US1940945A - Reactive stoker - Google Patents

Description

` Dfw. 26,1933.

F. c.y GREENE REACTIVE STOKER Filed Jan. 14. 192s 2 Sheets-Sheet l ATTORNEYS.

' Dec. ze, 1933.

F. c. GREENE f4 REAGTIVE sTo'KER med Jan., 14. 192e -2 ,sheets-sheet 2 INVENToR. l g/*azlt C. 'feerze 30 during operation of the stoker.

screw threaded to the projection 2 and is provided Patented Dec. 26, 1933 UNITED .STATES PATENT v'oF-Pict'.v

1,94o,945 REAc'rlvE s'roxn Frank o. Greene, Milwaukee, wis. Application January 14, 1928. lSerial No. 246,686 12 claims. (ci. 11o- 101) The present invention relates to a stoker intended for use in connection with domestic heating units, and the object of the invention is to provide such a stoker which shall be automatic in its operation, which shall require a minimum of attention, and which shall be simple in construction and extremely efcient in operation. To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims.

The annexed drawings scription set forth in detail certain mechanism embodying the invention, such disclosed means l5 constituting, however, but one of various mechanical forms in which the principle of the invention may be used.

In said annexed drawings:

' Fig. 1 is a vertical section through a stoker con- 'temp1ated by the present invention showing a urnace in dotted outline; and Fig. 2 is an enlarged horizontal section through the base of the stoker taken along the line 2-2 of Fig. 1.

The reference numeral 1 indicates a basin adapted to be mounted beneath the combustion chamber of the furnace and provided with an upstanding screw-threaded projection 2. The threads of the projection 2- are of the left-hand .type to insure against loosening of the stator 3 The stator 3 is with a thread 4 extending throughout its length. It will be noted that the lower portion 4*ik of the thread is much heavier than the upper portion 4b of the thread, and that the-thickness of the thread decreases progressively from the bottom to the top of the stator. Obviously this variation in the thickness of the thread causes also a variation in the distance between the adjacent convolutions of the thread at the lower and at the upper portion of the stator. Thus, the distance 4' is less than the distance 4'l'.. One reason for this variation lies in the fact that, as the fuel is heated, the evolved free moisture causes differing friction and the mass moves slower, hence it is necessary to provide increased space to accommodate such slower moving mass. Furthermore, the increase. in the distance between adjacent turns of thread 4 slightly releasesthe friction between the ribbon of fuel and the screw, thus increasing the efficiency of the screw. It will be readily understood that certain fuels will expand as they are heated, and this variation also compensates for such expansion. The stator is formed with a longitudinal bore 5 registering with a simiand the followingv de-` lar bore in the basin 1 and with outletports registering with a similar bore in the basin 1 and with outl'et ports 6 at its upper end providing for communication between the bore 5 and the interior of the furnace.

Through the agency of bolts 7, or similar fastening means, the downturned flange 8 of the grate 9 having air inlet apertures 10 therein is attached to a tubular rotor 40 hereinafter to be described.

A shield 11, comprising a cylindricall portion surrounding the muiile and spaced therefrom and a conical portion 12, theledge of which is received in a rabbeted recess 13 in the grate 9, insulates to a considerable and necessary extent, the tubular rotor and stator from the heat generated in the combustion chamber of the furnace. A cowl -14 is attached to the shield 11 and overhangs the shield as indicated at-15. The shield is provided with a plurality of apertures 16 at its upper end to permit the passage of air from the space 11' 75 between the shield and the tubular rotor into the combustion chamber of the furnace. If it should appear desirable, the shield space 11 may be partially or entirely filled with insulating material or olher heat shielding means to reduce the tem,- perature of the coal within the tubular rotor 40.

It will be readily understood that certain fuels become activated at a lower temperature than do l others, and if the fuel is raised beyond its critical temperature before it is discharged into the combustion chamber, the advantages of the activation areV reduced. As is clearly illustrated, the cowl 14 is frusto-conical in form, and the upper end of the tubular rotor is beveled as at 17 to form a continuation of theouter surface of the cowl 14.

