US1997833A - Damper control for stokers - Google Patents

Description

April 16, 1935. J. ROLAND i DAMPER CONTROL FOR STOKERS Filed March 2, 1933 2 Sheets-Sheet 1 f. ---nun IN VEN TOR ATTORNEYS.

April 16, 1935. J, ROLAND l 1,997,833

DAMPER CONTROL FOR STOKERS Filed March 2, 1935 Sheets-Sheet 2 INVENTOR Jaw/V KOL fir/v0.

ATTORNEYI Patented Apr. 16, 1935 UNITED STATES PATENT OFFICE Schwuler-Cummins Company,

Ind., a corporation Indianapolis,

Application March 2, 1933, Serial No. 659,321 3 Claims. (Cl. 137-153) This invention relates to an automatic damper control,` particularly adapted for use with furnace stokers and the like.

In connection with the usual furnace stokers there is a motor-drivenfan which produces a forced draft through an air conduit leading to the iire pot, which fan usually operates during all or a portion of the time that the fuel is being mechanicallyfed therein. Also during non-feeding of the fuel there is a natural draft through such conduit which facilitates the burning of the fuel. As a result thereof, the fuel may be too rapidly consumed under certain conditions. During mild temperatures when the fuel is intermittently fed during short periods of time, so as to maintain a low or kindling fire in the me pot, an excessive amount of air is forced therethrough, which quickly consumes the fuel. In addition thereto, and during the non-feeding periods, the natural draft continues to consume the fuel more rapidly than required. This sometimes results in the fire being burned out between the time of the last feeding and the next feeding of fuel. 'Ihe furnace then becomes dead and must be rekindIed in addition to quantities of unburned fuel being fed into the i'lre pot.

It is the object of this invention to automatically control both the forced and natural drafts in accordance with heat requirements and the character of the fuel bed in the fire p'ot. The ultimate object ofthe automatic control is principally to retard consumption of the fuel during non-feeding periods to maintain a kindling or pilot flre in the furnace overr a longer period of time when there is no heat requirement. 'I'his is accomplished by not only cutting down the forced draft during the feeding for kindling maintenance, but by closing the natural draft during the intervals between feedings.

The above is accomplished by' providing a butterfly type of valve in the air conduit which normally is in closed position, but which may be moved to open position or partially open posi--l tion by static pressure created in the conduit. Thus, during substantial periods of heat requirement when the fuel is continuously fed to the fire box and thereby becomes packed therein, and it is desirable to produce the maximum forced draft, the current of air delivered by -the fan strikes the' compact bed of fuel and thereby raises the static pressure in the conduit, resulting in the valve being opened so as to permit the maximum air ow to the fuel. When there is little or no fuel being fed into the fire bed, the air passage through the bed is more open so that the current of air freely passes therethrough, reducing the static pressure in the conduit, which results in the valve being wholly or partially closed to cut off the air supply and, therefore, prevent the fuel from being too rapidly burned.

This is accomplished by providing a pressureactuated member connected with the valve and mounted on the air conduit for moving said valve to its 'maximum open position when the pressure thereon is increased and permitting said valve to approach closed position as the pressure is decreased.

Ihe full nature of the invention will be understood from the accompanying drawings and the following description and claims:

In the drawings Fig. 1 is a diagrammatic illustration of a furnace showing a fire pot and draft conduit with a valve control mounted thereon. Fig. 2 is a sectional view through a portion of the draftfconduit and valve control showing the valve in open position. Fig. 3 is the same as Fig. 2 with parts removed, showing the valve in closed position. Fig. 4 is a section on the line 4-4 of Fig. 2. Fig. 5 is a central vertical section through a modified form of valve control shown in open and fully operative position. Fig. 6 is a section taken on the line 6-6 of Fig. 5, with the parts in partially operative position.

In the drawings there is illustrated a furnace I having the usual fire pot II containing a bed of fuel I2, the fuel beingforced therein by an underv feed stoker of the usual type from the fuel hopper I3. The fuel feed I3ay and the forced draft are operated from the usual electric motor I4. Driven by the motor I4 there' is a centrifugal fan I contained within a fan housing I6 connected with an air conduit I1 leading to the re pot I I for delivering thereto air by forced or natural draft.

