US2608199A

US2608199A - Gas mixing control method and apparatus

Info

Publication number: US2608199A
Authority: US
Inventors: Edwin X Schmidt; Charles W Warner
Original assignee: Cutler Hammer Inc
Current assignee: Cutler Hammer Inc
Priority date: 1946-03-06
Filing date: 1946-03-06
Publication date: 1952-08-26
Anticipated expiration: 1969-08-26

Description

g- 1952 E. x. SCHMlDT ET AL 2,608,199

GAS MIXING CONTROL METHOD AND APPARATUS Filed March 6, 1946 3 Sheets-Sheet 1 A g 1952 E. x. SCHMIDT ET AL 2,608,199

GAS MIXING CONTROL METHOD AND APPARATUS Filed March 6, 1946 3 Sheets-Sheet 2 26, 1952 E. x. SCHMIDT ET AL ,60 9

GAS MIXING CONTROL METHOD AND APPARATUS Filed March 6, 1946 3 Sheets-Sheet 5 I54 I55 I 6 I37 700 E oso-- 3 PEAK SHAVING GAS 6mm U k E 600. MINIMUM HEATING VALUE. Q Q 550-- 8 MJ W I I I l 30 4o a0 I00 PEAK SHAVING GAS IN MIXTURE- Patented Aug. 26, 1952 GAS MIXING CONTROL METHOD AND APPARATUS Edwin X. Schmidt and Charles W. Warner, Milwaukee, Wis., assignors to Cutler-Hammer, Inc., Milwaukee, Wis., a. corporation of Delaware Application March 6, 1946, Serial No. 652,431

8 Claims.

This invention relates to improvements in gas mixing control methods and apparatus, and although not limited thereto the invention relates more particularly to such methods and apparatus adapted for peak shaving.

In the operation of gas utilities it frequently becomes necessary or desirable to supplement the normal maximum supply of gas by an auxiliary supply consisting of a mixture with air of a liquid petroleum gas or gases. However, a mixture of such gases (propane and/or butane) with air which will function satisfactorily on gas burning appliances when used alone or as a relatively large percentage of the gas flow, invariably requires a heating value thereof which is substantially higher than that of the base gas. The result is that more potential heat is delivered to the domestic consumer per unit of volume, and the income of the gas company is reduced due to the lower volumetric consumption. Therefore when the demand for gas requires the use of a supplementary fuel, or peak shaving gas, it is desirable that such additional gas be supplied at the minimum heating value which will not cause trouble on consumer appliances. Moreover, inasmuch as the proportionality of the peak shaving gas in the mixture determines the amount of increase in heating value required to eliminate burner trouble, the volume of peak shaving gas must be properly proportioned with respect to the volumetric rate of flow of the base gas, and the heating value of the peak shaving gas should have a definite relationship to the preselected proportionality.

Assuming that a utility normally supplies carbureted water gas of 540 B. t. u. per cubic foot, 2. propane-air mixture of 720 B. t. u. would theoretically be required to provide for substitution thereof completely for the carbureted water gas (100 per cent interchangeability). However, we have found that a 700 B. t. u. mixture of propane and air will afford satisfactory burner performance. Similarly, we have found that a mixture of carbureted water gas of the aforementioned quality with up to about per cent of 540 B. t. u. propane-air (peak shaving) gas will likewise afford satisfactory burner performance. On the other hand, if one-half of the final mixture consists of carbureted water gas of the aforementioned quality and the balance a propane airgas mixture, a heating value of the latter of about 650 B. t. u. is required.

Furthermore, in the delivery of natural gas by pipe line companies to distribution companies, the contracts almost invariably prescribe maximum delivery rates; so that an auxiliary supply of peak shaving gas is absolutely necessary.

2 Even in those cases where the demand by the distribution company is permitted to exceed the maximum delivery rate specified in the contract, the charge per unit volume for the excess gas required to be supplied by the pipe line company will ordinarily be substantially greater than for that supplied just below the maximum delivery rate agreed upon.

A primary object of our invention is to provide novel methods of and apparatus for accomplishing the desirable results aforementioned.

Another object is to provide for use of any required volume of the peak shaving gas without deleteriously affecting the combustion or burner characteristics of the final mixture.

Another object is to minimize the required quality or heating value of the peak shaving gas when supplied.

Another and more specific object is to provide methods of and apparatus for. automatically varying the quality of the'peak shaving gas in accordance with variations in the proportionality or volume thereof required to be supplied.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate certain embodiments of our invention which will now be described; it 'being understood that the invention is susceptible of embodiment in other forms within the scope of the appended claims.

In the drawings,

Figure 1 illustrates schematically and diagrammatically a fully automatic peak shaving gas mixing control system constructed in accordance with our invention.

Fig. 2 illustrates a modified and simplified form of our invention, wherein a flow of peak shaving gas is effected at all times for mixture with the base gas flow, the percentage flow' of peak shaving gas being normally maintained low enough to avoid the necessity for any excess in the total heating value per unit volume thereof with respect to that of the base gas; the system of this figure including a hand set selector which not only controls the proportionality of theflow of peak shaving gas with respect to the base gas, but also effects the setting of the associated means for control of the total heating value per unit volume of the peak shaving gas.

Fig. 3 is a graph illustrating theincrease required in the minimum quality or heating value mixture with a base gas, such as carbureted Water gas of 540 B. t. 11. per cubic foot, whereby satisfactory burner. performance of the complete.

mixture is insured, and

Fig. 4 illustrates another form of our invention which is functionally quite similar to that shown in Fig. 2.

Referring to that form of our invention illustrated in Fig. 1, the numeral l0 designates a conduit throughwhich gas from a suitable relatively high pressure source is supplied to a line or conduit, designated by numeral II, for distribution to consumers. The gas supplied through conduit It may be of any suitable char; acter, such as natural gas, carbureted water gas, or the like. This gas will hereinafter be referred to as the base gas which will normally have pre-. determined substantially constant values of: total heat per unit volume, density and combustion characteristics. By way of example, it will be assumed that such base gas consists of a typical carbureted water gas of 540 B. t. u. per cubic foot.

