US1152222A - Furnace. - Google Patents

Description

S. RILEY.

FURNACE. 7 APPLICATION FILED AUG.I3, IQIO.

Patented Aug. 31, 1915.

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Patented Aug. 31, 1915.

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APPLICATION FILED AUG.I3. 1910.

Patented Aug. 31, 1915.

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APPLICATION FILED AUG.l3| 1910.

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ROBERT S..RILEY, 0F PROVIDENCE, RHODE ISLAND ASSIGNOR TO AMERICAN ENGINEERING COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORA- TION or PENNSYLVANIA.

FURNACE.

Specification of Letters Patent.

Patented Aug. 31, I915.

Application filed August 13, 1910. Serial No. 577,056.

To all whom it may concern Be it known that I, Rouun'r S. RILEY, of Providence, in thecounty of Providence and State of Rhode Island, have invented certain new and useful Improvements in Furnaces, of which the following is a speclfication.

This invention relates to furnaces, and particularly to automatic stoking apparatus for feeding fuel to the furnace and securing the greatest possible efficiency in the combustion of the fuel. In its fundamentals the stoking apparatus is of ,the same type as the stoker shown and described in the patent to Elwood E. Taylor, No. 7 92,862, but differs from the said patent in regard to certain improvements hereinafter described in detail, which are provided to improve the manner of fuel disposition and distribution, to obtain a more complete consumption of the combustible and thereby to diminish the percentage of combustible lost in the ash, and to increase the life of the working parts.

Referring to the drawings, Figure 1 represents a front view of the stoking apparatus and embodying the principles of the present invention. Fig. 2 represents a plan view of.the furnace and stoking apparatus. Fig. 3 represents a longitudinal sectional view. Fig. 4 is a view similar to Fig. 3, showing in addition an inclined rocking grate applied for carrying the combustion to a more complete point than has heretofore been found practicable. Fig. 5 is a plan view partially in section of the apparatus shown in Fig. 4. Fig. 6 is a sectional view partly in elevation of the rocking grate. Fig. 7 is an elevation on an enlarged scale of the rear part of the furnace installation shown in Fig. 4. Fig. 8 is an elevation of the bracket which supports the rocking grate. Figs. 9, 10 and 11 are respectively an elevation and longitudinal sectional view showing retorts having various outlines and illustrating different modes by which I secure substantially the same improved results in the feed of the fuel from front to rear of the furnace. Fig. 12 is a section on line 12-12 of Fig. 10. .Fig. 13 is a plan view of one of the twyer blocks.

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

Referring first to Figs. 1, 2 and 3, the numeral 1 represents the-{front wall of a furnace inclosure such as would be provided for the purpose of enabling steam to be genm the Taylor patent above referred to, the

fuel support consists in part of a number of vertical retorts 3 between which are air ducts and outletblocks or twyers which form grated surfaces, and in which. travel pushing means 5 and 6 for feeding the green fuel into and through the retorts and beyond the grated air supplying surfaces. The fuel is placed in a hopper 7 from which it falls in rear of the upper reciprocating cylindrical pusher or plunger 5 when the latter is at the forward limit of its stroke. Upon movement of the pusher to the rear the fuel in back of it and resting on the bottom 8 of the retort, is pushed to the rear, and a part of it falls behind the pusher 6, which latter is given a less extent of motion in synchronism with the upper pusher. The means for operating the pushers is in general similar to that shown in the Taylor patent, with the exception of improved means for governing the extent of movement of the lower pusher which will be presently described. Each retort contains one set of upper and lower pushers, and two or more sets are driven from the same shaft. The shaft is represented by the character 9 and has a crank 10 which is engaged by means of a pitman or connecting rod 11 with a wrist pin 12 on the upper pusher. The shaft is driven through compound worm andwheel gearing consisting of worm wheels 14 and 15, and the worms 16 and 17 (Fig. 3), the latter worm being driven from a concealed engine or motor by a chain or belt 18. In the case of large furnaces, it is sometimes desirable to have two or more shafts 9, each independently driven, as illustrated in Fig. 1. As the fuel is fed rearwardly by the pushers 5 and 6, it spreads out over the triangular ,twyer blocks 4 to meet the fuel fed through the'adjacent retorts and when it encounters the rear or bridge wall 19 of the furnace, it is crowded upward. The driving means for the two pushers of each set is so arranged as to give the upper pusher a longer travel than the lower one, so that the greater proportion of the fuel is fed into the upper and forwardp'art of the furnace, causing the fuel bed to heap up somewhat as indicated by dotted. lines in Fig. 3. The fuel bed at the rear of the furnace rests on dumping dead plates pivot- .extent necessitating its removal, the latter are tilted downward allowing the accumulation resting upon them to be dumped through the passage 22 into the ash pit.