Mounted within the air conduit I1 there is a draft control including a frame I8 adapted to extend into and lie adjacent the walls of the conduit. Pivotally mounted on said frame there is a. valve I9 formed of a plate of substantially the form as the cross sectional area of the conduit, said plate being provided with slightly bent end portions and-2l. On one side of said plate therel is a dependent counterweight 22, and on the other side thereof there is a bracket 23 to r which a control rod 21 is loosely connected. The frame I8 is secured to and supported by a housing 28. Said housing is mounted over an opening 29 `formed in the top of the conduit, through which opening the frame I8 and rod 28 extend.

The housing is provided with a saddle 30 by which it is secured over the conduit in fixed relation. to the slowest possible burning of the fuel, where- Closing the lower end of the housing 28 and .by the danger of its being consumed and the fire: sealed therein there is an upwardly-extending extinguished between operations of the stoker will thimble 3| which acts as a guide for the rod 21, be eliminated.

5 the walls of the thimble being spaced from the By slightly bending the ends of the valve plate, 5

walls of the housing. The rod 21 extends freely indicated at 20 and 2|, the automatic action of through an aperture 32 in the dome-shaped top the valve is facilitated. This is also assisted of the thimble to permit air to freely pass through through the medium of the counterbalance weight the top thereof. Mounted over and about the 22. Furthermore, a stop member, such as is inthimble there is a plunger or cup 33 provided with dicated at 43, may be mounted upon the frame lo a dome 34 adapted to'flt over the dome-like top I8 to limit the swinging action of the valve to of the thimble 3|. The sides of the cup extend open position, its swinging action to closed posiwell down between the thimble and housing and tion being limited by engagement with the bottom the edge of the open bottom thereof is immersed and" top of the frame. 4

in a bath of oil, indicated at 35. The oil level Pivotally mounted over the top of the housing l5 which at all times extends above the bottom of 28 there isv an adjusting rod 4| having a handle the cup is maintained by the filler inlet 36. The 42 movable to variouspositions in respect to a cup 33 is provided with a vent opening 31 in the plate v43. Said rod is provided with a U-shaped upper portion thereof. The rod 21 extends end 44 which, when moved'` to its upper position,

through the top of said cup and is sealed thereto as illustrated in Fig. 42, will limit the downward 2o so as to be air tight. Said rod also extends freely movement of the rod 21 and,` therefore, prevent through an aperture 33 in the top of the housing the full closing of the valve. When/it/is'" moved and is provided on the upper free end thereof with to the extreme lower posit shown in Fig. 3, an indicator button 39. it will permit the op of the rod and com- 25 In operation, assuming that the fuel I2 is tightplete clos' gpfie valve. g5 ly packed in the fire pot and is being contin- Irl/tlrlodined form of vulve control mueuously fed therein under heat requirement con.- rated in Figs. 5'an'd 6, the valve III is provided ditions, the resistance to the passage of r with a slightly bent end |2| and a bracket |23 is through the fuel will create a relatively high static connected to the plunger or disk |33 by a control 3p pressure in the conduit I1. This will cause air. rod |21. The plunger |33 conforms substantially 3p to be forced into the thimble 3| and through the to the cross sectional area of the housing |23 aperture 32 into the cup 33, creating the same so as to move upwardly therein under air prespressure therein. The air not being able to essure and downwardly by gravity. Rotatably cape from the cup by reason of the oil seal, will mounted over the closed upper end of thev housing 35 tend to raise said cup in order to increase the |28l there is arotatably adjustable control cap |33 35 capacity thereof. Upon the cup being forced uphaving downwardly extending flanges |44 closely wardly by the air pressure, the stem 21 will be fitting thel upper side walls of the housing and carried therewith to raise that portion of the provided with aplurality of apertures I4| adapted valve to which it is connected, whereupon the to be moved in and out of registry with the apervalve will be moved toward or into its open poitures |42 formed in the housing. Secured on thel 40 s itlon, as illustrated in Figs. 2 and4. Thus, the outer side of the housing, there is a corrugated draft conduit I1 will be free of obstruction by the plate |43 against which anl adjustable hand lever valve. |44 engages for setting a control adjustment rod When the heat requirement decreases and rel- |45 which extends diametrically through the 45 atively little fuel is fed or packed into the fuel housing so as to be rotatably supported therein. 45 bed, there will be less resistance to the flow of Said control rod is provided with a U-shaped air through the fuel so that the static pressure bend |46 intermediate the sides of the housing in the conduit will drop and no longer tend to and passing about the rod |21. raise-the cup 33 and open the valve. The drop This type of controloperates-upon the same 50 in static pressure will permit the cup 33 to drop principle and for the same purpose as the type 50 by gravity so as to tend to close the valve. The previously described, excepting that the resistposition of the valve will .thereupon be balanced ance to its upward or opening movement may. be

at 0r near closed position, depending upon variavaried and adjusted by rotation of the cap |33 tion of the static pressure, which in turn will deto vary the extent of registry of the apertures pend on the variationof resistance -to the pas- |4| and |42, when geld apertures ere closed, 55