Conduit lllis provided with afixedorifice. I2, 2. hand set valve I3, a firstpressure regulator, des ignated in general by numeral l4; anda second pressure regulator l5.-, which, is inthe form of a. pressure difference.regulator. Eegulator I sis. of a known form wherein the valve portion (not shown) is. adjustably biasedatQW n'd fully, openedposition; the regulaton including a diaphragm He whose upper surface is subjected; throughpipe M to the pressure ofzgas atthe downstream side of orifice l2. Regulator. |4..thus serves to initially control thedistribution. pressure, within conduit ll. As. the required flow (to meetthe demand from conduit ll): approachesa preselected max-i mum value, as. indicated. by the orifice. meter (comprisingorifice t2; pipes [Wand 15 anddiaphragm l5), thepressure drop across the orifice. l2 and hand set valve [3 approaches the prese-. lected setting of thepressure diilerence regulator l5, whereupon the. regulator l5. moves auto: matically. toward clgsed. position, thuslimiting, the. flow to establish afi-xed-orconstant pressure drop. across the orifice l2; and hand set valve i3- jointly. Inasmuch as the amount of restriction is fixed by valve [3 and orifice. I2, suchconstant pressure drop determinestherateof flowof. the gas in conduit 10, andif thisflow isinsufiicientto satisfy the demand; the. distribution pressurelin conduit H) willfall. In attempting to compensate for'thisfall in pressure, the. valveassociated with pressure regulator 14 may go. toward or to its fully opened position, but. this will-notafiect thefiowoigasthrough conduit l0, because the control of fiowhasbeen takenoverby the. pressure difference regulator l 5- Thus upon proper adjustment of valve lBrand adjustment or calibration of. pressure. difference regulator IS; the. samewill cooperate with orificel2 to limit. themaximuin volumetric rate. of flow of gas throughconduit ill' toconduit H, inaccordancewith the. contract. with a pipe line company, as. aforedescribed. It. follows. that, if: the rate of; demand from the distribution line-ll is greater than the aforementioned maximiun volumetric rateof supply. through conduit. [0, thegas pressurein line. will fall below: the predetermined desired pressuretherein. Therefore it is. necessary to provide an auxiliary supply of-gas, suitable for mixture with-the. base gas supplied through conduit l0;; to satisfy the demand for gasbeyond said maximum volumetric rate of sup; ply of the base gas, and-to-maint ain a substanl pns t, P s re. th s l' llillQidfiIi? u iq ine. I

In Fig. 1 we have illustrated means operable. automatically to supply the additional. volumeoj gas to meet the excessive demand from distribution line H, whereby the pressure in the latter is maintained at a predetermined substantially constant value. The means now to be described are also adapted to act automatically to control the quality or total heatingyalue per unit volume of the auxiliary supply of-gasat-a minimum value (which, however, will under no conditions be less than the quality or total heating value per unit I volume of the. base gas) thus minimizing the excess. in quality or richness of the gas supplied to distribution line H when the demand is greater than the-predetermined maximum rate of supply of base gas. Such minimized quality of the auxiliary supply of gas is likewise automatically varied, in accordance with variations in the rate of demand, in such a manner as to insure against improper combustion characteristics of the gas at the various points of consumption.

It may be assumed, for example, that conduit lilr is connected with a. highpressure. source of supplyof 'basegasof 540.3. t. u. per cubic foot; the aforedescribed elements. l2, l3xand l4 acting to normally insure a predetermined relatively lower prcssure'of thegaswithin distribution line i i. Further itmay'beassumed that the auxiliary gas (propane, for example) is. supplied to a conduit v H5.- at; a pressure. normally-substantially higher than the. predetermined relatively low pressure which it is. desired tomaintain inthe distribution line I h Associated with. conduit I6 is a so-called low pressure gas regulator. ll of known form, which includes a valve. (not shown) which is normally biased to openposition-to provide a. free flow of thepropane into the. portion 16 of conduit I6. However, a. pipe. [8; affords communication between theconduit. [that the downstream side of orifice l2. and thechamber- [1 which opens to the upper surfaceofa diaphragm H the arrangement being suchthat the valve of regulator i! will be. maintained closed so longas the pressure. in distribution conduit ll does not fall below the pressure preselected therefor. Upon a decrease in the. distribution pressure below said preselected value, as aforedeseribed, the valve of regulator H will open, thus providing a flow of propane through conduit portion I6 which in turn results ina pressure drop across'the butterfiy valve. l9. Valve I9 is connected by

suitable linkage

20, 21 and 22' with a butterfly valve 23 located in the air line or-conduit 24; said valves preferably being arranged at like angles; in each of their various positionsduring joint operation thereof. The means for effecting movement of valves 19- and 23 comprises;

linkage

25 and 26; link zit-consisting ofa rodattachcd to a piston 21, which is movable toward one end or the other of a cylinder 28- underconditions;hereinafter described.

Conduit 24 has its left-hand endconnected with any suitable source of air under pressure; such source being represented in Fig. 4 by a power-driven bloweror pump designated by immeral 29, the-inlet end of whicl is shown at 29*. Located within conduit 2415a shut-off'valvc 30 of'known form, which is-normally biased to its closed position as bymeans of a spring (not shown), orthe like. A chamberflll above a diaphragm 3i) is connected by pipe 3| witha threeway solenoid-operated valve 32, the operatingcoil of which is designated by numeral33. When coil 33gis deenergized valve 32 is adaptedto move to a positionwhereinpipe 3-! is vented to atmosphere,

h Qughanipeor opening 34, andto disconnect from pipe 3| the supply of air under pressure, through pipe 35, from the conduit 24 at the lefthand side of shut-off valve 30. Pipe 35 preferably has located therein a pilot regulator 36 of known form, whereby the pressure of air supplied to valve 32 is limited to a predetermined value. However, when coil 33 is energized, as illustrated, valve 32 acts to disconnect pipe 3] from vent 34 and to connect the former with pipe 35, Whereby valve 30 is moved to fully open position against the normal bias thereof.

Also located within conduit 24 at the upstream side of butterfly valve 23 is a pressure diiference regulating valve 31 (substantially like the regulator l5 aforementioned), the same having

pipes

31 and 31* respectively connecting the conduit 24 at the upstream and downstream sides of butterfly valve 23 with the chambers at the lower and upper sides of a diaphragm 31.

