US1920323A

US1920323A - rossman

Info

Publication number: US1920323A
Authority: US
Publication date: 1933-08-01
Anticipated expiration: 1950-08-01

Description

Aug. 1, 1933.- A. M. ROSSMAN METHOD AND SYSTEM OF REGULATION Filed Dec. 3, 1929 3 Sheets-Sheet l 59M Pit SURE 6/7065 Fl/IAIL'E P8553085 679065 Aug. 1, 1933. A. M. ROSSMAN METHOD AND SYSTEM OF REGULATION Filed Dec. 3, 1929 3 Sheets-Sheet 2 fflzyeniws M 7957720,

Aug. 1, 1933. A. M. ROSSMAN METHOD AND SYSTEM OF REGULATION Filed Dec. 3, 1929 3 Sheets-Sheet 3 lllflllillllllllllllllill Patented Aug. 1, 1933 uuirso sT r s PATENT .o Fics METHOD AND SYSTEM or nEGuLATI'oN Allen M; Rossman, Wilmette, 111., assignor to" Rossman; Sargent & Lundy Patents Corporation, ChicagoJlLla Corporation of Illinois Application December 3,1929; Sada-1N6. 411,336 19 Claims. (01. 23614.)

My invention relates to regulatinglsystems. While the specific embodimentherein shown and described is a system of combustion control of steam pressure. Thus I assume a mean steam pressure and deal only with variations-therefrom. It is always-assumed that so long as boiler pressure remains constant, the load is being properly carried. 7

Now, in considering how to relate combustion, namely, union of air and fuel to load, it is to be observed that the composition of atmospheric air is substantially a constant, whereas the composition of fuel may vary. Hence it is customary to relate steam delivery toair flow to the combustion chamber. ihat is to say, the factor in combustion which is most infiexibly related to load is air.

delivery to the combustion chamber. Or, the air flow to the combustion chamber may be related to the percentage of carbon dioxide in the flue gases.

In my system of combustion control I relate definite proportion or-relati'on between pounds of steam delivered per unit of time at a givenpressure, and pounds of'air supplied per unit of time F at a given barometric pressure.

A certainair fiow' per unit of time will support proper combustion ofacertain amount of fuel per a unit of time, other things remaining constant. While the fuel (usually, but not necessarily; coal) may be considered of afuniform composition for initial setting of the fuel feeding means, it varies,

and perfect combustion will not result when the.

assumed relation does not prevail. Therefore, an adjustment of the ratio must be made.

This maybe assumed to be repre examplawith the assumed mean ratio of steam meter-for example, a C02 meter. When, the efficiency meter reports too little CO; vpier unit volume of fuel gas the fuel feeding rate is increased, relative to the air supply, or viceversa.

New I am awarethat it has heretofore'been proposedto malre the rate of fuel feed dependent upon the rate of air feed. I wish topoinil out that I do not treat the fuel feed as a dependent variableand make it hunt the rate of air feed, but start with the assumption of a proper ratio offuel to air and deal only with deviations therefrom just as Itreatthe ratio of load to airflow as an assumed mean ratio and deal only with deviations from saidratio. V

This simplifiesthe entire problem by permitting one to adjust simultaneously the fuel and air for changes in load, as reflected in variations of gauge pressurefroma selected value.

Now in particular installations the problem of air supply; is divided'between induced draftand forced draft. Again I start with-an assumed ratio or mean Vanddeal with variations therefrom as detected by a furnace pressure gauge. Hence,

in controlling induced or forced draft I step up or down the-two draftcontrollers (whatever they may; be .:simultaneously, onthe assumption of the proper ratio, and .let. the adjustment between them be made under the control of the furnace pressure gauge,;or.a gauge which is sensitive to deviations from the proper ratio of induced to forced draft, pressure. 1 p

vAlso in particular, installations the fuel feed problem may be complicated by the burning of powdered coal, in that the feeding of powdered coal; into the furance is' to be promptly changeable with, change in rate of main air flow, whereasbringingup and grindingiof fuel is a matter which must also be adjusted. f

The relationof bringing, up and grinding of coal for feeding of powderedcoal to the furnace is :assumed to have a definite ratio and any deviation from said .ratio, maybe detected by variation fromfla mean in the amount of powdered ,coalavailable tothefeeder. This may be detected by weight and adjustment made 'accordingly, if desired Generally the coal grinder, maintains'a fairly. large accumulation of pow-u dered coal which-will take care of temporary deviationsfinrati b'ut automatic adjustment is desirable.

Nowit is to be observed that within the broad aspects 'ofimy invention any or'all of the steps of my method may be performed by hand. For

to air to fuelyany desired'i'ncrease in steam de- 110 adjustment of air and fuel-feeding rates.

The deviation required to secure accurate correspondence of results, i. e.,to hold up or down gauge pressure, is made byan adjustment regulated in accordance with the steam pressure gauge. Thus, increase of delivery ofthe boiler may be easily secured by selecting a higher pressure point on the gauge as the mean, or when orifice or valve control is employed to regulate the proportion of load of each boiler, such orifice or valve may be adjusted to control the actualrate of delivery and the rate of fuel 'and air supply changed accordingly to raise orlower the gauge Then, as between the proportions of fuel and air I may make an adjustment to secure the desired efiiciency of combustion, as detected by the CO2 meter. 1

Also, as between induced and forced draft, I may make the necessary differential adjustment as may be indicated as desirable by the furnace "value;

Proceeding upon the fundamental concept of regulation as'above I provide, according to the present invention, suitable means for carrying out the process in practice. The first problem in this connection is to provide a practicaLworkable way for regulating the air delivery. I secure this by driving a fan at variable speed.

