US2738261A - Apparatus for mixing air and liquified petroleum gases - Google Patents

Description

March 13, 1956 Filed Feb. 19, 1955 F. E. DRAKE APPARATUS FOR MIXING AIR AND LIQUIFIED PETROLEUM GASES '2 44 I 12 &4 41

2 Sheets-Sheet l 29 46 25 ii 31 6 v2 24 11 11 1/ 3 I L1 7 R l 13 FL "I [1 INVENTOR.

AT TOR NEYS F. E. DRAKE 2,738,261

APPARATUS FOR MIXING AIR AND LIQUIFIED PETROLEUM GASES March 13, 1956 2 Sheets-Sheet 2 Filed Feb. 19, 1953 INVENTOR. 'XW M BY ATT RNEYS FOR MIXING AIR AND, LIQUIFIED PETROLEUM GASES Drake, Pelham, N. Y., assignor of one-half to Harry W. Townsend, New Rochelle, N. Y.

Application February 19, 1953, Serial No. 337,763

7 Claims. c1. 48-180) APJP ARATUS This invention relates to apparatus for mixing air with vaporized petroleum products, such aspropane and butane. In order to control the heating value of gas made from propane, butane, or other volatile hydrocarbons, or mixtures of hydrocarbons, it is-the usual practice to mix a definite quantity of air with the vapor or gas before supplying it to the distribution lines.

It is an object of this invention to provide improved apparatus for mixing air with the gas from vaporized hydrocarbons; and it is a particular object to obtain a highly accurate control of the heating value of'the gas without the use of expensive and highly complicated control mechanism.

One of the simpler ways by which air can be supplied to use a plurality of aspirators, connected in parallel,

and the number of aspirators in use at any one time depends upon the gas demand. t v

It is another object of the invention to provide a gas mixer witha plurality of mixing devices connected in' 1 parallel with one another and operated by simple control rn e'chanism for determining which and how many of the mixers are to operate at any one time. Moreespecially, itis-an object of the invention to control the operation of the mixers by gas pressure and without the use of electn'city'. The mixers of the prior art which haveused electricity, are rendered inoperative or requiremanual operation in the event of a storm or other occasion which shutsofi the electricity, sometimes for substantial periods of time. l

Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.

In the drawing, forming a part hereof, in whichlike reference characters indicate correspondingparts in all theyiews,

Figure 1 is :a perspective view showing the outside housing of a mixer embodying this invention;

Figure Zis a plan view of the unit shown in Figures 1, 3 and 4, with the top of the housing removed;

Figure 3 is a rear elevation of the mixer unit of this invention with the. back of the housing removed;

Figure 4 is aside elevation of the unit shown in Figure 3, with the side of the housing removed;

Figure 5 is an enlarged, fragmentary and diagrammatieview of one of the gasflow control valves and its operating mechanism; Figure 6 is an enlarged, sectional view of one ofthe mixers, placed in a horizontal position.

"Figure 1 shows the mixer unit of this invention with a housing 10 supported onbed members 11. A gas'inlet connection 12 is located near the top and front or the and 21.

ice

2 housing 10; and a gas outletconnection 13 is located at the bottom and backof thehousing.

The gas outlet connection 13 is fora substantially larger size of pipe because'the gas flowing from the mixing unit has a substantial quantity of air mixed in-it and this makes the volume substantially larger.

tems having distribution pressures in excess of about 4 or 5 pounds (p. s. i. g.), compressed is supplied to the conduit 18. I

Figures 2, 3 and 4 showthe construction inside of the housinglt). There is an incoming gas header 20 communicating with the gas inlet connection 12 and there is an outgoing gas header 21 leading to the gas outlet connection 13. A system of piping 24 leads. from theupper gas header 20 to the lower and-outgoing gas header 21. A, similar system of piping 25 also connects headers. 20

In each of the systems of piping 24 and 25, there is a shutoff valve 27, operated by automatic control means whichfwill be described, for commanding the flow of gas from the header .20 to the header 21. I

The flow ofgas to each automatic shutofi valve 27 can be shut ofi manually by avalve 29 in series with the shutoff valve 27.. A by-pass. line 31 leads from .the in-,

coming gas header 20 to aconnection with thesystem of piping 24 beyond the shutoff valve. 27.- .1 A similar bypass line 32 leads from the header 20 to a location of the system of piping'25 beyond the shutoif valve 27 of that system of piping. I