Thus, assuming that valves l9 and 23 were in fully closed position at the time the valve of regulator I! was opened (due to a decrease in pressure of the gas in distribution line H, as an incident to an increase in demand beyond the permissible volumetric rate of flow of the base gas), the element 38 carried by the aforementioned link 26 will have acted upon the normally closed limit switch 39 to effect opening thereof, with consequent deenergization of coil 33, for the purpose aforedescribecl.

A fluid pressure operated ratio controller 40, of the general character disclosed in Wunsch Patent No. 1,558,529, dated October 27, 1925, and more particularly of the character shown in Fig. 1 of Schmidt and Brice Patent No. 1,999,740, granted April 30, 1935, is employed to effect movement of piston 21, with consequent joint operation of valves 1 9 and 23. More particularly, the pipes 4| and 42 respectively afford communication between portion [6 of conduit I6 at the upstream and downstream sides of valve I9 and the lower and uppers sides of a diaphragm 43; whereas the

pipes

44 and 45 respectively afford communication between conduit 24 at the upstream and downstream sides of valve 23 and the upper and lower sides of a diaphragm 46. Because the valve 30 is closed, as aforedescribed, at the time of opening of the valve of regulator 11, there will be no pressure drop across the air line butterfly valve 23, so that the resultant pressure drop across valve 19 will act in a well known manner to effect movement of piston '21 toward the left. Such movement of piston 21 not only eifects movement of valves [9 and 23 jointly from their closed position, but the resultant movement of element 38 toward the left also permits limit switch 39 to move to its normally closed position, as illustrated. The consequent opening of shutoff valve 3!] permits air to flow through conduit 24; the pressure diiference regulator 3! in conduit 24 controlling the pressure drop across butterfly valve 23 to maintain said pressure drop of substantially constant valve. If the pressure drop across the low pressure gas butterfly valve l9 continues to exceed the pressure drop across the air line butterfly valve 23 the duplex valves I9, 23 will continue to open jointly until said pressure drops are equalized; with the volumetric rate of flow of the mixture of low pressure gas (propane) and air through conduit 41 of the value necessary to maintain the gas pressure in the distribution conduit 11 at the desired value, for which the low pressure gas regulator l'lis set. As the demand for peak shaving gas (from conduit 41) decreases, due to a decrease in the demandfor gas from the distribution linev I I, the duplex valves [9 an'd23 will move jointly. toward their closed positions and eventually shut off the flow of low pressuregasthrough portion I6 of conduit [6 and the'flow ofairthrough conduit 24; the limit switch'39 being opened, as anincident to closure of said valves 19' and 23', to deenergize coil33, 'with resultant closure of the shut-off valve 30 in the air line 24.

It is obvious that when peakshaving gas is being added to the distribution conduit 1 I; the rate of flow of the base gas through conduit 10 is at a preselected maximum 'value; and that, therefore, the volumetric rate of flow of the peak shaving gas is definitely related to thevolumetric rate of flow of such base-gas.- Inasmuch as the pressure drop across the air valve 23 is maintained at a constant valve, by the differential pressure regulator 31, the position of the valves l9 and 23 jointly affords a definite indication of the volumetric rate of flow of air, which in turn is definitely related to the volumetric rate of flow of the peak shaving gas (propane-air mixture flowing through conduit 41). Said volumetric rate of flow of the propane-air mixture then determines the minimum heating value thereof which will afford a satisfactory mixture when the same is combined with the base gas flowing in distribution line H.

In accordance'with our invention a continuous sample of the peak shaving propane-air mixture flowing in conduit 41 is withdrawn and supplied through pipe 49 to a suitable calorimetric device, such as that shown schematically at 49. The calorimeter 49 is preferably of the quick-acting type disclosed and claimed in the Schmidt Patent No. 2,002,279, granted May 21, 1935, for Calorimetric Method andApparatus Adapted for Gas Mixing Control. Calorimeter 49 has associated therewith a peak shaving gas B. t. u. scheduling rheostat 50 (which is properly designed to provide resistance values, at different points in the range of movement of contactor 50, which will correspond substantially exactly with the required minimum heating values of the peak shaving gas, according to the percentage of the latter in the total flow of gas supplied to distribution line H, Fig. 1). 'Suchrequired variations in B. t. u. per cubic foot of the peak shaving gas in accordance with variations in the rate of demand for. the latter'are illustrated graphically in Fig. 3 hereof, as hereinafter more fully explained. I

By linking the contactor 50 of rheostat 50, designed and/or calibrated in the manner aforedescribed, with the operating mechanism for the duplex valves l9 and 23, as indicated at5l in Fig. 1, the total heating value per unit volume of the peak shaving propane-air mixture, supplied through conduit 41 to conduit II, will be maintained at the minimum value which will not cause trouble on gas burning equipment when mixed with the base gas in the predetermined variable proportions established by the gas mixing control equipment illustrated in Fig. 1. Such equipment will therefore deliver to the distribution line H either base gas or a mixture of base gas and peak shaving gas with the minimum heating value which will not cause defective burner performance. The advantage of this arrangement; when -tliecombinedfiows of base gas and peak shaving' gas are 's'old on a volumetric bas1s; is apparent." I Y 1 l As shown in Fig. 1, thecalorimetric device 49 acts, if necessary, 'to effectoper'aftion' of a splitfield reversible motor' 52 inone'direction or the other; motor 52 acting, through suitableispeedreducing gearing represented by numeral-52 and a. worm Iz todrive a nut: 53, which is attached to a rodzfl- 'tor adjusting the. position .of a slider (not: shown) ,of ,thecharacter illustrated in :Fig. 1 of said, Schmidt-and: Brice Patent No. 1,999,740; whereby the volumetric proportionality .of the flow of low'pressuregasin-portion I E ofconduit I6 is varied with respectto thevolumetricrate or flow otair in conduit. By this means :the total heating valueper unit volume .of the peak shaving as mixture flowing: conduit 47 is definitely controlled, in accordance with the volumetric rateof flow thereofixin a. manner to minimize the'heatlngvalue. thereof under various conditionsgraphically.depicted in Fig. 3.