The basin 1 is provided at one side with an inlet conduit 18 inclined upwardly as shown. A hopper 19 is mounted adjacent the furnace and is formed with inclined walls 20 tapering toward 95 its mouth 21. A hinge member 22 is carried by the hopper 19 at its upper outer' edge, and said hinge member cooperates with a container 23. The container 23 has its one end open, and the walls of said container are thickened'adjacent 100 said open end to form a beveled portion 24, which portion forms a seat for a slidable cover 25. The container 23 may assume either of the positions shown in the figure. In the dotted line position it may be filled with fuel, and in the full line position it is discharging into the hopper 19.

One wall 20 of the hopper forms a portion of a casing 26, in which is mounted a worm gear 2'? carried by a tube 28, hereinafter to be described, and cooperating with a worm 29 on the spindle 110 and finished appearance.

A conduit 33 is rigidly attached to the casing may all be enclosed in a rectangular housing in .order that 'the organization may present a neat 26 and, because of the inclination of the casing 26, is so inclined as tol extend toward the conduit 18. The conduit 33 is formed with an aperture 34 in its upper surface adapted to receive ashes from the rotating grate 9, and an ash ejector 35 com- 'prising a handle portion 36 and a hook portion 37 is provided for dragging the ashes fromv the grate into said aperture. It will be readily understood that the handle portion 36 of the meinber 35 is positioned adjacent the conduit 33 and outside the furnacewhile the hook portion 37 lies Within the furnace.

The tube 28 is rotatably mounted within the conduit 33 and is journaled at one end in the casing 26 and at the other end in the inlet conduit 18 of the basin 1. The upper end 38 of the tube is sharply beveled and preferably toothed and is positioned adjacent the'mouth 21 of the hopper 19. The lower end 39 of the tube is also beveled and is positioned adjacent the inner end of the inlet conduit 18.v A gear 4l carried on the tube 28 bears against the outer end'of the inlet conduit 18 and engages' gear teeth 50 formed on the rotatable/grate 9. The tube 28 is formed on its outer surface with a helical gapped thread 42 which contacts the inner surface of the conduit 33, and said conduit 33 is provided with an aperture 43 in the lower wall of its upper end overlying the ash container 31. Y

The tubular rotor.40 is a tubular element rotatably mounted to surround the stator 3 and has its lower end 44 enclosed within thebasin 1. The tubular rotor is provided in lits lower end with a lateral aperture 45- providing communication be-f tween the basin 1 and the space defined between the stator 3 andthe tubular rotor 40, and carries a suitably shaped fin 46 adjacent said aperture. Y

'lhe operation of the device is as follows. The container 23, having been lled with fuel, is rotated'upon the hinge member 22 to the position indicated in full lines in the drawings. The hopper 19 is thus filled with fuel. When the motor` 30,'is started, it rotates the tube 28 through the medium of the worm 29 and the worm gear 27,

'A and the beveled end 38 of the tube 28 tends to A 'agitate the fuel in the lower end of the hopper 19, to'- break up any lumps fed thereto, and to eject to the sides material which cannot be broken up. This action prevents clogging of the mouth 21 of the hopper 19 and causes'the fuel to fall' into the open end of the tube 28. Due .to the 'inclination' of the .tubel 28, the rotation thereof cause the fuel to gravitate therethrough and to be. discharged from the lower end C 39of the tube into-the conduit 18. 'Ihe rotatbeveled end 39 pushes the fuel thus discharged into the basin 1. The gear 41, rotating with the tube 28 and meshing with the gear teeth 50, rotates the grate 9, and, due to the connection 7 between the grate 9 and the tubular rotor 40,

said tubular rotor is likewise'rotated. The fin 46,- rotating within the. confines of the basin 1, di`