Now it is known to drive a fan at a fixed speed and regulate the delivery by means of dampers; and it is known to drive a fan at-variable. speed by a wound rotor A. 0. motor. In power gen erating plants, to which my invention is peculi-, arly applicable, fans of great-size are-required. For example, a fan requiring 500 H. 'P. is not at all unusual. It is highly desirable to supply the major partof the power to such apparatus by A. C. as that can be received through transformers directly from themain generators,

whereas the translation thereof to D. C. would involve large losses and large investment costs.

I have developed an A. C. variable speed drive as disclosed in my co-pending case, Serial No.

, 275,61, wherein the major part'of the motion and power issupplied by an A. C. squirrel-cage motor and the supplementary increase or decrease of motion and power is supplied or taken up by a D. 0. machine acting as either a motor or as a generator. This drive .is capable of operating at any predetermined speed within its range under the control'o'f a rheostat settingx That is to say, it will give a fixed speed for each rheostat setting so that its performance may be any desired fuel feed may be accurately attained.

Likewise, accurate adjustment as between induced and forceddraft is also attainable by this drive.

Next, in order to secure suitable adjustment of the rheostats, for air supply or fuel supply, or

' and simple livery may be made immediately by simultaneous adjustment of any mechanical or electrical de vice to control the rate of operation of any element enteringinto combustion control, I have been compelled to devise a regulating system.

This regulating system is novel in itself, independentof its particular function herein. That is to say, I have provided anew regulating or control systemper so which involves both'a novel 7 methodol' operation and a novel means to carry out the desired method of operation.

According to my novel regulating or relay system I control a desired consequent orplurality of consequents, according to the directions of one or more controls; The regulating system and method are applicable to any problem where one or more elements are tobe regulated, according to conflicting requirements of one or more con- 7 trols.

Now, in a boiler control system, the controls are, i'orexample', gauge pressure and efficiency of combustion.-

The conse uents are, for example, absolute values of air feed and fuel feed and the ratio of air feed to fuel feed. Also, for example, the control maybe furnace pressure, or variations from predetermined ratio between forced and induced draft, and the consequent may be the relative speeds of the forced draft fan and the induced draft fan, or the relative rate of forced draft air supply to the rate of induced draft exhaust.

In a more comprehensive system the controls may be all of the above recited or the consequents all of the above recited, and may be interrelated. 1

Where such plurality of controls and consequents are to be inter-related I proceed as followsp First, for any change in the main control, 1. e., gauge pressure, I make a definite step of change in both main consequents, namely, air supply and fuel supply, according to the initially assumed relation.

For example, if the gauge pressure drops, I advance the absolutevalue of both fuel and air feedrates but keep them proportioned according to a fixed-assumed relation. As soon as this definite step of change has been completed I wait a predetermined interval to let the change take I effect with respect to gauge pressure and to see if the assumed relation between fuel and air is proper. I then test the fuel to air relation to see if it is proper; if not, then an adjustment of the ratiois made, as by varying fuel in respect to air. l 1

Then I again test the maincontrol, i. e., the gauge pressure, to see whether the aforesaid fixed step is sufficient. If it is not, then I take another definite step of increase ordecrease of air and fuel in the initially assumed relation and again wait 'to'see both whether the relation is proper and whether the degree ofadjustment is proper.

My method of adjusting the consequents to the controls is based upon taking substantially fixed steps, which are adjustable, at timed intervals, whichareadjustable, but after being adjusted remain fixed.

I test the controls in succession. I may test them if they conflict or if they do not conflict, simultaneously or in succession. Hence, a consequent which is subject to two controls which may conflict can follow in an orderly way the conflicting requirements, even though they confiict. By thus. successively and alternately testing and adjusting I. do not require any of the the hoppers 13.

speed AFC. drive, hereafter described,. The-pulelaborate means .01 interlocks such ashave heretofore been required.

The testing and adjusting means tionis notably simple.- The controls are, simple contact needles swinging either: way; from a neutral positiontomake contact .By suitable contactor'relays, positive-or negative potential, forpositive or negativeadjustment, respectively, of i all related consequents, is provided. Since. the controlsmay have conflicting requirements,

so that both positive and negative-potentials might tend to be applied to the same consequents at the same time, I interpose a switching device.

herein designated as the timing controller, which, inan orderly manner and for defmite,

periods, gives each control complete, domina-, tion over all its related consequents. The inter val of waiting may be interposed at any point and it may be made as long or as short as desired,

This switching device is made up in thepreferred form of my invention as a series of rotary segments with adjustable stationary contactors. Obviously, a wide range of equivalentsis possible with; my switching device, but the speciiicform ,of the'switching device aboveis simple, il'iCX-v pensive and easily constructed, operated and adjusted;

- Now, in order to acquaint those skilled in the art with the manner of constructing and operating a device embodying my invention I shall describe, inconnection with the accompanying drawings, a specific-embodiment of the same and the manner of use thereof.