Ii thebase gas only'ifrom conduit I0. in. Fig. 1 is sold. and the .ultimate consumer supplies the peak, shavin .gas, ithesame' control system could be. used; butin such aninstallation changes inv the -peak shaving gas heating value schedule wou d either be, .unnecessary .or the required changes would be relatively small. However, in certain critical burner applications at least minorcontrolled variations-in the peak shaving gas heating value would be desirable. The desired-variationswould again be related to proportionalities of --flows, and would correspondingly be related to the aforementioned jointvariations i he po itions oi the. duplex valves [8; and 23.

Although: we havespecifically descr'ibed. our invention as applied. to. a system involving the e f carbureted Water-gas as the bas it is to be understoodgthatthe invention is adaptable for; usein systems wherein, the base gas is other than, carburetediwat r as. Thus if t basegas consists of natural; gas, a relationship of volumetric proportionality and total heating value per unit volume of the. peak shaving gas mixture with respect thereto similar to-tha-t, illust d i Fis-v 3 willzapply; ex ept...of course. that the magnitude of the t al hea n values p r unit volume of thebase and peak-shaving gases will be higher.

Various slight mod ications i theform and arrangement of the partsofjthe control system illustrated in l will at once suggest themselves tot-hose skilled in this art. For example, a high pressure air storage tank might. be substituted for the blower 2 9 shown inEig. l. Varione well known accessorifis-ln ght also be :in-

corporated in, the as :mixingcontrolsystem. For example, a pressure responsive. alarm switch might be associated with conduit lfl'toj indicate a failure of pressureofqthe. base gas supply. Similarly, lcnownforms of shut-oil devices, might be associated with the conduits 15,12 and 4:1.

o r po t0- f: i1. reof pr ssure of the peak shaving gas or vapor.

Referring more particularlyto 3,:we have graphically illustrated the-variation requiredain the total heating value per-unit volume of 'a peak shaving gas-air mixture of the-character herein specified, according to the required varia tions in the percentagepj the total volumetric rate of flow (to distribution rhneljl in-Eigil. for example) which must be composed of. the peak shaving gas-a-ir mixture toisatisfy the rate of demand from the distribution line; Thus the abscissa 55. bears legends 0. in icateth 'p centage of the total volumetric rate of flow of the base gas and the-peakshavi I :-gas-air;mixture which must consist of thedatter inmrder to satisfy the demand. The .ordinate-flfibears ends to indifla the .requiredqualitye imum total-hcating value' per: unit volume, of the peak shaving gas-air mixture supplied for use inconjunction with a base gas having a substantially constant total heating value of 540 B. t. u. per cubic foot, as aforedescribed.

As indicated by the horizontal portion 51 of the graph, if the peak shaving gas-air mixture comprises fifteen per cent or less of the total volumetric rate of fiow, the quality of said peak shaving gas-air mixture may likewise be maintained at approximately 540 B. t. u. per cubic foot without deleteriously affecting the combustion characteristics of the final mixture at the consumers appliances. The curved portion 58 of the graph illustrates the gradual increase in the required total heating value per unit volume of the peak shaving gas-air mixture, as the latter is required to constitute a larger and larger percentage of the total volumetric rate of flow. Thus if one-half of the total volumetric rate of flow is required to be of the peak shaving gas-air mixture, the total heating value of the latter must be increased to 650 B. t. u. per cubic foot, as indicated at the point 58 in Fig. 3, and so on. Moreover, as aforestated, each oi the total heating values of the peak shavin gas-air mixture indicated in the graph of 3 is the minimum value which we have f ound by experiment is satisfactory for our purpose (in that it has no deleterious effect upon theoperation of the various types of consumerappfifihflfis and in no case requires any readjustment of the latter) Such minimum value in each instance, of course, correspondingly reduces the cost to the gas distributing company of the additional gas required to satisfy the peale or abnormal rates of demand when they occur. Also, as aforeindicated, such minimum total heating value of the peak shaving gas-air mixture is in each instance substantially lower than the theorz tically correct value, with a corresponding saving to the gas distributing company. 1

In each of Figs. 2 and 4 we have illustrated modifications wherein a flow of peak shavinggas at all times is contemplated; the volumetric proportionality of such how, with respect-to that of the base gas, being preselected and maintained under conditions of variation in the volumetric rate of flow of the base gas as an incident to variations in the rate oi demand from the distribution line. Such an arrangement is desirable where the demand {or gas in excess of the maximum base gas supply over an extended period can be anticipated. For example, let it be-assumed that a given gas plant has -a twenty-four hour capacity of 240,000 cubic feet, whereas it is estimated that the -d emand during the next twenty-four hours will be approximately 264,000 cubic feet of .gas. By introducing peak shaving gas throughout such twenty-four hour period at a volumetric rate of flow equal to ten per cent of the total gas flow required to meet such demand it is-possible, as aforedescribed, to have the peak shaving gas of a total heating value. per unit volume .the same as that of the base gas. In contrast withthis, if the totalrequired amount of peakshaving gas were introduced during only a part (that is, the portions of peak demand Ijor gas) of the twenty-four hour period, the percentagesofpeak shaving gas would, of course, be substantially higher, and would likely require an increasein the total heating value per unit volume of the propane-air mixture, in order to avoid trouble on consumer appliances. 7

With such an arrangement it is, of course,

assumed that in a system-wherein the instantaneous volumetric rate of demand for gas is subject to relatively wide variations, 9. storage container for the temporary excess volumes of the mixture of base gas and peak shaving gas or of the base gas alone would be provided, in order to take full advantage of the maximum capacity of, the base gas producing plant throughout the entire period. 1

Referring more particularly to Fig. 2, the numeral 58 designates'a conduit through which the base-gas is adapted to flow, either directly from a producing plant of the aforementioned capacity, or from a storage container associated with such plant. A so-called butterfly valve 59 is located within conduit 58, said valve being adapted to act as a metering device. Valve 59 is adjustable automatically to maintaina preselected value of the pressure drop thereacross. The adjusting means comprises a lever 60 rigidly attached to valve 59, and a lever 6| pivotally connected to lever 69 and to a rod 62 attached to a piston 63; the latter being slidable within a cylinder 64. Pipes 65 and Gilead from opposite ends of cylinder 64 and have their outer ends arranged adjacent each other for cooperation with a movable jet or nozzle 61, which is connected with a source of fluid under pressure, as disclosed in the aforementioned Patent No. 1,999,740. 4

Pipes 68 and 69 are connected between conduit 58 at the upstream and downstream sides of valve 59 and the lower and upper chambers associated with a diaphragm I0. A stud Ill attached to diaphragm H! has its end engaging the lower side of nozzle 61; a coiled spring II being interposed under compression between the opposite side of nozzle 61 and an abutment in the form of a manually adjustable screw or bolt I2. Assuming that the base gas is supplied to conduit 58 at a predetermined substantially constant pressure, it will be apparent that upon a given adjustment of screw I2 the valve 59 will be opened automatically to a degree necessary to maintain the preselected pressure drop thereacross, under conditions of variations in the rate of demand for gas from the distribution line I3.