said tubularrotor and consequently the fuel is caused to rotate with the tubular rotor about the stator 3. Such rotation obviously will cause the fuel to travel upwardly along the threads 4 of the stator and to be discharged from the top. of the tubularf rotor onto the cowl 14. Said cowl 14 prevents the 'entrance of coal into the shield space 11 and directs it into the combustion chamber of the furnace where it falls onto the hearth portion 12 of the shield 11. Due to the draft in the furnace, air is continually being drawn through the apertures 10 o1- the grate 9, the shield space 11' and the apertures 16 in the upper end of the shield 11. The overhang l5 of the cowl 14 directs the air downwardly onto the bed of fuel. This stream of air obviously will actas an insulator between the combustion chamber of the furnace and the tubular rotor 40, and will consequently prevent too rapid heating of the fuel mass contained within the tubular rotor, and further, this stream of air becomes highly heated and thus promotes immediate combustion of the vapors which are discharged from theupper end of the tubular rotor. It is to be understood that any vapors generated by the preheating of the coal in the tubular rotor are discharged from the upper end of the tubular rotor together with the coal.' Air also enters the combustion chamber through the bore 5, discharging through the apertures 6 and thus coming into intimate contact with the said va- 'pors to ald in the combustion thereof, and around the edge 9 of the-grate 9 to enter the re bed from the bottom.

'I'he present invention has been described as a reactive Stoker, and its primary object is to supply fuel (and more especially slack coal) to a furnace, such fuel having been endowed with a high index reactivity. Reactivity maybe described as being a quality pertaining to solid fuels causing them to react with oxygen in a lively manner uponattaining their ignition ternperature. It has been determined that the reactivity of a fuel is inversely proportional to its kindling temperature. It is furthermore known that coals subjected to preheating sucient to distil 0E their tar vapors but not sufficiently preheated to crack such vapors to xed gases have a high index of reactivity. Thus, coal distilled at low temperatures (500 C.) will exhibit highreactivity (index 72.5 in air), whereas coal distilled at high temperatures (1000 C.) will exhibit low reactivity (index 61.0 in" air). The degree of reactivity appears to be affected by the time element as well. Thus, heating a suitable coal at a very low temperature for a great length of time may result in a fuel having an index of 'reactivity similar to that exhibited :by the same coal when i* has been heated at a somewhat higher temperature over a shorter period of time.' Experiments have shown that unless the tubular rotor of a stoker of the present type is shielded from the temperatures prevailing in the combustion chambers of the furnace, the coal in the tubular rotor is preheated to too high a temperature for satisfactory results. Since the lighter distillate from a bituminous coal may evolve at about 200 C. and the melting point of the coal may average 300 C. with its last condensate coming off at 400 C. and with the tar vapors cracking to fixed gases at temperatures between 600 C. and 800 C.,`it 'will be seen that the most desirable temperature ofthe coal upon delivery to the combustionchamber will be` somewhere near 450 C. Since the temperature of the combustion chamber may be 1000? C., or even higher, it is seen (about four or or at least incipient that it is necessary to shield the coal within the tubular rotor from such high temperature or to pass the. coal very rapidly into the furnace. The latter method appears to bei impractical, and the presenty invention contemplates the use of the former method.

To render coal active presumes a prior4 melting coke formation. It is not desirable to melt the coal below the top ofthe tubular rotor, for, if the coal is so melted, then the mass is in a partially fluid state, somewhat like a grease for purposes of propulsion, and does not move upwardly on the stator as fast as the unmelted coal below it does. The result, in such event, is that the faster moving unmelted coal invvades the melted coal and makes a very dense and tough mass which is anything but the desired fuel. Such desired fuel isaof very light weight five pounds per cubic foot). It is very much moreporous than any coke that is known to me. In this state it is highly reactive.v

ignites almost instantaneously, and, when discharged into the fire pot of a furnace, burns intensely with a draft and without smoke or resultstoker.

ing clinker.

I am unable to state exactly what the reactions within the tubular rotor may be, but apparently the coal is preheated therein to a degree slightly below its melting point. This temperature of melting may be said to range between 300 C. and 400 C. for a large number of coals. The preheated air coming from inside the stator 3 through the vents 6 combines with the gas'or vapors which seem to be generated immediately the mass exits from the'top of the tubular rotor, at an ignition temperature possibly initiated by radiation by the burning fuel in the re pot, or by radiation from the metal parts of the furnace or Once this burning of the gas, or vapors, is initiated, the combustion supplies the necessary temperature of further ignitions and such adjacent combustion further raises the temerature of the mass suiiciently to cause its assuming the peculiar weight-and structure mentioned above. In a fuel of the described characteristics, there appears no distinct bubble structure, but rather it appears uniformly granular to Upon examination under a magnifying glass, this fuel appears to have drusy cavities of very uniform size. 1

