US2369370A - Fuel feeding apparatus - Google Patents

Description

Feb. 13, 1945. c. SCHOLL FUEL FEEDING APPARATUS Filed Aug. 28, 1940 Patented Feb.'13, 1945 I FUEL FEEDING APPARATUS Clark Scholl, Springfield, Ohio. assignor to The Steel Products Engineering Company, Springfield, Ohio, a corporation of Ohio Application August 28,1940, Serial No. 354,599

, 4 Claims.

This invention relates to combustion apparatus and more particularly to fuel feeding or stoker mechanism.

It is the principal object of the invention to provide mechanism for feeding solid fuel from a bin in a smooth and regulated manner and without excessive grinding or comminuting action upon the fuel itself so that the mechanism operates efliciently with a small expenditure of power.

It is a further object to provide a stoker mechanism for feedingsolid fuel from a bin to a retort which provides for regulating the feeding progressively from one end of the bin toward-the other, the fuel being delivered through and under the body of fuelin the bin which is so supported and progressively throughout the extent thereof for delivery.

It is a still further object to provide such a mechanismhaving a conveyor tube guiding and supporting a feed worm of the stoker with the tube open along its top for the continuous entry of fuel thereinto and with its side walls so arranged as to provide support for the body of vide for storing a quantity of the fuel in a bin from which .it is fed by conveyor or stoker mechanism as required. Where such stoker operates in a bin of substantial length, or one having a considerable depth of the body of fuel overlying the worm, the power required may be quite substantial, particularly where the operation of the conveyor results in unnecessary churning or grinding of the fuel, necessitating the use of a large driving motor and correspondingly heavy drive and operating parts, with consequent increase in both initial and operating costs.

It has been found in accordance with. the present invention that a superior feeding action may be secured substantially without crushing or comminuting of the fuel and with a smooth and regu-. lated feeding action such as to supply a substantially uniform quantity of fuel into a closed conveyor tube, for example, to be transported therethrough to the retort itself. This regulated supply ,is important where the fuel is to be conveyed through a closed tube, since uneven feeding tends to cause the supplying ofexcessive quantities of fuel to the closed tube, beyond its capacity to receive the same, resulting in choking thereof with consequent grinding and attrition of the fuel and corresponding loss of efliciency.

The .present invention further provides for the discharge of the fuel from the inner or remote end of the bin progressively toward the outer end thereof, the feed advancing progressively toward the outer or delivery end as the supply is exhausted, the fuel in the conveyor being transported beneath the main body of fuel in the bin.

Fig. 1 is a broken side elevational view showing a complete installation of a stoker, includ ng of the stoker Fig. 4 is a vertical sectional view through the conveyor tube on the line 4--4 of Fig. 2; and

Fig. 5 is a sectional view through a modified,

form of conveyor tube structure.

In the supplying of solid fuel to a retort in which it is to be burned, it is convenient to pro- Notwithstanding the fact that the conveyor is adapted for receiving fuel along its entire length, the arrangement provides for an initial and continuing withdrawal of the-fuel at the remote end avoids the tendency to segregate the coarse from the fines which normally occurs with a tapered I worm because of the shallow flights having insufficient width to move the larger particles offuel readily and consequently exerting a selective transporting action with respect to the fines. lteferring to the drawing which discloses a preoutward bulging thereof.

ferred embodiment of the invention, and referring first to a typical retort and drive mechanism with which the stoker may be utilized, the retort is The feed worm continues through the closed supply tube which may be made in one or more sections joined together by a coupling member 2|, as required to cover the necessary distance from the bin to the location for the retort. A pair of such coupling members is preferably provided and spaced apart a distance corresponding to the length of the sections of the worm so that the worm may be removed therethrou'gh section by section. A shear plate 22 is provided adjacent the inlet to the closed tube 20 for the purpose of securing access thereto in order to clear out foreign objects such as tramp iron, stones, and the like. It will be understood that other forms of retort and drive mechanism may be utilized, that described above beingshown merely for purposes of illustration.

The bin is' indicated generally at, the floor of the bin being shown at 25 on which rests the body of fuel 26. The stoker conduit extends along the length of the bin to the inner end thereof beneath or in the lower portion of the body of fuel and comprises a cylindrical tube 21 having an opening 28 along its upper side. The opening 28 is of less width than the diameter of the tube and is symmetrically located so that the vertical projection of the walls of the tube along each side of the slot. form shoulder portions 29 in position to provide support for the body of fuel within the bin, so that the entire weight thereof does not press downwardly into the tube and yet providing for continuous feeding of the fuel into'the tube throughout its length.