In the drawings herein, similarreference numerals refer to similar parts;

Figure 1 is a diagram of a boiler having the various operating and control elements indicated in connection therewith; I v

Figure 2 is a diagram of the connections involved in the system and method of control;

. Figure 3 is a front elevational viewof th commutating or switching device and I Figure lis atransverse section'taken on the line 4 4 of Figure 3. I

Referring first to Figure 1, I have shown herein diagrammatically the j main operating and controlparts for a power generating boiler 1;,

which may be of any suitable type. This boiler 1 "is provided-with a steam pressure gauge 20f .a type suitable to operate the electrical controls hereafter to be described. The fire box 3 is shownin this case'as fired with powdered coal through two sets of nozzles, s and 5 respectively, having individual means for supplying powdered coal thereto. While the invention is. herein shown as embodied in a steam generating plant employing powdered fuel it is to be understood that this is merely by way of illustration and not of limitation. a a

The furnace 3 is fed with coal and air by du-- plicate apparatus for each, mainly fertile-sake of reliability. The nozzles i and 5 receive their mixture of powdered coal andair through a passageway 6 from the coal pulverizeif'lythis mixture, being moved by the exhauster Bfidriven by a suitable driving motor 9. i

As illustrated on the right hand side of Figure 1, fuel fromasuitable source of supply is delivered by a pain-of coal feeders 1c 10 from The feeders 10' are driven by feeder motors 12, the speed of these motors being regulable in order to control'the; rate-at whichfuel is supplied to the boiler. -This motor 12 may be avariable speed motor, for example, a D... C. motor or it may; be a variable of my invensure gauge 33.

verizer 7 has a grinding mill '14 driven by a variable speed electrical drive 15. The exhauster motor'gmay be driven at substantially constant speedalthough this may be a variable speed motor; or drive if desired. H

.Primary air. for carrying the pulverized fuel is supplied to the pulverizer '7 through the duct 16, this duct leading from the forced draft sup-- nished by a pair of forced

draft fans

22 and 22,

driven by variablespeed drive mechanisms 23,

23, These fans'22 and 22'-,deliver air'through the conduits 24, 24- to the

air heater

18,18

which is heated by the exhaust gases after they pass through the economizer 25.

After the air passes outof theair heater 25 into the conduits 17, 1'7? ,the major volume of the same is delivered to the furnace 3 through the secondary

air supply ducts

26, 26. The main volume of air is supplied

throughlthe ducts

26, 26, the air supplied through the

ducts

16, 166 being insuff cient to support complete combustion of the fuel and serving rather as a carrier,

of the fuelto bringit into the furnace 3. where it mixes with the main air supply which is required to support combustion.

The products of combustion pass up through the tubes of the boiler 1 then through the economizer 25.then through the air heater '18 and thence to the conduit 27- leading to the stack23.

The conduit 27 is divided into two channels,-29, 29', leading to the,

exhaust fans

30, 30, which are driven at any desired speedwithin limit by the variable

speed driving devices

32, 32, which are of acharacter similar to'the devices 23, 23' for driving-the forced draft fans. 1 I

The pressure of airv in the furnace ispreferably maintained at a pressure slightly below" atmospheric generally in the neighborhood of .01 5

of an inch of water. The pressure prevailing in the furnace 3 isindicated upon the furnace pres- When the ratio of induced to forced. draft is proper the above statedpres sure, slightly less'than atmospheric, is maintained within the furnace 3.

Obviously, in order to vary the-rate of steam:

delivery by the boiler 1,the amount of heat developed in the furnace must be likewise varied,

assuming a constant condition of efficiency andthe like in the boiler-and the furnace. Such variation in developed heatmeans variation of the chemical union of fueland oxygen of the air. In order to maintain efficient combustion it is necessary that the ratio of fuel to'air be maintained at a proper value. Variation of the heat developed, therefore, must be accomplished by simultaneous variation of airsupply and fuel supply in order to maintain the eiiiciencyof combustion which is desired. This problem of varying simultaneously the air and fuel is, in thepresent instance, complicated by the necessity for maintaining the proper ratio of forced to in duced draft,0r viceversa.

' The efficiency of combustionis determined by a carbon dioxide meter, generally termed a C02 meter; this is indicated at 34 as connected to the conduit 27, through which the productsof com bustion flow to the stack.

To obtain the best, possible combustionerilciency from the boiler it is necessary to mix with the fuel as nearly as possible the correct amount of air to provide twoparts of oxygen for each part of carbon in the fuel. If too much air is furnished too much heat is wasted up the stack.

If too little air is furnished, insufficient oxygen is supplied and not all the fuel is burned. Air

in excess of the amount necessary must be sup plied to insure that, so far as possible, each part of carbon comes in contact with the required amount of oxygen. This is checkedby measur ing the percentage of CO2 in the flue gases, this percentage being in the neighborhood of 12%; to 14% under the best practicable conditions.

With theboiler in continuous operation and connected to a steam main not shown, for delivery of steam to a turbine or the like, the load may be assumed to be properly carried, so long as the steam pressure gauge indicates that an adequate pressure is maintained. That isto say, so long as thesteam pressure gauge indicates that a constant pressure is maintained the'rate of combustion is proper for the load carried bythe boiler. Any deviation of the ratio of rate of fuel combustion to load will be evidenced by riseor fall gauge 2.

of steam pressurewhich will at once affect the Therefore, with a given speed of the induced draft fans and the forced draft fans forpassing a predetermined amount of air through the fire box per unit oftime and with a proper-setting of by the

meter

34,2. correction of the ratio of air Also, in increasing the coal feed 10 and-damper l9 tosupplythe necessary fuel for union with a predetermined.

volume of air and the steam pressure gauge indicating the desired pressure, the boiler maybe assumed to be in proper operation, carrying its a I. g

If. the boiler pressure should drop, indicating that the rate of heat development is not as great as required, fuelandair feed should be simultaneously increased-in such proportion to to fuel feed must be made. the rate of combustion. the, induced draft and forced draft must be simultaneously increased in such a manner as tov maintain the. furnace pressure at a proper value as determined by the furnace pressure gauge'33.

