US1090651A - Positive-cleaning and self-dumping stoker. - Google Patents

Description

R. s.- RILEY. POSITIVE onmnme AND SELF DUMPING STOKER.

APPLICATION FILED AUG. 31, 1912. 1,090,651 Patented Mar. 17, 191i 3 SHEETS-SHEET 1.

R. s. RILEY. POSITIVE CLEARING AND SEL'F DUMPING STOKER.

- APPLIUATION FILED AUG. 31, 1912. 1 ,O90,65 1

Patented Mar. 17, 1914.

3 SHEETS-SHEET 2.

wjmsses E. S. RILEY.

POSITIVE CLEANING AND SELF DUMPING STOKER.

V APPLIGATIONFILED AUG. 31, 1912. 1,090, 51 j Patented Mar. 17, 1914.

3 SHEETS-SHEET 3.

Zflifizesses: 1,5 Ina-621507 m L 5 W *7 UNITED STATES PATENT OFFICE.

ROBERT SANFORD RILEY, 0F PROVIDENCE, RHODE ISLAND.

POSITIVE-CLEANING AND SELF-DUMPING- STOKER.

To all whom it may concern:

Be it known that I, RoeER'r SANFORD RILEY, a citizen of the United States, and residentof Providence, in the county of Providence and State of Rhode Island, have invented certain new and useful Improvements in Positive-Cleaning and Self-Dumping Stokers, of which the following is a specification.

The present invention relates to positivecleaning and self-dumping stokers of the type in which the fresh fuel is introduced into the fire from a point below or in front of the air supply and is fed toward and past the air supply in order to become distilled and converted into coke before mingling with the burning fuel and becoming ignited, and in order that the volatile products liberated by such distillation must pass through .the Zone of combustion and be burned, before escaping from the furnace.

The object of the invention is to provide a self-feeding furnace with means by which the fuel feeding means is caused also to discharge incoinbustible residue at a rate of which the proportion to the rate of admission of fresh fuel is equal to the proportion of incombustible material in the whole quantity of fuel; to provide a furnace of the self-feeding underfeed type, with supporting means for the fuel which are also air supplying meansand so arranged as not to provide any flat fuel-supporting surfaces or plates for the fuel undergoing combustion; to provide a novel arrangement of adjustable refuse support and means for adjusting the extent of the same; to provide a novelform of air supplying -member; to provide in a self-feeding furnacea means by which there is both an underfeed of fresh fuel with respect to the air supply and an overfeed of ignited fuel, and in combination therewith to provide means for regulating the quantities and pressures of air supplied to the respective parts of the furnace, that is the underfeed portion and the over feed portion.

In some of its features the furnace herein illustrated, described and claimed is the same as in my previous co-pending applications for Letters Patent .of the United States filed October 20, 1911 and numbered serially 655,821, and 655,823, and such claims as cover subject matter common to Specification of Letters Patent.

Application filed August 31,1912. Serial No. 718,106.

Patented Mar. 17, 1914.

this stoker and to either of those shown in said applications are contained in the said prior applications.

As concerns the aforesaid priorapplications, the purpose of my present invention is to improve and carry forward some of the features illustrated in said applications, into more practical and better form.

Figure 1 is a' longitudinal section of a stoker embodying my present invention. Fig. 2 is in part a plan of the stoker and in part a horizontal section on line 2-2 of Fig. 1. Fig. 3 is an elevation of the stoker as viewed from within the furnace. Fig. 4 is a cross section on line 4-4 of Fig. 1, looking toward the right. Fig. 5 is a perspective view of a detail of the invention. Fig. 6 is a perspective view of one of the air conducting members. Figs. 7, 8, 9, and 10 are, respectively, a plan View, a side elevation, a bottom plan view, and a cross sectional View of one of the air emission members. Fig. 11 is a cross section on line 11-11 of Fig. 1.

The same reference characters indicate the same parts in all the figures.

In the drawings, 1,0 represents the front wall and 11 the bridge wall of a furnace inclosure. The stokrpr fuel feeding mechanism comprises a miimber of fuel-feeding passages with propelling means in such passages, and air-supplying means at both sides of the passages. In the present embodiment there are three of such passages, propelling means, and air-supplying means, each of which is a duplicate of the others. In the following description one of these units, including the parts above indicated willbe described in detail, and the same reference characters will be employed to represent corresponding parts in th other units.

