US1933641A

US1933641A - Method of and apparatus for proportioning gaseous fluids

Info

Publication number: US1933641A
Application number: US620967A
Authority: US
Inventors: Edwin X Schmidt
Original assignee: Cutler Hammer Inc
Current assignee: Cutler Hammer Inc
Priority date: 1932-07-05
Filing date: 1932-07-05
Publication date: 1933-11-07
Anticipated expiration: 1950-11-07

Description

Nov. 7, 1933. E. x. SCHMIDT 1,933,641

METHOD OF AND APPARATUS FOR PROPORTIONING GASEOUS FLUIDS Filed July 5, 1932 2 Sheets-Sheet 1 E. X. SCHMIDT Nov. 7, 1933.

METHOD OF AND APPARATUS FOR PROPORTIONING'GASEOUS FLUIDS Filed July 5. 1932 2 Sheets-Sheet 2 iii) Patented Nov. 7, 1933 UNITED STATES PATENT OFFICE METHOD OF AND APPARATUS FOR PRO- PORTIONING GASEOUS FLUIDS Application July 5, 1932. Serial No. 620,967

17 Claims.

This invention relates to improvements in methods of and apparatus for proportioning gaseous fluids, and although not limited thereto the invention relates more particularly to methods of and apparatus for proportioning butane gas and air to provide a gaseous mixture of predetermined quality or total heating value per unit volume under conditions of relatively wide variations in the demand for the mixture.

An object of the invention is to provide a novel method of varying the rate of supply of the gaseous mixture to compensate for variations in the demand therefor, while insuring a substantially constant quality or total heating value per unit volume of the mixture.

Another object is to provide novel means for performing the method aforementioned.

Another object is to provide a gas making and distributing system of the character aforementioned wherein a plurality of gas making units are employed, means being provided for automatically effecting operation of one or more of said units, depending upon the rate of demand for the gaseous mixture.

Another object is to provide such a system wherein continuous operation of one of the gas making units is contemplated,means being provided for transferring the continuous duty from one to another of the several units at will to substantially equalize the Wear upon the units and to render any one of the latter inactive for purposes of repair under conditions of low or minimum demand for the gaseous mixture.

Another object is to improve the details of construction and operation ofgas mixing control systems of the character aforementioned.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate certain embodiments of the invention which will now be described-but it is to be understood that the embodiments illustrated are susceptible of modification without departing from the scope of the appended claims.

In the drawings, Figure 1 is a schematic and diagrammatic view ofa gas mixing control system constructed in accordance with my invention, and

Fig. 2 is a similar view of a modified form of gas mixing control system.

Referring first to Fig. 1, the numeral 5 designates a tank or receptacle which may serve as a source of supply of one of the gaseous fluid constituents of the final gaseous mixture. Thus (Ci. 48ll80) it may be assumed that the tank 5 is partially filled with a volatile hydrocarbon liquid, such as butane,said liquid being inherently vaporable at substantially all normal atmospheric temperatures, although if desired suitable means (such as an electric heater, not shown) may be associated with tank 5 to insure vaporization of the liquid under extremely low temperature conditions. The upper portion of tank 5 thus serves as a storage chamber for the vapor under its own pressure, and communicating with said upper portion of the tank are a pair of branch pipes or conduits 6 and 7, said conduits having pressure regulating valves 6 and 7 therein whereby the pressure in said conduits at the right hand sides of the valves G and 7 is maintained at a substantially constant predetermined value.

Also located within conduits 6 and '7 are a pair of adjustable disk--or butterfly-valves 6 and 7 for controlling the rate of flow of the vapor or gas through said conduits-the latter being further provided with normally closed electromagnetically operable valves 6 and 7 which are controlled in the manner hereinafter described.

As shown the conduit 6 communicates with a conduit 8 the inlet end 8 of which communicates with the atmosphere for induction of air, or said conduit 8 may be connected with any other source of gas of relatively low quality or total heating value per unit volume. Conduit 8 in turn leads to the intake end of a positive displacement pump 9, said pump being mechanically connected through the medium of lever 9 fiy-wheel 9 and belt 9 with an electric motor 9 for driving thereof at a substantially constant speed by the latter. The discharge side of pump 9 communicates through conduit 10 with a conduit 11 which may communicate directly with the discharge line 12 of a distribution system, but as shown a tank 13 is interposed between conduit 11 and discharge line 12,-said tank serving as a high-pressure storage receptacle for the mixed gases, and a regulating valve 12 being interposed between tank 13 and discharge line 12 to maintain a relatively low and substantially constant pressure of the gas mixture flowing through the latter. A normally closed electromagnetically operative valve 10 is interposed between conduits 10 and 11, said valve being controlled in the manner hereinafter set forth.

