US2130329A - Overfeed stoker - Google Patents

Description

sept. 13,l 193s.

E. C. SAMMONS ovERFEEJ sToKER Filed May 6, 1935 22 ./N//EA/ TER bAMMoN Patented Sept. 13, 1938 UNITED sTATEs OVERFEED STOKER Edward C. Sammons, Portland, Oreg., assignor to Iron Fireman Manufacturing Company,

Portland, Oreg.

Application May 6, 1935, Serial No. 20,063

4 Claims.

This invention relates generally to coal burning stokers and particularly to stok'ers of the overfeed type.

The main object of this invention is to provide a new form of overfeed Stoker in which fuel is pneumatically fed from a remote storage point into a furnace and runiformly distributed over thev entire grate surface.

The second object is to construct the Stoker 10 so that it may be operated satisfactorily without regard to the kind of fuel being used, or the proportions of the various sizes and regardless of the moisture content of the coal and the rate of burnv ing, as well .as the particular type of furnace i with which the stoker is used.

The third object is to tilt the discharge nozzle in a vertical plane for the purpose of varying the trajectory of the fuel discharged therefrom in order to make it possible to deliver fuel to every part of the grate surface, lateral distribution being obtained mainly by the shape of the nozzle, while longitudinal distribution may be varied and controlled by the elevation of the nozzle itself, or by a rocking movement thereof, sep- 25 arately or in combination with variations in the velocity of the air stream.

The fourth object is to combine a mechanical fuel feeder which will discharge fuel at approximately the level at which it is to enter a fur- 30 nace, and to convey the discharged fuel pneumatically to said furnace.

I accomplish these objects in the manner set forth in the following specification as illustrated in the accompanying drawing, in which:

35 Fig. 1 is an elevation showing my device attached to a common form of furnace showing the furnace Walls in vertical section.

Fig. 2 is a vertical section through the coal feed mechanism.

40 Fig. 3 is a horizontal section taken along the line 3-3 in' Fig. 4 showing the tiltable burner nozzle in section.

Fig. 4 is a vertical section taken along the line 4-4 in Fig. 3.

45 Similar reference numerals refer to similar parts throughout the several views.

Referring in detail to the drawing, there is shown a common form of grate l0. A bridge walll extends across the rearward end of the o0 grate Ill, and a furnace front I2 is indicated, with a secondary air duct I3 projecting therethrough.

Air is supplied to the duct I3 by means of a fan I4 which is driven from. a motor I5,v which also rotates a crank shaft |6.

. l'n the front I2 is formed a tapering recess I1 into which projects the nozzle |8, which is mounted on the pivot bolts I9 on the arcuate portion 20 of the nozzle holder 2|, which is secured to the front I2 by means of the bolts 22.. The portion 20 forms a part of a cylinder and has 5 an opening 23 formed therein through which fuel can enter the nozzle I8. The nozzle holder 2| is provided with a flanged end 24, which is connected to a tube 25 forming a part of the pneumatic conveyor. It is not necessary that the nozzle I8 fit closely to the curved portion 20 since air is actually drawn into the nozzle I8 through the clearance space it is desirableto provide at this point.

On the side of the nozzle holder 2| is formed 1 5 a segment 26 provided with a series of holes 21 along an arc struck from the axis of the pivot bolts I9.

The nozzle I8 has secured thereto an arm 28 which may be adjustably positioned with regard to the segment 26 by means of the removable pin 29, which is preferably secured on a chain 30. The arm 28 is attached at one of the holes 3| in the connecting rod 32, which is connected to a crank 33 on the crank shaft IB. It will be 25 understood that the connecting pin 33A is made easily removable.

