US2178171A - Stoker control - Google Patents

Description

Oct. 31, 1939. HELLMANN ET AL 2.178.171

I STOKER CONTROL Filed 001:. 27, 1957 3 Sheets-Sheet l Oct 1939. F. A. HELLMANN El AL 2.178.171

STOKER CONTROL Filed Oct. 27, 1937 s Sheets-Sheet 2 MIM flatly R 5721160.???

may x W W 3 1939. F. A. HELLMANN ET AL 2,178,171

STOKER CONTROL Filed Oct. 27, 1937 3 Sheets-Sheet 3 mwwm wound/3 Patented Oct. 31, 1939 UNITED STATES:

PATENT OFFICE Frederick A. Hellmann,

Chattanooga, Tenn., and

Harry R. Statham, F 8118 Church, Va.

Application October 27, 1937, Serial No. 171,376

15 Claims.

a furnace or boiler so that the amount of coal and amount of air fed to the furnace are synchronized with each other and in accordance with the amount of unburned coal in the combustion chamber of the furnace, to thus provide a balanced ration of coal and air.

Another object of the invention is, to provide a control for a coal stoker where installed in a boiler or furnace, or as an attachment thereto,

whereby the stoker is operated entirely automatically andin conjunction with ,the usual ther-.

inostatic or other controls of the stoker.

Another object of the invention is to correct fire depth so that the proper amount of air and coal will be fed into the combustion chamber and at all times.

Still another object of the invention is the provision of an automatic damper control installed on the intake of the fan.

A further object of the invention is the provision of an automatic damper the operation of which is controlled by the condition in the fire box of the furnace.

Other objects will appear hereinaiter throughout the specification. r

In the drawingse Figure 1 is a side elevation of a furnace, a Stoker having the improved control attached thereto, the furnace being shown in section, and

the coal and air conduits inpartial section;

Figure 2 is a front elevation of the adapter plate and damper operating assembly, certain I parts being shown in section; Figure 3 is a top plan. view of the shown in Figure 2; I

Figure 4 is aside elevation of the structure shown in Figure 2,, s viewed from the left of said figure; I

Figure 5 is a side elevation of the structure shown in, Figure 2, as viewed from the right of said figure;

Figure 6 is a front elevation of a modified form of a damper control switch;

V c Figure 7 is a side elevation 'of the structure shown in Figure 6 as viewedfrom the right hand side, and

structure Figure 8 is a wiring diagram ofthe electric controls of the motors for operating the coal feeding mechanism and air. blower mechanism.

In the drawings, the numeral l designates'a furnace, although any other suitable heating apparatus may be used, and 2 indicates a stoker of any conventional type. It is common practice to provide such stokers with a coal feeding i conduit '3 having the usual. feed screw, not shown, located therein and an air conduit 4 located therebelow, said conduits being separated by a horizontal partition 3', as shown in Fig ure 1. The numeral 5 indicates a coal hopper, 0 the lower portion of which is provided with an aperture leading into the conduit 3.

The fan blower is indicated by the numeral 6. Such fan blowers are usually provided with a manually controlled damper, to control the en- 15 trance of air into the blower. The outlet i connects with a pipe 8, the opposite end of which opens into the air conduit 4. r

In the illustrative example of one application of this invention, as shown in the drawings, the 20 "usual side plate which supports a manually operated damper of the fan-blower, is removed, and there is attached in place thereof, an adapter plate 9, which is bolted to the casing by the conventional bolts [0. provided with an aperture ll, forming an air intake to the eye of the blower. Mounted on the plate in alignment with the aperture] II, is a thimble l2, forming an air inlet conduit, the diameter of which is substantially the same 30 diameter as the aperture II.

Mounted on shafts l3 and I4, is a damper ll. Said shafts extend through apertures or bearings inthe thimble l2.

