US2760508A

US2760508A - Bias adjusting means for fluid pressure relay

Info

Publication number: US2760508A
Application number: US253087A
Authority: US
Inventors: Paul S Dickey
Original assignee: Bailey Meter Co
Current assignee: Elsag Bailey Inc
Priority date: 1951-10-25
Filing date: 1951-10-25
Publication date: 1956-08-28
Anticipated expiration: 1973-08-28

Description

P. S. DlCKEY Aug. 28, 1956 BIAS ADJUSTING MEAN FOR FLUID PRESSURE RELAY Filed Oct. 25, 1951 5 Sheets-Sheet l FORCED DRAFT BLOWER INDUCED DRAFT FAN a J 4 Y m 2 R A 2 I Mm Y 6 RA M J E M M w Fm S 4 B 2 STEAM PRESSURE FURNACE VINVENTOR.

PAUL s. DICKEY P. S. DICKEY Aug. 28, 1956 BIAS ADJUSTING MEAN FOR FLUID PRESSURE RELAY 5 Sheets-Sheet 2 Filed Oct. 25, 1951 3H5 53mm um no Aug. 28, 1956 P. s. DlCKEY 2,760,508

BIAS ADJUSTING MEAN FOR FLUID PRESSURE RELAY Filed Oct. 25 1951 5 Sheets-Sheet s SAMPLE PIPE NO.|

SAMPLE PIPE NO. 2

Mum INVENTOR.

CAM CYCLE PAUL S. DICKEY FIG. 3 (7 A ORNEY P. S. DlCKEY Aug. 28, 1956 BIAS ADJUSTING MEAN FOR FLUID PRESSURE RELAY 5 Sheets-Sheet 4 Filed Oct. 25, 195] INVENTOR.

PAUL S. DICKEY 'NEY 28, 1956 P. s. DlCKEY 2,760,508

BIAS ADJUSTING MEAN FOR FLUID PRESSURE RELAY Filed on. 25, 1951. 5 Sheets-Sheet 5 VARIABLE NO. 1

o uz

123 102 BIASING H8 VARIABLE M or 5;, BIASED s9 I32 t /|25 |30 |3| FIG. 5

* FIG. 6

I32 F I39 I25 130 8 REMOTE J MORE MORE I ESS k LESS C .21

INVENTOR. PAUL S. DICKEY United States Patent Q BIAS ADJUSTING MEANS FoR FLUID PRESSURE RELAY Paul S. Dickey, East Cleveland, Ohio, assignor to Bailey Meter Company, a corporation of Delaware Application October 25, 1951, Serial No. 253,087

4 Claims. (Cl- 13782) My invention relates to the art of combustion control and particularly in connection with a furnace heated by die combustion of crushed solid fuel fired by one or more cyclone burners.

The construction, operation, features and advantages of such an installation have been described in the paper by Grunert, Skog, and Wilcoxson, entitled The horizontal cyclone burner, published in the Transactions of the ASME, August, 1947, volume 69, No. 6, and disclosed and claimed in Kerr et al. Patent 2,594,312, issued on April 29, 1952, application S. N. 552,120 filed August 31, 1944. Improvements in the control and operation of such a unit are accomplished through my invention.

Another object of my invention is the production of a single resultant control impulse from a plurality of separate primary impulses.

A further object is to provide a relay for the combining of a fluid loading impulse with an electrical impulse.

Another object is to provide means for biasing a fluid pressure relay by an electrical impulse representative of the value of a variable or of the departure of such value from a predetermined value.

Still another object is the establishment of the standard of a fluid pressure relay by a variable expressed in terms of an electrical impulse.

A further object is to provide a relay wherein an effect representative of one variable biases an effect representative of another variable.

In the drawings:

-Fig. 1 is a sectional elevation of the furnace portion of a commercial radiant type vapor generator and including in somewhat diagrammatic fashion a cyclone burner as well as fuel feeding and air feeding means.

Fig. 2 is a diagrammatic showing of metering and controlling instrumentalities for the unit of Fig. 1.

Fig. 3 diagrammatically illustrates an elaboration of certain of the elements of Fig. 2.

Fig. 4 is a side elevation, in somewhat diagrammatic form, of a biasing relay useful in the arrangement of Figs. 1, 2 and 3. Y

Fig. 5 is a diagrammatic showing of the relay of Fig. 4.

Fig. 6 is a wiring diagram in modification of Fig. 5.

Referring now to Fig. 1 it will be seen that I have illustrated therein in sectional elevation the furnace portion 1 of a radiant type vapor generator fired by one or more cyclone burners or primary furnaces generally indicated at 2. Inasmuch as the present description is based upon a commercial unit it may be said that the vapor generator is contemplated as having a normal steam capacity of 600,000 lb. per hr. and a maximum of 660,000 lb. per hr. at 1525 p. s. i. g. and 1010 F. It is equipped with forced draft blowers, induced draft fans, raw coal feeders, and various dampers; all provid ing controllable elements for maintaining operational variables Within desired limits. In Fig. 1 I show the said elements in functional relationship to the unit rather than in actual physical interrelation because the latter would add 'nothing to the understanding of my invention. Likewise I have not felt it necessary to show in detail the method of measuring the operational variables which in such a'unit are well recognized and the means for measuring them per se form no part of my present invention.