Conduit 7 similarly communicates with a conduit 14 the inlet end 14 of which communicates with the atmosphere or some other source of relatively lean gas. Conduit l l in turn leads to the intake end of a positive displacement pump 15, said pump being mechanically connected through the medium of lever 15, fly-wheel 15 and belt 15 with an electric motor 15 for driving thereof at a substantially constant speed by the latter. The discharge side of pump 15 communicates through conduit 16 with the aforementioned conduit 11,a normally closed electromagnetically operable valve 16 being interposed between the discharge side of pump 15 and conduit 11 for operation in the manner hereinafter set forth. While I have shown pumps 9 and 15 as being of like size or capacity and adapted for operation at like speeds by the respective motors 9 and 15 ,-it is to be understood that pumps of unlike capacities may be employed if desired, and motors operable at unlike but constantly proportional speeds may be substituted for those illustrated.

Associated with the tank 13 and subjected to the pressure conditions within the latter are a pair of pressure responsive switches the movable contactors l7 and 18 of which are adapted for cooperation with pairs of stationary contacts 17*, 17 and 13 18*, respectively. The pressure responsive elements of said switches are calibrated differently, and it may be assumed that the pressure within tank 13 has fallen a predetermined degree below the desired value, with consequent movement of contactor 17 toward the left into engagement with contact 1'7 (as shown). This completes an energizing circuitror the winding of relay 19,said circuit extending from line L by conductor 29 through a suitable current-reducing resistance 21, conductor 22 through said winding, conductor 23 through contact 17 and contactor l7, and by

conductors

24 and 25 to line L Contacts 19 of said relay are adapted upon closure thereof to complete a maintaining circuit for said winding shunting the contact 17 and contactor l7,--said maintaining circuit being obvious.

Said relay upon closure of its contacts 19 likewise completes an energizing circuit for the winding 26*: of an electromagnetically operable switch 26,-said circuit extending from line L by

conductors

25, 24 and 27 through said contacts 19 by conductor 28 through the

contacts

29, 29 and 29 of a double-pole, double-throw transfer switch 29, by conductor 30 through said winding 26 and by conductors 31 and 32 to line L Upon closure of the contacts 26 26 and 26 of switch 26 a circuit is completed forv the motor 15 ,said circuit extending from lines L L and L through

conductors

32, 33 and 25 and

conductors

32, 33 and 25 through said contacts to the respective terminals of said motor 15 Also upon energization of motor 15 the windings of electromagnetically operated valves 7 and 16 are energized to open said valves simultaneously with the initiation of operation of pump 15, said windings being connected in parallel relation across a pair of the motor terminals. Assuming a given adjustment of valves 7* and 1t the pump 15 will draw lean gas or air through conduit 14 and rich gas through conduit 7 at volumetrically proportioned rates,said gases being thoroughly mixed and then discharged through conduits 16 and 11 to tank 13.

.Also upon energization and closure of switch 26 the contacts 26 thereof will act through conductors 34 and 35 to pre-set the energizing circuits of a reversible motor 36 for completion to operate the latter in one direction or the other for opening or closing valve 7' to vary the rate of now of rich gas through branch conduit 7 in accordance with the determinations of a relatively quick-acting calorimetric device 37,the latter having permanent connections with lines L L as indicated at 38 and 39. As will be noted, the valve 6 is likewise splined to the operating shaft of valve 7 whereby like adjustments of said valves are simultaneously effected-suitable speed-reducing gearings 36* being preferably interposed between motor 36 and said operating shaft.

The calorimetric device 37 will preferably be of the character described and claimed in my copending application, Serial No. 540,863, filed May 29, 1931, although it is to be understood that any other suitable form of calorimeter may be employed if desired. Said calorimeter 37 is provided with a motor 37 which drives a pair of pumps (not shown), one of which is adapted to withdraw through conduit 37 a continuous sample of the mixed gases and the other of which supplies a volumetrically proportioned stream of combustion air, said mixed gas sample and said stream of air being supplied to a burner of suitable form; said calorimeter being provided with well known means including a galvanometer the needle of which is adapted to remain in an intermediate or neutral position so long as the total heating value per unit volume of the mixed gas sample is equal to the value preselected. Upon a decrease inthe total heating value per unit volume of the mixed gas sample the galvanometer needle is deflected a direction and to a degree to cause operation of motor 36 in a direction to effect the required degree of opening of valve 7 (valve 6 being correspondingly adjusted simultaneously) whereby the required degree or increase in the total heating value per unit volume of the gas mixture is insured. Similarly, upon an increase in the total heating value per unit volume of the gas mixture the calorimeter elements function in a known manner to effect operation of motor 36 in the reverse direction to partially close valve 7* (and valve 6*) thus maintaining said total heating value of the gas mixture substantially constant.