Referring to Figures-3 and 4, the systems of piping 24 and 25 both extend downwardly for a substantial distance 'in the housing 10, and each systemhas a mixer unitor aspirator 34 below the by- pass lines 31 and 32. I Another shutoff valve 35 is located between the automatic shutofi valve 27 and the by-pass 31. or 32. This makes it possible to close the piping on .both sides of the valve 27 so that this automatic valve can be removed from the line and replaced without relieving the pressure: in the line or in any way impairing the operation of the mixer. a

At each mixer unit 34 thereis an air inlet line 36, leading from the connecting conduitr 18 through which air flows from theair :filter 17. -.Each-.o f these air inletlines 36 containsa check valve 37 for preventing possible escapeof gas from the system in the event that flow. through the aspirator is blocked and. gas attempts to .back. up through the air inlet line 36. There is also a manuallyoperated air valve 38 in the air inlet line 36.

Both of these air inlet lines 36 connect with the connecting conduit 18 leading from the air filter 17. This construction makes the invention more compact, but it can be made with separate air'cleaners on the different airinletlines. a a r In -'the construction illustrated, the: connecting conduit 18, the air filter 17, and theupstr'ea'm ends of the air inlet lines 36, aresupported from the bottom of the housing by an'upstanding support 39. f v t t Each of the shutoff valves 27 has apressure-actuated operator 40 which will be described in detail in connection with Fig. 5. For the present, it is sufiicient to tounderstand that when pressure is applied under the operator 40, the valve 27 isopened. r.

The gas for actuating the operators-40 is controlled from pilot control assemblies 41 and; 42. The pilot control assembly 41 connects with' the operator for the valve 27 in the system of piping 24, andithe pilot-control assembly 42 connects'with the operator 40 for the valve 27 in-the system of piping 25. Y

'The pilot control assemblies41and 42 both-receive Patented -Mar-. 13, .1956.

7 Thereis a check valve 15 on the gasoutlet connection 13.. The. air which is to be mixed with the gas within the housing 10 is drawn through an air filter 17 and connect-- ing conduit 18 to the mixerswithin the housing. For sys-:

gas from the incoming gas header 20 through tubing 43 and a pressure regulator "44, connected in" series with the tubing 43. Each of the pilot control assemblies 41 and 42 is connected with the outgoing gas header 21 by tubing 45. Each pilot control assembly is connected with the operator 40, which it controls, by tubing 46. (Bornpressed air can be supplied to'the pressure regulator 44, instead of gas, at plants where compressed air is available. The use of gas as the working fluid tor th'evalve operators 40 has "the advantage of making the apparatus a self-contained unit.

Fig. shows the construction of the pilot control assembly 41 and itsassociated pressure-actuated operator. The construction of the other pilot control assembly is similar. The tubing 43 leads from the regulator 44 to a control device 47.

Inthe control device 47, the gas flows into a chamber 49 in which'there is a valve element 50. There are openings at both ends of the chamber 49. The gas fromthe tubing 43 enters the chamber 4 9 through the opening at the left-hand end of the chamber, and the opening at the right-hand end of the chamber leads to the ambient atmosphere. If desired, the left-hand end of the chamber 49 can be connected bytubing to the distribution header 21. This conserves gas and also prevents the gas from escaping in a confined room when the unit is indoors.

When the valve element 50 is at the left-hand end of the chamber 4.9 as shown infull lines in Fig. 5, it closes the opening which communicates with the tubing 43-and shuts off the flow of gas into the chamber 49.

When thevalve element '50 is at the right-hand end of the chamber 49, as shown in dotted lines in Fig. 5, it prevents the escape of gas from the chamber 49 to the ambient atmosphere.

The valve element 50 has a-valve stem connected with a metal flapper 51 which isheld, by amagnet 52, in position to locate the valve elements 50 at the left hand end of the chamber 49. The magnet 52 is secured to one end of an adjusting screw 53. This screw threads through a flange 54-extending upwardly from the control device 47. By turning the screw'53, the magnet can be advanced or retracted with respect to the flapper 51.