The unit is provided with forced draft blowers 3 discharging to a duct 4 in which are located one or more dampers 5. The supply of air for combustion is divided into primary, secondary and tertiary air through the

conduits

6, 7 and 8 respectively. The present unit has three cyclone burners so that air supply ducts similar to 6, 7 and 8 branch from the duct 4 to supply the other two cyclone burners (not shown) in a similar fashion.

One or more induced draft fans 9 provide for discharging the products of combustion from the unit. Control of the fans as well as of the dampers 10 is contemplated.

It will be appreciated that in a unit of this size and type it is usual to provide an economizer, air heater and superheater, but inasmuch as they form no part of the present invention, it is not felt necessary to complicate the drawing by including them.

The cyclone burner 2 is actually a primary furnace in which the elements of combustion combine and discharge the hot products of combustion to the secondary furnace 1 common to all of the cyclones. Crushed coal is admitted through a pipe 11 tangentially to the burner portion 12 in a stream of primary air at a sufiiciently high velocity so that the particles of coal will be thrown toward the interior surface of the cylinder 13 and will be carried in the air stream along the wall of the cylinder in the form of an increasing-pitch helix until the energy of the entering stream of air has been dissipated. In addition to the primary air sufiicient secondary air for complete combustion of the coal is admitted through the duct 7 in a path parallel to the primary airand coal and at a correspondingly high velocity. At the same time the temperature within the cylinder 13 is sufficiently high to promote and maintain combustion so that the volatile matter in the coal will first be distilled off and burned, then the remaining carbon will be burned, and finally the ash will be left. As the fusing temperature of the ash is usually lower than the temperature obtained from combustion, it will be in a molten state as slag, and, due to the energy in the stream of products of combustion, will be in contact with the surface of the burner so that it becomes entirely coated with molten or sticky slag.

By inclining the axis of the burner 2 at about 5 to the horizontal the molten slag will slowly drain toward its lowest point, indicated at 14, from which it can be continuously tapped. As the molten slag inner surface of the burner is established it will act like fly-paper to entrap further crushed coal admitted mary air and thrown to the surface of the burner by the energy of the conveying air. The movement of the slag on the surface of the burner, due to its viscosity, is very much less than the velocity of the entering air and this provides an intense scrubbing action of the high velocity air on the coal particles which are entrapped by and moving with the slower moving film of molten slag, with resulting extremely high combustion rate. The cylinder 13 may be surrounded by tube coils supplied with Water from the unit but constructional details are believed to be unnecessary herein.

The construction and operation of the cyclone burner 2 is such that nearly theoretically correct combustion occurs therein, normal commercial operation occurring at from 5 to 8% excess air.

with the pri-- In operation the molten slag resulting from the high rate of combustion of the coal forms a molten layer on the surface of the cyclone burner to which the newly admitted coal adheres with a certain amount of the finer coal and resulting particles of coke churning around continuously within the burner. The secondary air also admitted tangentially at high velocity provides an intense scrubbing action with resulting high combustion rate. Gases of combustion leave the cyclone burner through the central outlet at its end and enter the secondary furnace 1 passing through or in contact with the necessary screens or tube banks for heat transfer thereto. The molten slag in the cyclone burner drains to its lowest point 14 which is below the gas outlet and may flow continuously into the secondary chamber 1 from which it can be tapped continuously or intermittently as required.

In general, substantially complete combustion occurs within the cyclone burner 2 which discharges flame and products of combustion into the secondary furnace 1. Substantially all of the ash in the fuel remains within the burner 2 in the form of molten slag and thus the heating gases passing into and through the furnace 1 are substantially clean and free of fly ash, unburned carbon, and the like.

The secondary air duct 7 connected tangentially to the cyclone burner has three

adjustable velocity dampers

15, 16 and 17. In addition to controlling the high air velocity in the secondary air entrance port these dampers enable the operator to control air distribution to various zones in the cyclone burner. Coal enters at the front of the cyclone with the primary air at 12. Normal air distribution may be in the order of 10 to as primary air, 5 to 8% as tertiary and the remainder as secondary. The secondary air is distributed through the three compartmen-ts according to requirements for combustion to maintain ash fluidity at the primary furnace tap. Readjustment of air distribution may be necessary with substantial firing rate changes or deviation in coal size or volatile content. The practical requirement is to have sufficient velocity in the rear zone of the cyclone burner to sustain the protective slag coat on the walls but with the quantity of air limited locally to maintain ash fluidity at the tap.

Raw coal is fed through an adjustable feeder 18 driven by an adjustable speed motor 19, through a crusher 20 to which primary air is admitted from the duct 6, discharging to the duct 11 a mixture of primary air and crushed coal which may have particles up to /8 to V2". Speed control for the motor 19 is attained through the positioning of the rheostat 21.

