US2582583A - Stoker mechanism - Google Patents

Description

Jan. l5, 1952 c. w. BROS STOKER MECHANISM 5 Sheets-Shee?l l Filed Jan. 24, 1949 INVENTOR. CHESTER l/\/. BROS MMQ/m n: Uwe c P u ATTORNEYS Jan. 15, 1952 c. w. BROS STOKER MECHANISM Filed Jan. 24, 1949 5 Sheets-Sheet 2 j ma 45 46 IfV VEN TOR. CHESTER VL/ BROS ATTORNEYS Jan. 15, 1952 Q W BROS 2,582,583

, sToKER MECHANISM Filed Jan. 24, 1949 5 Sheets-Sheet 5 INVEN TOR. f 'Cf-STER W 5R05 ATTORNEYS Jan. 15, 1952 c. w. BROS 2,582,583

STOKER MECHANISM Filed Jan. 24, 1949 5 Sheets-Sheet 4 I N V EN TOR. CHESTER W BROS BUMMWW ATTORNEYS Jan. 15, 1952 c. w. BROS 2,582,583

STOKER MECHANISM Filed Jan. 24, 1949 5 Sheets-Sheet 5 D C (l Y INVENToR. CHESTER Vl/ BROS BTM/0mm ATTORNEYS Patented Jan. 15, 1952 UNITED STATES PATeNToFF1cE- sroKER MECHANISM chester W. Bros, Edina, Minn.,'assignor m Wm. Bros Boiler & Manufacturing Co., Minneapolis, Minn., a corporation of Minnesota Application January 24, 1949, Serial No. 72,4437' 7 Claims.

This invention relates to stoker mechanis and more particularly to overfeed stokers of the sprinkler type. Such stoker mechanisms are also sometimes called spreader stokers. VThe term .sprinkler will be used herein and will be understood to include both the sprinklerror spreader types, however designated. l

During the operation of overfeed sprinkler stokers the fuel is delivered intermittently by an intermittently operated feeding mechanism, and from this the coal falls upon a rotating element which strikes the falling coal and impels or sprinkles it into the combustion space where the lighter particles are burned in suspension, the heavier particles falling onto a grate where combustion is completed.

Various intermittent coal feeding. mechanisms have been provided, one type being exemplied by my prior Patent No. 2,163,825. In this patent the fuel is delivered from a hopper or feed spout to afeed plate where the fuel is periodically shoved forwardly toward the furnace by. means of a reciprocating feed shoe and a quantityv of coal, which is thus measured off and moved by each forward motion of the feed shoes, is pushed forward and shoved oif the deliveryend of the feed plate for each working stroke of the feed mechanism. As the fuel falls it is engaged by a Abladed rotor arranged below the delivery end of the feed plate, and since the rotor is revolving at relatively high speed, the rotor blades strike the falling particles of fuel and impel or sprinkle them into the combustion space where the particles are burned, partly in suspension and partly on the grate at the bottom of the combustion Usually the iiner particles burn in suszone. pension and the heavier particles, which may ignite and partially burn before they fall onto` the grate, are then consumed on the grate below.- In some instances a chain or traveling grate is used in a furnace of this type and always a thin fuel bed is used. This type of stoker mechanism is highly responsive to load fluctuation as the combustion rate can be changed widely and rapidly.

Other types of mechanisms are also used for intermittently moving forward measured (metered) quantities of fuel, which is then sprinkled by the revolving rotor situated below the feed device. In another form of such mechanism the coalis moved forward periodically and in somewhat metered amounts by a, small feed conveyor (belt or chain type) that is actuated intermittently, step-by-step, the coal being delivered 01T the end of the conveyor and onto the revolving rotor for the sprinkling-operation. i Thus, in all stokers 4of this character there isa.