.The fuel passage is formed by a sort of trough, consisting of side plates 12 "passing through the front wall, and extendiifg a considerable distance into the furnace inclosure, a top plate or hood 13 in the front wall,'and a bottom plate 14 extending. "the entire length of the side plates ant' supported on brackets or ledges 15 at th'elower sides of the side plates. The parts thus far described are stationary and are-supported by posts or the like 16 at the forward part of the furnace. Connectedwith the forward end of each such trough outside of the furupon the rod adjacent to the outer end of the nace is a tubular pusher guide 17 projecting from the front of the furnace wall and containing a pusher 18. The pusher guide is in effect the forward or entrance end of the fuel passage or retort, and is the part of that passage in which the propelling means is contained. A hopper or chute 19 for the fuel is arranged to discharge into the upper side of the guide 17 and the pusher is arranged to reciprocate back and forth horizontally across the outlet in the bottom of the hopper. The pusher is reciprocated by a crank 20 on a shaft 21 and a connecting rod or pitman 22. The shaft is rotated by any suitable means such as the worm and wheel gearing shown in Fig. 1.

The connecting rod 22 extends through a sleeve 23, forming part of a forked yoke, .which latter has separated arms 24 pivotally mounted upon wrist pins 25 secured in opposite sides of the pusher and projecting through slots 26 in the pusher guide. A shoulder formed on the rod 22, preferably by a nut 27 larger than the internal diameter of sleeve 23 lies within the inner end of the sleeve, and a collar or ring 28 is fastened sleeve by a pin 29. The distance between the respective arms 24 of the sleeve, and between the ends of the respective wrist pins 25 is greater than the width of the shoulder 27, so that if the ring 28 should be loose on the connecting rod, the latter would slide through the yoke on the feeding or inward stroke, without moving the pusher. It is in this construction and in the peculiar character of the ring 28 and pin 29, that one of the important features of the present invention consists.

The ring is preferably of hardened steel having sharp edges at the intersections of the hole which receives the pin 29, with the central opening, and the pin, which I call a shear pin, is of relatively soft metal. The particular metal and its'degree of hardness is material to this extent only, that the pin must be sufficiently weak or fragile to .be cut, sheared or broken by the ring in case excessive resistance should oppose the movement of the pusher. If a foreign body should block the pusher, or if the fuel should clog or am in the pusher guide or in i the hopper outlet so as to offer enough reof its travel until the obstruction can be re-,

moved and the ring is again connected to the rodby a new pin. The pin is thus a safety devlce designed to fail before any of the other parts of the mechanism breaks or bends, thereby guarding against breakage of important parts and loss of time and money in making repairs. The pin obviously is of such slight value as compared to the other parts of the mechanism and can be applied and removed so easilythat the expense occasioned by its breakage is inapto these bars pass freely through transverse holes in the outer ends of the wrist pins 25, and the heads 37 of such bolts and adjustable nuts 38 on the bolts form abutments adapted to be struck alternately by the wrist pins. The distance between the abutments 37 and 38 may be made less than the travel of the pusher by any amount, hence the side bars and air-conducting meansare given a regulatable amount of back and forth movement; Such movement is governed largely by the percentage of ash in the fuel, for, as the side bars are given this movement for the purpose of progressively advancing the burning fuel and disposing of the ash, as will be later described, it is, of course,

highly important that the movement be made just great enough to discharge all the ash which collects at the rear of the furnace, and without also discharging incompletely consumed fuel. Evidently, therefore, the volume of material displaced by the side bars and associated pushmg means, later described, should be approximately, and at least, the same proportional part of the total amount of fuel fed into the furnace by the pusher 18, that the ash is of all the ingredients of the fuel. A fuel analysis thus shows in advance what movement of the side bars is necessary and how the nuts 37 must be set.

