US1355157A - Furnace control - Google Patents

Description

E. McLEAN.

FURNACE CONTROL.

APPLICATION FILED JAN. 7. 191B.

Patented Oct. 12,1920.

5 ?HEETS-SHEET I.

1 INVENTOR 21 ATTORNEY McLEANL FURNACE CONTROL.

I APPLICATION FILED JAN- 7| I918. 1,355,157.

Patented on 12, 1920.

s SHEETS-SHEET 2.

lllllllll INVENTOR W 76040 7 Br I mom/firs E. McL EAN.

. FURNACE CONTROL.

APPLICATION 'FILED JAN-7,1918.

1,355,157. mm Oct. 12,1920.

5 SHEETSSHEET 3.

uwmme A rim/Er 1 E. McLEAN.

FURNACE CONTROL.

APPLICATION man JAN-7.1918.

Patented Oct. 12, 1920.

5 SHEETS-SHEET 4.

INVENTOR 360W E. McLEAN.

FURNACE CONTROL.

APPLICATION FILED JAN-7.19M}.

Patented Oct. 12, 1920.

5 FHEETS-SHEET 5- INVENTOI? C06. W

' A noimsrl wll aln UNITED STATES EMBURY McLEAN, OF BROOKLYN, NEW YORK.

FURNACE CONTROL.

To all whom it may concern:

Be it known that I, EMBURY MoLmN, a citizen of the United States, and a resident of New York city, borou h of Brooklyn, in the county of Kings and tate of New York, have invented certain new and useful Improvements in Furnace Control, of which the following is a specification.

My invention relates to new and useful improvements in furnace control and more particularly relates to a method and means for automatically controlling the operation of a fuel feeding means for feeding fuel to the furnace of a boiler. The invention contemplates an improved method and means for automatically varying the operation of the fuel feeding means to vary the rate or quantity of feed of the fuel to the furnace, so as to maintain the proper supply of fuel,

for example in the case of an'automaticstoker the proper thickness or resistance of the fuel bed, in accordance with the amount of draft supplied, orin accordance with the thickness or resistanceof the fuel bed.

The invention is particularly adapted for use in connection with a boiler furnace having an automatic stoker, and which is supplied with draft from a blower or other air impelling means, the speed of which may vary or remain constant, and Iparticularly contemplate the application of' the invention.

to aboiler furnace furnished with a blower delivering air to the ash pit beneath the fire bed, and in which means, such for example as disclosed in my Letters Patent No. 1,071,771, dated September 2, 1913, is provided for maintaining constant the fire box pressure for varying rates of combustion- .in accordance with the principleset forth in my prior Patent No. 826,349, July 17, 1906.. I am aware of the fact that means have previously been provided for automatically varying the speed of the stoker in order to increase or decrease the' quantity of fuel delivered which result was accomplished by mechanism acting. in accordance with variations of steam pressure inthe boilers,'or of ash pit air pressure. The first of these methods, that is, control of the fuel feedby the steam pressure, is objectionable because variations in condition of the fuel bed may take place due to unavoidable dif- Specification of Letters Patent.

Patented Oct. 12, 1920.

Application filed January 7, 1918. Serial 1%. 210,747.

of pressure in the ash pit acts to slow up the 7 feed of the stoker when in fact an increase of speed of feed is desirable. In my invention I overcome both of the objections stated and am able to vary the speed of the stoker and the consequent rate of feed of the fuel whenever there is such a variation in the relation between the fuel bed and the draft that the fuel bed does not ofier sufiicient resistance to the draft, or offers too great resistance to the draft, which may be due either to changes in condition of the fire bed, or changes in the speed of the blower.

In other words, in practising'my invention, whenemploying an automatic stoker,

a definite relation is maintained between the speed of the stoker or rate of feed of fuel, and the speed of the blower or supply of air to the furnace at all times so long as the resistance of the fuel bedre'mains normal.

If the resistance of the fuel bed is less than normal the relative speed of the stoker is increased, and if the resistance of the fuel bed is'greater than normal therelative speed of the stoker is decreased until the normal condition of the fuel bed is attained, or

'until the resistance of thefuel bed is such that the rate of fuel feed is equal to the rate -of fuel consumption.

