US2497628A - Crushed-fuel stoker having means for equalizing the distribution of fuel upwardly in the retort - Google Patents

Description

Feb. 14, 1950 c. QulsT 2,497,628

cRUsHED-FUEL sIoxER HAVING MEANS FOR EQUALIZING THE DISTRIBUTION oF FUEL uPwARDLY IN THE REToRT Filed OCT.. 17', 1945 2 Sheets-Sheet l SQ INVENTOR.

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c. QUlsT 2,497,628 cRUsHED-EUEL sToxER HAVING MEANS FOR EQUALIZING THE DISTRIBUTION 0E FUEL UPwARDLT IN THE EEToRT Filed oct. 17, -1945 2 Sheets-Sheet 2 Feb. 14, 1950 INVENTOR. Corneau@ Patented Feb. 14, 1950 UNITED STATES `PATENT OFFICE CRUSHED-FUEL STOKER HAVING MEANS FOR EQUALIZING THE DISTRIBUTION F FUEL UPWARDLY IN THE RETORT Cornelius Quist, Grand Rapids, Mich., assigner to Holland Furnace Company, Holland, Mich., a corporation of Delaware Application October 17, 1945, Serial No. 622,838

4 Claims. (Cl. 110-45) This invention relates to a stoker for furnaces and other heating units and more particularly to an underfeed stoker in which the crushed coal or other solid fuel of suitable fineness is forced upwardly through the retort with a uniform upward filling of the upper portion of the retort.

In stolcers as heretofore known the crushed coal or similar fuel, when being forced upwardly through the retort, under the action of a screw or other means for forcing the fuel from a hopper through the fuel tube, has had a tendency to climb up one side of the retort neck due to the rotation of the coal screw. This action causes the coal to move along one side of the retort more than the other with the result that the coal rises unevenly in the retort. In the present invention I have provided means for overcoming this difliculty and causing a uniform and even upward continuous lling of the upper portion of the ren tort. My present invention equalizes the distri bution of the coal so that in the upper portion of the retort all of the coal is moved vertically upward in parallel layers. Segregation of the larger particles of coal is prevented and the coal is kept thoroughly mixed.

Among the objects of my invention are to provide a novel and improved stoker; to provide a stoker in which coal segregation is eliminated, and in which the coal rises evenly in the retort; to provide a novel form of retort cooperating with the feed screw of the Stoker to attain such a result; more particularly to provide a novel form and arrangement of retort and rib for equalizing the distribution of the coal upwardly in the retort; to provide means for overcoming the disadvantages and accomplishing the advantages hereinbefore referred to.

Other objects and advantages will appear from the following detailed description, taken in connection with the accompanying drawings, wherein:

Fig. l is a side elevation of a stoker embodying my invention.

Fig. 2 is a longitudinal vertical central section through the retort and adjacent section of the coal tube and associated parts.

Fig. 3 is a top plan view of the retort and adjacent section of the coal tube shown in Fig. 2.

Fig. 4 is a fragmentary longitudinal enlarged section on the line 4 4 of Fig. 2.

Fig. 5 is a section on the line 5--5 of Fig. 2.

While my invention resides in the combination, construction and arrangement of parts illustrated in the accompanying drawings, I have shown therein for illustrative purposes only, a preferred 2 embodiment, Iand wish it understood that the same is susceptible of modification and change without departing from the spirit and scope of the appended claims.

While I refer herein to crushed coal as the preferred fuel, I wish this term to include any other crushed or sufliciently fine and solid fuel that may be adapted for use in the Stoker shown and described herein.

My improved stoker comprises generally a hop per I, a blower 2, a coal tube 3 and a retort having a bowl 4. Rotatably mounted and extending longitudinally in the coal tube 3 is a screw conveyer 5 for conveying the crushed coal longitudinally along this tube from the hopper to the retort. A conduit 6 leads from the blower to a sheet metal casing 1 and from said c-asing air passes to the upper portion of the retort. The conduit 6 is preferably placed to one side of the coal tube as indicated in Fig. 3. The sheet metal casing I is positioned around the coal tube 3 and has its side walls spaced a sufficient distance from the sides of the coal tube to provide an air passageway on each side of the tube for conducting the air along the coal tube and introducing it into the retort on both sides of the coal tube. Extending longitudinally along the top of the coal tube within the casing 1, is a rib 8 whose upper edge is spaced a distance below the top of the casing to permit passage of air from passageway 8' to passageway 8 as well as longitudinally of the -coal tube, which air may also pass laterally through any space that may be provided between the bottom of the coal tube and the bottom. of the casing 1 if desired. These air spaces 8 and 8" (Fig. 3) jointly conduct the air into space 9 in the hollow sectional casing I0, hereinafter rcferred to as tuyres, positioned around the retort 4 (see Fig. 2) and extending a desired distance thereabove to provide the upper portion II of the retort. Suitably formed in this upper portion of the retort are openings I2 for conducting air under pressure into the firebed in the top part of the retort. Should it be desired that the firebed extend somewhat around the outside of the retort top additional openings I3 may be provided in the outer tuyre w-alls I0 for directing air under pressure into that portion of the rebed. v