It should be noted that there are a pair of side bars 31 for each fuel channel, such bars flanking the channel, and being each independent of the other both in construction and in capability for movement. Each of these bars has its own operating bolt 36 and nut 38 and each nutmay be independently" to the intermediate bars, so as to shear clinker from the wall and advance clinker rapidly to the discharge point. Any one or more of the side bars and the air supplying means carried thereby may be given an exceptional range of travel where the fire has a tendency to become too heavy, so as to feed down the fuel in that part of the furnace more rapidly. To the lower end of each bar is connected a sliding shoe 39 which has a detachable plate 39 constituting a refuse pusher or pusher nose, by means of bolts 39 and such shoes rest upon a substantially horizontal plate 40 mounted upon girders 41 in the stoker foundation. Intermediate their ends the bars 31 haveshelves 42 whereon is supported a plate 43 which is secured to the rear ends of the side plates 12 of the fuel channel. The plate 43 is thus supported by the side bars, which, in turn, are supported by the guides 35 and by the plate 40, .such guides'and plate, shelves 42, and plate 43 all being substantially parallel. I The airconducting members or grate blocks 30 above the plate 43 are arranged only at the sides of the fuel passage, outside of the respective side plates-12, and rise above such side plates, forming continuations of the side bars 31 and defining the mouths of the retort. They overlap one another as shown in Fig. 1 and extend in a direction which is determined by the edges of the side bars 31 by which they are alined. Each of such air-conducting membershas an outer approximately vertical wall 44, as shown in Fig. 4, an inner wall 45 on the. side next to the fuel passage, partly vertical, partly inclined and having a top portion or lip 45, and a transverse wall or cross member 47 for supporting the. grate bars or longitudinal ribs 48. These ribs form the means for supporting the fuel between the passages, and constitute air supplying means analogous to grates. The transverse wall or cross member 47 is approximately as long only as the ribs 48 and terminates near the forward end, that is, right hand end with respect to Fig. 1 (see dotted lines) of the ribs. The lip or ledge 45 runs along the upper edge of the inner wall 45 from the forward end of cross member 47 to the forward end of wall 45. Between the lip 45 and outer wall 44 of each grate block'is an open space 46, and between the cross member 47 and lip 45 of each two adjacent blocks, is a space 46*, these spaces allowing the air back of the grateblocks to pass to the fuel. Between the top portion 47 and the ribs 48 are channels 49 through. which air may issue toward the rear of the furnace to support combustion of the fuel extending over the ribs. The cross members of the several air supplying members overlap one another and thus cover the opening between adjacent side bars into the air space b'e neath the furnace, preventing the smaller particles of fuel from falling through into this air space. At the same time the ribs 48, which are set edgewise to the cross member and to the fuel are the means which directly come into engagement with the fuel and support the same. Between the ribs and the overlapping cross members are ample air spaces through which the air may How to all parts of the furnace in sufiicient quantity to support combustion. Thus it will be seen that in my furnace there are no fiat i'inpervious fuel supporting surfaces or dead plates between the retorts at the side of each retort, which have hitherto been found necessary in furnace construction. ,These grate blocks are held in place by bolts 66, which secure them to the side bars and thus clamp them together. The bolts extend to flanges at the lower edges of the side bars, and their arrangement is such that the grate blocks are free to slide on the bars sufliciently to allow for contraction and expansion.

The air-supplying means analogous to the members 30 below the plate 43 are similar to the members 30 but of greater width, extending entirely across the unit, as appears from Fig. 2. These members consist essen tially of approximately horizontal cross members 50 which are attached to the side bars 31 and have upstanding parallel ribs 51. The spaces between the members 50 and ribs 51 are open at the rear to the space under the stoker, from which the air supplied may fiow through the channels thus provided to support combustion of the fuel lying on the ribs 51. Said air supplying members also have side walls 51 which walls of overlapping members interlock with one another, and of the lowermost 7 member rest on and lock with the shoe 39 beneath it, all as shown in Fig. 1.

The air space beneath the stoker, heretofore referred to, extends across the entire width of the furnace and is confined at the crosses the space bet-ween the side bars 31 ofone pair, the plate 40 and the plate 43, and is carried by an arm 56 pivoted at 57, whereby it can be adjusted so as to close such space or open it to any desired degree.

The fuel which is forced into the passage by the pusher 18 is caught by the reciprocatp the plate 43 until it finally passes over the ribs 51. Before the fuel passes the airoutlets 46, it is subjected to a process of distillation and coking. After it passes these openings and spreads outover the members 30 and ribs 51, the draft of air flows through it.