' The invention consists in the improvements to be more fully described hereinafter and the novelty of which will be particularly pointed-out and distinctly claimed.

I have fully and clearly illustrated my invention in the accompanying drawings to be taken asa part of this specification, and in which-.-

Figure l isa view in side elevation,partly in section, of a preferred embodiment of my invention, certain of the parts being shown enlarged in order that the construction and operation thereof will be clear.

Fig. 2 isa view in front elevation, and

partly in section, of a pressure regulator for I controlling the fluedamper of the boiler to maintain the pressure of gases in the fur nace substantially uniform, and to control the feed of the stoker.

Fig.3 is a section through the furnace wall showing the pressure regulator of' Fig.

2 in vertical transverse section,

Fig. 4 is a view in front elevation of means for regulating the extent of move ment of the stoker engine valve in order to bear a desired relation to the speed of the blower and the position of the fluedamper.

Fig. 5 is a transverse section on the line 5-5 of Fig. 4. v

Fig. 6 is a detail of the governor valve for the stoker engine. I

Fig. 7 is a view in side elevation partly in sect1on of an alternative arrangement.

Referring to the drawings by characters 'of reference, 1 designates a boiler for the generation of steam, and 2 is a furnace of any suitable type for heating the boiler.

The furnace is fed with fuel by a stoker 3,

including a hopper 4 and suitable feeding means driven ,by a power shaft 5 carrying a pulley 6 connected by a driving belt 7 with a driving pulley 8 on the shaft of a steam engine 9 driven and controlled in aa latter will 'be connected with the vent 24,

manner to be presently described.

I desire it understood that my invention is not limited to the particular type of stoker shown and described, inasmuch as the invention is applicable to other types of stokers without departing from the spirit and scope thereof. The stoker shown is of the type generally known in the art as a Taylor stoker.

10 designates a flue outlet from the furnace chamber the same being controlled a plate damper 11 mounted on a pivot 12, said plate damper being movable in order to vary the outlet area of the flue. Mounted on the pivot of the damper is a lever 13 connected by a flexible connection 14 with the piston rod 15 of the piston 16, slidably arranged within an operating cylinder 17 adapted to contain a fluid for moving and controlling the said piston to vary the position of the damper in the outlet flue. The upper end'of the cylinder 17 is connected by a pipe 18 with a feed pipe 19 leading to any suitable source of fluidunder pressure, for example, oil, water, air, or any pressure medium which will operate to move the piston.- This pipe 19 is-connected to a port 20 opening into a pilot valve chamber 21-, said chamber being also connected by port-22 with a pipe 23 leading to the lower a casing. 30, open on one side to the interior of thefurnace through the flue duct 31, and to the outside atmosphere on the other side through the open bottom 32 of the casing 30. The pivot 29 is preferably located at approximately the center of gravity of the plate 28 or in a position such that the movement of the plate will not be.

afl'ected by the action of gravity, The plate may beprovided with a depending weight 33 in order to provide for the balancing of the plate so that its movements will notbe alfected by the action of gravity; Mounted on the casing is an arm 34, to which are connected the ends of oppositely disposed springs 35, 36, connected to an arm 27 rigid with the plate 28 and operating to return the latter to 'a neutral position, forexample as shownin Fig; 3, when the pressure is the same on both' sides of said plate, 'or

when the desired difference in pressure is maintained. The'pilot valve 25 is so connected to the plate that when the latter is moved by a preponderance of atmospheric pressure over furnace pressure, said valve will uncover the said port 22 so that the permitting the fluid in the cylinder 17 beneath the piston 16 to flow out of'the cylinder. When the valve is in the position just described and there is no pressure below the piston the pressure medium from the supply pipe 19 which at all times acts on the upper side of the piston flows through the pipe 18 into the cylinder 17 above the piston 16, and moves the latter downward to cause the plate damper to be swung on its pivot and reduce the outlet area of thefiue. When the regulator plate 28 is moved by a preponderance of'the furnace gas pressure, .plus the power of the spring 36, in excess of the atmosphere pressure, the sliding valve is moved down to a position to cut off communication between the port 22 and the vent 24, and to establish communication between said port 22 and the supply pipe 19, whereby the pressure medium is permitted to flow from the pipe 19'through the pilot valve chamber and the pipe 23 to the cylinder 17 beneath the piston 16. In view of the factthat the exposed area on the under side of the piston 16 is greater than the exposed area on the upper side of saidpiston, said piston will be moved upward to permit the weight 12 on the plate damper pivot 12 to swing the plate damper to a'position to enlarge the outlet area of the flue. r