The conduit I4 is adapted to be supplied with peak shaving gas (such as propane) from a suitable source, said conduit having therein a butterfly valve and a butterfly valve 16. An air conduit 'II is supplied with air under pressure from a suitable source, such as the motor operated blower or pump I8; said conduit I'Ihaving therein a butterfly Valve I9. Valves I6 and I9 are of the duplex type, whereby the same when moved jointly are adapted to assume corresponding angular positions within their respective conduits. Thus said valves have rigidly attached thereto the levers 80 and BI, which are pivotally connected with a lever 82; the latter havingan integral upper end portion 82 which is pivotally connected with a lever 83. Lever 83 is pivoted at 83 to a fixed support. A second oppositely extending lever 84 is pivoted at 84* to a fixed support. A pair of

levers

85 and 86 are pivotally connected to each otherand respectively to the lever 89 and the valve 59.

An adjustable slider block or roller, 81 is interposed vbetweenthe levers 83 and 84, as shown.

The arrangement ispreferably such that with rollertl moved toward the right to a position in substantially'vertical alinement with the lower end of lever 85 and the upper end of lever portion 82* each of the valves I6 and I9 will assume a rotary or angular position exactly corresponding with that, of valve 59. Also with roller81 in such position any degree A of. movement, of valve 59 toward fully open or fully closed position will effect corresponding movement of valves I6 and I9 jointly. As shown, lever 83 is at all times biased toward lever 84, as by means of a headed rod or bolt 88 attached to lever 84, with a coiled compressed spring 89 interposed between the bolt head and the outer surface of lever 83.

In like manner, if roller 81 is moved toward its extreme left-hand position, as illustrated, the valves (-8 and 79 will be moved toward more nearly closed positions than'the valve 59 when the latter is in a fully openedflor partially opened position. Adjustment of roller 81 may be effected at will in any suitable manner, as by means of a pair of links or rods 90 and 9|, which are preferably pivotally connected at 99, rod 99 being at-, tached to roller 81 androd 9| having a screwthreaded right-hand end 9I which is adapted to cooperate with an internally threaded nut 92 which is held captive between a pair of

abutments

93 and 94. Nut 92 is provided with an intermediate enlargement 92 to facilitate manual rotation thereof. A rod 95 has a screw-threaded end 95 for cooperation with the other end of nut 92; so that as the rod 9l moves endwise in each direction the rod 95 will move endwise in an opposite direction. Rod 95 is slidably supported by a perforated lug upon a suitable member 96; the right-hand end of rod 95 having a, contactor 9! attached thereto and insulated therefrom, as diagrammatically illustrated at 98; said contactor 91 being adapted to cooperate with a peak shaving gas B. t. u. scheduling rheostat 99 of the aforementioned character shown at 59 in Fig. 1.

As shown in Fig, 2, the valves I5, I6 and I9 are operable automatically in a well known manner to normally insure a predetermined proportionality of the volumetric rate of flow of propane through conduit I4 with respect to the volumetric rate of flow of air through conduit TI. Such flow proportioning means is in general like that shown in Fig. l of the aforementioned Patent No. 1,999,740, to which reference may be had for a more detailed description of the construction and mode of operation thereof. Thus I have shown a device I09 which comprises essentially a nozzle [88 the instantaneous position of which is controlled in response to the differential value of the pressure drops across valves I6 and I9, as ascertained by diaphragms Illll and I00. The lower and upper sides of diaphragm [00 are subjected to the fluid pressures at the upstream and downstream sides respectively of valve I6, through the medium of pipes I90 and I99 whereas the upper and lower sides of diaphragm Hill are subjected to the fluid pressures at the upstream and downstream sides respectively of valve I9, through the medium of pipes I99 and lfifl A slider block N19 is" initially manually adjusted to provide the required proportionality between the volumetric rates of flow of air through conduit 'Il and propane through conduit 14 to afford a mixture of the desired total heating value per. unit volume flowing through conduit I 91 for mixture with the base gas flowing through conduit 58. Thus if said base gas has a total heating value per unit volume of .540 B. t. u. per cubic foot, the peak shaving gas flowing in conduit I91 will normally have the same heating value. Moreover, if the rate of flow of base gas is increased through farther opening of valve 59 to satisfy an increase in the rate of demand from conduit. 13, the means aforedescribed will act toefiect a proportional degree of opening valves I9. and I9. Such opening of valve I9 will immediately result in a correacoai'ee sponding increase in zit-he .rate of 'flow f .air

through conduit '11, :and the .device LL90 :will

.rate. of flow of propanegthusirestoring and mainitaining the preselected proportionality of the :flows of air-and propane.

The peak :shaving gas 13. t. u. scheduling rheostat-. 99 .isdesigned and calibrated in the .manner set P forth in the description of rheostat fEBof 1.

Ihat isto say, if it is desired-to maintain 'ithe volumetric rate of flow of peak shaving gas, through conduit 1 01, at a value corresponding {to ten per' cent (or not more than fifteen --per-cent) of thevolumetric rate of now throughdistribution line 13, the rheostat da -will haveno :efieet upon-the total heating value per' unit volume of the peak shaving gas' suppliedtosaid conduit I01. On the other hand, the calorimetric device 49 (like that described in -Figi 1) will act'in response to any variations in the total heating value of the sampleextracte'd through pipetS to efiect proper proportioning'of the '-volumetric rates of flow of 'air '(thro ugh conduit '11) and propane (through conduit 1-4) to maintain-the same at the value preselected therefor; any such adjustment being eiiectedaritomatically'by motor 52 acting (through elements 52 '52?, 53 and 54) upon slider block 100 "in the well known manner.