Thus, in. this form of stoker, as in those illustratedin my prior applications referred to, there is an underfeed of fuel before ignition and an overfeed above the points' of air supply after the volatile combustible constituents have been distilled off.

The solid residue of the fuel passing the ribs 51 falls upon an ash support 58, which is formed of a number of bars or plates connected to chains 59. These plates rest upon longitudinal movable bars 60 which have teeth -61 and are engaged by gear pinions 62 on a shaft 63. These bars 60 are symmetrical and reversible, hence the same casting may be used for right or left of each pair supporting the ash support plates 58. Said shaft extends outside of the furnace inclosure and is operated by a Worm and wheel gear, or other suitable mechanism whenever desired to advance or Withdraw the bars 60. When advanced as far as possible to the rear, these bars hold all of the plate sections 58 in the same plane, making of the latter a continuous surface extending practically entirely across the discharge opening at the rear of the furnace. lVhen the bars are retracted more or less, a greater or smaller proportion of the plate sections 58 is allowed to hang down as shown in Fig. 1, par tially or wholly uncovering the discharge opening.

The sliding shoes 39 at the ends of the side bars 31 at the rear endsthereof have removable upright rear faces or pusher noses 39 adapting them to act as pushers, whereby they force the fuel residue rearwardly across the support 58 until it falls from the rear termination of such support. The extent of the support and the size of the discharge opening are regulated by the means described, in accordance with the quality of the fuel, that is, the proportion of incombustible material contained in it, and the rate at which the furnace is run, to the end that there may be a continuous discharge of refuse practically Without combustible material at such a rate as to avoid too great an accumulation of refuse. In other Words the extent of this support is made approximately great enough to enable all the combustible material to be'c-onsumed before it reaches the end of the support, while the opening is suflieiently large to take care of the residue. When the adjustment has once been made, it requires no change and the furnace can be 65 run without other attention than to supply the fuel until the rate of feed or the quality of the fuel is varied.

Where there are two or more fuel feeding units in one furnace, the cranks for the pushers in the several units are set approximately opposite to one another, or otherwise spaced angularly about the shaft, and as a result the sliding bars and air-supplying means of one unit may be advanced, While those of the adjacent unit are retracted, as appears from Figs. 1 and 2. I have discovered that this movement of the bars 31 and air supplying members 30, or in other words, the Walls of.the fuel retort, keeps the fuel bed even and keeps the burning fuel in a homogeneous condition, breaking up lumps and distributing the fuel so as fill up any holes or depressions that might form. The shearing line thus formed in the fuel bed provides an exit for the hot gases so that they do not strike back and melt the grates, thereby obviating the necessity for providing the air-cooled dead plates" heretofore found necessary to prevent this striking back or reflection of hot gases. My cOnstruction allows the entire surface which supports burning fuel to be grated, having the metallic parts in contact with the fuel of the smallest possible area and such parts interrupted by numerous air conducting channels, thus greatly increasing the capacity and the efficiency of the furnace. At the same time the movement 'of the retort walls serves to break off lumps ofclinker and slag, which would otherwise have a tendency to form on the walls of the furnace and extend over the fuel bed with the harmful effect of interruption of the draft and reflection of heatupon the fuel supporting surfaces.

I have previously mentioned that the side bars extend on a slight downward slant from the front of the furnace to the rear. This slant is much less than would be necessary to cause a gravity feed of the fuel and refuse after emergence of the latter above the retort walls. Instead of such gravity feed there is a positive feed throughout the entire length of the furnace from the admission point of the fuel to the discharge point of refuse. The side bars and air supplying members, both the members 30 at the sides of the retort and the members 50 in rear of the retort, are moved positively and at a predetermined rate so as to advance the fuel throughout the entire length of the furnace by successive small amounts proportioned to the rate of combustion and the percentage of incombustible material in the fuel, so that finally the combustible is practically all consumed by the time the residue reaches the refuse support 58, and such residue is displaced from said support as fast as it accumulates. ments permit this regulated feed and refuse discharge in the manner already described.

The adjustable abut- The capacity of the refuse discharging pushers constituted by the pieces 39, which I have termed the pusher noses, may be increased or diminished both'by lengthening or shortening the amount of travel of these pusher noses, and by increasing or diminishing their depth.

