US1717923A - Furnace and stoker therefor - Google Patents

Description

June 18,l 1929. F. c. GREENE FURNACE AND STOKER THEREFOR Filed Feb. 2, 192s Q INVENTOR.

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Patente'd June 18, 1929.

UNITED STATES PATENT OFFICE.`

FURNACE AND STOKER THEREFOB.

Application inea February 2, 1928. serial No. 251,so2.

The present invention relates, as indi? cated, to a furnace specifically designed for use with a reactive stoker of the general type disclosed in my copending applicatlon Serial No. 246,686. The primary object of the invention is to eliminate all of the disadvantageous features of the usual type of furnace when used in connection with the reactive stoker, and certain modifications have been made in the Stoker itself to adapt it more specifically for use with the new furnace. To the Aaccomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out 1n the claims.

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

In said annexed drawing:

The single figure is a sectional view of the furnace and Stoker.

Referring more particularly to the drawings, the numeral 1 indicates a base plate having an annular upturned rim 2 and aI central raised platform 3. Said platform is reinforced by means of ribs 3, or the like, and is provided in its periphery with a plurality of air inlet apertures 4. Centrally of the platform 3 there is an upstanding annular' externally threaded flange 5, and the base plate 1 is formed with a low annular rib 6 adjacent the rim 2. A support 7 having the shape of a hollow truncated cone, has its larger lower end received within the annular rib 6 and is provided with an outstanding flange 8 at its upper The furnace proper, or fire pot, is formed of two substantially hemispherical sections 9 and 10, provided at their large open ends with external flanges 11 and 12 respectively, said flanges being grooved to form a channel 13 when the two sections 9 and 10 are brought into mating relation. External ribs 14 and 15 are formed on the two sections 9 and 10 respectively, upon vertical major circles, the ribs 14 being cut off adjacent their 1ower ends to form shoulders 16 adapted to rest upon the flange 8.

The upper open end of the section is formed with a fiange 18 adapted to support the flange 19 of a radiator 20. The radiator 20 encloses a humidifier 2l, the function of which will be hereinafter described.

At one side of the furnace casing 84 there is mounted a bracket 22 adapted to form a support for a flange 23 on a hopper 24. One Wall 25 of said hopper is formed to provide a chamber which may be closed by a mating member 26 to form a gear case, and laterally extending hubs 27 and 28 surround a substantially central aperture in said gear case. An ejector tube 29 'is `sleeved on the hub 27 and extends through an aperture in the opposite wall of the hopper 24, the projecting end of said tube being provided with handles 30. The portion of the tube 29 Within the hopper 24 is provided with an aperture 31 for a purpose to be hereinafter described. It is to be understood that the tube 29 is rotatable upon its longitudinal axis.

A conveyor tube 32 is sleeved on the hub 28 and extends through an aperture 33 inl the support 7. Said tube 32 is formed with a hoppered aperture 34 in its upper surface within the confines of the support 7 and with an aperture 35 in its lower sur-- fac/e adjacent the gear case 25-26. Within the conveyor tube 32 there is rotatably mounted a conveyor 36 comprising a tube having a gapped helical thread -37 formed thereon or secured thereto. Said tube 36 is keyed to a worm wheel 38 within the gear case 25-26, and said worm wheel is adapted to be driven by a worm 39 on the spindle of a motor 40. The upper end of the tube 36 extends `to a point within the hopper 24 and is sharply beveled at 41. Said beveled. end 41 is preferably cut to form serrations or teeth 42. Adjacent the lower end of the tube 36 there is carried a pinion 43 for a purpose to be set out later. Said lower end is beveled as at 44 and extends into an inlet conduit 45 giving access to the interior of a basin 46.

Said basin 46 is formed at its upper end to provide a journal for the hub 47 of a rotatable ash pan 48 said hub being non-rotat-` ably engaged about the base of a muille 49. The ash pan 48 is formed on its under surface with a series of teeth 50 in mesh with the pinion 43. Immediately surrounding the hub 47, the ash pan 48is formed with a series of air inlet apertures 51, and a flange 52 in the form of an upstanding frustum of a cone surrounds said series of apertures.

The rounded upper end 53 of the Inutile 49 is flanged for cooperation with the flange l54 at the upper end of a depending skirtlike hearth member 55 adapted to be secured thereto by machine screws 56, or the like. The lower end 57 of said hearth member 55 is flared outwardly and engages smoothly with the internal surface of the aperture in the lower end 58 of the section 9. Said end 57 is provided with a plurality of air inlet openings 59. A cylindrical shield 60 provided with a series of openings 61 adjacent its upper end is clamped at its upper end between the flanges 53 and 54 of the mullle 49 and hearth member 55, respectively, and its lower end 62 is snugly received within the open upper end of the flange 52.