Inthe device of i Fig. 2-it isto be-understood that the butterfly-valves 5116, 1,9 and are so designed that 'a predetermined degree of rotary or angular movement of thedisks thereof will client a corresponding percentage change in fluid flow ,therethrough. The valve '59 in the base gas conduit-58 will therefore assume an angular position proportional to the volumetric rate of flow of gas through conduit 58, and this position is normally transmitted to the valves 'lfiand 19 in the propane and air lines,through"thejmedium of the

levers

83 and 84 and interposedjroller or slider 81, when the latter is inits aforementioned neutral position. With valve ,59 closed the arrangement is such that valves '18 and [9 would also be closed. With valve '59 fully opened the duplex valves ".6 andls would be opened toadegree depending upon the position of the "hand set roller or slider'block 81 which has associated therewith the aforementioned rheostat 99.

The pressure in the conduit '13'is normally maintained at some predetermined distribution pressure by any suitable means (not shown in Fig. 2) in conduit 58. The air blower I8 supplies ,a substantially constant discharge pressure, so that the ,fiow of ,air is determined by the ,position'of the duplex valve 79 in the air line TI. The flow ,controlvalve 15 in the propane line '14, actuated by piston [00 control theiiow of propane at a rate to establish a pressure drop acrosslthe duplex valve [6 which is proportional to the'lpressure drop across the valve 19. The-exact proportionality of air and propane pressure drops (and rates of flow) is adjustable over a fixed range by the motor operated adjuster I00, the operation of which is controlled by the calorimetric device 49. The control point of the latter is in turn controlled by the rheostat 99 associated with roller 81, which is manually preset at the desired position.

Assuming that it is desired to have the pro- 132" pane-air mixture supplied -through conduit !;0 I; constitute ten per cent of: the totalivolumetric rate of flow through. distribution line "|r3;iit-.will

be understood that with thezvalves 1-59, 1B and 13 initially closed, the manual adjustment .of roller 8? and rheostat contactor ii'l .would not change thesetting oi valves'l9 and' lS. However, as the metering valve 59 movestoward fully opened position, under the influence of the required volumetric rateof fiow of-base gas through conduit 58, the duplex valves "19 and 78 will open proportionately; the degree of opening the latter depending upon 1 the preselectedrati'o setting (ofioller 'fll) and the degree of opening of metering valve 59 With roller 8? so positioned that the peak shaving gas supplied from conduit lfll forms ten per cent-or less ofthe mixture flowing in distribution line i3, the rheostat 419 would then maintain the control point settingof the calorimetric device is? to provide a peak shaving gas-air mixture of a total heating value per unit volume substantially equal to that of the base'gas flowing in conduit 58. However, when the proportionality of peak shaving gas is increased to more than fifteen per cent of the total flow through line 13, the necessary increase in thecontrol point setting of calorimetric device =49 is automatically changed as a'result of movement of rheostat contactor'sl as an incident to adjustment ofroller 81.

The gas mixing control system diagrammaticaliy illustrated in Fig. 4 is functionally quite similar to that of Fig. 2. 'However, in Fig. 4 the conduit I92 through which the base gas is adapted to how is provided with a 'metering device in the form of a fixed orifice 103. Any suitable means (not shown) "may be employed for insuring maintenance of apredetermined pressure of the base gas atthe upstream side of orifice I93, whereby a predetermined pressure will normally be providedin the distributionline, notwithstanding variations in the rate of demandfrom the latter. By way of 'an example, it may be assumed that the base :gas supplied from conduit I02 to distribution line 1,64 has a total heating value per unit volume of 5,40,B.-t. u. per cubic foot.

The peak shaving gas, :such .as propane, is supplied from 'a suitable source :to "conduit and air for mixture therewith 'is supplied, "by blower "N16, for example, to conduit I01. The peak shaving gas and air mix with each other during their flow through conduit 1.08 to distribution line I04. Conduits 105 and I0! are .respectively provided with butterfly valves IDS land I it; said valvesbeing of'the duplex type; the same having like angular positions and the same (when moved) beingiconstrainedto move jointly to :like degrees through the'medium o1 linkage .Hl, H2 and H3.

Conduits llliand I01 are also respectivelyprovided with valves 1 Hand ,I;l,5,' w,hich are adjustable automatically to normally maintain substantially constant the preselected values of .the pressure drops across the respective valves .109 and H5 aforementioned.

Thus, a pair of pipes ITS andllgl .leadlfrom the upstream and downstream sides .of .valve N19 to the. chambers at the upper and lower surfaces respectively of a diaphragm-l I! having associated therewith a stud .Il9 which engages the-upper side of a nozzle I 20 connected to a suitable source of fluid ,under pressure. Nozzle 1 20 cooperates with the adjacent open ends .of pipes HI and I22 leadin to opposite ends of acylinder 123 having therein a piston I 24; the latter being connected by rod I25 and link I26 with lever I 21 attached to valve I I4. A spring I28 is interposed between the lower side of nozzle I20 and an adjustable abutment I29. The degree of compression of spring I23 may be initially manually adjusted in any suitable manner to preselect the value of the pressure drop across valve I09, and hence the angular position of valve II4 for any given adjustment of valve I09. Normally, however, the degree of compression of spring I28 is merely subject to automatic control by operation of a reversible electric motor I 30 through the medium of reduction gearing I3I and an associated crank I 32, to effect either an increase or decrease in the degree of compression of spring I28. Motor I30 is in turn subject to control by the action of a calorimetric device 49, like that of Figs. 1 and 2, to normally maintain the mixture of peak shaving gas and air at the aforementioned total heating value of 540 B. t. u. per cubic foot, so long as the volumetric rate of flow thereof does not exceed fifteen per cent of the total volumetric rate of flow through distribution line The valve H5 is likewise adjustedautomati cally in response to automatic adjustment of valve IIO (jointly with valve I09), whereby the pressure drop across valve I I is maintained substantially constant and normally proportional to the pressure drop across valve I09. The means associated with valves H0 and H for eifecting such adjustment of the latter are, for the most part, identical with the elements associated with valves I09 and H4, as indicated bycorresponding numerals of reference. However, the compression spring I28 is interposed between the lowerside of nozzle I and a manually adjustable abutmentin the form of a screw or stud I 33; the latter being manually adjusted .upon installation ofthe system to so proportion the flow of air through conduit I0'I as to provide the desired total heating value perunit volume of the mixture flowin in conduit I08, when the volumetric rate ofiiow of the latter does not exceed fifteen per cent of the total flow through distribution line I04,