" .The dead plates are then raised into the horizontal position. After dumping, the dead plates of course are uncovered and the fuel bed extends only to the forward edge of such plates. It is, of course, desirable then to cover'the dead'plates as quickly as possible with fuel in order that the area of the fuel from which heat radiates may not be unnecessarily restricted. In order to ena'blethis result to be accomplished I provide means by which the feed of the lower pusher may be largely increased during a period long enough to feed the fuel out to the rear of the fire space. This means forms part of the mechanism for reciprocating the lower pusher and will now'be described.

The connecting rod previously described is made as a bell crank lever and carries on its downwardly projecting arm a pin 23 which is'engaged with a rocker 24: having.

a pivotal support 'at25 with a link 26 connected between lugs 27 on the under side of the guide'for the lower pusher. A bar 28 projects forwardly from "the lower pusher and carries upon it a fixed dog or shoulder 29 and amovabledog 30, which is pivoted at 31. As'the connecting rod 11 is reciprocated,the rocker 24.- is oscillated back and forth, striking alternately the shoulder 29 and the do 30. Thelatter, however, is normally hel rout of the way by means of a weight '32, which is connected to or formed in-onepiece with a dog, and holds the latter elevated insuch manner that on its rear- War'd' swing the rocker 24 strikes the hub of the dog 3'0 rather'than the end of the dog. L'ost'mot'ion between therocker and pusher is thus providedfor so that only at the end of'eachswin ofthe rocker is the lower 'pushermoveld. When it is necessary to increasethe feed of the lower,pusher for the urpo'se above mentioned, the dog 30 is glaced in'its operative position, whereupon the pusher isinoved at each rearward reciprocation a greater distance toward the rear, thereby'causingthe fuel at the bottom of the furnace to be fed more rapidly rearward over'the uncovered dead plates. A -com-- parativ'ely small number of reciprocations of the pusher at its increased rate is sufficient to cause the fuel area of the fire space from front to rear'to be covered over with the faeL 'and'the stroke of the pusher is thenshort'enedto its normal amount. The

means for thus moving the dog 30 into and out of the path of the rocker consists of a weight 33 pivotally hung from the pin 31, and connected with an operating arm 34 by means of a flexible connector such as a chain 35. Thearms 34 for all the retorts are socured upon a shaft or shafts 36, to one end of which is attached an operating handle 37. The latter may be so turned as to raise all the arms 34, causing the weight 33 to be lifted, and allowing the weight 32 to overbalanee the dog 30 and swing the latter out of the way of the rocker 24. \Vhen the weight 33 is allowed to drop, it catches the dog and swings it into the position shown in the drawings, where it may be struck by the rocker. This is an exceedingly simple and easily operated means for instantly causing the feeding stroke of the lower pusher to be increased at need, and as quickly to be diminished, while the action 'of the pushers continues.