The present invention contemplates not only automatic stoking of the furnace, but also semiautomatic ash disposal. As the grate 9 rotates slowly, the ashes evolved by the combustion of the fuel in the furnace are carried into contact with the hook end 31 of the ash ejector 35. Some of the ashes will be automatically directed to and through the aperture 34, and the remainder may be 'carried to said aperture by manual actuation of said ejector. When the ashes fall through the `aperture -34'into theconduit-33, they. are picked up by the thread 42 on the tube 28 and carried to the upper end of the tube.33, where they are allowed to fall through the aperture 43 into the ash container 31. The gaps in the thread 42 make that thread inefcient and provide for the retention in the tube 33 of rings of ashes which seal said tube to prevent the flow of air through the aperture 43, tube 33 and aperture 34 into the combustion chamber.

It Jwill be obvious that numerous variations may be addedto the described construction without 4comprising a basin,

, the discharge mouth the naked eye.`

comprising a basin, a stator' stationarily mo within the container 23, thus doing away with the nuisance of dust and dirt which will be thrown into the air if the container 23 is filled by a shovel or the like. Again, theelements 19, 23 and 31 may be dispensed with, and the conduit 33 and tube 28 may be extended to the point of storage of a very large supply of coal a'nd to a point where a large amount of ashes may be deposited. By such means, it will be possible to operate a furnace for a whole season without any attention other than varying the time of operation of the motor 30 to provide for larger or smaller fires, since the stoker is of such capacity that it need not be run more than about tenv minutes in every hour under normal conditions.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the mechanism herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention:

l. The combination'with a hopper provided with a discharge mouth positioned adjacent said fur nace, means for supplying solid fuel to said hopper, a rotatable, inclined tube extending from of said hopper to said basin, means for rotating said tube to cause the fuel in the hopper to gravitate therethrough toward said basin, and means for carrying such fuel frorr` said basin to the combustion chamber'of said furnace.

2. The combination with a furnace of a stoker comprising a basin, a hopper provided with a discharge mouth positioned adjacent said furnace, means for supplying solid fuel to said hopper, a rotatable, inclined tube having its upper end located in the discharge mouth of the hopper and its lower end located in an inlet conduit formed on said basin, means for rotating said tube, the upper end of said tube being beveled to agitate the fuel in the mouth of said hopper upon such rotation, and means for carrying the fuel delivered through said tube from said basin to the combustion chamber of said furnace.

3. The combination with a furnace of a stoker comprising a basin, a hopper-provided with a discharge mouth positioned adjacent said furnace, means for supplying solid fuel to said hopper, a rotatable, inclined tube havingits upper end located in the discharge mouth of the hopper and its lower end located in an inlet conduit formed on said basin, means for rotating said tube to cause fuel from said hopper to gravitate through said tube and into said conduit, the lower end of said tube being beveled and adapted to push fuel through said conduit and into said basin upon such rotation, and means for carryingthe fuel from said.basin tothe combustion chamber of said furnace.

4. The combination with afurnace of a stoker comprising a basin,`a hopper provided with a discharge mouth positioned adjacent said furnace, a rotatable, inclinedtube having itsupper end beveled and located in of the hopper and having its lower end beveled and located in an inlet conduit formed on said basin, means for rotating said tube, and means for carrying fuel from said basin to the combustion chamber of said furnace.

' 5. vThe combination with `a furnace of a stoker ted in said basin and projecting upwardly ther from into said furnace, a rotatable cylinder-surrounding said stator and communicating with said connected to said cylinder and rotatable therev with, gear teeth formed on said grate, a .hopper provided with a discharge mouth and located -adjacent said furnace, means for supplying solid fuel to said hopper, a rotatable, inclined tube extending from the discharge mouth of said hop-A per to said basin, a motor mounted adjacent said tube, a worm and gear connection between said motor and said tube, and a gear onsaid tube in mesh with the teeth of said grate.