Means are provided for normally automatically insuring that the volumetric rate of flow of peak shavinggas through conduit I08 shall constitute a preselected proportion (say one-tenth) of the total volumetricrate of flow through distribution line I04. Said means comprises a pair of pipes I34 and I35 respectively connected withconduit I02 between the upstream and downstream sides of orifice I03 and the chambers at the upper and lower surfaces of a diaphragm I36. A stud I3! is attached to and projects downwardly from diaphragm I 36 for engagement with the upper side of a nozzle I38 connected in the usual manner with a source of fluid under pressure. A coiled compression spring I39 is interposed between the lower side of nozzle I38 and an abutment I40, which is adjustable automatically in the manner hereinafter described. Assuming a givenadjustment of abutment I40, the arrangement is such that upon a variation in the volumetric rate of flow of base gas through conduit I02 the associated means will provide for a corresponding or proportional variation in the volumetric rate of flow of peak shaving gas through conduit I08, so that the percentage quantity of the latter will be maintained constant at the value preselected therefon a Thus, in' the event of an increased demand from distribution line. I04, the pressure at the'do'wn- 92 to' facilitate manual rotation thereof.

'14 stream side-of orifice 103 ,would belowered, and as aconsequence'di'aphragm I36 would effect downward movement of stud I31 to bring nozzle I38 into'partial or full alinement with the end of a. pipe jI 4I leading to the, left-hand end of a cylinder I42, with resultant movement of piston I43 toward the right. ,Upon such movement of piston fl'43-the cam member I55 attached thereto will automatically effect adjustment of abutment I40gto increase the, loading of spring I39 until the "jet .I38 ;is restored to neutral position; in this' manner insuring the required degrees of opening of ;the respective valves I09, I I4 and I I0, I I5 topro vide the required volumetric rate of fiow ;of the, propane-air mixture fromconduit I08 to distribution line I04to meet the'demand from the; latte r.-;v As ;will be apparent, such increasedrate ofrfiow of the propane-airmixture will restore the desired distribution pressure in line I04. Piston rod I44 has a pin and slot connection I45 witha lever having angularly arranged arms-I45and I41 and a'fixed point of pivotal support at I48; Arm I4'Iis so arranged withrespectto alever I49 -(having a fixed pivot at I50)- that any; up or downmovement of arm I41. is transmitted to said lever I49. Such movement is transmitted: through; the'medium of a manually adjustable slider block in the form of a roller I5I;- suitable means, such as a headed stud, I52 and a coiled compression spring I53 being interposed between arm I41 and lever I49 to resiliently bias the latter and roller I5I toward arm- I4'I.

Under the condition last mentioned'the downward movement oi arm; I41 and lever I49 will be transmitted, through-a lever I54 to the aforementioned levers; I I3, II 2 and III, to efiect the required degree 'ofjoint movement of valves I09 and I Illtoward fullyopen position to provide the desired increase inthe volumetric rate of flow of peak shaving gas through conduitl08; the aforedescribed means acting automatically to effect the necessary movements of valves I I4 and I I 5 to maintain the total heating value per unit'volume of the peak shaving gas substantially constant.

In the event that it is desired to increase or decrease the volumetric proportionality of the.

peak shaving gas flowing through conduit I08 (with respect to the total volume flowing in distribution line I04) this may be efiected by manually adjusting the positionof roller I5I with respect to arm I4'I-and levr'l49., Thus roller I5I has attached thereto a yoke member I5I which is pivotally connected at I5I to a rod 9I, whose right-hand end 9I' isscrew-threaded for cooperation with a rotatable nut 92. Nut 92 is held against endwise movement between a pair .of fixed abutments' '93, and 94, as described in connection with the system of Fig. 2. Nut "92 isshown as provided with an enlarged portion Also, as shown, nut 92 is adapted for simultaneous cooperation with'the threaded end 95 of a rod 95, which has attached thereto (but insulated there- :from, 'as'indicated at 98) a contactor 9? for cooperation with the resistance of rheostat 99.

rheostat contactor 91 will be such as to set the calorimetric; device 49 to. maintain a predetermined higher total, heating value of the peak shaving gas flowing-in conduit 1108, as indicated by the values graphically illustrated in Fig. 3.

1. In a- -method-of control of gas mixing for peak shaving, the-steps which comprise, effecting a fiow of base gas having a predetermined substantially constant. total heating value per unit volume at a volumetric rate variable with the rate of demand of a distribution system to provide a predetermined substantially constant pressure-in the distribution system effecting a flowof peak shaving gas at a pressure substantially corresponding to that aforementioned 'to supplement said flow 'of base gas, to thereby substantially increase the-flowoi gas to the distribution-system, said peak shaving gas having a total heating value per unit volume substantially correspondin 'to thatlo'f saidfbase gas when the volumetric rate of flow of peak shaving gas does not exceed apr'ede'termined proportion of the total flow throug'h said-distribution'line, whereby the mixtureof base and peak shaving gases will have the desired combustion characteristics, and increasingthe total heating value perunit volume of said peak shaving' gas .for the purpose last mentioned, in aceordance with a predetermined schedule, when said peak s'having'gas-exceeds said predetermined proportion of the total flow through said di'stribution'lin'e, said schedule being such as to minimize the excess in total heating value per unit volumeof the mixture of base and peak'shavi'n'g gases.