If the rate of demand for the gas mixture is greater than the rate of supply thereof by pump 15, obviously the pressure within tank 13 will drop to a still lower value and the other pressure responsive device is calibrated to respond under such conditions to effect engagement of its contactor 18 with stationary contact 18, thus completing an energizing circuit for the winding of relay 40,which circuit may be traced from line L by

conductors

25 and 24 through contactor 18 and contact 18", conductor 41 through said winding, thence through a suitable protective resistance and conductor 20 to line L Contacts 40 of said relay are thereupon closed. to provide a maintaining circuit for the winding thereof (said maintaining circuit shunting the contactor 18 and contact 18 as will be obvious). Also upon closure of contacts 40 of said relay a circuit is completed for the operating winding 43 of switch 43, said circuit extending from line L by

conductors

25, 24 and 44 through said contacts 40, conductor 45 through

contacts

29, 29 and 29 of transfer switch 29, conductor 46 through the winding 43, and by conductors 47 and 32 to line L-".

Contacts 43 43 and 43 of said switch act upon closure thereof to complete the circult of motor 9, said circuit being obvious. The operating windings of electromagnetically operable valves 6 and 10 are connected in parallel relation to each. other ac s a p r of the motor terminals, whereby opening of said valves is effected simultaneously with initiation of operation of pump 9. Contacts 43 are adapted to perform the same function as contacts 26' of switch 26, and hence the former contacts are primarily adapted to function upon movement of transfer switch 29 to its opposite extreme position, wherein the

contacts

29 and 29 are bridged by contact 29 to render switch 43 subject to control by the pressure responsive switch 17.

As aforestated the valves 6 and 7* will have been adjusted correspondingly through the medium of the calorimetric device 37, and hence upon initiation of operation of pump 9 the mixture of rich gas and air supplied by the latter will have the desired total heating value per unit volume as preselected by the setting of the calorimetric device 37,-it being understood that the valve 8 will have been previously adjusted to provide the same volumetric proportionality of air to rich gas flowing in branch conduit 6 as is provided by the adjustment of valve 14 with respect to the volumetric rate of flow through branch conduit 7.

The conduit 3'7 through which the gas sample is withdrawn from conduit 13 (for burning in the calorimeter 3'7) is preferably provided with a pressure regulating device 37 of the character described and claimed in Packard. Patent No. 1,852,330, dated April 5, 1932,the arrangement being preferably such that the gas sample is supplied to the calorimeter at substantially atmospheric pressure, to correspond with the pressure of the combustion air.

When the pressure within tank 13 reaches the desired maximum value, the left-hand pressure responsive device effects movement of its contactor 18 to the right into engagement with contact 18 This short circuits the winding of relay 40, with consequent opening of the contacts 40 for deenergization of switch 43 and stopping of motor 9 ,the windings of solenoid valves 6 and 10* being simultaneously deenergized to permit closure of said valves whereby leakage of the rich gas or of the gas mixture is prevented. If the rate of supply of mixed gases by pump 15 thereafter exceeds the demand, the right-hand pressure responsive device will effect movement of its contactor 17 into engagement withcontact 17 with consequent deenergization of relay 19, and the contacts 19 of the latter will open to deenergize switch 26 for stopping of motor 15 ,solenoid operated valves 7 and 16 being simultaneously deenergized and closed to prevent leakage as aforedescribed.

It will be understood that under normal load or demand conditions the pump 9 will remain inactive, and hence the same is rendered accessible for inspection or repair without interruption of the normal gas mixing operations. In like manner the pump 15 may be rendered inactive under less than peak load conditions by moving the switch 29 to its opposite extreme position, thus transferring the initial pumping operation to the unit comprising pump 9. Transfer switch 29 may be utilized in a like manner to periodically transfer the major burden from one gas mixing or pumping unit to the other, whereby the wear upon the units throughout a long period of time is substantially equalized.

While I prefer to employ motors 9 and 15 of substantially constant speed, it will be apparent to those skilled in the art that by my novel arrangement of parts such provision is not necessary, since it is contemplated that the rich gas branch conduits 6 and 7 and by inserting similar flow-controlling valves in the air conduits'B and 14, preferably in advance of the points of junction of the latter with said branch conduits 6 and 7. While I have described my control system as particularly applied to the proportioning and mixing of rich gas and air, it is to be understood that a lean gas or gases other than air may be utilized with equal facility and accuracy in the production of a gas mixture of predetermined heating value per unit volume.