Vvamounts of coal onto the sprinkler element. The

average feed rate is varied, either by changing the frequencyA of stroke ormovement ofthe feed means or bychanging theY length of thestroke or distance of movement of feed belt or other feeding means for each feeding movement of the device. v v

In the operation of sprinkler stoker mechanisms of the aforesaid type the fuel does not fall constantly upon the rotor but is delivered to the rotor intermittently due to the reciprocatingmotion of the feed shoehonthe feed plate or intermittent forward motion of feed conveyor *or other feed means. yAccordingly, the yrotor delivers fuel particles linto the furnace in a cyclic manner with practically all the coal 'beingv delivered on the forward movement of the intermittent feeding mechanism and practically none during the pause or back stroke of the feeding mechanism preparatory to obtaining Va 'fresh charge of fuel for thefnext cyclefThe'refore, in the operation of sprinkler Stoker mechanisms, whetherof the feed shoe or conveyor feed'type,

'there is an appreciable period of 'time yin each feeding cycle (40% to 50%) during which fuel is not being fed, and during these periods of mini.- mum feeding there is little or no coal impelled into the furnace. This intermittent feeding of fuel into the furnaceA causes uctuation'in'the furnace draft, puflng out of ltheV furnace, difficulty with 'draft'controlapparatus and, to some degree, unfavorable vcombustion eiciency which arises out of thej following circumstance.

In the operation of all spreader stokers the coal, consisting of fine and coarse particles in a variety of sizes, isA impelled into the combustion space. Ignition is'rapid, almost to the pointl of explosion, and fine particles are consumed before they 'can fall to the grate. Any lparticle 'which is'not completely burnedduring its fall through the combustion space burns on the grate. As explained above, the coal feed is intermittent, being usually about 25 to 50 strokes or feeding motions per minuteA with 'a pause (or a condil ltion of non-feeding) between eachfeeding' rnction. Integrated, there is a conditionof coal feeding for roughly 50% of the time and a conbefore falling on the grate, constant feed of air for combustion has oifered the disadvantage that if the combustion air is sufficient in amount to effect complete combustion of the fines in suspensionY while they are being fed, the same rate of feed of air for combustion represents an excess when nov (fines)A coal is being fed. This has the net effect of increasing the average excess air passing through the furnace and* a consequent decrease in CO2 content in the nue gases. There is presently available no practical way of varyingVV combustion cyclically to compensate for thes cyclical feed of the fuel. There has likewise been no practical way, prior to this invention, for at taining a reasonably constantl rate of fuel in? jection into the furnace with sprinkler stokers.

It may be stated parentheticall-y'thatintermittent feed mechanisms are universally usedin sprinkler feed stokers because of their many adb and 'reasonably''goed;operation.` 'They can vbe ay wide" range" off feedingrates*y while-still being driven by small horsepower' alternatingoiirreht motorsof conventional-design. The design Aand construction of accurate" continl'l'olisefeed coal feeding' dev'cselplbl'e l0f AWide'I varitions'riilerate of feed is dinicult and costly and such few'devices'l that' have bere'lf'l eliperimente'd With have not been" s''atisfact'oly"fony thestahd'pOit' of peiatn. There-fore;- ffr is known, theyfha've never been 'usedl in commercial ingstallations.l

'It is lorie Of the "bl"'aidf" bjects'ff the vies'erlt inventior to provide' ani i'r'ilpr'oved= cyclic sprinkler Stokermeclianish-wherein the fel is' delivered to the-finnace in accurately-'controlled amounts and at-y substantially constantx rate, throlighout''thecomplete'v cycle to thel rotating distrihuting'nlfechanism'. Y e l Itis' ai 'further' object'A of the V.invent-ion toi p'rovideV an improved overfeedistoker of'thespr'inkier-type wherein granular fuel is fedinterr'nitten'tlyV and fyet" delivered at a; substantially Vconetant rate throughot' the cycle offo'per'ation of the feedmecha'nisln to therot'or mechanism 45 oftheiistokerfordstributionthereby'into the conlbustionspace.`