Themetal flapper 51- extends upwardly between-an adjustable abutment 58 and a fixed pivot 59. The abutment 58 can be shifted'toward and from the flapper 51 by an adjusting-screw 60. The .upper end of the flapper 51 is connected to anend fitting '61 of a .bellows 62 carried-by a fixed support 63.

' The bellows 62 is connected with the tubing 45, and through this tubing-communicates with the'distribution header. When the-pressure withinthe-distribution header decreases, the -bellows 62 contracts and pulls the upper end of the-metal-flapper 51 toward the-left in Fig. SJ'This tends to rock'the' flapper 51 counter-clockwise, but because of the attractionof-the magnet 52 for the :flapper, the initial contracting motion-of the bellows- 62 merely bends the metal flapper 51.

As additional energyis stored in the metal flapper .51 by bending, the energy-eventually becomes sufficient to pull the flapper away from the magnet 52 so that the flapperpulls-the.valveelement'50. to the right hand end of thechamber 51. .With the-valve element 50 in this position, gas flows-from the tubing43, through the chamber 49, and from the chamber.49 through tubing 6.4 to a control pressure chamber-.65 of a diaphragm-operated valve 66.

'-'The.-valve'66 contains anvalve element 67 having a valve stem which is-lpushed downwardly by .diaphragms 68 when the pressurein the chambenGSincreases sufficiently to overcomethe pressure of a spring 69 which is compressed between the :lowerndiaphragm 68; and a partitioned wallet-the casingof the valve 66. DownwardmovementotlIthe-yalve element 67;, shifts it, into open positionand permits-gas from the regulator. 44 to flow past the valve element 67 tothe tubing 46, and through thistubingdo thexalvercpcrator 40.

When the gas pressure in the distribution header rises,

the bellows 62 extends and pushes the upper end of the metal flapper 51 toward the right hand in Fig. 5. This rocks the flapper 51 about the abutment 58 and shifts the lower end of the flapper toward the magnet 52. The flapper 51 moves the valve element 50 from the dotted line to the full line positions shown in Fig. 5 so that the flow of gas from the tubing 43 is shut off, so that the gas in the chamber 49, and in the control pressure chamber 65, is free to escape past the valve stem and into the ambient atmosphere through the opening in which the stem of the valve element 50 slides.

This escape of gas reduces the pressure in the valve chamber 65- rapidly, and the spring 69 pushes the diaphragms 68 upwardly so that the valve element 67 is moved into closed position by a spring 69 located under the valve element.

The upper end of the stern of the valve element 67 is pointed so as to serve as a needle valve. This pointed end of the valve stem closes a port through thecenter of the lower diaphragm 68 when the diaphragms are depressed, but after the valve element 67 closes, the further upwardmovement of the diaphragms 68, under pressure from'the spring 69, lifts the lower diaphragmabove the pointed end of the valve stem and permitsuthei gas under the lower diaphragm 68 to escape vinto the space between the diaphragms. From this space the gas passes through .tubing connecting with the distribution header 21, as indicated in Fig. 5. This bleed outlet provides for the escape ofgas from the pressure chamber of thevalve operator 40 so that the valve operator can return to its normal positionunder influence of spring-operated means which will be, described.

The tubing 46 communicates with a diaphragm ,chamber 70 on the underside of a diaphragm 71. Therc'is-a diaphragm plate 72 on top of the diaphragm 71. ,This diaphragm plate 72 and the diaphragm 71, are. urged downwardly by a spring 73.

A push-rod 74 is threaded into a boss on top. of ,the diaphragm plate 72 and this push-rod 74 slides in-a bearing 75 held in the frame 76 of the operator 40.

The'valye. 27 includes a valve element 77. This. valve element 77 is moved into open position by a valve lifter 78 that has a stem 79 which slides through a stuffing 00x80 and bearings 81. The lower end of t he valve lifter stem 79 is connected with the upper end of;,the push-rod 74 and operates as a unit with the push-rod. An indicator;82 ;on the push-rod 74 moves, alonga scale 83 to indicate the. extent of opening of the valve element 77.