Now it can be seen that theautcmatic control system is called upon to vary at least three things,

namely, forced draft, induce d draft and coal food,

while maintaining a predetermined ratio between 7 total air flow and fuel supply and between forced and induced draft, total air flow inthis case being controlled by thetwo factors, namely, the forced 'draft fan'22 and the induced draft fan 30.

The system of control shown in Figure 2is of relatively great simplicity as compared with devices of the prior art for accomplishing the same object.

' The simple variable speed drive which I have recently developed and which is the subject matter of the aforesaid co-pending application, whereby fan 30, shown at the left of FigureZ.

of air tofuel is not.

the speed of the fans may be varied smoothly and continuously throughout their working range, permits the correspondingly simple scheme of automatic combustion control which is herein shown.

This drive will now be described briefly in conneotion with the operation of the induced draft This drive comprises a squirrel-cage motor 37 having the outer part which is usually the stator or case indicated at 38, mounted for rotation and having also the squirrel-cage rotor 39, the shaft of which squirrel-cage. rotor 39 is connected to the drive shaft the fan. The outer rotating member 38 is'provided with windings which are supplied with alternating current through suitable slip rings.

A direct current machine 40 has a stationary field'42 and a rotatable armature 43, the shaft of which is connected to the outer rotatable member 38 of the squirrel-cage motor 37. 1

A D. (3. generator 44 has a stationary field 45 and an armature 46, the armature 46 being connected in series with the armature 43 of the machine 40.

The armature 46 of the generator 44 is driven by an AC. motor '47 which may be of any preferred type, as for example, either a squirrelcage induction. motor or a syncl-irono'us motor.

The main squirrel-cage motor 37 and the motor 4? of the motor generator set 48 are fed in parallel from the A. C. mains 49. 7

While I have shown three phase current supply and this is preferable, it is to be understood that I am not to be limited to three phase current as single phase or other type of alternating current supply may be employed.

The fieldof the D. C. motor 40 is separately ex cited from the D. C. constant potential supply mains 50. An adjusting rheostat 52 is inserted in the separately excited field circuit for the. motor 40 for the purposes of adjustment. This rheostat is suitably adjusted for operation within a certain range and then is not disturbed during variations of speed of the drive, except as the range" is changed.

The separately excited field 45 of the generator 44 is supplied with a potential which is varied to control the speed of the drive. A potentiometer type of rheostat 53 is connected across the constant potential mains50 and the terminals of the field winding 45 are connected to the

brushes

54, 55, these brushes being adjusted as shown in the present instance by the pilot motor 56 and a suitable worm drive 57.

The squirrel-cage motor 37 provides the base speed and the direct current motor 40 which is of .much smaller rating furnishes the increase or .decreasein speedfrom the base speed.

' The part 38 which is the case of the induction motor is mounted on bearings so that it may be rotated about the same axis as the rotor 39.

The case may be driven in either direction by means of the small D. C. motor 40, which draws power through the motor generator set 48. The speed of the D. C. motor 40 and its direction of drive are varied by varying the voltage of the generator 44 from. maximum positive to maximum negative. V

The speed of the fan 30 is increased above the base speed by causing the direct current motor 40 to drive the stator of the A. C. motor 3'7 in the same direction as the rotor. The speed of the fan then is the sum of the rotor and case speeds.

The speed "of the fan 30 is decreased below the base speed by causing the case 38 to rotate in the opposite direction to that of the rotor 39.

It then drives the D. C. motor 40 as a generator, which forces power back through the series connection between the

armatures

43 and 46 and through the A. C. motor 47 backon to the A. C. mains 49. The fan speed then is the difference between the rotor and case speeds. When the fan speed has reached the lower limit of'speed by armature voltage control of the 11:0. motor 40, the speed range may beextended still lower by field control at the rheostat 52 of the D. C. motor 40 if desired.

The H. P. ratings of the two

motors

37 and 40 on the induced draft fan 30 are in the ratio of A. C; motor seventy-nine percent (79%) and D. C. motor twenty-one percent (21%) in one example of my invention.

The drive for the forced draft fan 22 is identical. However, the H.. P. ratings of the two motors on the" forced draft fan are in the ratio of A. C. motor 85.5% and D. C. motor 14.5%.

Inpractice I may employ several fans for forced draft and several fans for induced draft,

as shown in Figure 1, in which case the motordirect current means 50 and having brushes 631 and 64 connected mechanically together and rotatable by the pilot motor 65 through the worm gear transmission 66. The brushes 63 and-64 are electrically connected to the terminals of the field'Winding-of thegenerator 59. In all other respects the forced draft fan drives for. the fans 22 and 22' are like thedrives for the induced draft fans 30--and 30'.

The pilot motor 67 acting-through a suitable worm gear transmission 68 shiftsthe contact brush 69 of the rheostat '72 forcontroll-ing' the motor 12 of the coal feeder 10.

Instead of controlling .the motor 12 directly,

the pilot motor 67 and rheostat 72 may control the coal feed in any other preferred manner.

'The pilot motor '74, through a suitable worm gear transmission 75, controls the positionof the damper 19. This damper in the conduit'16 controls the rateat'which primary air is sup--- plied to thepulverizer for carrying the powdered spectively, as selected by the selector contact pointer 85. Theserelays control' branch circuits coal intov the furnace 3.