A suitable door III is provided in the top of the hopper I and provided with suitable hinges (not shown) and a securing latch I5 to hold the lid or cover closed in an air tight condition if desired. A suitable motor I5 is provided adjacent the hopper for rotating the fan blades of the blower 3 2. Gearing 35 between the motor shaft and the feed screw provides a drive for the screw. As stated, the air conduit from the blower is outside of the coal tube. A suitable door l1 is provided for enabling access to the chamber within which the blower and motor are mounted.

In screw conveyor stokers known prior to my invention there has been an undesirable tendency of the feed screw to feed the coal excessively atA one side of the retort thus giving an uneven distribution of the coal upwardly inthe retort. Thisy greatly lessens the efficiency of the rebed and prevents the desired results of the stoker. In these old stokers heretoforeknown, the coal while being forced forwardly by the screw conveyor, has a tendency to climb up one side of the retort neck due to the rotation of the feed screw.

I have overcome the above-mentioned difficulties in part by placing a rib lll in the retort as shown in Figs. 2-5, which rib as shown extends downwardly at any angle along one side of the throat I9 of the retort andapproximately along thejuncture of the throat wall and the wall of the retort bowl. This rib, as will .be understood in Figs. 4 and 5, is gradually curved on its forward and rear sides tomerge intothe retort wall il` and the'wall i9 of the throat,.respectively, asshown at 2U and 2l in Fig.. 4. Asv seen in Fig. 5, the inner edge of the rib I8 extends inwardly a substantial distance with relation to the circumference or'wall 23` of the.` coal tube, and the rib extends'from the bottom 24 of the retort throat i9 tog-the upper side ofthe throat I9. A neck portion 22`of the retort is preferably'flared as shown at23ito form a graduallyenlarging entrance into the retort bowl from the coal'tube.

`Wth a feed screw as shown, rotating in a clockwise direction as viewed'in Fig. 5, the front end of the screw acts'to push the coal forwardly intov` the retort but also in a predominantly upward? direction on the left hand side only of the axis of the. screw. By placing rib I8 adjacent the juncture of the neck with the retort, the movement of; coal from thescrew is diverted in such a way that substantially equal amounts move towards both sides of the retort and the coal is liftedl by the action of the screw conveyor and rib into the-narrow angular channel which forms the retort throat'. In this waythe coalis not only evenly distributed in the retort, but also enters the retort with'a minimum of segregation. The neck and throat beingy flared as shown. in the drawings', this provides: room for the coal to rise and be distributed as referred to above, instead of `packing tightly. The. rib` holds back the coal so thatit may riseon the screw to the top of the screw and then be ejected' upwardly; The coal. is thus lifte'dup into the throat rather than pushed directly from the coal tube to rise too fast up the back side of the retort. This action of the coal in the throat continues until the coal is about levelr with the throat and then part of the coal lifts up through the throat and part is pushed over the heel 24 of the retort so that the coal rises uniformly in parallel strata to evenly distribute the coal in the retort and to rise to the top thereof' with a crownedsurface. This equalizes the distribution ofy the coal' and prevents segregation of the larger particles from the smaller particles which remain thoroughly mixed.