Air under pressure is supplied to the furnace under the fuel bed by means of'a blower 37, delivering the air into. a .duct 38 opening as at 39 under the fuel bed of the furnace. This blower may be driven by a steam engine, or other motor, 40, fed with steam from the boiler through a feed pipe 41, controlled by a valve 42, preferably in the form of a potary valve having a transverse port 43, and carrying on one end a weighted lever 44. The operation of this valve is controlled by automatic means controlled and actuated by the steam pressure of the boiler, which means will now be described.

'45 designates a diaphragm chamber containing a diaphragm 46 exposed on its under face to steam pressure from the boiler admitted to a diaphragm chamber through a feed pipe 47 connected to the boiler. Connected to the upper face of thediaphragm 46 is a thrust rod 48 carrying at its upper end a knife-edge fulcrum 49, upon which rests a lever 50 fulcrumed at one end on the diaphragm casing, as at 51, and. carrying at its free end fixed weights 52, and at an intermediate point an adjustable slide weight 53. Arranged above the diaphragm chamber is a piston cylinder 54 containing a slide piston 55, connected to a piston rod 56, which at its upper end is connected to a flexible connec-.

tion 57 passing over guide pulleys 58 and connected to the said valve lever 44, as shown at 59. The cylinder 54 is adapted to receive a suitable fluid under pressure inorder to control and actuate the piston 55, the flow of the pressure medium to andfrom said cylinder being controlled by a pilot valve, which I will now describe. 7,

60 is a valve casing-containing a valve chamber 61 connected by ports 62,63, with the cylinder 54, and opening on opposite sides of the said piston 55. In the valve chamber 61 is a double slide valve carrying valve heads 64,- 65, mounted on a valve rod 66, said valve operating to control the inlet and outflow of the pressure medium through the said ports 62 and 63. In Fig. 1 the said valves are shown in a neutral position, closing both said'ports. Fluid under pressure is fed from any suitable source to the valve chamber 61 at a point intermediate the said valve heads through a pipe 67, and said chamber is provided with vents 68, 69, located respectively above the valve head 64 and below the valve head 65, the arrangement being such that when the valve heads 64 and 65 are simultaneously 'moved the ports 62 and 63 may be alternately connected with the supply 67 to the cylinder, and with one or the other of the vents 68, 69; The

- lever 50 is connected by a rod 70 to an intermediate point on the link member 71, the opposite ends of which are pivoted loosely or by :a slotted joint to the rod 66, as at '72, and a at 73 also by a loose joint to one end of the lever 74, which is fulcrumed at an intermediate point 75. The opposite end of the lever 74 from-that mounted on the ful crum 75 is connected by a link 76 to one end of a bracket rod 77, which is rigidly fixed, as at 78, to the said rod 56, heretofore described.

lVhen the steam pressure of the boiler act- 70 ing under the diaphragm 46 is just balanced by the weights 52 and 53, acting through the lever 50, the valve heads 64 and 65 close the ports 62 and 63 leading to the 'top and bottom of the cylinder 54. Should the boiler 75 pressure exceed the action of the weights 52 and 53, the diaphragm 46 will be pushed upward and the push rod 49 will raise the lever 50, causing the rod 70 to raise the link 71, elevating the end 72, and lifting the valve 80 stem 66 so that the valve heads 64 and 65 make connection for the fluid under pressure from the pipe 67 to pass through the port 62 and act on the upper side of the piston 55, while the port 63 allows the fluid in the 86 cylinder 54 beneath the piston 55jto escape through port 63 tothe vent pipe 69, where- .upon piston 55 and piston rod'56 and bracket 77 move downward. This motion is communicated by the link 76 to the lever 74, piv- 90 oted at 75 and causing the end 73 'to be raised. The link 71 will move about the joint 70 as a pivot, lowering the end 7 2, and

actuating the valve stem 66 and valve heads 64 and 65. The piston 55 will continue to96 descend until the valve heads '64 and 65 have closed theports 62 and 63, under which conthe lever 44, moving the valve 43 toward its closed position, and reducing the speed of loli the blower engine 40 and the blower 37. If the steam pressure acting under the/ diaphragm 46 is less than the action of the weights 52 and .53, acting through the lever 50, the lever 50 will be lowered and the reverse action from'that above described will take place and the piston 55 will move upward,and through its connections Wlll lower the lever 44, moving the port of the valve 42 toward its open position, increasing the supply of steam to the blower engine 40, thereby increasing the speed of the engine and blower, and increasing the amount of air .fed to the furnace.-