I claim: I

1. A furnace comprising in combination with a fuelguiding channel, a pusher movable reciprocatively along said channel, a connection to said pusher having a guideway, a driving member for operating said pusher contained in said guideway with provision for movement therein, and a member arranged to transmit the power of said driving member to the pusher and constructed to fail when the. pusher encounters an exceptional resistance.

2. In a stoking mechanism in combination with a reciprocating fuel pusher, a yoke pivoted to said pusher, a connecting rod slidingly engaged with said pusher, a collar on said rod bearing against a portion of the yoke and a pin passing through said collar and rod, the collar being harder than the pin, whereby to shear the projecting ends thereof and allow the connecting rod to move independently of the collar and v movement of the pitman through the sleeve,

pusher, when the pusher is opposed by extraordinary resistance.

3. In a fuel feeding mechanism, a. recip rocating pusher, a sleeve pivotally connected to said pusher, a connecting rod passing through said sleeve and movable therein, a collar having a sliding fit on said rod and bearing against the end of said sleeve, and a pin passing through the collar and rod, said collar being sufiiciently harder than the pin to shear the same and permit free movement of the connecting rod when the pusher encounters an extraordinary resistance.

a. A fuel feeding mechanism including a fuel channel, a pusher for feeding fuel into said channel, means for further propelling the fuel, and a mechanism for actuating said pusher and propelling means with provision for yielding in case of obstruction,

' comprising a pitman, a sleeve in which said pitman is contained and is movable endwise,

pivoted to said pusher, and a pinpassing through said pitman, and arranged totransmit pressure to said sleeve and to be broken in case of excessive resistance opposed to the movement of the sleeve, and lost motion connections for imparting movement from the pusher to the further propelling means.

A fuel feeding mechanism including a reciprocating pusher, a yoke pivoted to said pusher and having a guideway, a pitman having one end contained in said guideway, means for moving said pitman in the general direction of travel of the pusher, and abutments on said pitman at opposite ends of said guideway, the abutment at the outer end being relatively fragile, whereby to I fail before any other part of the mechanism breaks when an obstruction is encountered.

6. In a fuel feeding mechanism a pusher, a pitman for reciprocating said pusher, and a coupling between said pitman and pusher, said coupling having an endwise sliding engagement with the pitman and a pivotal engagement with the pusher, the pitman and coupling having interengaging abutments arranged to engage and become operative in the outward stroke only of the pitman, being free to separate on the inward stroke thereof, and having also abutments arranged to engage and become operative on the inward stroke of the pitman and constructed to fail upon encounter of the pusher with 'a resistance of more than predetermined amount.

7. A fuel feeding mechanism comprising and a relatively weak abutment mounted on the pitman adjacent to the outer end of the sleeve and constructed to give way upon encounter by the pusher with an obstruction.

8. In a furnace including a fuel retort and air supplying means beyondthe retort, a pusher for feeding fuel into said retort,

said air supplying means being movable for further feeding the fuel and refuse, and lost motion connectlons between said fuel feedmg and air supplying means comprising cooperating pro ections and complemental abutments connected to said pusher and air supplying means and arranged with said abutments on opposite sides of said projections whereby to be engaged alternately by the projections upon the reciprocations of the pusher.

. 9. A furnace including in its construction side bars and air supplying members carried by said bars arranged to define a fuel feeding passage and retort, a reciprocable pusher arranged to feed fuel into said pas sage, mechanism for reciprocating said pusher, and complemental abutments connected with said pusher and side bars respectively arranged to be engaged upon opposite strokes of the pusher, whereby said bars and air supplying means are reciprocated.

10. A furnace including in its construction side bars and air supplying members carried by said bars arranged to define a fuel feeding passage and retort, a reciprocable pusher arranged to feed fuel into said said pusher oppositely, and lost motion conpassage, mechanism for reciprocating said pusher, and 'complemental abutments connected with said pusher and side bars respectively arranged to be engaged upon op- I posite strokes of the pusher, wherebysaid bars and air supplying means are reciprocated, said abutments being adjustable whereby to provide for a variable amount [of lost motion between the pusher and the side bars.

11. A furnace comprising in combination movably mounted side bars and air supplying members carried thereby defining a fuel retort and movable to propel fuel in said retort, a fuel pusher arranged to feed fuel into the retort, mechanism for moving nections between said pusher and both said side members, the side members being independent of one another and the lost motion connections being independently adjustable, whereby either side member may be given a greater amount of travel than the other.