The method of and apparatus for mixing gases illustrated in Fig. 2 are essentially like the method and apparatus described with reference to Fig. 1, but differ therefrom in certain details of construction and in the mode of operation of the control elements. In Fig. 2 the tank 50 designates a source of rich gas supply, as for instance a tank partially filled with liquid butane, the vapor of which is forced by its own pressure through a conduit 51 shown as having three branches 51 51 and 51, which respectively lead to differential-pressure-operated valves 52, 53 and 54. Said valves (which are in general of a well known form) may be of identical size. The valve 52 is shown more in detail as comprising a diaphragm 52 to which is attached the element 52 the position of which controls the rate of flow of the rich gas through branch Sl t-as:

suming open positioning of an electromagnetically operable valve 52 and proper adjustment of a manually operable valve 52 The valve 52 includes a closed container 52 carrying a body of liquid 52 above the diaphragm 52 said container communicating through

conduits

52 and 55 with a relatively larger closed container 55 carrying a body 55 of said liquid. In this manner the level of the liquid in container 52 will be maintained the same as that in container 55 ,the latter being provided with a movable member 56 whereby said common liquid level may be varied.

Thus with electromagnetically operable valve 52 in open position branch conduit 51 is in communication with a relatively large conduit 57, the latter serving as a mixing chamber for the rich and lean gases supplied by each of the gas making units, and as a distributing conduit for the mixed gases. The lower side of diaphragm 52 is shown as subjected to the pressure conditions on the downstream side of valve 52', as by means of the relatively small conduit 52, piping 58 being provided whereby the liquid in chamber 52 is subjected to the pressure conditions existing in conduit 57. By the arrangement illustrated a predetermined pressure drop across

valves

52 and 52 is insured, said pressure drop being variable automatically in accordance with variations in the level of liquid 52. The elements of -the differential-pressure-operated valves 53 and 54 function in'a like manner,it being noted that piping 58 likewise communicates with the consaid unit will normally be operated continuously, although subject to the automatic control hereinafter described. Thus I have shown three pressure-responsive switches 59, and 61 all of which are subjected to the pressure conditions within conduit 57, said switches being calibrated to respond sequentially under different pressure conditions corresponding to variations in the rate of demand for the gaseous mixture. The contactor 59 of switch 59 is shown in engagement with stationary contact 59*, thus completing an energizing circuit for the operating winding of a relay 62, which circuit may be traced from line L through knife switch 63, contactor 59 and contact 59 conductor 64 through said winding, and by conductors 65 and 66 to line L Contacts 62 of said relay provide a maintaining circuit therefor shunting said contactor 59 and contact 59 said maintaining circuit being obvious.

Also upon closure of contacts 62 of said relay an energizing circuit is completed for the operating winding 67 of a switch 67, said circuit extending from line L by conductor 68 through said contacts 62 conductor 69 through said winding 67, and by conductors 70 and 66 to line L Upon closure of switch 67 the contacts 67*, 67 and 67 thereof effect completion of the circuit of a relatively small motor 71, said motor circuit being obvious. The operating winding of the aforementioned valve 52 is connected across a pair of the motor terminals, whereby said valve is opened simultaneously with the completion of the motor circuit. Switch 67 by closure of its contacts 67 completes circuit, through

conductors

71 and 72, for certain of the control elements of the calorimetric device 73 (the latter being identical with the device 37 described in connection with Fig. 1), certain of said control elements being permanently connected with lines L and'L as shown.

The calorimeter withdraws a continuous sample of the mixed gases from conduit 57, through conduit 74 having the pressure regulating device 74. Motor 71 operates at a substantially constant speed to drive the relatively small positive displacement pump 75 whereby a predetermined volumetric rate of flow of air or other lean gas to conduit 57 is effected. Assuming careful manual adjustment of valve 52 the volumetric proportionality of the air supplied by pump 75 and the rich gas supplied through branch conduit 51 will normally be such as to provide a flowing gaseous mixture in conduit 57 of predetermined heating value per unit volume. However, the calorimeter 73 provides for a continuous determination of the total heating value per unit volume, and upon a decrease in such value with respect to a preselected value the control elements will function to complete circuit for a motor 76 in a direction to cause downward movement of element 56 within container 55. The resultant rise in the level of liquid 52 in container 52 will automatically increase the degree of opening of valve 52 to effect the required change in the pressure drop across

valves

52 and 52 with a consequent increase in the rate of flow of the rich gas, and such adjustment will be continued pending attainment of the required total heating value per unit volume of the gas mixture flowing in conduit 57.