Located in the primary air duct 6 is a damper 22 while the tertiary air duct 8 is provided with a damper 23.

I have now indicated the various controllable factors or elements in the operation of the unit as a whole. In either manual or automatic control of the unit it is important to ascertain the instantaneous value of certain variables in the operation thereof. To those familiar with this art it is known that the pressure of the steam leaving the unit is desirably to be maintained at a predetermined value. In this connection I indicate a Bourdon tube 24 connected to the steam outlet main 25. Positioned in the main 25 is an orifice 26 providing a means for producing a pressure differential bearing a known relationship to the rate of steam outflow which is of course a demand factor upon the unit.

I desirably ascertain the rate of air flow through the unit by the differential pressure between two selected locations across tube banks, air heaters or locations dictated by the particular design and construction of the unit.

By air flow I intend to include the rate of flow of gaseous products of combustion and excess air passing through the generating unit, i. e. the assembly of vapor generator, superheater, etc. As is well known by those familiar with the art, air flow has long been utilized as an indicator of firing rate or heat liberation and thereby an indication of heat available for vaporizing the liquid and superheating the vapor. On the other hand, the rate of flow of steam produced under constant conditions of temperature and pressure is a measure of heat absorption. Thus an interrelation of steam flow and air flow becomes a comparison of heat liberation and heat absorption.

Inasmuch as steam outflow and air flow are indexes related to the operation of the unit as a whole and I am preferably describing a unit having a plurality of cyclone burners 2 it is under certain conditions desirable to have a further individual indication of combustion conditions within each cyclone burner with the possibility of correcting the fuel-air ratio thereto as distinct from the other burners and from the operation of the unit as a whole. To obtain such an indication of the quality of the products of combustion discharging to the furnace 1 from a cyclone burner 2, I have indicated in Fig. l a gas sampling tube 27 so located as to sample the products of combustion discharged from the burner to the secondary furnace 1. In the present embodiment the gas sample through the pipe 27 passes through a washer system (not shown) and under pressure is supplied to an analyzer for ascertaining the percentage of free oxygen in the gases. The measuring instrumentality may be graduated in terms of free oxygen or in percent of excess air as desired. In the. analyzer catalytic combustion of a vaporizable liquid fuel in the flue gas atmosphere is effected wherein the resultant temperature is a measure of free oxygen content of the gas sample.

The cyclone firing method is characterized by success ful operation with very low excess air, i. e. nearly theoretical combustion proportioning of fuel and air. Precise control of the fuel-air relation has been accomplished by the use of the excess air recorder-controller sampling as at 27 and regulating the fuel feed ratio discharged through the conduit 11 to the entrance of the burner 2. Adjusting the coal feed rate to total air supply with excess air as the criterion in effect tend to provide total heat input regardless of variations in coal analysis, size or moisture content. This characteristic is demonstrated by recorded feeder speed variations of as much as 20% during the maintenance of practically constant boiler steaming rate. Such variations in magnitude are probably due to irregularities in the operation of the feeder and air pressure and in the characteristics of the coal itself, and indicate that a measure of feeder speed is not necessarily a correct measure of fuel input rate. In addition to controlling to maintain a minimum excess of air and thus a high combustion efliciency it is of course desirable to maintain proper draft or pressure conditions throughout the unit.

Having now described the steam generating unit as a whole, along with the various controllable factors and elements, and having mentioned the variable conditions in the operation which are desirably to be measured and! or controlled, I refer now to Fig. 2 wherein I have diagrammatically indicated these various elements and variable conditions and the preferred arrangement of control. I have felt that for clarity of illustration and description and therefore of understanding that it is desirable to separate Figs. 1 and 2 rather than combine the two for such a combining would lead to a complexity of illustration more diflicult I believe for understanding. Reference will now be had to Fig. 2 in detail.

I indicate in Fig. 2 that the Bourdon tube 24, sensitive to pressure of the steam leaving the unit, is arranged to vertically position the movable element of an air pilot valve 28 thereby establishing in the pipe 29 an air loading pressure representative of steam outflow pressure. The

and which provides a proportional control with reset char:

acteristics. it provides for the final control index (steam presusre) adelaye'd'action floating control or liigh snsi ple rnentary action to prevent overtravel' and hunting; The

output of the relay 30, available through the pipe 31, is admitted to a rnanual-automatic selector, valve 32 providing the possibility of controlling the various controllable elements of the unit either automatically or manually from a relatively remote centralized panel location. Preferably the selector valve 32 is'of the type disclosed in the patent to Fitch 2,202,485 and is provided with load limiting relays 33. The limiting relays 33 are respectively connected to the air supply and exhaust connections of the. selector relay 32 and are adjusted to limit the maximum and minimum values of the control pressure output of the selector valve 32 available in the pipe 34. Through this arrangement the loading pressure available in the pipe 34 cannot decrease below a predetermined minimum nor increase above a predetermined maximum. Both minimum and maximum limits are adjustable.