The steam pressure gauge 2 has a :movable pointer '77 which; when steam pressure is prop-- erly maintained, lies between the increase and decrease. contacts "78 and '79, this pointer 77 being connectedatothe negative bus of the D. C.

supply mains 80.. Inv like manner, the furnacepressure gauge 33 has a movable pointer82 which? operates. as a selector: contact between'theincrease and.

decrease contacts

83 and 84.

7 Similarly the CO7. meter has: a selector switch member 85 which operates betweenincrease and I ing controller, as diagrammatically indicated in decrease contacts. 86 and .87, respectively.

, The steam pressure gauge 2 indicates by movement of the pointer contact 77' to'lthe left'that steam. pressure is fallin'gand that the rate of firing-should be increased. Likewise, if the pointerselector 7.7 movestto the right it means:

that steam pressurei isv buildingup and that the rate of firing .shouldbe decreased.

Thefurnace pressure gauge33 likewise indicatesbylnovement.of the pointer 82.700 theright-L tively.

that the pressure in the furnace has decreased below its predetermined value and movement of the pointer 32 to the left indicates that the furnace pressure has increased above the predetermined value.

The 002 meter 34 which represents proper ratio of air to fuel indicates by movement ofthe pointer 85 to the left that the rate of coal feed should be increased, and indicates by movement of the pointer 85 to the right that the rate of coal feed should be decreased. 7

I provide a series of'increase'and decrease circuits between the steam pressure gauge and the pilot motors of the induced draft control rheostat return wire90 is connected to all of the pilot motors.

In like manner the forceddraft fan pilot motor 65has a forward drive wire 92 and a reverse drive wire 93. Thepilotmotor 67 has a forward drive wire 9.4 and a reverse drivewire 95. The pilot motor '74 has a forward drive wire 96 and a reverse drive wire 9T1.

Thebranchcontrol wires are extended to relay contacts of the steam pressure gauge, the furnace pressure gauge and the CO2 meter, respec- The forward contact, 78at the steam pressure gauge 2 controls the relaywinding 98 of the increase relay.-"99. The contact '79, on the other hand, controls the relay winding 100 of the'decrease relay 102'. A series of four wires,'103, 104,

105 and 101 lead tow the

forward wires

88,92, 94 and 96,respectively, of the

pilot motors

56, 65, 67 r Likewise a series of branch wires, 106, 107, 108 and 109 lead respectively to the decrease or reverse

wires

89', 9,3, 95 and 97 of the

pilot motors

56', 65, 67 arid 74.

The furnace pressure meter 33 has a pair of relays 110 and 112controlled by

contacts

83 and 84, respectively,gunder the influence of selector switch pointer 82 for closing forward and reverse branch circuits 113 and 114, respectively, to the forward and reverse

wires

88 and 89 of the induced draft pilot motor 56, respectively.

The COrmeter 34 has a pair of

relays

115 and 116 under the control of contacts 86 and 8'7, re-

1-1-7and 118;respetively, leading to the forward or increase and reverse or decrease

wires

94 and 95, respectively, of the pilot motor 6'7 for coal feed. I

controller 120, the details of construction of whichare shown in Figures 3 and 4. This-tim-' Figure 2', comprises a rotatable shaft 122 upon which are mounted a series of circular discs bearbrushes. These discs with segments, together with their brushes, constitute commutators' or switching devices all in timed relation to each other. .Thus the disc 123, which bears a con--' ing conducting segments and engageable by The brushes 125 are adjustable relative to each other and angularly about the axis ofthe shaft 122 so as to control not only the exact time at which-the circuit is closed and/or opened, but

also the duration of time of such closing and/or opening. The commutator 126 is connected in the branch wire 113 between the forward induced draft wire 88 and thefurnace pressure gauge 33.

Thecommutator 127 is connected in the branch wire 1% between the steam pressure gauge and the forward or increase wire 92 for forced draft. 1

The commutator 123 is connected in the branch circuit 105 leading to the forward wire 94 for coal feed. The commutator 129 is connected to the branch wirell'l between the CO2 meter 34 and the forward or increase wire 24 of coal feed.

The commutator-130 is connected in the branch 161 leading to the forward wire 96 of the primary aircontrol dampers. A number of spare commutators, 132 on the increase end of the timing controller 126 are shown. In fact, as many commutators as may be required may thus be mounted upon the shaft for either increase or decrease operation or" the respective pilot motors or other electro responsive devices or the like.

The reverse end or decrease end of the shaft 1 122 bears a series of

commutators

133, 136, 137,

138, 139 and 140 which are connected in the re-' verse or decrease branches in the same order as the forward or

increase'comrnutators

123, 126, 127, 128, 129 and 130, abovedescribed. H

Now it is to be observed that in the timing controller120 the conducting segment such as 2 can cooperate with only one at a time of the forward and reverse contacts 78.and "79, respectively.

The brushes for each commutator are, however, adjustable toward or away from each other so as to increase or decrease the duration of contact. Preferably, but not necessarily, they terminate contact at approximately the same'an gular position so that the common return relay contact 143, may, under the influence of the commutator 144 and relay 145, break the comthe conmon return wire 90 and thereby relieve tactors or commutators of arcing. 7

The

commutators

126 and 129 on the increaseend and the commutators 136 and 139 .onpthe decrease, end haveconducting segments of substantially the same angular extent and position; Their brushes-likewise are adjustable with respect to each other to increase or decrease the duration of contact. a 1 g The shaft 122 is rotated ina clockwise direction as .viewed from the left-hand end and as inolicatedtby the arrow adjacent said left-hand end. i l