Sage 0f air through the fuel bed. .assuming there can be no air leakage there- Thus 1t Win' be undelStOOd that the quantity 0f through, the valve is inoperative, since the static all' driven through the f llel bed by the fan, Or fan pressure will be 'the same on both gldeg 0f the capacity, will be automatically maintained subplunger |33, However, with the apertures open stantially constant irrespective of variations in or partially opemeo. that )he muy escupe 60 the resistance t0 its passage Created by the packtherethrough, there will be a differential pressure, ing of the fuel, since a balance is maintained bewhereby the pressure on the underside of the tweenthe resistance of the fan and fuel, i. e., plunger may be greater than on the upper side as the fuel resistance increases, the valve reso4 as to raise the plunger and open the valve.

sistance decreases and vice versa. However, when the static pressure in the con- 65 vWhen no heat is required and the/Stoker is dull; l1 drops to atmospheric pressure, then there merely operated to maintain a kindling or pilot will be en equelizlng of pressure such es to perre, the passage of air will be so'freely permitted mlt the plunger to drop by gravity and close the through the fuel bed as to eliminate 4any static valve By adjusting the registry 0f the ape!- pressure in the conduit so that the cup 33 will tures, a greater or less Statie pressure lmuy be 70 drop to closed position, as Shown in Fig. 3, required to open the valve, as will be.. clearly whereupon the valve will be completely closed understood from the ebove l and substantially cut olf both the forced draft By moving the rod |45 about its pivotalmountand natural draft. This substantial elimination ing, the U-shaped portion |43 maybe raised or of either forced or natural draft will be conducive lowered into or outv of the way ofthe plunger.

Thus, by moving it to its extreme upper position, Y

the plunger will be restricted in its downward movement so that the valve will at no time be entirely closed, but remain partially open. The extent of the closing of the valve may, therefore, be varied, depending upon the position of the rod, its lower position being such as topermit the full drop of the plunger and the full closing of the valve.

'Ihe invention claimed is:

1. A draft regulator comprising a butterfly valve pivotally mounted within a conduit for partially closing said conduit when swung to one position and substantially opening said conduit when swung to another position, a housing open to said conduit, a plunger iloating in said housing andv operatively connected with said valve,4

said plunger and valve being so positioned with respect to said conduit as to cause said plunger to be lifted by an increase in pressure in said conduit to move said valve to open position and lowered by gravity upon a decrease in said pressure to move said valve to partially closed position, and adjustable means for effecting a resistance to the movement of said plunger and valve toward open position.

2. A draft regulator comprising a butterfly valve pivotally mounted withinV a conduit for partially closing said conduit when swung to one position and substantially opening said conduit when swung to another position, a housing open to saidconduit, a plunger oating in said housing and operatively connected with said valve,

said plunger and valve being so positioned with respect to said conduit as to cause said plunger to be lifted by an increase in pressure in said conduit to move said valve to open position and lowered by gravity upon a decrease in said pressure to move said valve to partially closed position, said housing having an aperture therein, and a control cap for varying the area of said opening to control the resistance to the lifting movement of said plunger.

3. A draft regulator for a draft conduit comprising a butterfly valve pivotally mounted intermediate its ends within said conduit so as to partially close said conduit when moved to a vertical position and open the passage thereto when moved to a substantially horizontal position, a housing in communication with said conduit adjacent said valve, a plunger reciprocable within said housing, a connecting rod connecting said plunger and valve and so arranged with respect thereto as to swing said valve to substantially a horizontal position when said plunger is forced upwardly by pressure in the conduit and permit said valve to swing to substantially a verjtical position by gravity upon decrease in pressure, said housing having an aperture therein, and a control cap pivotally mounted on said housing for varying the effective area of the aperture therein for varying the effective pressure upon said plunger exerted from within said conduit and housing.

. JOHN ROLAND.

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