Considering the control arrangement of Fig. 2 as a whole it will be observed that steam pressure (being the final controllable factor in the operation of the unit) primarily dictates the controlling position of forced draft,

induced draft and fuel feed in parallel. The various con trollable elements may, however, be subject to readjustment from one ormore of the othervariables in the unit operation as will be described.

Considering first the speed of the forced draft blower 3 it will be observed that the steam pressure representative loading pressure in the pipe 34 is applied to an expansible-contractible metallic bellows 35 of a ratio device 36 having an opposing diaphragm 37 which is sensitive to forced draft duct pressure; the arrangement being such that forced draft duct pressure is maintained at a predetermined value regardless of variations in steam outflow pressure. Thus the ratio device 36 operates to control the speed of the forced draft fan or fans 3 to satisfy load variations upon the unit as indicated'by steam pressure and to maintain forced draft duct pressure at a constant predetermined value.

The device 36 is arranged to position the movable element of an air pilot valve 38 for establishing in the pipe leaving the D chamber is effective through a pipe 41 and manual-automatic selector valve 42 for positioning the inlet vanes or other output controlling instrumentality of the forced draft blower. 3. Where a plurality of forced draft fans are utilized on the unit, the control is branched from the pipe 41 as shown and a plurality of manual-automatic selector valves 42 are provided so that each forced draft blower may be selectively operated by hand or automatically.

Connected to the air loading pipe 34 i a branch pipe 43 leading to a manual-automatic selector valve 44 for positioning the primary air damper 22 and the

secondary air dampers

15, 16, 17 simultaneously responsive to steam pressure variations. Preferably the

dampers

15, 16, 17 are so arranged that they may be individually positioned the one relative to the others as previously mentioned to properly distribute the secondary air along the axial length of the burner chamber. Preferably the total supply of primary air and secondary air, through the selector valve 44, for an individual cyclone burner, is raised or lowered in accordance with the dictates of steam pressure or manually through the agency of the selector valve 44. It will be appreciated that control for the second and third cyclone burners will be taken care of in similar manner by 'branchingfrom the loading pressure pipe 43 as clearly indicated in Fig. 2 of the drawing.

Control Ofinduced draft is also primarily under (the.

control of the steam pressure Bourdon tube 24. A pipe 45, branching from the pipe 34, joins the A chamberof an averaging relay 46 whose output iseffective in the, pipe.47. A. device 48, is sensitiveto furnace draft for establishing in the pipe 49 an air loading pressure representative of furnace draft. Such pressure is imposed upon the A chamber of astandardizing relay 50 whose output is available through a pipe 51 joining the C chamber of the averaging relay 46. The pipe 51 is provided with an adjustable throttling means 52 for restricting the effect of furnace draft upon the relay 46 in a manually adjustable manner. Itwill be seen .that the arrangement is such that the loading pressures of the

pipes

45 and 51, are averaged within the relay 46 so that the resultant is available within theoutput. pipe 47 upon manualautomatic selector valves 53 in the control of induced draft dampers10 and simultaneously through the manual-.

automatic selector valves 54 to assist in control of speed,

of the induced draft fan 9.

As a check back upon the actual speed andoperation: of the induced draft fan 9 I provide a tachometer 55, which continuously establishes a loading pressure with in the output pipe 56 representative of speed of the in; duced draft. fan 9.. The pipe 56 joins the B chamber of an averaging-standardizing relay 57 whose D chamber output is available .within a pipe 59 joining the A cham-. ber of an accelerating relay 60 whose output in turn is adapted to positionthe speed. regulating device of the induced draft fan 9. i

It will thus be seen that the basic operation of l;he in-;

duced draft fan is conjointly under the control of steam pressure, furnace draft and fan speed while the position, ing of the induced draft dampers'is undert he control, of steam pressure and furnace draft.

Control of the rate of fuel supply to the cycloneburn-l ers is primarily in accordance with steam pressure;vari-, ation and secondarily from the relation between steam. flow from the unit and air flow through the unit. The, speed of the;individual fuel feeder to the individual cyclone burner is then further adjusted in accordance. with an analysis of the products of combustion entering the secondary furnace 1 from the outletof-theburner. per se. ,Thus the control of fuel supply to theunit as. a whole is arranged to satisfy demand upon the unitas. indicated by steam pressure and to approximate best combustion efficiency as dictated by the relation betweenthe rate of steam outflowfrom the unit and the rate of airflow throughthe unit. The three cyclone burners are then separately readjusted insofar as fuel-air ratio is concerned in accordance with the completenessof corn-, bustion in the individual burner chambers as indicatedby an analysis of the gaseous products of. combustion. leaving the individual cyclone and entering the secondary. furnace 1. 1

At 61 I indicate asteam flow meter preferably con. nected across the orifice 26 for continuously measuring the rate of steam outflow from the unit. In similar fashion I indicate diagrammatically an air flow meter at 62 for continuously determining the rate of flow of the products of combustion and excess of air through the unit. The

instrumentalities

61, 62 are adapted to position the movable element of an air pilot valve 63 upon departure of steam flow and air flow from desired relationship. Pilot valve 63 establishes an air loading pressure within the pipe 64 representative of such relation between steam flow and air flow and by departure in one direction or the other from desired value indicates whether the air flow is greater than or less than that which should exist for the actual rate of steam out flow. The air loading pressure within the pipe 64 is available within the A chamber of a standardizing relay 65 whose output is effective through a pipe 66 within the C chamber of an averaging relay 67, to the A chamber of which is led the loading pressure within the pipe 34 representative of steam pressure. Thus the averaging relay 67 receives a primary impulse from steam pressure as a measure of demand upon the unit and a secondary or modifying impulse representative of relation between steam flow and air flow or combustion efficiency within the unit as a whole.