It will be apparent that the aforedescribed movement of member 56 within container 55 effects a like change in the level of the liquid in chambers 53 and 54 even though the other gas making units are inactive. Thus it follows that if the rate of supply of the constituent fluids through pump 75 and branch conduit 51 is less than the rate of demand for the mixture the pressure within conduit 57 will drop still further, and when said pressure reaches a predetermined low value the contactor 60 of device 60 will move into engagement with contact 60 This completes a circuit for the operating winding of a relay 77, whose contacts 77 provide a maintaining circuit therefor shunting contactor 60 and contact 60 and whose contacts 77 complete an energizing circuit for the winding 78 of switch 78. Switch 78 is provided with

contacts

78, 78 and 78 which are adapted upon closure thereof to complete the circuit of a relatively larger motor 79 driving pump 80, the operating winding of valve 53 being connected across a pair of the motor terminals to provide for simultaneous opening of said valve. In this manner an additional flow of the constituents of the gaseous mixture is eifected,it being understood that valve 53 has been previously adjusted manually to provide a volumetric proportionality of said constituents corresponding to that afiorded by the relatively smaller gas making unit aforedescribed. Any variation in the total heating value per unit volume of the gaseous mixture will result in the required degree of movement of member 56 to vary the rates of flow of the rich gas through branch conduits 51 and 53 through automatic variation of the level of liquid in the differentialpressure-operated valves of the several units.

If the demand exceeds the rate of supply by the two gas making units aforedescribed, the pressure within conduit 57 will drop still lower, and contactor 61 of device 61 will engage contact 61 to complete the energizing circuit of the winding of relay 81, whose contacts 81 will provide a maintaining circuit therefor, and whose contacts 81 will complete a circuit for the operating winding 82 of a switch 82. Contacts 82 82 and 82 will complete circuit for a motor 83 which drives a pump 84 corresponding in size with pump 80. Contacts 78 of switch 78 and/or contacts 82 of switch 82 function to complete circuit for the aforementioned control elements of calorimeter 73, in the event that the pressure responsive switch 59 is disabled through manual opening of knife switch 63. The consequent inactivity of the relative small gas making unit comprising pump 75 may be utilized to provide for inspection or repair of the latter and to prevent the normally continuous operation thereof.

A transfer switch 85 of the character described in Fig. 1 may be provided for reversing at will the sequence in which the motors 79 and 83 are rendered active, by merely subjecting the same alternately to control of the respective pressure responsive devices 60 and 61. By this means pumps 80 or 84 may be rendered inactive selectively under low load conditions to provide for inspection or repair thereof and to equalize the wear thereupon, as set forth in connection with the device of Fig. 1. Upon a decrease in the demand for the gaseous mixture after peakload conditions, with the parts arranged as illustrated, contactor 61 of device 61 will first en-- gage its cooperating contact 61 to short circuit the winding of relay 81 with consequent opening of the latter and opening of switch 82 for stopping of motor 83, valve 54 being simultaneously closed to prevent leakage of the rich gas from branch conduit 51. A further increase in pressure of the fluid mixture in conduit 57 will cause engagement of contactor 60 of device 60 with its cooperating contact 60 to short circuit the winding of relay 77, with consequent deenergization and opening of switch 78 and stopping of motor '79,-valve 53 being simultaneously closed through deenergization of its operating winding as will be obvious.

While as aforestated it is contemplated that motor 71 will normally be operated continuously, nevertheless the device 59 is designed to function, under predetermined relatively high pressure conditions within conduit 57, to effect engagement of contactor 59 with its cooperating contact 59 to short circuit the operating winding of relay 62,-whereas upondeenergization and opening of the latter the switch 67 is likewise deenergized and opened to temporarily discontinue the operation of motor 71,valve 52 being simultaneously deenergized and closed to insure discontinuance of the supply of all of the fluid constituents to conduit 57 pending the required reduction in fluid pressure in the latter.

As will be apparent the arrangement in each form of gas mixing control system herein described is such that the respective units may be initially adjusted to provide the required volumetric proportionality of the gaseous fluid constituents to provide a mixture of predetermined total heating value per unit volume, whereas automatic and rapid adjustment of the volumetric proportionality of such constituents is effected by the quick-acting calorimeter aforedescribed. Moreover, it will be noted that the adjustment of all gas making units is effected simultaneously regardless of whether one or more of the units is active at the time such adjustment is effected, so that any units subsequently rendered active to meet an increased demand for the gaseous mixture will be initially prepared to supply the fluid constituents in the proper volumetric proportionality to afford a mixture of the desired total heating value per unit volume. This is an imprtant feature since it insures against any substantial variation in the total heating value per unit volume of the mixture flowing into the distribution line or into the mixed gas storage tank or container.