, w The combined function of the damper reg- 'ulating means heretofore described, and the blower engine speed controlling means heretofore described, is to establish-and maintain a uniform steam pressure in theboiler for varying loads, and a uniform pressure 125 of furnace gases in the furnace for varying rates ofcombustion in the furnace.

This operation broadly is the subject matter of applicants prior Patents 817,438, April 10, 1906',"-and 826,349, July .17, 1906. 130

I will now proceed to describe my im-' proved. method and means for controlling the rate of feed of the fuel supplied to the furnace constituting my present invention. In the present embodiment this means consists of a method and mechanism for'automatically varying the rate of' feed of the stoker in accordance with the amount of draft supplied, or in accordance with the.

thickness or resistance of the fuel bed, and is shown and hereinafter described as controlling and varying the speed of the stoker driving engine 9 to thereby var the rate at which the fuel isfed to the rnace by thelstoker 3. 79 is a governor valve casing "connected by a pipe 80 to the engine, and

alsoconnected by a pipe 81 to the steam pipe 41, communication between said pipes 81 and- 80 being controlled by a valve 82, 'coiiperating with a valve seat 83 in said valve casing.

The valve 82 is mounted on a valve stem 84, extending above thevalvecasing and surrounded by a sleeve 85, which .is slidable longitudinally onsaidstem under the influence of the governor balls86"fulcrumed,'

as at 87, on the frame 88 of the machine. Mounted below the said sleeve 85,\sur'rounding the valve stem and exerting its force against the said frame and the lower end of said sleeve is a spring 89, and a second spring 90 also surrounds said stem an'd is 7 arranged above said sleeve, "and abuts the 94 fulcrumed as at-95 'ona frame 96,

upper end of said sleeve and the lower face, of an abutment 91 rigidly mounted on the upper end of the valve stem and carrying a rack 92 meshing with a rack se%nent 93 carried on one end of'a lever 94. he lever 9 from pipe 81 t rough the valve 79 due to the decreased clearance between valve seat 83 and valve 82. This will cause engine 9 to slow down to some lesser speed, and the balls 86 will move inward due to the decreased centrifugal force act ng upon them I (it being understood that the governor balls I support 88 is rotated by suitable driving connection, for example, abelt or c'hain'connecting the governor support with the driving shaft of the engine through a pulley 85 on shaft 86", connected'by bevel gear- The i1 1g 88 to said governor support). amount of this inward movement of the balls 86 depends u on the centrifugalforce exerted' u on t cm by the desired reduced speed-o engine 9 governed. by the upward position of lever 94. The balls 86 will now slightly move inward or outward slightly 9 varies slightly in its speed due to its variable load.

If the lever 94 is moved.downward, the reverse actionvto that above described will take place-and the piston 84 will be raised admitting more steam to engine 9, and the balls 86by their variation of position will keep engine 9 at an increased but constant speed by varying the amount of steam supplied to meet the requirements of the load on engine 9.- Spring 89 is to keep sleeve 85 in close contact with governor ball arms and acts in opposition to centrifugal force on the balls, and spring 90 is to take up an'y'lost motion between rack 92 and segment 93 on the lever arm 94.

- the movements of the damper, orthe varia tion of the speed of the blower or air supply. In order to accomplish thispurpose the lever 94 may be connected by any suitable means to either the damper or its operatin mechanism for accomplishing the desire result. In the embodiment shown I provide a rotary element 97 mounted on a shaft '98,

arranged in suitable bearings, '(not shown), said rotary element carrying inner and outer concentric plates 99, 100, connected to said member by bolts 101 and spaced from each other by spacing sleeves 102, mounted on said bolts between said plates. These plates are provided-with alining radial slots 103,

in which are arrangedradiallyadjustable abutments, preferably consisting of bolts 105, carrying spacing sleeves 106 located between said bolts and fastening nuts 107 threaded on the outer ends of said bolts,

said bolts serving to) clamp the abutments rigidly in position, and also as abutments tocoeperate with, the lever 94, as will be presently described.