Rigidly mounted on the adapter plate is a 35 float chamber l6 and an hermetically sealed chamber i1; said chambers are connected to each other by means of a pipe I8 which passes through-the lower extremities of the chambers. The chambers are partially filled, preferably with 40 a non-vaporizing liquid i9, such as oil, or a non-inflammable liquid may be used instead of oil. Within the chamber i6 is' a float 20, having a a stem 2| and a right-angled portion 22, which latter PIOjEOtSEfill'Ollghan aperture 23 o! a t crank 24. is rigidly attached to the shaft l3 so that asthe floatrises and falls, the damper i5 is turned from the fully closed posi-. tibn' shown in Figures 1 and 2, and in dotted lines in Figure 4, to the inclined position indicated in dotted lines in Figure 3, or to the fully, 'open' or horizontal position shown in. dotted lines in Figure 4.

An air pressure pipe 25 extends into the hermetically sealed chamber I! so that its open end The adapter plate is 25' 26 is at all times in. communication with the air space above the liquid l9. The opposite, end

of the pipe 25 communicates with the interior oi. the pipe 8, but this end may be connected to the air conduit 4, instead of the pipe 8, as shown. In either instance, the air space above the liquid in the hermetically sealed chamber I1 is exposed to pressure conditions within the pipe 8, and conduit 4. Such. pressure conditions are affected by the rate burning, and the amount of coal within the furnace I. The coal feed conduit 3 and air conduit 4 are connected, as is the usual practice, so as to feed coal and air to the retort ;21, which retort is provided with the usual tuyeres, not shown.

Referring now particularly to Figure 5, there is rigidly mounted on the shaft |4, so as to be rotated thereby, when the damper |5 is rotated, a disk 28. Foxed on the disk are spring clips 38 and held by these clips is a single pole, double throw, mercury tube switch 3|, controlling the operation of the two-speed motor 32, which drives the fan blower 6. The numeral 33 indicates a pivot having an arm 34 adapted to pivot thereabout. spring clips 35, which rigidly hold the single throw mercury switch 36, which latter controls the coal feed screw driving motor 31. The opposite end of the arm 34 may be adjustably positioned and held by the rack 38, mounted on the disk 28. By this means the proper adjustment may be effected for causing the coal feed motor 31 to operate under different conditions of use, and in accordance with the size of the furnace I, the grade of coal being used, furnace draft conditions, etc.

Referring to Figure 8, the numerals 39 and 40 are line connections from a source of current. The wire 38 is connected to the left end of the mercury tube switch 3| by means of a wire 4|, and to the right end of switch 36 by wire 42. The wire 44 connects the left end of switch 3| to a terminal 45 of the two-speed fan motor. Wire 46 connects the right end of switch 3| to terminal 41 of this motor. Wire 48 connects the right end of mercury tube switch 36 to terminal 43 of the coal feed motor. Line connection 40 is connected to terminal 50 of said motor by wire 5|, and is connected to terminal 52 of the fan motor by wire 53. r

In place of the single pole, double throw, mercury switch 3|, shown in Figures 1 to 5, the speedof the fan motor 32 (which motor would be of the single speed variety), may be controlled by a rheostat, such as the rheostat shown in Figures 6 and '1, wherein is shown the disk 28' rigidly mounted on the shaft l4, and turnable therewith. The shaft I4 is rotated by damper I! by means of the shaft l3, in the same manner as described in connection with the form shownin Figures 1 to 5.

Mounted on the thimble I2 is an insulated support 54 having a plurality of. contacts 55', having-the usual resistances and to which are connected wires 58'. The terminal 51' is mounted so as to extend through disk 28'. Attached to the terminal 51 on opposite side of the disk is a. wiping contact 58'. As the'damper l5 is rotated, due to different conditions of pressure in conduit 8, the disk 28! is rotated and as this takes place, the wiping contact 58' moves into successive engagement with the several contacts 55', thus changing the speed of the fan motor and increasing or decreasing the amount of air forwd into conduit 4 and retort 21. All of the The arm 34 has attached thereto wires 56 connect to one terminal, and wire 53' connects to the other terminal of a fan motor which, in the present instance, is of the ordinary type. The bundle of wires leading to the several contacts is indicated by the numeral 68'.