The motor 76 in Fig. 2 is of course preferably provided with speed reducing gearing designated by the reference character 76*, and suitable gearing '76 is provided for connection thereof with shaft 76. Container 55 is preferably rendered fluid tight as by means of a removable cover 55 which provides a suitable fluidtight bearing for said shaft- '76,the lower end of said shaft having a bearing at 55 within said container. Member 56 which is preferably hollow to minimize the weight or inertia thereof is provided with an internally threaded portion 56 which cooperates with the threaded portion '76 of shaft 76 Member 56 is preferably closed or sealed at its upper end, as indicated at 56, to insure against ingress of liquid thereinto. A coiled spring 56* surrounds bearing 55 to cushion the movement of member 56 to its lower extreme position. As will be apparent the arrangement is such that the driving engagment between the threaded portion "id of shaft 76 and member 56 is automatically interrupted upon operation of shaft 76 beyond the desired limits, thus insuring against possible injury to the parts aforedescribed.

What I claim as new and desire to secure by Letters Patent is: v

1. In a method of mixing combustible gases of unlike quality or total heating value per unit volume, the steps which comprise effecting one flow of one of the constituents of a combustible mixture of fluids to satisfy a given rate of demand for the latter and automatically effecting one or more additional flows of said one of said constituents upon given increase or increases in the rate of demand for said mixture, effecting a corresponding number of flows of another of the constituents of said mixture in each instance, initially volumetrically proportioning the flows of said constituents to provide a mixture of predetermined total heating value per unit volume, and automatically varying the volumetric proportionality of the flows of the respective constituents in accordance with and to compensate for variations in. the total heating value per unit volume of said combustible mixture with respect to a preselected value.

2. In a method of mixing a plurality of combustible fluids of unlike quality or total heating value per unit volume to provide a combustible fluid mixture of substantially constant total heating value per unit volume whose volumetric rate of flow varies in accordance with the demand therefor, the steps which consist in providing a number of units each of which is adapted when 01)- erated to effect flows of all of the constituent fluids in predetermined volumetric proportionality to each other, subjecting said units to influence of pressure conditions which vary in accordance with variations in demand for the mixture, whereby said units are rendered individually or jointly operative to maintain said pressure conditions substantially constant, continuously ascertaining the instantaneous total heating value per unit volume of the mixture supplied by the active units, and automatically and simultaneously adjusting said units in accordance with variations in said value with respect to a predetermined value, whereby the volumetric proportionality of the constituents of the mixture supplied by each unit is modified to maintain said value substantially constant.

3. The method which consists in automatically initiating operation of one or more of a plurality of gas mixing units in accordance with variations in pressure conditions incident to variations in demand for the mixture, each unit when operated being normally adapted to effect a plurality of flows of gaseous fluids of unlike quality or total heating value per unit volume, said flows being definitely proportioned volumetrically to provide a, gaseous mixture of predetermined total heating value per unit volume, withdrawing a continuous sample of the gaseous mixture supplied by the active units and calorimetrically ascertaining the total heating value per unit volume thereof, and automatically varying the relative rates of flow of the constituent fluids supplied by the respective unitsin accordance with and to compensate for the ascertained variations in said total heating value with respect to a given value.

4. The method which consists in automatically initiating operation of one or more of a plurality of gas making units in accordance with variations in pressure conditions incident to variations in demand, each unit when operated being normally adapted to efiect a flow of relatively rich gas and a flow of relatively lean gas in definitely proportioned relation by volume, withdrawing a continuous sample of the mixture of gases and calorimetrically ascertaining the total heating value per unit volume thereof, and automatically varying the rates of the individual flows of rich gas per unit volume with respect to a preselected value.

5. In a method of maintaining substantially constant the total heating value per unit volume of a composite flow of combustible gaseous fluids to be supplied from one or more gas making units, each unit being normally adapted to effect a flow of relatively rich gas and a flow of relatively lean gas in definite volumetric proportionality to each other to provide a gaseous mixture of predetermined total heating value per unit volume, said units being operable automatically either individually or jointly in response to variations in demand for the gaseous mixture, the steps which consist in continuously ascertaining calorimetrically the total heating value per unit volume of the gaseous mixture, and simultaneously adjusting the rates of the individual flows of relatively rich gas in accordance with and to compensate for variations in said total heating value per unit volume of the gaseous mixture with respect to a preselected value.