The mulile 49 is provided with an aperture 63 in its lower end, said lower end being enclosed within the basin 46, andsaid muille' carries a suitably shaped curvediin 64 adjacent said aperture 63. The lower end 65 of a. stator 66 is screw-threaded for cooperation with the threads on the flange 5, and said stator is formed with a bore 67 registering with the aperture 68 in the base 3 surrounded by said llange 5. A helical thread 69 is formed on the external surface of said stator 66, said thread being so proportioned as to engage snugly the internal walls of the mullle 49. The upper end of the stator is flared and is formed of integral staggered sections 70 and 71 separated from the body of the stator and from each other to provide outlet openings 72 and 73 therebetween. The open upper end of the stator is adapted to be substantially closed by a cover member 74 spaced slightly from the section 71 to provide outlet o enings 75.

he urnace is provided with a kindling .door 76 which ispreferably formed half in the section 9 and half in the section 10. This method of forming the door 76 is preferable because of the fact that, when the door is so formed, the two sections 9 and 10 may be ldentical save for the cutting olf of the ribs 14 to provide the shoulders 16. An ash ejector 77 comprising a rod having a hooked low er end 78 extends through the support 7 and has it-s end 78 lying upon the upper surface of the ash pan 48. The opposite end of the ejector 77 is pivoted to a link 79, which in turn, is pivoted to a bracket 80 secured to the member 26. A draft door 81 is provided on the support 7, and said door is preferably formed with apertures 82 to provide for a desired minimum draft when the door 81 is closed.

In operation, the hopper 24 which, of course, may be of any desired practical size, is filled with coal. Preferably this coal should be of the type known as slack, since slack coal contains few large pieces and may be handled more easily through the conveyor 36 and in the Inutile 49. If the motor 40 is now energized, the conveyor 36 will be rotated through the worm wheel 38. lVith the ejector tube 29 in the position shown in the drawing, the coal will fall through the aperture 31 into contact with the upper beveled end I41 of the conveyor 36. This beveled end 41 will agitate the coal and bite7 into the mass of coal to cause the fuel to fall into the conveyor 36. Any large lumps of coal will be chewed up into small bits by the teeth'42, and any large lumps of hard material will be rejected by the open end of the conveyor and left within the tube 29. The coal which falls into the tube 36 Will be tumbled about by the rotation of said tube and will fall by gravity through the length of the tube and into the basin 46. The beveled end 44 of the tube will push the coal downwardly into the basin after the same has left the tube 36. Coaction of the pinion 43 with the teeth 50 of the ash pan 48 will cause rotation of said ash pan and, as the hub 47 of the latter is nonrotatably secured to the inuHle 49, the inutile will likewise be rotated. The fin 64, in its rotation, will scoop the coal in the basin 46 y through the aperture 63 and into the space defined between the muille 49 and the stator 66. The interior surface of the inutile 49 is opening in the support, and one portion of such air will follow a path through the apertures 51, the space between the shield 60 and the mulile 49, the apertures 61, the space between the shield 60 and the hearth member 55, andthe apertures 59 into the fire pot. It will -readily be seen that this stream of air insulates, to some extent, the space within the mule 49 from the heat in the fire pot, and that the air stream itself will be preheated in its passage along the above described path. The coal in its passage upwardly along the thread 69 is preheated in the manner described in my copending application, Serial No. 246,686, filed January 14, 1928, to the desired temperature as described in said copending application. As the coal emerges from the top of the muflle, it enters suddenly into a region of high teinperature, and vapors and gases deficient in oxygen are evolved therefrom. The remaining portion of the air which enters through the draft door in the support 7 will flow through the apertures 4, the aperture 68, the

bore 67, and the apertures 72,7 3, and 75, to come into immediate contact with these gases and vapors, and the high temperature in this portion of the furnace will cause combustion of said gases and vapors. Obviously, this second stream of air will be heated in its passage up the stator bore 67. The element 21 may be used as a humidifier preferably, or as so much increased radiator surface. Owing to the combustion having fully occurred below the radiator section, the usual large space of the radiator required to finish the combustion of long aming fuels may be diminished to advantage by increasing the radiator surface.

It will be seen that the combustion takes place within this furnace in two distinct parts, one part being combustion of the socalled volatile portion of the coal in the upper part of the fire ot adjacent the air discharge openings 72, 3, and 75, and the other part beingthe combustion of the socalled fixed carbon part of the coal completed adjacent the bottom of the fire pot. Each of these parts has its own suitable air supply, the first being delivered through said discharge openings, and the second bein delivered through the apertures 59. It w1ll be seen, then, that the furnace required is far different from the usual standard type of furnace wherein the attempt is made to burn the volatile and fixed carbon parts of the fuel within substantially the same space and usually with a single primary air supply and an entirely inadequate secondary air supply which is too cold to react with the relatively cold volatiles evolved.