The shaft 122 is rotatedby a motor 146 through back gears147 and the circuit of the motor 146 is under the, control of :arheostat 148 and a commutator 149, the purpose of which is to cut p the rheostat liii in'and out of circuit with respectto the driving motor 146 so as to change the angular rate of motion, of the shaft 122 for 1 different partsof a rotation. That is tosay, the commutator 149;preferab1y hasa conducting segapplication of successive impulses.

ment corresponding with the angular extent of conducting segments on the active commutator discs so that the rate of motion of the motor 146 is increased as the contacts arrive under the brushes and then the shunt about the rheostat 148 is opened and the rheostat 148 thrown into the circuit with the motor 146, causing it to slow down and thereby drive the shaft 122 through the remainder of its rotation at slower speed so as, to introduce a desired interval of waiting. It will be observed that the brushes of the commutator 144 are so disposed that the segment breaks the circuit in each case justbefore corresponding branch circuits are broken at the other. commutators, in order to permit the common returnwire 90 to be interrupted so to relieveeach set of contacts of theduty of breaking the respective. current flows. Thus, arcing at the controllers or commutators is avoided.

Now it is to be observed thatin the orderly sequence ,of events a test-sis made of furnace pressures and carbon dioxide by closing both iorward andr everse branch wires at the

respective commutators

126, 136 and 129 and 139, respectively, to detect any deviation offurnace pressure from the selected or predetermined standard- 'orthe coal feed may be varied as determined. by

the selector contact. r

Thereafter the circuits for the steam pressure gauge contacts are closed to test whether an in creaseor decrease of firing is required. Since the selector contact'l'l can cogact with only, one of its pair of contacts and since the circuits of the pilot motor leading to the pressure gauge 22 are closed only after the circuits for the furnace pressure gauge and CO2 gauge or meter are closed, no conflict can occur. 1

After the testing ofthe steam pressure gauge theicommutator 149,1which-con'trols the speed of the motor 14.6, acts to interposea period of waiting before the next period of test is'made.

The timing controller thusperforms several functions. I

1.. It permits the pilot motors .to turn their respective rheostat arms for a period, then it cuts them out of service fora period, thereby giving the furnace time to. respond between the An adjustable rheostat which is cut into and out of the circuit of the motor which drives the intermittent contact device mechanism with the on and ,ofii switching of the pilot motors regulates the ratio of the time between successive impulses.

2..It permits an independent adjustment of the time each pilot motor is in circuit, with respect to the'other pilot motors. ment is'made bymoving the upper contact finger shown inFigure 4 up or down onits support. 3. It prevents the simultaneous closing of the increase and decrease circuits. It will be noted that the increase or decrease contactors of any given-gauge cannot be closed simultaneously as the gauge can make contact in but one direction at .a time. Two different gauges may, however,

This adjust- 1- 1 n, lo

simultaneously call for opposite actions on one s of the pilot mo tors.

the induced draft fan while the furance pres sure gauge may call for decreased speed. This is preventedby staggering the corresponding segments on the shaft so that the impulse of the second gauge is not transmitted to the pilot motor until after the first gauge has completed the transmission of its impulse. i Y

In Figures 3 and 4 I have shown an embodiment of the timing controllerin which the segments employed are all alike and interchangeable. them on the shaft 122 the leading end of the They are so designed that in assembling shaft supported at its ends. in suitable bearings,

one of which is shown at 152 mounted upon the insulating base 153. This base has a rectangular opening 154 formed therein through which the individual commutator segments -or contactors project. The motor 146 is back geared to the shaft 122 through gears 147 comprising a suitable countershaft for reducing the mo tion of the motor shaft to a suitable speed for the operation of the-contactors.

While in the diagram of Figure 2 the commutator elements are shownas discs of insulation bearing conducting segments in the construe tion showninFigures 3 and 4, the conducting segments are formed integral, with supporting arms such as the arm 155'having a'clamping foot .or hubportion 156'formed integral therewith.

A cooperating cap'or strap 157 is bolted to the clamping portion 156'as by means of the bolts 158,158; In the case of the

circuit controllers

144 and 149, two such metal segments have their hub portions bolted together so that the arcuate contact portions 159- and 160 for the controller 144 are in the same plane. Likewise the contacting portions 162 and 163 for the controller 149 are in the same plane. The square shaft 122 is provided with a sleeve 1640f insulation so as to insulate all of the controllers to vary the angular position of the contactor brush 170 which is pivotally mounted as at the' pivot 172 upon the clamping portion 167.

The clamping portion 167 makes electrical contact with the arcuate supporting rod 168 and this rod inturn is connected to a circuit ter minal, as indicated at 173. The end of therod forms a suitable binding post as indicated at 174', 174 for connecting the circuit wire 173. 5

The brush member 166 is of a construction similar to the brush 165 with exception that it is insulated from the supporting rod 168 by a sleeve 175 of suitable insulating material. This brush 166 is intended to be relatively stationary although it has a smalldegree of'adjustment in the the form shown. W Naturally if desired a suflicientgly long flexible lead may connect the brush mem her 166 with the stationary binding post 176 to permit of any desired degree of adjustment of the pos'itionof the brush 166. As shown the brush 166 is connected to the binding post 176 by a lead 177 and'the post 176 is connected to a circuit wire 17S upon the opposite side of the board.

I have shown a square shaft, since in the particular timing, controller which I employ herein eight different positions of a contactorsegment may be secured as it will be observed that the arm 155 is angularly disposed with respect to the diagonals of the square-shaft 122 so that by disposing the arm 155 on one side or the other of theadjacent.

corner of the shaft 122, a suitable variation in angular position may be secured to make up the eight separate positions in which'the contactor may be disposed on'the axis of the shaft 122. Obviously Ido not intend to limit the invention to this specific construction as the shaft maybe a round shaft provided with suitable splines or otherwise constructed to provide predetermined seats or shoulders 'or grooves for aligning the contactors in a predetermined manner.