6. In a mixing control system for combustible gases, in combination, a conduit for mixed gases, a plurality of units each adapted when operated to supply to said conduit a plurality of constituent gaseous fluids of unlike quality or total heating value per unit volume, each of said units being initially adjusted to insure a predetermined volumetric proportionality of the constituent fluids supplied thereby whereby a gaseous mixture of predetermined total heating value per unit volume is provided, means for rendering said units operative either individually or jointly in response to variations in pressure of themixture in said conduit as an incident to variations in demand for the mixture, means including a calorimeter for continuously withdrawing and burning a sample of the mixture whereby the instantaneous total heating value per unit volume of the mixture is ascertained, and means controlled by said calorimeter for adjusting each of said units whereby the volumetric proportionality of the fluid constituents supplied by the latter is varied in accordance with and to compensate for variations in the total heating value per unit volume of said gaseous mixture.

7. In a gas mixing control system, in combination, a plurality of units each comprising a positive displacement pump adapted when operated to effect a flow of air or other lean gas and each unit also comprising a branch conduit through which rich gas is adapted to flow in predetermined volumetric proportionality to said flow of air or other lean gas, pressure responsive means operable automatically for controlling the operation of said units either individually or jointly in accordance with and to compensate for variations in the demand for the gaseous mixture, and means responsive to variations in the total heating value per unit volume of said gaseous mixture with respect to a given value for automatically varying the volumetric proportionality of the flows of rich gas and air or other lean gas supplied by each and all of said units, whereby the total heating value per unit volume of said gaseous mixture is maintained substantially constant.

8. In combination, a plurality of gas making units, each unit when operated being adapted to individually effect volumetrically proportioned flows of fluids of unlike quality to normally provide a fluid mixture of predetermined total heating value per unit volume, a common discharge conduit for said units, means for selectively renderins said units operable either individually or matically varying the volumetric proportionality of said fluids of unlike quality in response'to variations in the total heating value per unit volume of said fluid mixture, whereby said total heating value per unit volume is maintained substantially constant.

9. In combination, a distributing conduit for a composite combustible fluid, pressure responsive means associated with said conduit, a plurality of gas mixing units, means controlled by said pressure means for rendering said units either individually or jointly operable in response to the combustible fluid demand, each unit when operated being adapted to effect a substantially constant volumetric rate of flow of a composite combustible fluid, the constituent flows of said composite combustible fluid being volumetrically proportioned relatively to each other to normally provide a mixture of predetermined total heating value per unit volume, calorimetric means for continuously ascertaining the total heating value per unit volume of said mixture, and means controlled by said calorimetric means for varying the volumetric proportionality of said constituent flows whereby said total heating value per unit volume is maintained substantially constant.

10. In combination, a distributing conduit for a composite combustible fluid, pressure responsive means associated with said conduit, a plurality of gas mixing units, means controlled by said pressure means for rendering said units either individually or jointly operable in response to the combustible fluid demand, each unit when operated being adapted to effect a substantially constant volumetric rate of flow of a composite combustible fluid, the constituent flows of said composite combustible fluid being volumetrically proportioned relatively to each other to normally provide a mixture of predetermined total heating value per unit volume, calorimetric means for continuously ascertaining the total heating value per unit volume of said mixture, means controlled by said calorimetric means for varying the volumetric proportionality of said constituent flows whereby said total heating value per unit volume is maintained substantially constant, said last mentioned means comprising a plurality of flow regulating valves associated with the respective units, and power means for simultaneously effecting like adjustments of all of said regulating valves.

11. In combination, a distributing conduit for a composite combustible fluid, pressure responsive means associated with said conduit, a plurality of gas mixing units, means controlled by said pressure means for rendering said units either individually or jointly operable in response to the combustble fluid demand, each unit when operated being adapted to efiect a substantially constant volumetric rate of flow of a composite combustible fluid, the constituent flows of said composite combustible fluid being volumetrically proportioned relatvely to each other to normally provide a mixture of predetermined total heating value per unit volume, calorimetric means for continuously ascertaining the total heating value per unit volume of said mxture, means controlled by said calorimetric means for varying the volumetric proportionality of said constituent flows whereby said total heating value per unit volume is maintained substantially constant, said last mentioned means comprising a plurality of flow regulating valves associated with the respective units, and power means for simultaneously effecting like adjustments of all of said regulating valves, each of said valves including means for automatically maintaining a predetermined pressure drop across a restriction located in a fluid supply line of each respective unit.