The member 97 is provided with a circumferenti'al groove 108, about which is wound 1 a flexible connection or chain 109, having at its free depending end a weight 110, and

at its intermediate portion carried over guide rollers 111 and connected at its free I end to the piston 15, as at 112, the arrangeto rotate the member 97 against the force of the weight 110. By the use of the adjustable abutments constituted by the nuts 107 I am able to insure such movement of the lever 94 as will cause the valve 82 to properly control the speed of the stoker engine in accordance with definite positions of the damper, which in turn is controlled longitudinally by the speed of the blower through the medium of the furnace gas pressure. In order to properly position the abutments the blower is operated at say one-quarter its normal speed. The damper, through the action of the regulator 28, will assume a position to maintain the desired pressure:

of furnace gases over the fire. The lever 94:- is then adjusted by hand until the stoker speed gives a rate of feed of fuel which will maintain a fire of the desired thickness or resistance. One of-the adjustable abutments 107 is then moved through vone of the radial slots 103 until it comes in contact with the under side of the lever 94. The.

nut 107 is then screwed up, holding the abutment rigidly in this position in the slot, so that whenever the radial member 97 is in this particular position, corresponding to one-quarter speed of the blower, and there is a normal fuel bed in the furnace, this fuel bed will be maintained automatically by the rate of feed of fuel. is operated at other speeds and the expanding position of the abutments fixed to give the desired rate of fuel feed desired for each speed of the blower, for example as shown in Fig. 4 of the drawings. The rotating member 97 could manifestly be connected to the flexible connection ,or chain 57 and be controlled in accordance with the variations of the blower speed, which latter is controlled directly by the steam pressure (see h Fig. 7). The advantage, however, of varying the rate of fuel feed in accordance with the.

movement of the flue damper when controlled by the regulator 28, is that in addition to varying the rate of fuel feed in accordancev with the variations of blower speed, the fuel feed is varied inversely in accordance with the resistance or thickness of the bed of fuel, so that if for any reason due to physical differences in the coal supplied to the stoker the resistance of the fuel bed It be understood that my invention is not limited to its use and combination withan apparatus in which the speed of the blower is varied in order to vary the supply of air to the furnace, as, for example, an equivalent would be to operate the blower .at a constant speed and suitable means be provided for varying the amount of air passing to the furnace, for instance, by means of a controllable damper in the air duct.

I also desire it understood that the invention is not limited to feeding means for any specific form of fuel, but includes in its scope means for feeding solid, pulverized, or

chamber a substantially uniform pressure under varying rates of combustion, and in regulating the resistance of the fuel bed to bear any desired relation to the rate of com bustion by controlling the rate of feed of fuel in accordance with variations in the means for maintaining in the furnace a substantially uniform pressure.

2. The method of regulating furnaces which consists in maintaining in the furnace chamber a substantially uniform pressure under varying rates of combustion, and in automatically regulating the resistance of the fuel bed to bear any desired relation to the rate of combustion by controlling the rate of feed of fuel in accordance withvariations in the means for maintaining in the furnace a substantially uniform pressure. Similarly the blower correspond to different rates of combustion controlling the rate of feed of fuel in accordance with variations in said means for maintaining in the furnace a substantially uniform pressure.

4. The method of regulating furnaces which consists in maintaining in the furnace chamber a substantially uniform pressure under varying rates of combustion, and in automatically regulating the resistance of the fuel bed to correspond to different rates of combustion by controlling the rate of feed of fuel in accordance with variations in said means for maintaining in the furnace a substantially uniform pressure.

5. The method of regulating furnaces which consists in maintaining in the furnace chamber a substantially uniform pressure under varying rates of combustion, and in remilating the rate of feed of fuel 1n accordance with variatlons 1n the means for maintaining in the furnace a substantially uni- 45 rate of outflow of the furnace form pressure, and in such manner that the rate of feed of fuel will vary inversely as-to variation in relation of fuel bed resistance to rate ofair supply, and directly as to the rate of air supply.