According to the, present invention, two primary'air supplies are present. The usual method of burning coal might be considered analogous to an attempt to burn an intimate mixture of gasoline and heavy fuel oil through the agency of a carburetor.` It is true that a compromise may be made in the air mixture so that an optimum result of combustion occurs, but this optimum is not of the highest efficiency where it is attempted to burn the volatile and fixed carbon parts of carbonaceous fuel with intimacy. The present furnace has been devised to cooperate with the reactive stoker to obtain the greatest possible efficiency of combustion, andthe furnace is so designed as to fit and develop the advantages of this stoker.

When a shovel full of coal is cast into an ordinary furnace, there is thrown in the equivalent of the whole range of combustibles from gasoline to amorphous carbon. The ignition temperature of the former is very low, while that of the latter is about as high as is possessed by any combustible material. In between are all sorts of combustibles having graduated ignition points. Therefore, with a single air supply, the combustion can,J be only a `compromise. The

lighter constituents, of the fuel ignite first, i

but even though the overdraft is opened, the

constituents have cooled; the air is. cooled;l

bustion reaction are hot when brought into contact. With a fire in the firepot, the coal which is delivered to the fire pot through the mufile 49 is hot.` The volatiles which leave the coal at the discharge mouth of the muffle are hot. The air which meets such volatiles, being discharged from the apertures 72 73, and 75, is hot, having been preheated in its passage through the stator bore 67. Immediately smokeless combustion of the volatiles ensues upon the contact of said air with such volatiles. When the volatiles are thus consumed at the top of the mufiie, the remaining carbon drops into the fire pot Where the temperature is very high. Here it is brought into contact with hot air, such air having been preheated in its passage through the apertures 51, the space between the shield 6() and the muifle 49, the apertures 61, the space between the shield 60 and the hearth member 55, and the apertures 59. The combustion of the carbon is, therefore, complete. lThese reactions take place at the highest efficiency because of the particular design of the furnace herein disclosed, the dimensions and proportions of said furnace having been specifically designed to cooperate with the Stoker to attain this high efficiency.

As the fuel is burned within the fire pot, the ashes will fall through the apertures 59 onto the ash pan 48 and be carried around4 into contact with the hooked end 78 of the ash ejector 77. Said ejector may be actuated to drag the ashes from the ash pan and cause them to fall through the hoppered aperture 34 and into the `interior of the conveyor tube 32, where the ashes are picked up by the thread 37 and carried to the upper- Vend of said tube where they fall through. the aperture 35 into the ash container 85.

The material rejected by the bevelled end 41`of the conveyor 36 will be retained in the ejector tube 29 until such time as an operator rotates said tube to brin the aperture 31 into a lower position, uch material will then fall into the bottom of the hopper, whence it may be removed through the door 83.

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 dlsclosed, 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 1. A furnace comprising a base plate, a support formed as a truncated cone provided with an external annular flange at its upper end, said support being mounted on said base plate, a substantially hemispherical fire pot section having circumferential ribs formed thereon, said ribs providing shoulders adapted to rest on said flange, a second mating substantially hemispherical section superimposed on said first section and secured thereto, a radiator mounted on the open upper end of said second section, a conical member in said radiator having its apex directed downwardly, and a furnacel casing secured to said base plate and enclosing all of said parts.

2. The combination with a reactive stoker of a furnace enclosing said Stoker, said furnace being generally spherical i-n contour andopening at its top into a radiator mounted thereon, and a conical member having its apex directed downwardly in said radiator immediately overlying said stoker.

3. The con'xbination with a reactive stoker mounted on a base plate, of a furnace resttop of said section, a conical humidifier having its apex directed downwardly within said radiator arid immediately overlying said stoker, and a support for saidfurnace engaging `shoulders on said first section formed by cutting off` saidribs.

5. In a heating unit, a base plate, an annular support mounted on said base plate for supporting a furnace, a furnace comprising a pair of mating, substantially hemispherical sections, one superimposed upon the other, ribs formed externally of said sections and extending upon vertical circumferences of said furnace,'the ribs of the lower of said sections being cut away to form shoulders adapted to rest upon said support, and a reactive stoker mounted on said base plate and extending into said furnace, said stoker including a rotatable ash pan adapted substantially to close the open lower end of said lower section.

6. In combination with a reactive Stoker in which fuel is adapted to be preheated to a desired degree during its slow progress upward through a tubular member and discharged into a fire pot at a. point above the level of the fire bed therein in a highly reactivated state, a furnace comprising a pair of mating substantially hemispherical members adapted substantially to enclose such lStoker and to form a fire pot, the uppermost of said members being formed with an open top lying substantially in a horizontal plane with the points of upper air discharge of such stoker, a radiator superimposed on .said uppermost member' and presenting a relatively large surface, and means to prevent entrance of air to said fire pot save through channels in the' passage through which the entering air will be preheated to a high degree.

Signed by me, this 30th day of January,

FRANK C. GREENE.

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