Operation Assuming that the stoker has been shut down, with the damper in a closed or substantially closed position; in this position the disk is, as shown in Figures 1, 2 and 8, with the mercury in tube 3| at the right end of the tube so as to allow current to pass from Wire 42 to wire 46, and thence to the lower speed terminal 41 of the fan motor. As will be seen by referring to Figure 5, the terminals within the tube 36, which are connected to wires 43 and 48, are connected by the mercury within the tube so that the coal feed motor is thereby operated. In this position, the fan motor is operated at low speed, and the coal feed motor is running, to thereby feed coal into the retort. As the internal air pressure within the conduit 4 is built up, due to the increasing depth of the fire bed as the coal is fed to the same, and the consequent inability of the air to escape only slowly through the retort, air pressure increases in conduit 4 and pipe 8, as well as in the air space within the chamber ll, because of the connecting pipe 25. Increased air pressure in chamber |1 forces the fluid l9 through pipe |8 into float chamber l6, thereby raising the float 20 which, by means of the crank 24, rotates shafts l3 and I4 and the damper I5.

It is to be understood that with the damper closed, and the fan rotating at slow speed, some air is being forced continuously into conduit 4 and retort 21, due to the fact that some air enters around the periphery of the damper |5.

The opening of the damper l5 permits the entrance of additional air to be sucked into the fan chamber, whereupon such additional air is forced through pipe 8 and conduit 4, and into the retort 21, where it passes through the tuyre gates.

' As the damper |5 continues to open, the disk 28 rotates in a counterclockwise direction (see Figure 5). Such rotation of the disk 28 continues until the mercury within the tube 3| moves from the right end of said tube to the opposite or left end thereof, thereby completing contact between the terminals of tube 3| which are connected to the two wires 4| and 44, to thereby switch the fan motor from low to high speed.

Simultaneously, the rotation of the disk 28 will cause the tube 38 to move to a position (according to its position of adjustment) where its left end becomes lower than its right end, whereupon the mercury leaves the right end of the tube, thereby breaking the connection between the wires 43 and 48, and stopping the coal feed motor. In this position of the disk, the coal feed motor has stopped, but the fan motor continues to operate at high speed. This operation continues until such time as the fuel bed is burned down to a point which allows air to pass more freely through the fire bed, whereupon the pressure gradually drops in conduit 4 and pipe I. The drop in pressure allows the damper to move back, or in a reverse direction, toward the closed position, the disk moving in a clockwise direction. As the disk moves in a clockwise direction, the lower tube rotates to such position that its right end becomes lower than the left end, whereupon the mercury within tube 36 moves back so as to again connect the wires 43 and 48, and thereby tion of said motor in accordance with the amount starting the coal feed motor operating again, and the tube 3| again assumes the position shown in Figure 5 to thereby again switch the fan motor to its low speed of rotation.

By the abovedescribed operation, it will be un derstoodthat both the feeding of air and .coal is controlled by the depth of the fuel bed and the control of each is synchronized with the other,

thus insuring a balanced ration of feed for the furnace. v

The control shown in Figures 6 and 7 operate coal and air substantially the same as that shown in other figures, except that the'fan motor is gradually accelerated, or decelerated, according to the direction-in which the disk 28" is moved. In the position-shown in Figure-f7, the motor isrunningj at low speed. Itsspeedis acbelerated asthel disk rotates in a counterclockwise' direction,;and as pressure is being -buiIt -upflinF-Qtheconduit-J until it reaches its speed, gabout -the'; time when the damper reaches its openpo'sitmn-r'J c intoacombustion-chamber including a damper,

Also, the coal motor, according to the position of.

adjustment to which the coal motor thermostat-.

' switch 36' has been set, will be cut outof circuit during the rotation of disk 28. Subsequently, as. r the coal in the combustion chamber burns shown, a condition of gradually reduced pressure in conduit results, and the parts slowly return to the position shown in Figures ,6 and 7, with the coal motor again operating and theian motor running at reduced speed, with thedamper IS in" closed or substantially closed position. The parts remain in this position until there is again in, conduit La condition of higher pressure whereupon the operation is repeated.