It can be seen that as the motor 146 rotates the shaft 122 through the reduction gears 147 the cir- I cuits arecontrolled as follows:

The circuit is broken at the contact 143 in the common-return by the controller 144, then a I period of waiting occurs to'perrnit the adjustment which has previously been made, to take effect. Then the controllers 126, 136, '129 and 139 close their contacts for the induced draft control and coal feed control, respectively. If the furnace pressure gauge 33 closes either the increase or decrease circuits, a corresponding adjustment of carbon dioxide gauge 34 closes itscircuit'for increase or decrease,.a corresponding action of pilot motor 67 will occur.

Immediately thereafter the circuit is broken at contact 143 to relieve the

controllers

126, 136 or 129, 139 of breaking the connection, and then immediately thereafter the circuit is again established to prepare for the test of steam pressure which thereupon occurs. The test for steam pressure closes the circuit for all four pilot moill) tors both for increase and decrease and the steam gauge selector contact 77 selects which if either action is to occur. Just before the contactsare broken at the controllers the common return con tacts 143 are again opened to relieve the controllers of the duty of breakingthe current flow.

It will be observed thatthe brushes of thecontroller 144 are set close to each other and are in a predetermined angular position with respect to I all of the other controllers so that the circuit is broken at the brushes of the controller 144 just in advance'iof breaking the circuit at any ofthe other controllers.

I'wishto call attention tothe fact thattheoretically the timing controller would not need to be connected inthe individual branch circuits of the pilot motors but might be connected merely inthe common return branches182, 183 and 184 for the selector switches of the "gauges 2, 33, and 34,. I-Io'wevenit would be then impossible to make the different relative adjustments between the acti'ons of the various pilot motors in response to the action of each gauge as ispossible in the system as shown. That is to say, in the present schemeyas 115 the pilot motor 56 will be made. Likewise, if the shown in Figure 2, by adjustment of the brushes of the individual controllers relatively greater or less action of the corresponding pilot motors may be secured for-each on period. For example, consider thecontrollers123,127, 128 and 130. It may be desirable to have the pilot motor 74 make a larger number of revolutions than some of the other pilot motors. If so, the brushes for the contactor 130 are moved closer together so as to give a longer periodof. closed circuit for'the said motor '74. Thus individual adjustments of the response of the Various pilot motors for the control of each gauge may be made to secure optimum conditions in theresponsive apparatus;

It is to be observed that the variable speed drive of my invention iscapable of simple rheostat control and for a given position of the controlling rheostat a fixed speed will be held by the drive. In this manner, due to the simplicity of the control of speed of the largepower units, as well as'of the small power units, a simplified sys-' tem of control is made possible. 7

In compliance with the requirements of the patent statutes I have herein shown and described apreferred embodiment of my invention. It is however to be understood that'the invention is not limited to the precisearrangement herein disclosed, the same being merely illustrative of the principles of the invention. What I consider new and desire to secure by Letters Patent is pointed out in the appended claims:

I claim:

1. The method of regulating the movement of air through a furnace having forced draft and induced draft which. comprises periodically adjusting the value of both forced and induced draft according to a fixed ratio, and periodically adjusting the relative values of forced and induced draft between periods of simultaneous adjustment of the values of the same.

2. The method of regulating combustion in a furnace having air supply controlled by forced draft and induced draft and having coal feed, which comprises, comparing total combustion with a predetermined standard, making a definite step of adjustment of the values of air supply and fuel feed in the direction determined by said comparison, comparing the ratio of forced draft to induced draft'with a predetermined standard and making a definitestep of adjustment of the relative values of forced to induced draft in a direction determined by said comparison, said steps of adjustment'being made during separate periods of time occurring in an orderly progression.

I 3. The method of regulatingcombustion in a furnace having air supplied byforced draft and induced draft and having coal feed which comprises comparing total combustion .with a predetermined standard, making a definite step of adjustment of the value of air supply and fuel feed in thedirection determined by said comparison, comparing the ratio of forced to induced draft with apredetermined standard, making a definite step ofadjustinent of the relative values of forced to induced draft a direction determined by said comparison, comparing the, ratio of air feed to fuel feed with a predetermined standard and making ,a definite step ofadjustment of the ratio of fuel to air in the direction determined by said comparison,certain of said steps of adjustment being made during periods of time occurring alternately in an orderly progression.

4. In a; system of combustion, the methodof controlling a plurality of inter-related actions which control a commonresultant which comprises comparing the absolute valueof the resultant action with a predetermined standard, positioning a responsive element in accordance with said comparison, periodically testing at predetermined intervals the position of said responsive element with respect to a predetermined standard position and simultaneously varying the absolute values of a plurality of the interrelated actions in a direction determined by the deviation of the position of said responsive element from said standard position, comparing the relative values of two of said inter-related actions, positioning a'second responsive element'in accordance with said second comparison, periodically testing at predetermined intervals which intervals alternate between intervals of the first periodical tests, the position of said second responsive element with respect to a predetermined standard position, and simultaneously with said second intervals of testing varying in a direction determined by the position of said responsive element the relation between said two last named actions.

5.111 a system of the classdescribed a plurality of devices havinginter-related actions, a plurality of controllers governed bythe inter-related actions of said devices, regulators for said devices adjustable by said controllers, and means for subjecting certain of said regulators to the action of different controllers in predetermined sequence.