It is another ob'jeet' oftheinventiorr td' provide; an'l improved" sprinkler' ovevrfeed Vstoke'r inechar'iisln` wherein thefllel fed intermittently` in accurate, yetv selectivelyv variable amountshy an rostillsting mechanism oh a feed plate' ahdthe'ieedi'plateis deflected ora lpart thereofjose'illated*during a portion of theoscillating cyel'eof the 'feed mechanishizso as to provde a nearlyv unifrmdelivery ofthe" granular fcelfrom therfeeeplate to the rotating' element o'f the sprinkler mechanism. Y y l Itk f iither" object-.of the invention Vto profvide an improved sprinkler Stoker nfehaflislrl hating a fuel feeaiiiate provi-dec,withv a deniectable,` slidable', ,or otherwise lmovable tip and an oscillatory feed 'shoe Vinteroei'iheeted' therewith forl changing thejpo'sitionof th tip to cause `fuel to' lie-delivered' therefrom during those portions of the oeciliatory action,v or theY ieee shoe when nfuel would normally be delivered by" th'e latter.

ther and further objects of theV invention i'ncludei'the provision of specicmechaniss lfor a'cemplihi'rl'g the aflesaidreslll-ts and also include those objects inherent in theapparatu's herein'Y illustrated;V described andi claimed:`

'I'hei invention. isY illustra-ted vwith" @reference to, thev 'drawings iff-WhichL corresponding numerals refer to' thsameparts and inwhich Figure 1 is a side elevational View, partly in section, of one illustrative embodiment of the invention showing the stoker mechanism and a section of the boiler or furnace wall to which the stoker mechanism is applied. Figure 1 shows the intermittent feed mechanism at the completionof a feeding stroke; A

Figure 2 corresponds to the apparatus shown in Figure" l' and is an enlarged fragmentary side sectional view of a portion of the apparatus illstrating the apparatus at an intermediate position-,during its cycle of operation;

Figure 3 corresponds to Figures 1 and 2 and is also an enlarged'fra'gmentary side sectional view showing th'apparatus at the beginning of its y'cleof' operation;

Figure .4'i`s alfragmentary Side elevational View,

partly in section, showing another illustrative embodiment of the invention; e Figure 5 is a fragmentary sectional view taken aliigf the'line and inv the direction of arrows 'shovving the tip Aplate adjustment screw-of theapparatusshown inFiguree;

Figure 6 is a'fiagme-'lltary Side"elvati`onalview, partly in section,v ofi a further illustrativeA form of theinvention;V

Figure 7 is a vertical* side* elevational view, partly" in section, Sliovi'fing'r another illustrative embodiment of the invention; i Figure 8v is' a Yfr'a'-glider'itary side elevation'alview showing another' slightly" modified' for-m of' appara-tus.-

The illustrative embodiment of the invention shown in-Fi'g'uresV 1, 2 and 3 isla stoker mechanism of the oseillating lfeed-shoe type of the same basic character asill'ustrated in my Patent No. 2,163,825; to whih reference is made-for certain details of the mechanism. In Figures 143i emphasis is givenfto' thoserportions of the apparatus whichY are modified as compared with the Stoker Villustrateci in Patent No'.v 2,163,825 and reference is' made to that patent for manyd'etails `of the vapp'aratusthati are not illustrated in the instanti disclosure; these details lbeing portant toY the* apparatus" but for simplicity yolrlitted herein.

Referringn to Figure' 1Y there is illustrated; 'a furnace'orflboiler generally designated l having a front Wall-'generally designated 2 and a Vcom bustion space e' defined' by the ignition va'rch'f and the front'fwall 2. "The"brickvvork'forming the karchi encloses anair'duct lto Which'there areeattached'a pl'uralityfof air inletl tuyres' by means ofV which o'veiriire combustion air is de'- v livered to' the combustion space immediately adjacent to then irl-flowing' delivery of fuel through the fuel aperture '8.

Upofthe front w'all ofthe boiler or furnace there is moiihtedthe mail Stoker frame generally 30 designated llwhic-h is providedwith a mountflange lll` 'thatis attached tothe front wall 2 of the furnace or boiler by means of bolts9.