The output of the relay 67 is available within a pipe 68 branching to the

pipes

69, 70, 71. By way of example, the pipe 69 joins a manual-automatic selector valve.

72 and thence is arranged to position the rheostat 21 for regulating the rate of coal feed to the crusher for cyclone burner 1. In similar manner the

pipes

70 and 71 are arranged to regulate the speed of the coal feeder to the other two cyclone burners respectively.

interposed between the pipe 68 and the

pipes

69, 70, 71 are three air relays respectively designated as 73, 74, which may be individually loaded or adjusted in accordance with the determination of the excess air condition of the flue gases leaving the individual cyclone burners. By way of example the control impulse regulating the speed of the coal feeder for cyclone burner No. 1, primarily representative of steam pressure and relation between steam flow and air flow may be further adjusted, relative to the other two burners, through a loading of the air relay 73. I will now explain the manner in which such loading is to be accomplished.

I have chosen to illustrate and describe the use of a single gas analyzer 76 periodically switched from one sample tube 27 to another and cyclically elfective upon the related relays 73 or 74 or 75. It might, of course, provide individual gas analyzers in connection with the individual gas sampling pipe and its related cyclone burner.

In Fig. 2 it will be seen that sample pipe 27, from in front of cyclone burner 1, is effective upon the gas analyzer 76 because the switching valve 77 is open while the switching

valves

78 and 79 are in closed position. As will be explained I provide a mechanism whereby cyclically the valve 77 is opened, then the valve 78, and then the valve 79, in each case the other two valves being closed ofl, so that cyclically the analyzer 76 is connected to draw a sample from in front of each of the three cyclone burners. The analyzer 76 is electrically connected to a timer and interrupter mechanism 80 which is electrically connected to control the

motors

81, 82 and 83. The arrangement is such that the motor 81, through the necessary gear reduction, is adapted to load or unload the spring 84 which controls the relation between the input pressure from the pipe 68 and the output pressure of the relay in the pipe 69. In other words the relay 73 is arranged in such a manner that the air loading pressures within the

pipes

68, 69 may be in a 1-1 ratio or in any given ratio depending upon adjustment of the loading spring 84 and such loading spring adjustment is varied through the agency of the motor 81 under the control of the analyzer 76.

In Fig. 4, and diagrammatically in Fig. 5, I have shown as a somewhat different relay structure than the relay 73 of Fig. 2 although its general operation and function in the system is similar.

Fig. 4 shows a somewhat phantom side elevation of the relay 100. A reversible electric motor 101 is preferably an alternating current type, and in Fig. 5 I designate its power source as and merely for convenience in explanation. The motor is provided with the necessary reduction gears and drives through a friction clutch to prevent damage to the motor or gears should the motor be urged to rotate a cam 102 (carried by a low speed output shaft) more than some predetermined angle of less than 360. The motor, and cam 102, are moved under the control of the timer 80 and analyzer 76, as will later be explained in connection with Fig. 3, and the position of the cam 102 may be said to represent the value of a r of link 106, or by both.

biasing Variable No. 2, or the departure of said value from a predetermined value. Specifically, the cam position' may be representative of the oxygen content of the discharge of a certain one of the plurality of cyclone burners or primary furnaces 2 of Fig. 1.

Riding the contour of cam 102 is a roller 103, carried by an arm 104 which is pivoted as at 105. A link 106 is pivotally connected to the arm 104 and is positioned thereby over a relatively longitudinal path; the other end of the link 106 being pivoted to one arm of a bellcrank 107. The bell-crank 107 is pivoted, as at 108, near one end of a beam 109 whose other end is pivoted by a leaf-spring 110 to a fixed abutment 11-1. The beam 109 forms the movable end closure of a bellows 112 whose other end is fixed to the abutment 111. Fluid loading pressure, representative of Variable No. 1" or of departure thereof from a predetermined value, is admitted to the bellows 112 from the pipe 68, and this fluid pressure is visually indicated upon a pressure gage 113.

The beam 109, and thereby the bellows 1-12, is loaded by a spring 114 having one end fixed to the abutment 111 and its other (movable) end fastened to a branch 115 of the beam. Spring tension is varied by an adjustment 116 acting between parts 109 and 115.