6. The method of regulating furnaces which consists in maintaining in'the furnace chamber a substantially uniform pressure under varying-rates of combustion, and in automatically regulating the rate of feed of fuel in accordance with variations, in the means for maintaining in the furnace a substantially uniform pressure, and in such manner that the rate of feed 'offuel will vary inversely as to variation in relation of fuel bed resistance to rate of air supply, and directly as to the rate of air supply.

7. The method of regulating furnaces which consists in maintaining inthe furnace chamber a substantially uniform pressure under varying rates of combustion, and in regulating the rate of feed of fuel in accord ance with variation in the means for maintaining uniform pressure under varying rates of combustion, so that the rate of feed of fuel will vary inversely as the resistance of the fuel bed, and directly as the rate of suppl of air to the furnace.

8. l he method of regulating furnaces which consists in maintaining in the furnace "chamber a. substantially uniform pressure under varying rates of combustion, and in automatically regulating the rate of feed of fuel in accordance with variation in the means for maintaining uniform pressure under varying rates of combustion, so that the rate offeed of fuel will vary inversely as the resistance of the fuel bed, and di- I for feeding- 50 'rectly as the rate of supply of air to the" furnace.

. 9. The method of operating boiler fur-' naces which consists in maintaining a substantially uniform furnace gas pressure for varying rates of combustion, and regulating the rate of fuel feed in accordance with the ses. 10. In a boiler furnace, a1r impelling means for su plying draft thereto, a stoker fiiel to the furnace, regulating means for maintaining the pressure of the furnace gases substantially uniform for varying rates of combustion, and means whereby the stoker is controlled by said regulating means.

11. In a boiler furnace, means for feeding fuel thereto, regulatin means for maintaining the pressure of t e furnace gases substantially uniform for varying rates of combustion, and means whereby the fuel feed-- ing means i's controll'ed by said regulating means."'.'

12. Ina 'boiler furnace, air impelling;

plying draft thereto, a stoker means for su for feeding el to the furnace, regulating regulator.

, of said damper.

means for maintaining the pressure of furnace gases substantially uniform for varying rates of combustion, and means whereby the speed of the stoker is controlled by said regulating means.

13. In a furnace, a stoker for feeding fuel thereto, a regulator acting in response to fluctuations of pressure of furnace gases to render saidpressure uniform,and fuel feed ing means for the furnace controlled by said 14. In a furnace, a stoker to feed fuel thereto, air impelling means for furnishin draft, means for controlling the air impe ling means by the steam pressure of the boiler, means for controlling the stoker in accordance with the variations of the air impelling means, and means'for maintaining a substantially uniform gas pressure in the furnace for varying rates of combustion, which last named means also varies the relative speed of the stoker to that of theair impelling means;

15. In a furnace, in combination, a damper, means affected by the pressure of furnace gases for operating said damper, a stoker, a motor for driving thestoker, a controller for the motor, and means for auto- I nace gases for operating said damper, a

stoker, a motor for driving the stoker, a controller for the motor, a movable member having a variable engagement with said controller, and means for moving said member in accordance with positions of said damper.

18. In afurnace, in combination, a damper, means alfected by the pressure of furnace gases for operating said damper, a stoker, a motor for driving the stoker, a' controller for the motor, a rotatable member havin an abutment to engage and operate the sa1d controller, and means for rotating said rotatable member in accordance with positions of said damper.

19. In a'furnace, in combination, a damper, means affected by the pressure of furnace gases for operating said damper, a

stoker, a motor for driving the stoker, a controller for the motor, a rotatable member having a plurality of radially ad'ustable abutments, to engage and operate t c said.- controller, and means for rotatin said rotatable member in accordance wit positions 20. In a furnace, incombination, a damerated in accordance With positions of said per, means aflected by the pressure of furdamper. 10 naee gases for operating said damper, a sto- In testimony whereof I have hereunto ker, a motor for driving the stoker, a consigned my name in the presence-0f a sub- '5 troller for the motor, a rotatable member for scribing Witness.

operating the controller, and a flexible con- EMBURY MCLEAN. nection connecting said damper and rota- Witness: table member whereby the controller is op- E. M. LOCKWOOD.

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