The number of dumping plates 20 is preferably as great as the number of rotorts 3 in the furnace, there being one plate at the rear of each retort. These plates are ordinarily made with flat faces, practically impervious to the flow of air for various reasons, and on this account are called dead plates. Owing to the fact that the plates are subjected to great differences in tem- V perature, there is a tendency for them to warp and break, and in' order to obviate this tendency I have adopted a novel construction which is of great importance from a practical point of view. To this end the dead plates, instead of each being made as a single piece, are made in sections, each.

plate being in fact a composite plate made of a number of relatively narrow subdivisions placed closely side by side and rigidly secured together. As shown in Fig. 2, each of the dead plates consists of six narrow plates 2O which are substantially duplicates of each other with the single exception that the endmost plates are cut away to give space'for the brackets 38 which support the pintle rods 21 of the dead plates. The plate sections are formed with fiat upper surfaces and have comparatively slight thickness, while centrally on the under side of each is a longitudinal stiffening web 20 shown in Fig. 3. The sections are secured together into a rigid unit by means of a key bar 39 which passes through the webs of all the sections. Owing to this construction the strains caused by irregular heating and cooling of the different parts of the dead plate are taken up locally and the various sections are free to undergo considerable distortion, without rupturing the plate as a whole. The Webs 20 under the several plate sections give 'sufiicient stiffness to the sections, and thereby to the plate as a whole, to avoid the necessity of making the plate excessively thick. For the purpose of of the operating arms 42 therefor are secured to the same shaft. In Fig. 1 of the drawings two shafts 43 are shown, each operable independently to control several of the dumping plates. These shafts may be rocked at need by means of a bar inserted into an opening 44 in the side of a head 45 secured upon the end of the shaft. The bar 41 slides in a guide 46 shown in Fig. 4, and is normally held in its rearward position wherein it holds the dumping plate horizontal by means of a latch 47 hung upon a pivot 48, and lying in front of an abutment or shoulder 49 on the side of the bar. To the latch is connected a rod 50 which has a handle on its forward end accessible at the front of the furnace, and is hung when not in use in a stirrup 51. By manipulating the rod 50 the latch 47 may be swung to one side of the shoulder 49 and the bar 41 allowed to slide forward, whereby the dead plates are allowed to drop and discharge the ashes resting upon them. The locks for the bars 46 which are operated by the same rock shaft 47 are preferably so connected that all may be released at one time. As shown in'Fig. 1, the locks are divided into two sets, those of each set being connected by a rod 53 so that only two operating rods 50 are needed.

As in the prior patent above referred to, air is supplied to the furnace from a conduit 54 which discharges into a horizontal air trunk beneath the retorts; The side partition walls of the several retorts are-sepa rated far enough to leave spaces which open into the air trunk and constitute air ducts. The forward sides of these ducts are closed by air-tight plates, and the rear sides by the twyer blocks 4, which in the manner shown in the prior patent, are so made that they may be placed one upon another in an inclined series, so as completely to close the air duct except for the outlet openings 56 in their sides. The blocks are interlocked to prevent the weight of the upper blocks from tipping up the rear ends of the lower blocks by means similar to that shown in my application No. 414,900, filed February 8, 1908, and consisting of a hook 57 on the under side of each block, catching into an opening 58 in the top of the block beneath. The

lowermost block is thus locked with the top plate 59 of the air trunk. In addition to the hook each block has a stud 60 which enters an orifice 61 in the block beneath. The forward edge of the block bears against the edges of the Walls of the air duct while an extension 62 centrally located between the sides of the block projects into the air duct a sufficient distance to insure passage of the air through the block and out of the discharge openings 56 therein, \vithout leakage around the blocks.

Another important feature of the invention is in the provision of means connected with the lower pusher for acting upon the fuel at the bottom and rear of the retort to feed the fuel more effectively out upon the dead plates, and to supply air to this portion of the fuel, thereby more completely consuming the combustible mingled with the ash. To this end each lower pusher has secured to its rear end a plate 63 elevated somewhat above the bottom plate 64 of the retort, and having its rear end formed in a series of steps 65 of a height approximately that of the twyer blocks. Between 2 the steps 65 are outlets or twyer openings 66 to supply air to the lower part of the fuel bed. The forward part of the plate or slide 63 is equal in width to the space between the air ducts and is contained in such space, forming the bottom of the retort and a support for the fuel, while the rear part of the slide on which the steps are formed is widened on each side by an amount equal to half the width of the air ducts, and crosses the open side of the adjacent duets beneath the lowermost twyer blocks. The lowermost block of each set of twyer-s is supported and secured by bars 67 which lie alongside the partitions of the retorts and are rigidly attached thereto. Thus the widened rear ends of the slides are enabled to move back and forth beneath the twyers Without dislodging them. Those parts of the slides which overlap the air ducts cause air to be admitted to the interior of the slides, from which the air issues through the openings 66 to the fire. It will be noted from an inspection of the plan view (Fig. 2) that the slides collectively at their rear ends extend across the entire width of the furnace and that the openings 66, which are slots nearly as long as the width of the rear ends of the slides,