The other arm of bell-crank 107 carries a link 117 pivotally suspended therefrom and joining, at its lower end, a floating cradle 118. The cradle 118 forms part of an assembly 119 for establishing a fluid control pressure and is more fully disclosed, and is claimed, in the copending application of Harvard H. Gorrie, S. N. 169,751, now Patent No. 2,675,015. Briefly, the floating cradle 118, has its other end pivotally positionable by a beam 120 in turn positioned by a restoring bellows 121. Intermediate the ends of the cradle 118 is suspended a pilot valve stem 122 controlling the fluid pressure in output pipe 69, within the restoring bellows 121, and which is visually indicated upon a pressure gage 123.

It will now be apparent that, assuming the cam 102 immovable in a predetermined position, the pressure within pipe 68, acting upon the bellows 112 against spring 114, will position the pilot stern 122 to produce in the output pipe 69 an output fluid pressure equal to, or in desired proportionality to, the incoming fluid pressure in pipe 68. If the link 106 is longitudinally moved to angularly position the bell-crank 107 around its pivot 108, and thereby change the vertical position of link 117 (the beam 109 remaining unmoved), the result will be a positioning of pilot 122 and a variation in fluid pressure output in pipe 69.

Thus the pressure within pipe 69 may be varied either by change in pressure within pipe 68, or by movement I have, then, a possibility of biasing a Variable No. 1 specifically, fluid pressure within pipe 68, by a Variable No. 2 specifically, cam 102, to produce a resultant output fluid control pressure in pipe 69.

The motor 101, and cam 102, are positioned representative of oxygen value or of departure of such value from a predetermined value. It will be evident that there may be times when it is not desired to have the oxygen value bias the loading pressure of pipe 68 and in that event the cam 102 should be made inoperative. For this purpose I have provided a switch 125 in the control circuit of motor 101 to turn it on or turn it off. The switch is preferably labeled Automatic and Off" as representative of having the bias automatically applied, or not.

Merely turning off the electric power from motor 101, and thereby keeping it immovable, does not completely satisfy the desire, however, because that would leave link 106 in its last biasing position. When motor 101 is made inoperative, I additionally provide that all previous bias be removed, as by returning link 106 to a predetermined position wherein it effects no biasing action upon cradle 118. Such a position is, in the present embodiment, the position shown in Fig. 4 wherein the center line of link 106 coincides with the pivot center of leaf spring 110 and roller 103 is at mid-rise point of cam 102.

The switch 125 is provided with three contacts 130- 131-132, shown in Fig. 4 with contacts 130-131 closed and contact 132 open, for the automatic position of the switch. In the ofi position contacts 130-131 are open and contact 132 is closed.

The slow speed motor output shaft 133 carries two

disc cams

134, 135 angularly adjustable around the shaft in relation to each other and to the cam 102. The periphery of the one cam is engaged by a switch-actuating follower 136 and the other cam by a follower 137.

Switches

138, 139 may be actuated, respectively, by the

followers

136 and 137. Each of the cams has a single low portion into which the respective follower drops for opening the related switch, and the spacing of the two low portions is adjustable. The arrangement is such that a switch is maintained open as the related follower rides out of its depression in one direction but the switch is maintained closed if the follower rides out in the opposite direction. With the closed and open directions different for each switch, it is only necessary to rotate the

cams

134, 135, and thereby the drop-in points, until both followers drop in together when the roller 103 is at predetermined peripheral position on cam 102, representative of zero bias effect by motor 101 upon cradle 118.

Refer now to Fig. 5. The switch 125 is in automatic position. The motor 101 is energizable in a selected direction by impulses receivable through 96, 97 (Fig. 3). Contact 132 and switches 138, 139 are open. The loading pressure within pipe 68 is effective in positioning pilot 122 and its effect is biased by motor 101 acting through cam 102. On the panel face of device 100 the

pressure gages

113, 123 provide a visual comparison of the fluid loading pressure representing Variable No. l and that same loading pressure biased by Variable No. 2 to become a bias output in exit pipe 69.

If the swicth 125 is now turned to off position the

contacts

130, 131 are open and contact 132 becomes closed. The motor 101 is no longer under the control of timer 30 and the pilot would be left in its degree of bias. However, assume that some bias had previously been applied. The switch 138 (or 139) is closed and when contact 132 is closed it completes a circuit to rotate motor 101 (and earns 134, 135) in proper direction to run the follower 136 of switch 133 to its depression, thereby opening switch 138 and stopping motor 101. That is the position of rest shown in Figs. 4 and 5, wherein all bias has been removed.

\ When it is again desired to automatically apply oxygen bias to the pressure of pipe 68 then switch 125 is turned to Automatic, the

switches

138, 139 are made ineffective, and the motor comes under the control of 96, 97.

Referring now to Fig. 3 I will describe more in detail the function and operation of the devices 73 to 84. In the timer 80 I provide a continuously running motor which through the proper gear reduction rotates a series of six generally circular cams on a three minute cycle. While it is possible to utilize another time of cycle I have preferably indicated that three minutes is the time for a complete revolution of the six cams and the arrangement is such that the first pair of cams utilize their effective surface over the first minute of operation, the second pair of cams over the second minute, and the third pair of cams over the third minute. The first pair of cams is related to operation of the first cyclone burner while the second pair is in connection with the second cyclone burner and the third pair in connection third cyclone burner.