2. In a method of control of gas mixing for peak shaving, thesteps Which-comprise efiecting a flow of'base gas at a predetermined substantially constant pressure and of a-predetermined substantiallyconstanttotal heating value per unit volume, at a' volumetric rate corresponding to the rate of demandth'erefor from adistribution line, said base gas increasing in price per unit volume above "a certain volumetric rate of flow, and when the demand for gas exceeds said certain volumetri'ctrate of'flow of: base gas, maintaining the flow of base :gas at said :certaini volumetric ratev of, flow while simultaneously effecti'ng a flow of'.:a..pea-k shaving gas ata pressure substantially"corresponding =to that aforementioned and -a;t a =:volumetric rate corresponding to the" dff'erence betweenthe of demand for gas and said .cer-tain volumetric 'rateof how of base gas, to thereby =restore-,said substantially constant -pressure,.said peak. shaving gas having a'total heating value 'per unit volume atlea-st as great as 'thatof said'base gas.

3. In a methodorcontroi of gas mixing for peak shaving, the steps "which comprise, effecting a flow of base gas ata' predetermined substantially constant pressureyand of'a predetermined substantially constant totalheating value perunit volume, at a volumetric rate corresponding to the'rate of demand therefor from a distribution line, effecting-a how of peak shaving gas at a pressure substantially corresponding to that aforementioned and at :a volumetric rate corresponding tothe difference between the. rate of demand for the base gas and a-maximum vol- 1 .peakshaving gaseswi'll'ha've'the desired comb'ustion characteristicswhen used-in consumer appliances, and increasing the total heating value per unit volume of said peak --shavinggas for the purpose last men-tioned in accordance with a schedule based upon the volumetric proportionality .oi the peak shaving gas'with respect to thebase gas, whereby the excess in total heating value sper unit volume of said mixture of base andipeak shaving gases may be minimized.

4. Ina gas mixing control system for peak shaving, in :combination, a distribution line, means for supplying l to said distribution line more or less of a predetermined maximum volumetric rate of flow of a base gas of predetermined total heating value per unit volume, in accordance-with the rate of demand for the latter, to normally maintain in said distribution line apressure of at least apredetermined minimum value, a separate source of peak shaving gas, means responsive to a predetermined drop in pressure-of the base gasinsaid distribution line, as an incident toademand-greater than the .volumetric'rate of supply of base gas to said line, to effectavolumetrierate of flowof peak shavinggas suchas to restore and maintain the desired minimum gas pressure in said distribution line, and said last mentioned means including means operable automatically in accordance with the proportional volumetric rate of flow of said peak shaving gas, with respect to the volumetric rate offlow of'base gas, to efiect'variationin the totalheating'value per unit volume of said peak shaving gas in such a manner as to minimize the excess of such value over-that required to atford proper combustion of the mixture of base and peakshaving gases in gas burners adjusted for use of said base gas.

5. In a gas mixing control system for peak shaving, in combination, a distribution line, means for supplying to said distribution line a portion or all of a predetermined maximum volumetric rate of flow of a base gas of predetermined total heating value per unit volume,'in accordancewiththe rate of demand for the latter, -to normally maintain in said distribution line a substantially constant predetermined pressure, a separate source of peak shaving gas,

means responsive to a predetermined drop in pressure ofthe-base gas in said distribution line, as an incident to a demand therefor greater than said maximum rate of flow thereof, to effeet a volumetric rate of flow'of peak shaving gas such as to restore and maintain the desired minimum gas pressure in said distribution line,

and said lastmentioned means including means operable automatically in accordance with the proportional volumetric rate of flow of said peak shavinggas, with respectto the volumetric rate offlow of base-gas, to effect variation in the total heating value 'per' unit volume of said 'pea'k-shaving'gas in such a'manner as tominimize the excess of such value over that required to afford proper combustion of the mixture of base and peak shaving gases in consumer appliancesof various types.

means includingmeans acting in response to variations in-the rate of demand from the distribution line tonormallymaintain a predetermined substantially constant pressure of-gas in the latter, means responsive to a predetermined drop in gas pressure in said distribution line to effectJaLflowing mixture of peak shaving gas -andair to :said:distribution'line-at such a volumetric rate as to restore the aforementioned pressure in the latter, and means for controlling the total heating value per unit volume of said mixture of peak shaving gas and air, whereby the latter when mixed with said base gas Will have proper combustion characteristics when used in consumer appliances.

7. In a gas mixing control system for peak shaving, in combination, a conduit through which a base gas of substantially constant predetermined total heating value per unit volume is adapted to flow to a distribution line, means in said conduit for limiting the maximum volumeric rate of flow of base gas therethrough, said means including means acting in response to variations in the rate of demand from the distribution line to normally maintain a predetermined substantially constant pressure of gas in the latter, means responsive to a predetermined drop in gas pressure in said distribution line to effect a flowing mixture of peak shaving gas and air to said distribution line at such a volumetric rate as to restore the aforementioned pressure in the latter, means for controlling the total heating value per unit volume of said mixture of peak shaving gas and air, whereby the latter when mixed with said base gas will have proper combustion characteristics when used in consumer appliances, and said last mentioned means including means for varying the total heating value per unit volume of said mixture of peak shaving gas and air, in accordance with the required variations in the volumetric proportionality thereof with respect to the base gas, in such a manner as to minimize the excessive total heating value per unit volume of said mixture of peak shaving gas and air when supplied under all conditions.

8. In a gas mixing control system for peak shaving, in combination, means for effecting a flow of base gas having a substantially constant total heating value per unit volume at a volumetric rate variable with the rate of demand of a distribution system to provide a predetermined substantially constant pressure in the distribution system, means for effecting a flow of peak shaving gas at a pressure substantially corresponding to that aforementioned to supplement said flow of base gas, to thereby substantially increase the flow of gas to the distribution system, said peak shaving gas having a total heating value per unit volume substantially corresponding to that of said base gas when the volumetric rate of flow of peak shaving gas does not exceed a predetermined proportion of the total flow through said distribution line, whereby the desired combustion characteristics of the mixture of base and peak shaving gases when used in consumer appliances are insured, and means for increasing the total heating value per unit volume of said peak shaving gas for the purpose last mentioned, in accordance with a predetermined schedule, when said peak shaving gas ex ceeds said predetermined proportion of the total flow through said distribution line, said schedule being such as to minimize the excess in total heating value per unit volume of the mixture of base and peak shaving gases.

EDWIN X. SCHMIDT. CHARLES W. WARNER.

REFERENCES CITED UNITED STATES PATENTS Name Date Bucknam June 18, 1946 Number