thus form twyers extending across the ends of the retorts as well as across the air ducts, and by means of them air is supplied to the fuel at places Where the air issuing from the inclined sets of twyer blocks cannot so readily penetrate.

From the foregoing description it will be seen that the greater proportion of the fuel is supplied by the upper pusher 5 to the upper part of the fuel zone. The portion of the fuel supplied by the upper pusher, however, falls in rear of the lower pusher upon the slide 63, and is fed step by step to the rear by the more limited travel of this pusher. When it reaches the end of the slide it falls in rear of'the steps 65 and is edges of the slide and steps.

thereby forced upon the dead plates by the The .twyer openings 66' are so narrow as to exclude pieces of coal of large size, while the smaller particles and ash" are prevented from passstepped rear end and twyer openings, is

' shownin Figs. 4, 5, 6 and 7. This means consists of a rocking grate 70 mounted at the rear of the air trunk and between the latter and the dead plate. In a wide furnace there should also preferably be a number of such rocking grates, the number being conveniently equal to that of the retorts and dead plates. Each of these rocking grates -is supported at its-ends in brackets 71 secured to the rear side of the air trunk, the grate having semi-circular studs 72 on its ends which form trunnions and are contained in bearing recesses 73 in the brackets. The brackets are formed not only as supports for'the grates, but also as conductors for leading air thereto from the air trunk, and to this end their parts which. lie next to the wall of the air trunk are provided with inclined walls 74, which, with the end walls of the bracket, form three sides of an air-conducting passage. of the rocking grate which rests on the upper side of the bracket and contacts with the wall of the air trunk forms the fourth side of the conduit. The upper part of Fig. 5 shows the bracket partly broken away, from which the form and location ofthe air conduit will be seen. A partition in the'cen-' ter of the bracket divides the air passage therein into two conduits for apurpose to be described. The wall of the air trunk against which the bracket is secured is provided with anopening 76, for the purpose of admitting air to the conduits. A damper 77 extends across the opening and is operated by a rod 78, the latter being pivoted to a connecting rod 79 extending to the front of the furnace and having a handle 80 for manual operation to open or close'the damper and thereby cause admission of air into the conduits to any desired or necessary extent. The portion of the rocking grate which supports the fuel is arranged as an inclined series of steps 81, between which are formed outlets or twyer openings for the admission of 'air. The grate has a box-like form, inclosing an air chamber 83 by means of a p 89 with the connecting rod 88.