The invention is not limited to the construction shown and described, such being merely one application of the invention. ,We desire to be limited only to the extent indicated by the appended claims. We'claim: 1

1. In a coal stoker of the character wherein the stoker is provided with means for feeding coal and air into acombustion chamber includ- 7- ing a damper, acoal passageway and an air j ipassageway; the combination with such. means,'

of damper"control meansfoperatively connected to said air passasewam and electrically operated switch means adapted to be actuated by said damper controlmeans for-controlling the operationlofisaid coal feeding and air feeding means; yand said damper by means of said damper control means according to theamount of unburned iuel within .conibustior'rchainber,- said first named means additionally'f ncludins a motor for feeding f 00111 n fa sepaifittegmotor for feeding gain said last;named-'mot'or havingimeansffor yaryingthe amou t or airfed tu sle, (combustion "chamber synchmmm hhel movements 1 m mpen I V,

. 2. an a-coalstoker, oI -tlicfoh 7$ it wh r i oi the 'stoker is provided "with means" {for leading-9f 1 coal and air into a combustionchamber; the come;

theiliquid in saidlast-vnamed chamber, and its bination with such means, of automaticmeans operativelyconnected to'saidi'firstenamed means c M s and-switch means electrically connected to both for controlling the operationroi' said coalv feeding may regulate said damper and control 'the opera r and air into a combustion chamber; means operatively connected to said first-named means for controlling the amount of airaccording to the amount of unburned fuel within said combustion chamber, said control means including a damper and electrical switch means operated thereby, .and electrical connections from said switch means to said means first named, said 'first named means additionally including a motor for feeding coal'and'a separate motor for feeding said last namedmotor having means for Lvaryirig the amount of air-fed to said combustion. v

chamber insynchronismwith the movements of Zamfla ne .-L i. k 4. QZ rassoQatiDn with a coal feeding stoker, which comprises for feeding coal and air an .electricmotorllor pperating said air feeding means-and a second"riibtnr ifor'operating said coal feeding means; mean pperanveiy connected to saidjmotors and aamperaanag ngseparate electric switches for said motors-am ectrical connections thereto, and a niechani ection to said damper for controlling the amoimtfotgiair and coal according-to theamount-golunbiarnbdal fuel within sai combustionchamber. I:

5; In a coalstokerof the character other? the stokeris provided with motor means iorfeed,

.ing coal and air-into a combustion chamber and including a blower driven by said motor means, a damper for said blower, and air and-coal passageways to said combustion chamber; the; combination with such means, of i switch means actuated by said damper and electrlcally connected to said motor means, and pressure means connected. tosaid damper for operating said damper, said pressure means being actuated by difi'erences ofpressure 1 within said air passageway, said motor means including [a multi-speed motor {foi' driving said blower to varythe amount of air fed to said combustion chamber in syn-' chronism with the movements of said damper. I

'6. In a coal stoker ofv the character wherein the stoker is provided with coal feed means, a

motor for driving'said coal feed means, an air blower, a second motor for operating said air blower, :a hopper for coal, a retort, a coal passageway from said hopper to said retort, an air passageway from said blower to said retort, a

damper for controlling the entrance of air to ."J

said blower; the combination with .said stoker, or afioat chamber, a float in said float chamber,-

means connecting said float to said 'damper', an

hermetically sealed chamber, a conduit from said hermetically sealed chamber to said float chamber, liquid in saidchambers, a pressure pipe in said hermetically sealed chamber, and having one of its ends located above the level of other. end connected into said air passageway,.

of said motors and operatively connected to said and actuated thereby to control said coal feed motor and said air blower motor andautomatioally thereby the amount of coal and air fed to's'aid-retort.

'- 7. In-ia coal stoker of the character wherein the' stoker is provided with coal feed means, a

afor drivingsaid coal feed means, an air blcwer asecond-motor for operatingsaid air blower, a hopper for coal, a retort, a coal passageway from said hopper to said retort, an air passageway from said blower to said retort, a damper for controlling the entrance of air to said blower; the combination with said stoker, of a float chamber, a float in said float chamber, means connecting said float to said damper, an hermetically sealed chamber, a conduit from said hermetically sealed chamber to said float chamber, liquid in said chambers, a pressure pipe located in said hermetically sealed chamber, and having one of its ends located above the level of the liquidin said last-named chamber, and having its other end connected into said air passageway, a rotatable disk operatively connected to said damper, a plurality of mercury tube switches mounted on said disk, said switches being electrically connected to said coal feeding motor and said air blower motor to automatically thereby control the amount ofcoal and air feed to said retort.