The lowerportion ofy the frame I2 is provided with an access'. door I3` thatisheld in place by 05 as utablelatch I4. Y M

At theY` lower part=of the stoker frame l2fthere is va bladed sprinkler rotor generally designated Il whichA rotates continuouslvand at a relai-"- tively high speed fori'striking the fuel particles andimpelling them through the. fuel inlet 8 and into 'the' combustion ,'spac'e 4; The rotcr Vis `contained `within a partial cylindrical 'space4 defined removably attached: to" the'iflower' portion offthe Stoker -framesbyra ,plurality-:of capscrewsi The space in which the bladed rotor I1 is positioned is also partially defined by the middle portion -I of the stoker main frame. The direction of rotation of the rotorA I1 is shown by the arrow vshown adjacent its periphery. In rotating, the blades of the rotor engage and impel the fuel particles through opening 8 and into the Vcombustion zone.

The details of construction of rotor I1 are described in my Patent No. 2,163,825 wherein it is stated that the rotor I1 may be composed of one or a pluralityof segments mounted upon a tubular shaft 22 which is supported in spaced relaution in respect to shaft I8 by suitable collars not herein illustrated. The rotor I1, tubular shaft 22 and shaft I8 all rotate as a unit, the space between the tubular member 22 and the shaft I8 serving to restrict heat communication from the rotor I1 to the shaft I8. The shaft is thus spared from operating at high temperatures. The mechanism for continuously revolving the rotor I1 in the direction shown need not be specifically described herein since it is described in detail'in my patent referred to above. Y

Upon the front of the stokerv mechanism there -is provided a fuel hopper generally designated 3| that is mounted upon a bracket 32 attached to the main frame I2 of the stoker mechanism. The bracket 32 includes an integral bar 36 and an integral apertured guide 39 which serve jointly a threaded on the inside to receive the threaded f portions 31 of an adjustment fbolt 46. The -adjustment bolt is provided with a collar 42 suitably attached to the bolt so that it rotates with the bolt. The collar 42 is positioned in a notch in the guide 39 and by this means the bolt 46 is permitted to rotate and yet is held-from moving endwise. Accordingly, by rotating the bolt 46 the lug 44 is moved longitudinally of the bolt and in this manner the feed plate may be moved back and forth toward and away from the boiler or furnace wall, and hence the fuel delivery end ofv the feed plate may be adjustably positioned in respect to the rotor so as to vary the point of delivery of fuel to the rotor.

At the rear end of the bolt 46 there is provided a square sleeve 45 which is positioned between the head on bolt 46 and the adjacent wall of the guide portion 39. The sleeve is loosely mounted upon the bolt and accordingly, as the bolt 46 is turned, the sleeve 45 does not turn, being held from rotation byits square configuration which abuts against the lower surface of the feed plate 35. An indicating finger 41 is attached to the rear part of the feed plate and a plurality of indicia are placed upon the square sleeve 45 so that the operator may know the fore and aft adjustment of the feed plate.

The feed plate 35 may be mounted horizontally, although it can also be mounted at a slight angle, as shown in my patent above referred to. Upon the feed plate there is mounted an oscillatory feed shoe generally designated 48 which has a plurality of vertical walls 49 and 5I and interconnecting top surfaces. The walls 49 and 5| are connected by the portion 52 which forms a stepdown from the top of the feed shoe. The lower and rear portion of the hopper 3| is provided with a seal plate 13 having a flexible sealing member 12 attached thereto by screws 14. vThe position ofthe seal is adjusted so that it slides upon 8 the smooth upper surface of the feed shoe, vand therebyas the shoe is oscillated, as hereinafter described, the fuel is prevented from being pulled back as the shoev moves backwardly. The base of the front wall 49 of the shoe slides directly upon the feed plate 35. f

Oscillatory motion of the feed shoe is imparted bymeans of a plurality of forked rocker arms 55 that are attached to an oscillating shaft 53. The rocker arms are rotated back and forth in the direction of the double arrow shown adjacent the shaft 53 due to the oscillatory motion of the shaft, and accordingly the upper ends 51 of the arms 55 arelikewise moved back and forth in the direction of the double arrows shown adjacent to the upper ends. The upper ends 51 of the forked arms 55 are attached by links 56 to the shoe 48 and therefore as the arms 55 are moved back and forth, the shoe 48 is likewise moved back and forth andr serves at each oscillatiombackwardly (away from the rotor I1) to receive the downwardly 'moving fiow of granular fuel from the hopper 3| and on each forward movement (toward the rotor and lboiler or furnace), theffuel is shoved along the -feed plate 35, as shown in Figure 1v, toward the delivery end of the feed plate, whence it falls upon rotor I1.