6. The combination with a furnace of an automatic stoker and ash remover comprising a rotatable grate, an inclined conduit mounted adjacent said grate, a rotatable tube in said conduit, a hopper for supplying-fuel to said tube, said tube communicating with said furnace, an aperture in said conduit .adapted to receive ashes falling from said rotatable grate, a thread externally formed on said tube and contacting the inner wall of said conduit, and means for rotating said tube'.

'1. The combination with a furnace of a stoker and ash remover comprising a basin, a stator stationarily mountedin said basin and projecting upwardly therefrom into said furnace, a tubular rotor and a rotatable hearth surrounding said stator, a thread on said stator'contacting the inner cylindrical surface of said tubular rotor,

a grate connected to said tubular rotor and rotatable therewith, gear teeth formed on said grate, a shield concentric with said tubular rotor 'and spaced therefrom, said shield being mounted on said grate, a'cowl projecting from the upper open end of said tubular rotor and overhanging ,the upper end of said shield, a hopper for solid fuel positioned adjacent said furnace, an inclined conduit extending between said hopper and said basin, a. rotatable tube in said conduit having its upper end beveled and located in n the discharge mouthof the hopper and having its lower beveled end located in an inlet conduit formed on said basin, an aperture in said inclined conduit adapted to receive ashes falling from said rotatable..grate, .athread externally` formed on said tube and contacting the inner wall ofl said conduit, a motor mounted adjacent said.

tube, a worm on the spindle of said motor, a Worm gear on said tube and engaging said worm, a gear on said tube meshing with'the.

teeth on said grate, an aperture formed in said tubular rotor within said basin, and a fln carried .by said tubular rotor adjacent said aperture.

8. The combination with a furnace of a Stoker comprising a basin, a stator stationarily mounted in said basin and projecting upwardly therefrom into the combustion chamber of said furnace; a hearth in saidfurnace disposed above said basin, a tubular rotor surrounding said stator and in communication 4with said basin, a

tubular shield surrounding said rotor and spaced therefrom, means for feeding fuel to said basin, and means includings'aid stator and rotor for bustion chamber.

9. The combination with a furnace of a ,Stoker comprising a basin, a stator stationarily mountvconveying said fuel from said basin to said comed in said basin and projecting upwardly therefrom into said furnace, a hearth in said furnace disposed around said stator adjacent the bottom thereof, a tubular rotor surrounding said sta-l er comprising a basin, a stator stationarily mounted in said basin and projectingupwardly into 'said furnace, the combustion. chamber of said furnace surrounding said stator Vfor `the greater part of its length, a tubular rotor disposed around said stator and in communication with said basin, a tubular shield concentric with .said rotor and separating the same from said combustion chamber, means for feeding fuel to said basin, and means'including said stator and rotor for conveying said fuel from said basin into said combustion chamber.

l1. The combination with a furnace `of a stoker comprising a basin, a stator` stationarily mounted in said basin and projecting upwardly into the combustion chamber of said furnace, a.V

hearth in said furnace disposed above said basin, a tubular rotor surrounding said stator, the stator being provided with a'screw thread contacting the adjacent surface of the rotor, a tubular shield surrounding said rotor, means for feeding fuel into said basin, an aperture in the wall of said rotor within said basin for admitting fuel to the space between said stator and said rotor, and means for rotating said rotor to force fuel upwardly through said space to the top of said rotor and into said combustion chamber.

12. The combination with a furnace of Va stoker comprising a basin, a statorstationarily mounted in saidbasin and projecting upwardly into' the combustion chamber of said furnace, a hearth in said furnace disposed around said stator adjacent the. bottom 'thereof,` a tubular rotor surrounding said stator, a tubularshield.

surrounding said rotor, a screw thread on said stator contacting the' inner surface ofsaid rotor, 'means Afor feeding fuel into said basin, an f aperture in thewall of' said rotor within said basin, a n carried by said rotor adjacent said aperture, and adapted to direct said fuel through saidaperture from said basin to the lower part of said screw thread, and means for rotating said rotor.

-FRANK C. GREENE.

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