The end or edge bottom plate 84 and webs at the ends of the grate. Air is supplied to the box chamber 83 from the bracket conduits through inlet nozzles'85, of which each grate is provided with two, one at each end projecting into the bracket conduits adjacent the ends of the grates respectively. The nozzles 85 are curved at the bottom concentrically with the axis of oscillation of the grate and project so far'into the bracket conduits as to extend to some extent therein at all times. They fit sufiiciently closely in the conduits as to conduct practically all the air which issues from the conduits into the box inclosure 83, and prevent any material amount of leakage outside of thegrate. The grate is kept in continuous oscillation by mechanism conveniently operated by and in synchronism with the motion of the pushers. The element directly acting on the grate is a cam lever 86 having a shoulder 87 projecting under the grate and upon which the bottom wall thereof rests. This lever has a downwardly extending arm which is pivoted to a connecting rod 88 driven by the pusher actuating mechanism. The latter is the same as that already described with reference to Fig. 3, with the single exception that in place of the rocker 24, a rock lever 24 is provided having an arm extending downwardly beyond its point of pivotal support 2-5, and connected by means of a pivot pin By this means, whenever the upper pusher is reciprocated the grate is rocked correspondingly up or down. In order to permit rocking of the grate by hand the connecting rod 88 is provided with a handle 90 by which, when therod is disconnected from the rocker 24, the grate may be oscillated. This rocking grate performs a function similar to that of the slide 63 in agitating the fuel and admitting air thereto at the final stage of com- .bustion to produce as complete a degree of pendently of each other, yet it is possible to combine them in one installation with advantage, as thereby a greater supply of air and more complete combustion may be obtained. Moreover as the rocking grate is placed in rear of the air trunk and below the bottom of the retort, its extent is not limited in the same manner as' is the height of the slide 63, which latter must be less in height than the lower pusher, and thereby the fuel may be'agitated and supplied with air through a greater distance. Furthermore the addition of the inclined grate behind and below the air trunk enables the fuel to be fed through a still greater distance than in the stokers heretofore designed, be fore it lodges upon the dead plates, thus affording longer time for combustion, without diminishing the supply of fuel, or retarding the rate of its feed. The rocking cam 86 and the dead plate 20 are pivotally mounted upon a rod 21 supported in bearings in arms 91 extending from the brackets 71. The construction of dead plates in this modification of the stoker, and the means for operating them to dump the ash, are substantially the same as that above described. with the exception that owing to the lower location of the dead plates a link 92 of different form than the link l0 previously de scribed, is pivoted to an arm 93 extending downwardly from the dead plate and rigid with the latter. The sliding rod 41, lock 47 and arm l2 on the shaft 4-3 are the same as previously described.

Another important improvement which I have made in connection with this invention resides in a modification of the outline or shape of the retort mouth. In the Taylor patent referred to; the mouth of the retort extends on a slope following a straight line from the bridge wall to the bottom of the retort, and conforming in a general and approximate way to the gravity feed of loose material. I have found in practice, however, that the actual feed of the fuel is in a more nearly horizontal direction in the upper part of the retort while under the influence of the upper pusher, and upon a more abrupt slope at the rear than accords with the uniform slope of the retort mouth shown in the patent. In order to get the best results in the supply of air and combustion of the fuel, it is desirable that the line of twyer openings should follow more nearly the outline of the fuel surface. To accomplish this end the retort mouth and line of twyers should be horizontal or on a gradual slope at the forward and upper ends of the retort and on a relatively steep slope at the rear and lower end thereof. However, many different constructions may be employed for securing this efiect within the limits represented by Figs. 3 and 9 on the one hand, and Fig. 10 on the other. One of these limits is a form in which the twyer blocks and outlines'are arranged on a line of continuous and regular convex curvature, and the other limit is one inwhich the upper twyers are on a horizontal line, and the lower and rear twyers on a steep incline. Between these limits the different parts of the retort mouth and line of twyer openings may extend at various angles. In all the forms typified by the drawings in which Figs. 3 and 9 represent one limit, Fig. 10 the other limit and Fig. 11 one of the many intermediate forms, the idea is essentially the same, that is the upper and lower parts of the rotary mouth extend on difierent angles or slopes, whereby the contour of the retort mouth as a whole is brought into substantial coincidence or arallelism with the slope of the fuel sur ace.