The tube is supported at its inner end by means of a plate 30 having a circular cut-out portion ment therebetween. The flights on each section adapted to he slipped over the end of the tube and attached thereto as by welding, and having an angle member 3| fastened at its bottom portion serving as a foot for resting upon the floor 25 of the bin. Additional similar brackets 32 having angle members 33 welded thereto may be provided as desired giving intermediate support to the conveyor tube the tube being supported relatively close to the floor to provide for'more completely discharging the bin contents. In addition the tube is reinforced by means of plates 35 which have asimilar cut-out portion adapted to be received over the outside of the conveyor:

tube and which are trimmed off at the top at the level of the upper wall of the tube, as shown for example in Fig. 4. These brackets are spaced suitably along the length of the conveyor tube and welded in place, so that they provide rein-.

forcement for the walls of the tube and prevent The forward end of the tube 40-is suitably attached to an end plate 4| by means of welding,

the end platebeing adapted .to stand at the outer itate the removal of foreign objects which may get caught between the worm and the shear plate, the side wall of the tube immediately adjacent the plate 4| is preferably beveled down to the center line at an angle of about 30 as shown at 42.

Within tube 21 is the feed worm 45 having continuous flights 46 formed thereon. Preferably the worm is made in a plurality of sections which are joined by a coupling 41 formed with a tongue 48 in one section fitting within a groove 49 in the other section permitting relative angular moveextend to the ends thereof, and in the assembled position match up with each other to provide a continuous and unbroken feeding surface free of obstructions or'pockets such as would interfere with the smooth uniform feeding operation.

Such cooperating flight ends are adapted to bear against each other, so that a substantial part of the torque is transmitted from the driving section to the driven section in this manner, relieving the load upon parts 48 and 49. The coupling member may be disconnected, in order to provide for the removal of the sections ofthe worm axially, provision usually being made for such removal in the space between the bin and the retort, the length of .the sections being suitably selected so that they may be pulled axially into this zone and then withdrawn upon the removal of the coupling members 2| as above described. Where there is insuflicient space for this, the drive unit may be removed, and the worm withdrawn from the drive end,section by section.

As will be clear from the drawing, the'conveyor worm is entirely supported and guided by the walls of tube 21, and no additional bearings either at the inner or theouter end of the bin being provided. This assures that the flights of the worm will run freely, and usually in contact with the lower wall of the bin so as to provide for the continuous discharge of particles of all ranges of size. It also provides for limited lifting movements of the worm within the tube which may occur as the worm accommodates itself to the movement of the fuel in operation. As clearly shown in Fig. 2, the top edge of the flights 48 extends slightly above the wall portions 29 of the tube, and in position to readily engage and pick up the body of fuel for transport through the conveyor.

It has been found that the width of the slot should bear a proper relation to the size of the worm, in order to provide for proper freedom of access of the fuel to the worm and at the same time to assure the desired support for the fuel upon the shoulders of the tube. Further the opening in the slot should not be so wide that it would permit the worm to rise and wedge itself in the slot. It is ordinarily found that the width of the slot should be approximately 75% to of the diameter of the worm, the remainder of the projected worm diameter forming the shoulders 29 and serving to support the fuel thereupon.

.In the operation of the device, with the bin containing a body of solid fuel over the conveyor tube, rotation of the worm tends to cause the flights to pick up fuel, and after being loaded with the fuel, nofurther feeding action occurs except at the innermost end where the worm begins. At this zone, fuel is progressively fed into the worm, and carried along by the worm, beneath the main body ofthe fuel.- This main body is thus supported above the worm, the shoulders 29 of the tube giving support thereto so that the entire weight thereof does not press downwardly on the worm. N

Any tendency for the fuel to pack in the tube is overcome by the free and unconfined movement of the fuel, with resultant lifting of the fuel outwardly and upwardly through the open slot in case of any tendency to crowd or to build up pressure within the tube. As the feeding action continues, and as the body of fuel is progressively ex-.

hausted, the fuel rolls downwardlyalong the outer edge of the pile and into the portion of the worm which lies beneath the edge thereof,'to-fill the.

of the worm which is possible in the tube it is l found that the tendency of the worm to tunnel,

and of the fuel to bridge over the conveyor tube a and thus terminate its feeding action is substantially eliminated, no tendency to stop feeding by reason of the fuel bridging over the slot having been observed even in the case of fuel of small particle size and in a damp condition. The worm, being freely supported in the tube, is allowed certain movement which may be imparted to the conveyor tube as well, and this movement sufficiently agitates the body of fuel to cause it to flow downwardly into the slot in the desired progres sive manner from the inner to the outer end of the bin.