The? forward end 38 of the feed plate is provided with a movable tip |65 extending entirely across the front edge of the feed plate.

` In the construction, as shown in Figures 1, 2 and 3, the tip plate, which is generally designated |65, is supported by a plurality of bell crank levers |68, these in turn being pivotally mounted on pins |69 that are carried by brackets on the under side of the feed plate 38. The bell crank levers |68 have downwardly extending portions I1I to which there is pivotally attached one end of the links |12 which extend back to the oscillating arms 55 to which the links |12 are also pivotally attached at |13. The length of the links- |12 is made adjustable so that when the forked oscillating arms 55 are in the maximum forward position, as shown in Figure 1, the bell crank levers |'68 are held in such a position that the tip plate |65 is in a plane approximately parallel to the feed plates 38 when the feed plate adjustment 46-41 is in its middle position. In this position the tip plate just underlies the feed plate, as shown in Figure 1. As the oscillating 'forked arms 55 move rearwardly and hence draw the feed shoe 48- rearwardly, to the position shown in Figure 2, the links |12 are moved rearwardly and this causes the bell crank levers |68 toY be moved, and this causes the tip plate |65 to be tilted downwardly to an intermediate position shown in Figure 2. Accordingly, approximately one-quarter of the fuel fed by the shoe on its forward stroke, which had up to that time been reposing on the end 38 of the feed plate and tip plate |65, is permitted to slide-down the tip plate |65, due to the downward tipping action of the tip plate which changes the forward point of support of the coal. The coal will immediately assume its natural angle of repose ofl 45`degrees and the change in position of Vforward support of the coal will permit' about one-quarter of the fed amounttofsli'de onto lthe rotor.

As the motion o f the forked oscillating arms 55 isl continued to the position shown `in Figure y3 9. as shown in Figures 4 and 5, there is a threaded portion |8| terminating in a hand wheel |81. The threaded portion 8| passes through a threaded connector |82 which has a pivot shank |83 passing through the oscillatory lever |15, the shank |83 being held in place on the oscillating lever arm |15 by means of a collar |84 that is pinned or otherwise suitably attached so that the entire connector |82-|03-I84 is free to pivot in the oscillating lever |15 as the lever oscillates back and forth in moving the feed shoe. By means of this arrangement, which is shown in detail in Figure 5, the position of the sliding tip plate |16 may be adjusted with reference to the feed shoe 48. I v

. It will be noted that the point of pivotalconnection of the member |82 to the oscillating lever |15 is about midway between the pivot shaft |85 upon which the oscillating lever |15 is mounted. Accordingly, as the lever |15 oscillates back'and forth and moves the shoe 48 back and forth on the feed plate 35, the lever |15 through the link |80 also imparts a back-andforth sliding movement of the sliding tip plate |16, but the total distance (back and forth) through which the tip plate moves is approximately one-half of the total distance moved by the feed shoe 48 due to the fact that the distance from the center of the pivot shaft |85 to the center of the member |82 is approximately one-half as far as from the pivot shaft |85 to the pin 51 by which link 56 is attached to the upper end 51 of the oscillating lever |15. Accordingly, as the feed shoe 48 moves forwardly (and therefore moves a measured amount of coal forwardly), the tip plate |19 is also moving forwardly but at a rate approximately half as fast. Therefore, the coal which is being pushed forwardly overtakes the front edge |16 of the` sliding tip plate and some of the coal, approximately one-half thereof, is shoved off the endy of the plate and thereby falls onto the rotating spreader |1. As the feed shoe 48 reaches its position closest to the furnace (and closest to the rotating spreader I1) the coal that is deposited on the exposed upper surface of the tip plate |16 is left there preparatory to being dumped as the tip plate is then drawn rearwardly during the reverse half cycle of the oscillating movement of the mechanism. Accordingly, approximately one-half of the coal is dumped on the reverse half of the cycle and approximately one-half is dumped on the forward half 4of the cycle, thus distributing the coal relatively uniformly upon the revolving spreader rotor |1 during' the complete cycle of back and forth movement of the feed shoe 48.