In the form shown in Fig. 3 the walls which form the dividing partitions between the retorts and air ducts are convexedly curved on the edge against which the twyerblocks 4 abut, and the latter are made somewhat wedge-shaped, so that when assembled together they will form a partial arch. In Fig. 10 the twyer blocks at the rearmost part of the retort extend on a straight line slant of relatively steep inclination, while at the top of the air duct a horizontal series of twyers 95 is provided, which are supported upon the partition walls and have openings 96 in their sides. In Fig. 11 the twyers 97 of the upper set are generally similar to the twyers 95' of Fig. 10,.with the exception of a difierence in proportion and slope. The form and manner of supporting the twyers 95 and 97 iswell shown in Fig. 12, which represents a section of one of the air ducts. At the angle between the two sets of twyers a triangular key block twyer 98 is provided. This twyer has openings in its sides similar to the opening 56 of the twyers 4, and other openings similar to those 96 of the twyers 95 and 97. In Fig. 9 the twyers 99 are in general similar to those shown at 95 and 97, although rhomboidal instead of rectangular to allow of the lowermost twyer resting squarely on the retort bottom. They are also slightly wedge-shaped or, in other words, shaped like the blocks of an arch, whereby they form an arch when assembled together. The outlet openings of these twyer blocks are designated by 99. All the blocks are crowded together by a wedge 100 bearing on the foremost one. In each of these various forms of retort, shown respectively in Figs. 3 9, 10, and 11 the retort mouths are flanked by lines of air-discharge openings which at theforward end of the retort follow approximately the line of feed of the fuel when acted upon by the mechanical feeding means, and at the rear follow the direction of gravity feed of the fuel as it descends on the dead plate. Thus the fuel in its whole passage through the furnace until it is finally consumed is supplied with air and its combustion thereby made complete. In addition, owing to the peculiar arrangement of twyers shown in these figures, the line of air outlets is longer and consequently the zone of incoming air is of greater-extent and the fuel is supplied over a greater area with air than in the fur-.

naces as heretofore made.

1. In a furnace, automatic stoking mechanism comprising reciprocating fuel pushing means for feeding fuel into the furnace, means for reciprocating said pushing means, comprising a backwardly and forwardly moving member, and dogs connected to the pushing means on each side of such member in the path of movement thereof, one of said dogs being pivotally mounted, and means for swinging the dog into and out of the path of the reciprocating member for causing the stroke of the pusher to be increased or diminished in length.

2. In a furnace a reciprocating pusher for feeding fuel into the furnace, a backwardly and forwardly driven actuator for moving. said pusher, dogs or abutments connected to the pusher lying in front and rear respectively of the said member and in the path of movement thereof, one of said dogs being pivotally mounted and weighted so as nor- .mally tolie out of the path of the member, a

weight mounted adjacent to said dog and adapted to be engaged therewith for swingingthe dog into the path'of the member, and means for lifting said weight so that the dog may be left free to swing out of the path of the member.

3. In a furnace a'fuel passage having upright bounding walls, air discharging means at the terminations of such walls arranged on a rearward and downward slope,

means for propelling fuel rearwardly through the passage and past the air-discharging means, an air trunk extending be-.

neath, the passage and having a connection with theair-discharging means, a rocking grate pivotally mounted on ahorizontal axis adjacent to the rear end of the passage, having a fuel supporting surface arranged in a descending series of steps with air passages between them, and having an inclosed interior, space into which such passages open and, in communication with said air trunk,

and mechanism for oscillating. the grate.

4.. In afurnace provided with vertical retorts having sloping mouths and air-admitting means on each side of the mouth of each retort, upper and lower pushers arranged to reciprocate back and forth in each retort, a

- plate secured to the lower pusher and having end being'in communication with the air ductsiand being provided with twyer openings conduct air to the fuel in the final stage of combustion, thereof.

6. In a furnace having air ducts forming the sides of vertical fuel retorts, the mouths of which are inclined, a series of twyer blocks closing the rear of each air duct, and following the sloping lines of the retort mouths, upper and lower pushing means in each. retort, and each lower pushing means having a rear extension with its rear end widened to extend into the air ducts on each side of the retort and into communication with the air ducts and arranged beneath the twyer blocks of the air ducts, suchextensions in the several retorts collectively extending throughout the entire width of the furnace and having air emission openings at the rear, whereby to inject air into the fuel at the bottom and rear of the furnace and across the entire width thereof.