This arrangement provides for a regulated and substantially uniform feeding action, and the worm does not tend to pack, to grind the body of fuel therein, or to deliver an excessive quantity of fuel from the bin. Hence the closed tube 20 may be of the same or larger diameter, than tube 21, and assurance is provided that no excessive loading or packing of the fuel into the closed tube will occur. Thus a relatively small sized drive motor may be utilized, and the conveyor operated with the expenditure of only a very small amount of power, resulting in economical and highly eflicient supply of fuel in substantially the condition in which it exists in the bin, into the retort for ,the invention, it is to be understood that the invention is'not limited to these precise forms of apparatus and method, and that changes may be made therein without departing from the scope of the invention whichis defined in the appended claims: I

I What i claimed is: a

1. A stoker of the character described fordelivering solid fuel from a bin containing a quantitythereof to a closed conveyor tube for delivcry to a retort comprising a cylindrical tube extending through the wall ,of said bin and into the remote end thereof, means for supporting said tube close to the bottom of said bin, said tube having a continuous slot opening directly upwardly along its entire length within the bin forming a central longitudinal continuous opening for the introduction of fuel thereinto and leaving shoulders at the sides of the tube for supporting the weight of the fuel thereon, a plurality of spaced plates fastened to the walls of said tube adjacent the sides of said slot to reinforce the same and prevent the spreading thereof, a conveyor worm of uniform diameter greater than the width of said slot extending through said tube and entirely supported and guided by contact with the walls thereof and capable of limited movement relative thereto, said worm being adapted to fill itself with fuel at the inner end of the bin and to deliver said fuel along the tube beneath the body of fuel supported on the shoulders of said tube, a closed delivery tube in line with said slotted tube and adapted to receive the fuel therefrom, and a continuation of said conveyor worm extending into said closed tube to continue the regulated feeding of said fuel thereinto.

2. A stoker of the character described for delivering solid fuel in a relatively loose and unpacked condition from a bin containing a quantity thereof to a closed conveyor tube for introduction into a retort with a minimum expenditure of power and in the absence of grinding and crushing of the fuel comprising a screw conveyor having continuous flights thereon and of substantially uniform diameter, a cylindrical tube supported adjacent the lower part of the bin and extending from an inner portion thereof throughout the feeding zone and forwardly to the Wall of the bin through which the fuel is discharged, said tube providing the sole support for rotatably supporting said screw conveyor through contact with the inner wall surface thereof, the top portion of said tube being cut away to form a continuously open slot the cross dimension of which is approximately 75% of the projected diameter of the tube, said slot being of such width that said screw conveyor is rotatably retained within said tube and leaving shoulders at either side of the slot providing continuous support along the sides of the tube for the main body of fuel within the bin and relieving the flights andthe fuel moving through said tube from the weight thereof, said slot providing an entrance open along the length of the tube for passage of the fuel into the flights of the screw conveyor in that l I portion thereof not filled with fuel, the fuel passing into and filling the conveyor at the inner end' of the body of fuel and being conveyed forwardly with the flights maintained substantially filled with fuel beneath the main body of fuel with the point of entrance of the fuel into the tube progressively moving forward with the advance of the inner boundary of the body of fuel, and means confined to the space outwardly of the cylindrical surface of said tube for reinforcing the walls ofthe tube to provide for maintain ing the original size and shape thereof and avoiding irregularities in the flow of fuel theretherein directly in contact with said body of fuel,

said tube being of substantially cylindrical shape and having a continuous open slot extending along its upper portion over substantially the en width of said slot and with a substantial num- Y ber of such flights being exposed through said open slot, thetopmost portion of said flights extending into the area of said slot above said shoulders tofeed fuel forwardly from said body of fuel, said worm providing for picking up fuel and filling its flights at the innermost portion of the tube above which there is a body of fuel and progressively at all points forwardly thereof as the body of fuel is exhausted to move the same feeding solid fuel from a, bin comprising a generally cylindrical tube in the lower portion the bin beneath and in direct contact with body of fuel therein. said tube having an open slot on its top portion extending continuously over its lengthwithin the bin providing for entrance of fuel thereinto at any point with the fuel passing into said tube to flll the same progressively from the remote end of the bin, said slotbeing of less width than the tube'diameter forming continuous fuel supporting shoulders in the walls of the tube above the level of the tube axis at either side thereof, and a worm conveyor having flights thereon the uppermost portions of which project above the level of said shoulders and within the uppermost projection of the cylinforwardly beneath the remaining body of fuel I thereover without additional filling and with substantially minimum grinding and packing of the fuel. I

4, Apparatus of the character described for drical surface of the tube, the topmost portion of a substantial number of said flights being exposed along said open slot and above said shoulders, said exposed flights remaining fllled with fuel as initially received therein and conveying said fuel beneath the remaining body of fuel without substantial addition to or replacement thereof.

CLARK SCHOLL.

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