular clinker breaker is mounted within and under the bottom of the annular upstanding grate with teeth on the upper face of the annular clinker breaker to break and discharge ash clinker from the bottom peripheral 10 surface of the grate when the breaker is oscillated.

CHESTER E. SHAFFER.

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

UNITED STATES PATENTS Number Name Date 2,240,972 Winkler et a1 May 6, 1941 2,248,206 Suman July 8, 1941 2,306,189 Schweickart et a1. Dec. 22, 1942 2,359,638 Greger Oct. 3, 1944 2,378,376 Ackron June 19, 1945 2,380,260 Pilcher et al July 10, 1945 2,388,294 Shaffer et al Nov. 6, 1945

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