Air is supplied to the tube by means of a fan 34 which is operated-by a motor 35, which for the purpose of illustration, is shown as separate from the motor 36, which drives the fuel feeding worm 3l disposed within the worm casing 38, which is connected to a transfer box 39 interposed between the tube 25 and the fan 34. In the connecting pipe 40 between the fan 34 35 and the transfer box 39 is a damper 4|, which is rocked by means of an arm 42 and the connecting rod 43 from the crank 44, which is d isposed on the crank shaft I6. y

It is desirable to provide the fan 34 with a form 40 of control similar to that shown in the Banfield Patent No. 1,938,241, wherein the size of the fan inlet is controlled by the position of an operating lever which is referred to later as` a control lever 45. 45

It is desirable to provide the connections between the crank 44 and the damper 4| with some means for rendering the damper 4| inoperative, preferably by means of a loose pin at either end of the rod 43.

The operation of the Stoker is as follows:

Assuming'that the damper 4| is being rocked and that the nozzle I8 is also being rocked through the operation of the cranks 33 and 44,A which means that fuel is sprayed upon the grates I0, it is evident that not only is the trajectory of the fuel stream varied in a manner to cause it to discharge fuel along the entire length of the grates I0, but there is also maintained a surging action in the force of the conveying air which brings about a complete and uniform distribution of the fuel over the entire surface of the grates IU.

It is also desirable to provide the fan 34 with some form of damper control lever so that it will not only be possible to cause the air in the tube 25 to surge, but that the quantity of air flowing therethrough can also be varied, giving thereby an almost unlimited control in the delivery and distribution of the fuel by the nozzle I8.

It will, of course, be understood that the motor 36 and its intervening drive to the worm 31 in,- cludes a variable speed arrangement not shown. These are in common use in stokers of all kinds, and their purpose is to vary the rate of coal feedmg.

It is desirable to make the nozzle I8 removable and this may be accomplished in any convenient manner, preferably by means of a flange IBA. It is also desirable to provide openings 2 IA in the nozzle holder 2| through which air may be drawn for the protection of the nozzle itself.

I claim:

l. In an overfeed stoker for continuously feeding mixed ne coal and lump coal to a furnace grate, a laterally widened adjustable nozzle mounted above the grate level and pivoted so as to throw the lump coal on the grate through different trajectories depending upon the angle to which the nozzle is set, a motor driven Ian, a pneumatic conveyor tube delivering air from said fan to said nozzle, means for feeding mixed fine and lump coal laterally into the air stream in the pneumatic conveyor tube, thereby insuring the mixture of the coal with the air, means for altering at will the quantity of the air delivered by the fan, and automatic means for independently causing a regularly timed, constant increasev and decrease in the velocity of air delivered by the fan, so that the lumps will be distributed over the entire grate surface.

2. In an overfeed stoker for a grate furnace, a pneumatic fuel conveyor duct, a motor driven fan for discharging air through said fuel conveyor duct at a high velocity, a feed worm for feeding coal into the high velocity air stream whereby the rapidly moving air will convey the coal from the point of discharge of the feed worm, a nozzle at the end of the fuel conveyor duct for distributing the lump coal on the grate and for discharging the fines into the burning space above the grate, an air duct for delivering air to a space beneath the grate of the furnace, and a second motor driven fan for discharging the main air supply for combustion through said air duct, said motor driven fans being entirely independent of each other, whereby the rst fan may be of high speed, high velocity type and the second fan may be of low pressure type, and either air supply may be changed in volume without affecting the volume delivered by the other fan.

3. The device of claim 2 in which there is also provided means for altering at will the quantity of the air through the pneumatic conveyor duct so that the coal will be discharged on a chosen area of the grate.

4. In an overfeed stoker for a grate furnace, a conveyor tube for feeding air, fine coal, and lump coal to said furnace, a fan for discharging a continuous stream of air at high velocity through said tube, a nozzle at the end of said tube for discharging the lump coal to the grate and the fine coal into the burning space above the grate, and automatic means for constantly varying the velocity of the continuous high velocity air stream so that the fuel is constantly fed but due to the surging of the air stream the lumps of coal are delivered to the far side of the grate when the velocity is greatest and to the near side of the grate when the velocity of the air stream is least, whereby the constant change in the trajectories of the lumps of coal will tend to insure a uniform bed of coal on the grate.

EDWARD C. SAMIMONS.

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