12. A furnace comprising a plurality of side bars set approximately parallel to one another and at suitable distances apart, each of said side bars being mounted with capability of movement and being independent of all of the other bars, the spaces between certain of said bars constituting fuel channels and between other bars providing for flow of air, air supplying grate blocks mounted on said bars, and bridging the air spaces, said air supplying members having outlets, a pusher arranged at the entrance end ofeach of said fuel channels, mechanism for moving said pushers so as to feed fuel into its respective channel, and lost moto be engaged when the pusher is moved,

to impart movement to the side members, and driving mechanism designed to yield in case of obstruction to the movement of said side members or pusher, said mechanism 7 comprising a pitman having a direct line end thrust upon the pusher, and a comparatively fragile abutment carried by said pitman and arranged to apply force to the pusher.

I 14. In astoker of the character described, a reciprocating fuel support, a refuse support at the rear end of said fuel support,

said refuse support comprising linked plates and bars underlying said plates, the bars being movable transversely of the plates whereby to vary the supported extent thereof.

15. In a furnace having-a fuel passage or retort composed essentially of a stationary floor and air-supplying means at the sides and above said floor to provide an underfeed of fuel, said air-supplying means being reciprocable in a forward and rearward direction for feeding the fuel, and extending beyond and below said floor, to provide also an overfeed of part1 burned fuel, a normally stationary and fixed refuse support at the rear of and directly below said air-supplying means, arranged so that the refuse may be pushed across said support by said means, and means for so adjusting said support as to vary its extent beyond the airsupplying means and to vary conversely the size of the discharge opening at the rear of said support,

16. A furnace including a fire space and an inclosure containing air under pressure, bars arranged intermediate said fire space and said inclosure and having spaces to permit passage of air from the inclosure to the fire space, and grate blocks bridging the spaces between said bars and constituting fuel supporting elements with intermediate air channels on their upper sides, said air channels being in communication with the spaces bridged by said blocks, and the blocks having overlapping portions arranged to deflect the outflowing air.

17. In a furnace, bars forming air conduits and defining the boundaries of a fuel retort, and grate blocks supported and alined by said bars, said blocks having overlapping walls and lateral air outlets between such overlapping walls and having upstanding fuel supporting ribs on the said walls, said ribs extending longitudinally-of the furnace and having air channels between them, through which air is adapted to flow.

18. In a furnace the combination of a se ries of grate blocks with confining bars or walls on which said blocks are supported and by which they are alined, each of said blocks having outer and inner side walls with an air space between them, a top wall on one of the side walls, a cross member between said walls, and upstanding fuel supporting ribs on said cross member, the cross members of adjacent blocks being arranged to overlap and provide an air outlet at the side of' the blocks between the crossmember of one block'and the top wall of the next adjacent block.

19. In a furnace a plurality of bars forming the boundaries of fuel retorts and of air conduits, grate blocks supported by said bars and bridging the air-conducting spaces defined thereby, and plates between certain of the adjacent bars forming the bottoms of fuel retorts, said bars and grate blocks and plates dividing the interior of the furnace into a fire space and an air space adapted to contain air under pressure, and means located in the air space and beneath said plates for limiting the amount of air which is permitted to pass through certain of said grate blocks in proportion to the quantity of air passing through other of the grate blocks. Y

20. In a furnace a fuel retort having a bottom and sides, said sides being composed of endwise moving bars and grate bloc-ks carried by said'bars, having air emission outlets, and other grate blocks carried by said bars arranged below the retort and across the entire width thereof, means for delivering air under pressure to said grate blocks, and means for causing a smaller pro-' portion of air to fiow through the last named blocks than through the first named blocks.

21. In a self-feeding furnace the combination with air supplylng means defining a fuel retort and movable to feed fuel in said retort, a stationary retort bottom between said air supplying means, mechanism for feeding fuel into said retort in front of and below the air emission points of said air supplying means, additional air supplying means in rear of and below the retort bottom co-extensive in width with the re of the auxiliary air supplying means adapted to regulate the amount of air which passes through such auxiliary means.