In Figure 6 there is illustrated another exemplary form of the invention similar to that shown in Figures 4 and 5 but simplified in that the link generally designated |90, which corresponds to the link |80 of Figures 4-5, is made non-adjustable -and is fitted so that it protrudes through openings .|3| and |92 in the walls 5| and 49 of the feed shoe and then extends outwardly to the left and above the feed plate 35 and is connected to an upwardly extending lug |93 which extends upwardly from the upper surface of the slidable tip plate |94. The plate |94 is mounted for sliding motion back and forth in parallel guides |11 on the lower side of the feed plate 35 in the same manner as shown in Figure 4, but in this instance the lug for oscillating the sliding tip |94 protrudes upwardly and to it there is pivotally attached the clevis |95 on the forward end lil of'the linkzll). The rear end of the link |90 is likewise provided with a clevis |96 which is pivotally attached at |91 to the oscillating lever |89.' The point of pivotal attachment |91 in Figure 6, and the point of -pivotal attachment of the member |82 of Figure 4 may be varied up and down in any design so as to adjust the relative movement of tip plate and feed shoe and hence the amounts of coal delivered during each half of the cycle. The clevis |95 is' preferably made with a'knifeedge stern |98 so that it cuts through the coal on its rear stroke and a slot is provided in the feed plate |35 at |99 so as to provide a space in which the lug |93 is free to operate. The operation of the device shown in Figure 6 is substantially identical with that shown in Figures 4-5.

In Figure '7 there is shown a further illustrative form of the invention wherein the fuel is fed step-by-step in measured amounts by means of a small conveyor from which it is delivered onto the revolving spreader or sprinkler rotor in fa manner similar to the apparatus previously described. In the device shown in Figure rI'the stoker frame 209 is provided with a coal feed; opening defined bythe water cooled casting 20|i which at its lower side 202 forms a part of the partial cylindrical chamber 203 in which the spreader rotor 204 revolves. The outer' portionA of the chamber `203 is formed by `theframe plate 205. Upon the frame 200 there is mounted 'a hopper 206 which is supported bytheauxiliary' frame member 201. The bottom of the hopper empties through a delivery opening 208 upon a conveyor mechanism generally 4designated 209 which is mounted between side wall frame platesv 2|0. The conveyor mechanism is provided with a table portion 2| upon which the upper portion of the conveyor belt 2|2 travels, the belt moving toward theV furnace at its upper surface .v and .thence over the front conveyor roller 2|3'rand thence away froml the furnace at its lower course of." travel until it reaches the conveyor drive roll 2|4. The conveyor drive roll is mounted upon the shafts 2|5 which are driven by a ratchet 4 wheel 2 I6. Freely pivoted upon one of the shafts y 2 l5 there is also provided van oscillating lever 2|1 which is moved back and forth by means of 'the' link 2|8. Member 2|8 moves back and forth in the direction of the double headed arrow 2| 9 beingV driven by a mechanism not illustrated,

A such as the revolving crankshaft driven from( (ifi a suitable power source. The oscillating lever 2|1 thus oscillates back and forth on the shaft 2| 5, as shown by double arrow 2 I9. The oscillating'lever 2|1 is provided with a pawl 220 which engages the teeth of the ratchet wheel 2|6 causupper end of the lever 2|1 moves laway from'thefurnace. Thus, the conveyor belt 2| 2 is caused to move step-by-step and the upper surface thereof accordingly carries the coal C or other granular fuel forward toward the delivery end of the conveyor at roll 2|3 in a step-by-step motion, a measured amount of coal being thus propelled for each step-by-step movement of the conveyor. If desired, the ratchet drive mechanism comprising ratchet wheel 2|6, oscillating lever and link 2|1 and 2|8 and pawl 220 can be mounted so as to drive the front roller 2 |3 rather than the rear roller 2| 4. To do this it is only necessary to connect ratchet wheel 2|6 to the tion of said plate, said tip portion being above said rotor, means mounting said tip portion for oscillatory tipp-ing about a substantially horizontal axis and means for moving the tip portion downwardly as the feed shoes move back to receive a fresh charge of fuel and for moving the tip portion upwardly as the feed shoe means is moved towards said tip portion.