7. In a furnace havingspaced air ducts forming retorts, a reciprocating pusher in the space between said ducts, a plate secured to each said pusher and extending rearwardly therefrom forming the bottom of the retort, such plate being widened at its rear end to extend partly across the air duct at each side of the retort, and having a" rear wall with passages therethrough for permitting discharge of air across the mouth of theretort at the rear and below the bottom thereof.

8. In a furnace having a plurality of horizontally extending fuel channels with fixed upright lateralv bounding walls and means for discharging air at the upper portions of said walls, reciprocating pushing means for feeding the fuel in'said channels, and rear pushing means collectively extending across the entire width of. the furnace at the rear and bottom thereof and having portions forming the bottoms of such channels and connected to the. first named pushing means. I

9. In combination with a furnace, an air trunk extending horizontally across the furnace, air ducts rising on a forward slant from such trunk and having air outlets at their rear, the spaces between such air ducts constituting fuel passages or retorts, reciprocating fuel-feeding pushers in said retorts, a fuel support arranged oscillatively on a horizontal axis at the rear of the air trunk and having its supporting. surface arranged in a series of steps, with perforations between successive steps, means for giving. a limited oscillative movement to said support, and provisions for conductingair from the trunk to such perforations.

l In a furnace a laterally extending air trunk, conduits rising therefrom and having outlets near their upper and rear terminations forming. the boundaries of fuel passages, brackets extending rearwardly from said trunk and having conduits communicating with the interior of the trunk, fuel supports mounted upon said brackets having a,

box-like structure, and having inlets coma municating with the bracket conduits, whereby air is admitted from the air trunk into the interior of the fuel supports, the portion of such support on which the fuel rests being. formed in a series of steps, and; having perforations between the steps,

rwaaea 4 comprising a fuel support at the rear of the furnace having its supporting surface provided with perforations and being constructed in box form with side and bottom. walls to inclose an air chamber which is connected with the air conduit so as to admit air into said chamber, and means for oscillating the fuel supporting part of said support, whereby the fuel is. agitated and aerated.

12. In a furnace an automatic Stoker includingia plurality "of separated air ducts forming retor'ts and being provided with outlet openings, upper and lower pushing means in eachretort, slides arranged to form the bottom of each retort and connected with the lower pushing means, such slides being widened at their rear to overlap. the air ducts at the sides of the retort, and having twyer outlets. to inject air into the fuel at the rear thereof, perforated fuel supports arranged below and in rear of such slides upon which the fuel falls from the latter, means for causing air to pass through such fuel supports, means for agitating said fuel supports, and dead plates upon which the residue of the fuel finally is discharged from said supports, and from which it is from time to time ejected.

13. In a furnace, the combination withunderfeed stoking mechanism, including upper and lower reciprocating pushers, a rocking grate at the rear of the furnace, and means for reciprocating said pushers and rocking said grate in unison, comprising a crank, a connecting rod driven by said crank and engaged with the upper pusher, a rocker pivoted to said connecting rod and oscillated thereby, means connected with said lower pusher engaged and reciprocated by the rocker, a connecting rod engaged with the rocker, and a pivoted cam lever with Which said connecting rod is engaged and by which it is oscillated, arranged to bear on and oscillate the rocking grate.

14. An .underfeed furnace comprising separated air supplying means forming the sides of an intermediate fuelpassage, mechanism for feeding fuel into the furnace through said passage, whereby an under- .feed of fuel is introduced, an overfeed fuel support in rear of said passage and below the bottom thereof, said overfeed support having outlets for emission of air and being oscillatively mounted on a horizontal axis immediately in rear of the passage, a refuse depository in rear of saidoverfeed fuel support arranged to receive the residue of fuel discharged from the latter, an air trunk arranged to deliver air to said air supplying means, and having a connection with said overfeed fuel support, whereby air under pressure is supplied to said support, and mechanism for giving a continuous oscillation to said support.

In testimony whereof Ihave aflixed my signature, in presence of two witnesses.

' ROBERT S. RILEY.

Witnesses:

\ ARTHUR H. BROWN,

P. N. Pnzzn'r'rr.

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