23. A self-feeding furnace, comprising in its construction a fuel retort and air-supplying fuel-supporting grates, said furnace having a confined air containing space substantially coextensive in length and breadth with the retort, and the grates overlying said space and arranged to admit air laterally from such space into the retort at each side of said retort, and means for feeding fuel into said retort, the air-supplying grates being above the bottom of the retort at the admission point of the fuel and inclined downwardly in the feeding direction, and being movable in a forward and rearward direction to produce a further feed of fuel and to distribute the fuel evenly.-

its construction a fuel retort having a bottom and upright side walls, and having a fuel-admitting opening at its forward end,- air-admitting, fuel-supporting grates at each side ofthe retortand at the top of said walls above the fuel admitting opening, and a fuel-supporting, air admitting grate at the rear of the retort and below the retort bottom, over which the fuel issuing from the retort passes for final combustion, said rates having fuel-supporting ribs and intermediate air-supplying channels.

26. In a furnace construction in combina- .tion with a retort having a bottom and upright side walls, which walls extend beyond and below said bottom toward the rear of the furnace, the space beneath saidretort being adapted to contain air under pressure, fuel sup-porting grates having air passages mounted in series on the upper edges of said walls outwardly from the retort over the air spaces at the sides thereof, supplemental air-supplying grates supported on said walls below and in rear of said bottom and having communication with the air space, and a damper located below said bottom and between the said walls in front of the supplemental grates and adjustable so as to obstruct more or less the quantity of air flowing through grates.

27. In a furnace,'the combination with a fuel retort having a bottom and sides and means for supplying air to said retort from points within the upper limits of said sides, an overfeed grate arranged in rear of the retort to receive and support fuel issuing from the retort, an air chamber containing air under pressure and having communication both with said air-supplying means and said overfeed grate, a damper in said air space arranged to obstruct and. check flow of air to said overfeed grate, and a refuse depository on which the refuse of the fuel is discharged from the overfeed grate.

28. In a furnace, the combination with a fuel retort having a bottom and sides and means for supplying air to said retort from points within the upper limits of said sides,

said supplemental an overfeed grate arranged inrear of the retort to receive and support fuel issuing from the retort, .an air chamber containing -.a1r under pressure and having communication with both said air-supplying means and said overfeed grate, a damper in said air space arranged to obstruct and check the flow of air to said overfeed grate, a refuse depository on which the refuse of the fuel is discharged from the overfeed grate, and

automatic mechanism constructed, arranged,

ran 'ed to reci rocate in a ath between the a: P P

forward ends of said bars whereby to feed fuel into the space between them, a refuse depository extending beyond the rear ends of the bars, a pusher device connected to the rear ends of said barsand driving connections between said feeding means and bars including separated adjustable abutments carried by the bars and a complemental member carriedby'the feeding means be tween said abutments and arranged to press against the latter alternately upon opposite strokes of the feeding means.

31. In a furnace separated bars forming the walls of a fuel retort, a plate forming a retort bottom extending between said bars, grate members carried-by said bars above said bottom plate and located wholly outside of the retort, grate members carried by the bars below the rear end of the retort bottom plate and crossing the space between the bars, the furnace being provided with an air space beneath said bottom plate and rate members, and a damper arranged .beneath the rear portion of said bottom plate and located so that it may shut oif'to, a variable extent the supply of air admitted to the last named grate members.

32. In a furnace, bars forming the walls of a retort, a bottom plate between said bars, grate members carried by said bars outside of the retort arranged to admit air for underfeed. combustion, grate members extending in rear of and below the rear termination of the retort bottom plate for overfeed combustion, means for supplying air under pressure to the space below said bottom plate, bars, and grate members, and a damper arranged to obstruct the flow of air to said 'overfeed grate members.

33. In a furnace, bars separated from one another to form the sides of a retort and being movably mounted, a bottom member between said bars forming the bottom of a retort, a reciprocating fuel feeder mounted to travel in a path extending between the forward ends of said bars, grate elements carried by said bars'at the upper terminations of the latter, pr0jecti0ns on said bars extending parallel to the path 'of movement of the fuel feeder, abutments on said projections, extensions from the fuel feeder located between said abutments and arranged to engage the latter alternately upon oppo- ROBERT SANFORD RILEY.

. Witnesses:

C. F. BROWN, P. W. PEZZETTI.

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