5. An overfeed sprinkler stoker mechanism having a substantially upright frame, said frame being provided with a fuel delivery aperture therein, a bladed rotor mounted for rotation about a substantially horizontal axis positioned adjacent said aperture for impelling solid fuel particles therethrough, means for revolving said rotor, a fuel feed plate positioned substantially horizontally and having a delivery edge generally parallel to the axis of rotation of said bladed rotor and above the same, a fuel delivery chute positioned above the fuel feed plate for delivering granular fuel downwardly thereon, feed shoe means mounted on the feed plate and means for oscillating the feed shoe means back and forth from a position where it receives the fuel to a position where the fuel is pushed towards the delivery edge of the feed plate and onto the rotor, an auxiliary delivery tip for said feed plate, means mounting said delivery tip adjacent the delivery edge of said feed plate for oscillation back and forth between a position in which it intercepts fuel delivered to the delivery edge of the feed plate and a position in which it spills fuel thus intercepted, and means for oscillating the tip to intercepting position as the feed shoe is moved towards said delivery edge of the feed plate and for moving the tip to spilling position as said feed shoe is moved away from said delivery edge.

6. An overfeed sprinkler stoker mechanism comprising an upright frame wall having a central fuel delivery aperture therein, a partial cylindrical housing on said frame and a bladed fuel sprinkler rotor mounted about a generally horizontal axis in said housing, said housing being open to the fuel delivery aperture, means for revolving said rotor, a fuel feed plate mounted above said rotor in a generally horizontal position, said fuel feed plate having a delivery edge above and generally parallel to the axis of rotation of said rotor, a fuel chute for delivering granulated fuel downwardly on said feed plate, feed shoe means slidable back and forth on said plate, means for oscillating said feed shoe means back and forth on said feed plate in a direction to push the granular fuel toward said delivery edge and then to withdraw said feed shoe means from the delivery edge of said feed plate, auxiliary delivery tip means adjacent and underlying the delivery edge of the feed plate, means mounting said delivery tip means for oscillation from a position in which it forms a fuel supporting extension of the feed plate to a position in which it spills fuel supported thereon, and means connecting said delivery tip means for oscillating said delivery tip means to spilling position as said feed shoe is moved away from said delivery tip means and for oscillating said delivery tip means to fuel supporting position as said feed shoe means is moved towards said delivery tip means.

'1. A sprinkler stolzer mechanism comprising fuel supply means. a feed plate on which the fuel is delivered and along which said fuel is movable, a rotor horizontally situated below said supply means and of about the width of said plate for impelling into a combustion space granular fuel falling downwardly off of an edge of said plate onto said rotor, means movable along a fraction of the length of said plate towards said edge for moving towards said edge successive portions of fuel during successive time intervals spaced by periods of non-delivery and for dropping said fuel off vof said edge and along the entire Width of said rotor, said fuel being moved from said supply means to said rotor to be impelled thereby and means for intercepting a part of each successive portion of fuel and for delivering said intercepted parts across the entire width of said rotor during said spaced periods of non-delivery, said means for moving successive portions includes a feed plate having a delivery end and a feed shoe mounted for oscillation thereon for moving the fuel in successive portions to said delivery end, said means for intercepting cornprising a tilting plate mounted adjacent the delivery end of said feed plate.

CHESTER W. BROS.

REFERENCES CITED The following references are of record in th lle of this patent:

UNITED STATES PATENTS Number Name Date 2,163,825 Bros June 27, 1939 2,390,155 Kessler Dec. 4, 1945 2,391,597 Schwendner Dec. 25, 1945 2,487,464 vMosshart Nov. 8, 1949

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