In Fig. 3 I have laid out in straight line the surface contour of the six cams and the arrangement is such that the cam surfaces are presumed to move toward the left as the drawing is observed. Thus cam surfaces 85,.

86 aer effective for the first minute in connection with cyclone burner 1, cam surfaces 87, 88 for the second minute in connection with cyclone burner 2, and car'rr surfaces 89, 90 for the third minute in connection with switch 91 is arranged to complete the circuitto solenoid 93 overcoming a spring 94 and positioning the valve 77 to an open position thereby connecting the sample pipe 27 for cyclone furnace 1 to the analyzer 76. As shown the switch 92 is open so that the motor 81 is' not energized for operation in either direction. At this time in the cycle of operation the sample switches 78 and 79 are closed and the

motors

82 and 83 are deenergized.

As the cyclic operation proceeds there is a time interval of 15 seconds during which the just mentioned conditions prevail. At the end of 15 seconds the switch 92 becomes energized thereby allowing the motor 81 to have its common return connected to one side of the elec trical power source. If the actual value of free oxygen within the gaseous products of combustion leaving the cyclone furnace 1, as sampled through the pipe 27, is

above or below the desired value by a predetermined amount then the contact 95 will engage either the contact 96 or the contact 97 and complete a circuit to the motor 81 to operate the same in one direction or the other for loading or unloading the spring 84 and thus varying the relation between the pressures in the

pipe

68 and 69 effective for varying the speed of the coal feeder 21 to cyclone burner 1. The contact 95 is connected to the power source through a switch 98 positioned by an interrupter motor 99 so that the electrical impulses which may pass to the motor 81 are not continuous but are adjustably of relatively short duration to prevent overcorrection until the effect of such correction is felt in the combustion within the burner. Preferably the

contacts

96, 97 may be adjustably spaced apart so that a permissible variation in oxygen content of the flue gases will exist without varying the loading of the

relays

73, 74 or 75.

As the earns to inclusive move toward the left it will be apparent that at the end of the first minute the

switches

91, 92 become ineffective and the switches for the second burner may be effective for the second minute of the cycle.

In general the operation of the arrangement of Fig. 3 is that successively burners 1, 2 and 3 may be readjusted insofar as the fuel-air ratio is concerned if the products of combustion leaving the respective burner indicate that readjustment is necessary to take care of variations in the particular coal feeding rate. When the analyzer 76 is connected in relation to a particular burner, the first 15 seconds that the related sample pipe is connected to the analyzer 76 is utilized for clearing the sampling and analyzing system of the gases from the previously connected burner and, while the recording chart of the analyzer may show, during said 15 seconds interval, a reading which is incorrect for any burner, it is only the final 45 seconds of the 1 minute interval wherein it is possible for a readjustment to take place on the related burner coal feed. The recording chart of the analyzer 76 may preferably be provided with a second recording pen which would show which of the three burners is connected to the analyzer. t

As I have mentioned, it may in certain installations be desirable 'to have an individual gas analyzer in connection with each'of the burners, in which event the cyclically switching of sample tubes and of control for the air relay motors may be dispensed with. The most important feature of the present invention, insofar as this portion of the control is concerned, is that control of the coal feeder speed, while primarily from steam pressure and relationship between steam flow and air flow is readjusted if necessary from an analysis of the products of combustion leaving the individual burner.

Steam pressure as an indication of load or demand upon the unit is the primary controllable variable which operates to adjust the forced draft, induced draft and coal feed in parallel. Load limiting relays may be provided for limiting the maximum or minimum air and fuel supply rates to the unit as a whole and thus limiting the maximum and minimum loads which may be carried.

The forced draft supply blowers are controlled primarily in accordance with steam pressure deviations from standard and with readjustment if necessary to maintain the pressures in the forced draft supply duct at a predetermined value.

The primary and secondary air supply dampers to the individual cyclone burners are controlled in parallel from steam pressure and with the possibility of individual readjustment relative the one to the other manually.

The induced draft fans and dampers are controlled in parallel responsive to steam pressure and to furnace draft within the unit. The induced draft fans are further readjusted in accordance with actual speed of the fans.

The rate of supply of raw coal to the three cyclone burners is controlled in parallel in accordance with steam pressure and relationship "between steam flow and air flow on the unit as a whole. The rate of supply to the individual cyclone burner is readjusted if necessary in accordance with a determination of the excess air of the products of combustion leaving the related burner if departing over an allowable amount in either direction from desired value.

Provision is made for selectively imposing manual or automatic control upon the controllable elements of the unit as a whole or upon the individual dampers, fans and feeders selectively as desired. Adjustability is, in common manner, provided at the various measuring and controlling instrumentalities and need not be further elaborated upon.

I have also provided a specific pressure relay structure capable of being remotely biased in accordance with an electric signal which may be actuated by hand pushbutton, or may be atuated automatically in accordance with the value, or change in value, of another variable. At the relay per so I provide the possibility of changing the biasing, removing the biasing, or making it ineifective.