6. In a system of combustion, a plurality of devices having inter-related actions controlling a common resultant action, an element responsive to the deviation of the resultant action from a predetermined standard, a first means controlled by said element for regulatingthe action of said plurality of devices to vary the resultant action, a second element responsive to the deviation of the relation between the actions of two of said devices from a predetermined standard, a second means controlled by said second element for regulating the action of one of said two last named devices to vary the ratio of their action, and a timing controller for allowing said first means and said second means to act alternately for predetermined periods of time.

721111 a boiler control the combination of air supply means, fuel feeding means, a steam pressure gauge, a combustion efficiency meter, adjusting devices for the air supply means and the fuel feed means subject to the control of the steam pressure gauge andthe efliciency meter and a timing control for permitting the steam pressure gauge to govern the adjusting devices for predetermined periods of time, said timing controller permitting the efficiency meter alternating between periods of control by the steam pressure gauge to control one of the adjusting devices.

8. In a combustion control system induced draft supply means, forced draft supply means, fuel feed means, a gauge responsiveto conditions "affected by the combustion, a gauge responsive to for periodically regulating one of said adjusting devices in accordance with the draft ratio gauge,

the first, second and third recited means of the timing control acting in predetermined order.

9. In a combustion control system air supply means, fuel feed means, adjusting devices for said means comprising rheostats, a gauge responsive to conditions affected by the combustion, a gauge responsive to efiiciency of "combustion, electro-- 10. In combination, a forced draft fan, a variable speed electric drive therefor. an induced draft fan, a variable speed electric drive therefor, a coal ieedingdevice, a variable speed electric drive therefor, individual rheostats for said variable speed drives, reversible electromagnetic devices for adjusting said rheostats, a gauge responsive to conditions affected by the combustion, a gauge responsive to the ratio 'of forced draft to induced draft, a gauge responsive to efficiency of combustion, selector contacts governed by said gauges, forward and reverse circuits from said gauges to certain of said devices controlled by said selector contacts, and a timed sequence controller for closing certain of the circuits in predetermined sequence.

11. In a system of the class described, the combination of a plurality of-controlling devices, a plurality of controlled devices of which one controlled device is subject to control by more than one controlling device and a sequence timing controller for subjecting said one controlled device to the control of said controlling devices in predetermined sequence.

12. In a system of the class described, the combination of a furnace, an induced draft fan, a forced draft fan, a furnace pressure gauge, alternating current mains, variablerspeed drive units operated by currentfrom said mains for driving said fans at variable'speeds extending throughout the range of operation of the furnace, rheostats for varying the speeds of said drive units, said units having definite speeds for definite positions of the rheostats and means controllable by said furnace pressure gauge for shifting the rheostat of the drive unit of one of the fans to maintain a desired ratio of induced draft to forced draft.

13. In a steam generating plant,'a boiler, a furnace, an induced draft fan, a forced draft fan, a furnace pressure gauge, a steam pressure gauge, attending current 'mains, variable speed drive units including squirrel cage A. C. motors operated by current from said mains for driving said fans atspeeds which are variable throughout the range of draft required, potential control rheostats for varying the speeds of said drive units in any desired degree within the range of control, said units .having definite speeds for definitepositions of the rheostats and means for subjecting said rheostats periodically to the control of the steam pressure-gauge and-between each period subjecting one of the rheostats to the control of the furnacepressure gauge.

V 14. The method of'regul'ating a plurality of interrelated actions controlling combustion, which comprises periodically adjusting the values of two of the actions in fixed ratios and between the periodic adjustments adjusting the relative values of said two actions.

15. The method of regulating a plurality of interrelated actions controlling combustions, which comprises measuring variations in the ratio of the load demand to the output, periodically making an adjustment of the factors of combustion in fixed ratios in accordance with the variations, measuring the efiiciency of combustion, and alternately with said periodic adjustments adjusting the fuel to air ratio in accordance with the variations in efliciency of combustion. 16. In a combustion control system means f0 feeding one of the elements of combustion, means including an adjustable rheostat for ad justing rate. of feed, means responsive to predetermined conditions for adjusting the rheostat at a constant rate, means for-periodically interrupting said last named means, and means forvarying the ratio of duration of periods of adjustment and periods of interruption.

1'7. In a combustion control system means including pilot motors for controlling the'rates of feeding of the elements of combustion, means'responsive t0 the conditions'of combustion for adjusting said pilot motors at a constant predetermined rate, a timing controller for periodically interrupting the adjusting of the pilot motors and variable rheostat means for adjusting the duration of the periods of interruption.

18. In a combustion control system a plurality of devices having interrelated actions controlling a common resultant action, an element responsive to the deviation of the resultant action from a predetermined standard, a first means controlled by said element for regulating the action of said plurality of devices to vary the resultant action, a second element responsive to the deviation of the relation between the actions of two of said devices from a predetermined standard, a second means controlled by said secperiods of rest or inactivity, and means for adjusting the relative durations of times of action and of rest.

19. In acombustion control system, a furnace, air supply means, fuel feeding means, a device responsive to heat demand on the furnace, a combustion efficiency meter, adjusting devices for the air supply means and the fuel feed means subject to the control of the demand responsive device and the efficiency meter, a timing controller for permitting the demand responsive device to govern the adjusting devices for predetermined periods of time alternating with periods, of control of one of the adjusting devices by the emciency meter and periods of interruption for allowing conditions to equalize, and adjustable means for varying the relative durations of periods of control and periods of interruption.