12. In combination, a distributing conduit for a composite combustible fluid, pressure responsive means associated with said conduit, a plurality of gas mixing units, means controlled by sa'd pressure means for rendering said units either individually or jointly operable in response to the combustible fluid demand, each unit when operated being adapted to efiect a substantially constant volumetric rate of flow of a composite combustible flud, the constituent flows of said composite combustible fluid being volumetrically proportioned relatively to each other to normally provide a mixture of predetermined total heating value per unit volume, calorimetric means for continuously ascertaining the total heating value per unit volume of said mixture, means controlled by said calorimetric means for varying the volumetric proportionality of said constituent flows whereby said total heating value per unit volume is maintained substantially constant, said last mentioned means'comprising a plurality of flow regulating valves associated with the respective units, and power means for simultaneously effecting like adjustments of all of said regulating valves, each of said valves including means for automatically maintaining a predetermined pressure drop across a restriction located in a fluid supply line of each respective unit, the means for adjusting said valves including a displaceable body of liquid common thereto.

13. In a gas mixing control system, in combination, a plurality of gas making units, a common discharge condut for said units, each unit when in operation being adapted to supply a gaseous fluid at a substantially constant volumetric rate, means responsive to operation of each unit for effecting a separate flow of rich gas in definite volumetric proportionality to said first mentioned fluid for mixture with the latter, calorimetric means for continuously ascertaining the total heating value per unit volume of the mixture in said conduit, and means controlled by said calorimetric means for simultaneously adjusting and/or pre-adjusting the volumetric rates of supply of said rich gas by the respective units, whereby the total heating value per unit volume of the mixture within said conduit is maintained substantially constant under conditions of individual and/or joint operation of said gas making units.

14. In combination, a plurality of gas mixing control devices, each device comprising means for eifecting a plurality of volumetrically proport oned flows of fluids of unlike quality or total heating value per unit volume to normally provide a fluid mixture of predetermined total heating value per unit volume, means responsive to pressure variations of the fluid mixture, as an incdent to variations in demand for the latter, to effect operation of said control devices either individually or jointly, means for ascertaining the total heating value per unit volume of the fluid m xture, and common means controlled by said last mentioned means for varying the volumetric proportionality of the flows effected by each of said control devices, whereby the total heating value per unit volume of said fluid mixture is maintained substantially constant.

15. In a gas making and distributing system, in combination, a plurality of gas making units, a common source of rich gas supply therefor, means individual to each unit and operable in response to operation thereof respectively to effect a predetermined volumetric rate of flow of the rich gas, each unit also including means for effecting a flow of lean gas or air in definite volumetric proportionality to the flow of rich gas for mixture with the latter, pressure means operable in response to variations in demand for the mixture to selectively effect operation of said units either individually or jointly whereby the pressure of the mixture is maintained substantially constant under conditions of variation in demand for the latter, means for continuously ascertaining the total heating value per unit volume of said mixture, and means controlled by said last mentioned means for varying the volumetric rate of flow of the rich gas in accordance with and to compensate for variations in said total heating value per unit volume with respect to a given value. 00

16. In a butane gas mixing control system, in combination a source of butane gas supply, a plurality of branch conduits communicating with said source, means operable automatically to maintain substantially constant pressures of gas in the respective branch conduits, a plurality of positive displacement pumps having air intake conduits with which the respective branch conduits communicate, manually operable means for initially adjusting the relative rates of flow of gas and air to the respective pumps to normally provide a gaseous mixture of predetermined heating value per unit volume, a common discharge conduit for said pumps, means responsive to pressure conditions within said discharge conduit for rendering said pumps operable either individually or jointly to thereby maintain the pressure within said conduit substantially .constant under conditions of variation in demand for the gaseous mixture, means for continuously ascertaining the instantaneous total heating value per unit volume of the gaseous mixture within said conduit, and means controlled by said last mentioned means for simultaneously varying the relative rates of supply of gas and air to each of said pumps, to thereby maintain the total heating value per unit volume of the gaseous mixture substantially constant under all conditions.

17. In a butane gas mixing control system, in combination, a source of butane gas supply, a plurality of'branch conduits communicating with said source, a valve in each of said branch conduits, pressure operated devices associated with the respective valves to maintain substantially constant pressure drops across restrictions respectively associated with the latter, manually operable means associated with the respective branch conduits for initially adjusting the volumetric rates of flow therethrough, a discharge conduit with which each of said branch conduits is adapted to communicate, means including normally closed electromagnetically operable valves individual to each branch conduit for normally interrupting communication between the same and said discharge conduit, a plurality of power driven positive displacement pumps, the discharge ends of which likewise communicate with said discharge conduit for supplying air or other lean gas thereto, means adapted upon' operation 150 mixture, and means controlled by said last mentioned means for simultaneously varying the pressure drops across said restrictions aforementioned, whereby the volumetric rates of flow of butane gas in said branch conduits are adjusted to maintain the total heating value per unit volume of the gaseous mixture substantially constant.

EDWIN X. SCHMIDT.