In Fig. 6 I show a modification of the electrical arrangement of Fig. 5. Instead of the forward-reverse connections 96, 9'7 of Fig. 5, I herein provide a More- Less push-button station locally and a similar push-button station remotely, through whose agency the loading pressure in pipe 68 may be biased by push-button manually.

It will be seen that the motor 81, as well as the motor 101, each comprises the receiver of an electric telemeter of which the oxygen analyzer 76 may be the telemeter transmitter or sender. Thus a telemeter system is provided whereby a second variable remotely biases a first variable.

While I have chosen to illustrate and describe a commercial unit having. two forced draft blowers, two induced draft fans, numerous dampers, as well as three cyclone burners each with its related coal crusher and feeder, it will be ap reciated that these are not limiting factors and that my invention may equally as well be applied to a unit of ditferent size or design and having a different number and type of fuel and air feeding devices.

This application forms a continuation-in-part of my copending application SN 789,416 filed December 3, 1947, now Patent No. 2,623,698 issued December 30, 1952.

What I claim as new, and desire to secure by Letters Patent of the United States, is:

l. A fluid pressure relay including in combination, structure forming a chamber having a movable wall whereby the chamber is eXpansible-contractible when subjected to a variable fluid pressure, spring means biasing the movable Wall in one direction, a fluid loading pressure supply for the chamber representative of the value or change in value of a first variable, a fluid pressure pilot valve means positioned by the movable wall and arranged to establish a fluid output pressure bearing predetermined relation to the loading pressure, a supply of substantially constant pressure fluid for the pilot valve means, a telemeter receiving means comprising an electric motor positionable representative of the value or change in value of a second variable, mechanical means positioned by the motor and connected with the movable wall to bias the eflective positioning of the pilot means by the movable wall in direction opposite to that of said spring means, and an electric switch means for the motor arranged selectively to two positions one of which provides biasing of the first variable by the second variable and the other of which makes the motor ineffective for further biasing and at the same time removes the previously applied bias if any.

2. A fluid pressure relay including in combination, structure forming a chamber having a movable wall whereby the chamber is eXpansible-contractible when subjected to a varying fluid pressure, a fluid loading pressure supply for the chamber representative of the value of a first variable, a fluid pressure pilot valve means positioned by the movable wall and arranged to establish a fluid output pressure bearing predetermined relation to the loading pressure, a supply of substantially constant pressure fluid for the pilot valve means, an electric telemeter receiving means including a movable electric motive means, said telemeter receiving means arranged to mechanically bias the effective positioning of the pilot valve means by the movable wall, multiple cam means rotated by said electric motive means, each cam means having a recess therein, multiple switching means cooperating with said multiple cam means, whereby said cams and cooperating switching means makes effective one of the said multiple switching means to drive the electric motive means to a predetermined position to remove said bias, and hand operable switching means for controlling the start-stop directional operation of the electric motive means.

3. A fluid pressure relay including in combination, structure forming a chamber having a movable wall whereby the chamber is expansible-contractible when subjected to a variable fluid pressure, a fluid loading pressure supply for the chamber representative of the value or change in value of a first variable, a fluid pressure pilot valve means positioned by the movable wall and arranged to establish a fluid output pressure bearing predetermined relation to the loading pressure, a supply of substantially constant pressure fluid for the pilot means, a telemeter receiving means comprising an electric motor positionable representative of the value or change in value of a second variable, mechanical means positioned by the motor and arranged to bias the effective positioning of the pilot means by the movable wall, an electric switch means for the motor including a multiple cam ,means driven by said motor whereby one of the cam means biases the etfective positioning of the pilot means by the movable wall, another of the plurality of cams is provided with a recess, still another cam is also provided with a recess, and contact switches adapted to be operated by the last two-mentioned cams and their recesses, whereby the selective operation of the electric switch means is made eflective to drive the electric motor to a predetermined position in either direction thereby removing the respective bias.

4. A fluid pressure relay including in combination,

structure forming a volumetrically expansible chamber having a movable wall whereby the chamber is expansible-contractible when subjected to a varying fluid pressure, a fluid loading pressure supply for the chamber representative of the value of a first variable, a fluid pressure pilot valve means positioned by the movable wall and arranged to establish a fluid pressure output bearing predetermined relation to the loading pressure, a supply of substantially constant fluid pressure for the pilot valve means, an electric telemeter receiving means including a movable electric motive means and mechanical linkage arranged to bias the effective positioning of the pilot valve means by the movable wall, plural switch means at the electric motive means for making ineffective the telemeter receiver in biasing the pilot valve means positioning, and means actuated by the plural switch means for removing any residual bias at time of making the biasing means further ineffective.

References Cited in the file of this patent UNITED STATES PATENTS Cunningham Ian. 18, Deuringer Mar. 12, Annin July 29, Annin Sept. 9, Philbrick Oct. 24, Gess Aug. 14, Hart Dec. 4, Gillespie Feb. 7, McLeod May 16, Sawyer Jan. 16,

FOREIGN PATENTS Great Britain