Formed centrally of the upper side of the coal tube 3 and spaced longitudinally within the casing 1 are two hollow members 25 and 26, the adjacent top side of the coal tube having a pair of slots 21 and 28 leading from the hollow interior of these members to the interior of the coal tube. Member 25 is formed in each of its lateral sides with openings 29 and 30 whereby air under pressure may be forced from the interior of the hollow casing 1 through slot 21 to the interior ofk the coal tube to create a pressure of air in the coal tube toward the retort. This tends to drive any smoke or gases of combustion coming from the retort in the opposite direction, that is, away from the hopper and back toward the retort, due to thefact that coal entering the coal tube from: the hopper isk tightly packed at the spike trap. Screwed into the top of member 26 is a pipe 3| leadingto theinterior of the hollow member 26' and communicating with the slot 28, the other end of the pipe generally communicating with the interior of the furnace or connected in any manner with the flue so as to take advantage of its suction, through pipe 3l, which will in turn create a focal discharge point at slot 28 for smoke or gases of combustion from the interior of the coal tube and lead the same into the furnace or flue to eventually pass out through the flue. The sides of the member 26 will preferably be closed by plugs 32 to prevent entry of air from the interior of the casing 1 to the interior of the pipe 3| so that the only passage into pipe 3l will be throughslot 28 and through the hollow interior of member 26. This construction forms an efficient` means for preventing the passage of smoke-or gases of combustion backwardly from the retort to the hopper.

Il claim:

1. A stoker comprising a hopper, a fuel tube, a screw conveyer in the tube, a retort having a heel wall, an outwardly flaring neck having a throat betweenvthe tube and the retort, and a rib positioned on the wall of the retort adjacent the throat and near the upwardly movable side of the screw, and extending upwardly along one side of the neck, said rib being formed with a gradual curve onits'twosides mergingv into the respective walls of: the neck and the retort and at its ends merging into the throat and heel walls respectively, and having. its edge extending inwardly and gradually increasingv from` bottom to top and extending inwardly a substantial distance at the top,.the screw when theneck is full of fuel lifting up part of the fuel into the throat at the rib side and pushing part of it along the bottom of the retort so thatthe fuel rises to the top of the retort with a crowned. surface in uniform upward distribution.

2. Astoker comprising a tube adapted to have fuel such as crushed coal forced therethrough, a rotatable screw for forcing said fuel through the tube, a retort at the outlet. end of the tube having a bowl and having a neck increasing in size from the diameter of, the tube to the lower interior of the bowl to form a throat at the junc-v ture ofthe neckv and bowl, and. means in the retort adjacent the throat thereof for obstructing free passage of the fuel into the retort bowl comprising a rib in the-retort beginning at the upper side of the throat and extending downwardly at an angle and approximately along one side of the throat at the juncture of the neck and the wall of the retort bowl, said rib being gradually curved on its forward and rear sides to merge into the wall of the retort.. bowl and the wall of theV neck respectively, and having its edgev extendingy inwardly and gradually increasing from bottom to top and extendinginwardly a substantial distance at the top and" stretching from the bottom of the retort bowl to the upper side of the throat.

3. A stoker comprising a tube adapted to have fuel such as crushed coal forced therethrough, a rotatable screw for forcing said fuel through the tube, a retort at the outlet end of the tube having a bowl and having a neck increasing in size from the diameter of the tube to the lower interior of the bowl to form a throat at the juncture of the neck and bowl, and means in the' retort adjacent the throat thereof for obstructing free passage of the fuel into the retort bowl comprising a rib extending from a point near the bottom of the throat upwardly along the side along which the screw surface rises and merging into the wall of the throat above the top of the screw,

said rib being gradually curved on its forward l and rear sides to merge into the retort wall and the wall of the throat respectively, and having its edge extending inwardly and gradually increasing from bottom to top and extending inwardly a substantial distance at the top.

4. A stoker comprising a fuel tube, a rotatable screw in the tube for forcing fuel such as crushed coal therethrough, a retort at the outlet end of the tube and having a bowl, a neck gradually enlarging in size from the inside diameter of the tube to the lower interior of the bowl to form a throat at the juncture of the neck and bowl, and means in the retort adjacent said throat for equalizing the distribution of fuel upwardly in the retort comprising a rib extending from the bottom of the throat diagonally upwardly and rearwardly of the throat to a point higher than and to one side of the screw, said rib having its longitudinal free-edge concave, said free-edge extending inwardly and gradually increasing from bottom to top and extending inwardly a substantial distance at the top and being gradually curved on its forward and rear sides to merge into the wall of the retort bowl and the wall of the neck respectively.

CORNELIUS QUIST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,787,671 Daniels Jan. 6, 1931 1,830,798 Leach Nov. 10, 1931 1,856,557 Hoke et al. May 3, 1932 2,004,813 Jones June 11, 1935 2,028,274 Cross et al Jan. 21, 1936 2,039,389 Buskard May 5, 1936 2,051,282 Yerges Aug. 18, 1936 2,118,104 Peck May 24, 1938 2,118,625 Scholl May 24, 1938 2,124,317 Schweickart July 19, 1938 2,272,438 Sourber Feb. 10, 1942

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