8. In a coal stoker of the character wherein the stoker is provided with coal feed means, a motor for driving said coal feed means, an air blower, a second motor for operating said air blower, a hopper for coal, a retort, a coal passageway from said hopper to said retort, an air passageway from said blower to said retort, a damper for controlling the entrance of air to said blower; the combination with said stoker, of a float chamber, a float in said float chamber, means connecting said float to said damper, an hermetically sealed chamber, a conduit from said hermetically sealed chamber to said float chamber, liquid in said chambers, a pressure pipe located in said hermetically sealed chamber having one of its ends located above the level of the liquid in said last-named chamber, and having its other end connected into said air passageway, a rotatable disk operatively connected to said damper, a

plurality of mercury tube switches mounted on said disk, said switches being electrically connected to said coal feeding motor and said air blower motor to automatically thereby control the amount of coal and air fed to said retort, said blower motor having a plurality of speeds and one of said mercury tubes having two sets of contacts connected to said blower motor, one set of contacts being opened and the other set being bination with such means of means for auto-,

matically operating said damper, and including pressure operated means actuated by differences of pressure within said air passageway, to thereby actuate said damper, and a plurality of electrical switch means operated by said damper and electrically connected to each of said motor means to thereby control the operation of the same.

10. In a coal stoker of the character wherein the stoker is provided with motor means for feeding coal and separate motor means for feeding air into a combustion chamber, and including a blower driven by said motor means, a blower damper and air and coal passageways; the combination with such means, of means for automatically operating said damper, and including pressure operated means actuated by difierences.

of pressure within said air passageway, to thereby actuate said damper, and a plurality of electrical switch means operated by said damper, and electrically connected to each of said motor means to thereby control the operation of the same, one of said switch means including a rheostat switch connected to said fan blower motor.

11. In a coal stoker of the character wherein the stoker is provided with motor means for feeding coal and air into a combustion chamber and including a blower driven by said motor means, a damper on said blower, and air and coal passageways to said combustion chamber; the combination with such means, of pressure means for operating said damper, said pressure means being actuated by diiferences of pressure within said air passageway, said motor. means comprising a two-speed motor for feeding air, and a single speed motor for feeding coal, and means actuated by said pressure means for controlling the operation of both motors.

12. In a coal stoker of the character wherein the stoker is provided with motor means for feeding coal and air into a combustion chamber, and including a blower driven by said motor means, a damper on said blower, and air and coal passageways to said combustion chamber; the combination with such means, of pressure means for operating said damper, said pressure means being actuated by diiferences of pressure within said air passageway, said motor means including a motor for feeding air, and a separate motor for feeding coal, and mercury tube switch means actuated by said pressure means for controlling said motors.

13. In a coal stoker of the character wherein the stoker is provided with motor means for feed ing coal and air into a combustion chamber, and including a blower driven by said motor means, a damper on said blower having supporting means therefore, and air and coal passageways to said combustion chamber; the combination with such structure, of pressure means for operating said damper, said pressure means being actuated by diiferences of pressure within said air passageway, and switch means mounted on said damper supporting means for controlling said motor means, said switch means having means for controlling the speed of said blower at high and low speeds, and said switch means including means for stopping the feeding or coal when the .blower is operating at high speed.

14. In a coal stoker of the character wherein the stoker is provided with motor means for feeding coal and air into a. combustion chamber, and including a blower driven by said motor means, a damper on said blower, and air andcoal passageways to said combustion chamber; the combination with such means, of pressure means for operating said damper, said pressure means being actuated by difierences of pressure within said air passageway, a rotatable support, rotatable by said damper, and mercury tube switch means mounted on said support, said switch means havincluding a blower driven by said motor means,

air and coal passageways, and damper means for said blower; the combination with such means, of pressure means for operating said damper the speed of said blower at high and low speeds,

and said switch means including means for stopping the feeding of coal when the blower is operating at high speed.

FREDERICK A. HELLMANN. HARRY R. STATHAM.

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