Figure 6 shows the construction of the mixer unit-or aspirator-34. A nozzle 85 discharges a stream..of,;gas from the incoming header 20 into a throat 86 andthis stream of gas; from the nozzle 85 draws air into the throat 86 from an air chamber 88 surrounding the nozzle,85.

The air chamber 88 is kept filled withair by the flow of new air through the air inlet line 36 and through the check. valve 37. I It is a feature of the invention that the check valve 37 includes a very light valve element 90, and it is another feature of the invention thatthe air inlet line 36-is of short length. These featurescombine to keep the air pressure in the chamber 88 nearly'constant, becauseany slight drop in pressure in the air chamber- 88 is sufficient to draw new air into the chamber through the short air inlet line 36. The light weight of;the check valve element 90 results in there being very little pressure drop necessary to hold this valve element open.

.Both of. ,the mixers or aspirators 34 of the apparatus are similar in construction but they may befartd preferably are,;of diflerent size. For example, .th e mixer unit. 34 in the system of piping 24 may be designed' for a flow. of 50 0,,cubic feet of gas per hour, and,the n1ixer in the system of piping 25 may be designed for a larger rate of flow. I

going gas header 21 by the tubing 45.

The two mixer units shown in the drawing are merely representative of a plurality of mixer units connected in parallel between the incoming gas header 20 and the outgoing gas header 21.

When the apparatus is installed, the pilot control assemblies are adjusted so that they do not operate at exactly the same pressure. The bellows 62 (Figure 5) of each pilot control assembly, is connected with the out- In order to make the pilot control assemblies operate in sequence, the adjustable abutment 58 or the magnet 52 of one pilot control assembly is adjusted so that it does not operate until the bellows pressure drops to a somewhat lower value than is required to operate the other pilot control assembly. When the mixer units are of diiferent capacity, the pilot control assemblies are adjusted so that the mixer unit of smaller capacity operates first when a demand for gas reduces the pressure in the outgoing gas header.

When the gas demand becomes so great that the first mixer cannot supply it by working continuously, then there will be a somewhat further drop in the pressure in the outgoing gas header and the second pilot control dc vice will operate to cause gas to be supplied through the second mixer.

When the second mixer is of considerably larger capacity than the first, and the apparatus is in a plant with I an attendant, the lower-capacity mixer may be cut out of operation by closing the valve 29. This has the efiect of making the larger mixer remain open for longer periods. Frequently repeated opening and closing of the gas line through either of the mixers is undesirable because there is a'tendency for the mixer to supply a flush of overly rich gas to the line when the mixer first begins to operate, and to supply a flush of lean gas to the line as the mixer stops operating.

The preferred embodiment of the invention has been illustrated and described, but changes and modifications can be made without departing from the invention as defined in the claims.

I claim as my invention:

1. Air-gas mixing apparatus including in combination a gas supply header for high pressure gas, a distributing header for an air-gas mixture at lower pressure, connecting means through which gas flows from the supply header to the distributing-header, said connecting means including a pressure regulator and a mixer, an aspirator in the mixer operated by flow of gas through the mixer toward the distributing header, an air inlet communicating with the aspirator and through which air is drawn by the aspirator, a valve for controlling the flow of the gas through the aspirator, actuating mechanism for the valve operated by gas pressure, gas passage connections between one of the headers and the actuating mechanism for the valve, said actuating mechanism including a chamber communicating with said gas passage connections to the header, a movable element forming a wall of the chamber and movable.

in response to pressure changes in the chamber, and motion transmitting means comprising direct mechanical connections between the valve and said movable element, a three-way valve system for controlling flow of gas to and from the chamber of the actuating mechanism, the three-way valve system including a shut-off valve located in said gas pressure connections, and other actuating mechanism for operating the three-way valve system including a pressure responsive device communicating with the distributing header.

2. The air-gas mixing apparatus described in claim 1 and in which the gas passage connections lead from the gas supply header to the actuating mechanism chamber.

3. The air-gas mixing apparatus described in claim 2, and in which the chamber is also connected with the distributing header through the three-way valve system for the exhaust of the gas pressure from the chamber into the distributing header.

4. The air-gas mixing apparatus described in claim 1, and in which the connecting means through which gas flows from the supply chamber to the distributing chamber includes a plurality of parallel connections each of which includes its own mixer and its own valve for controlling the flow of gas through the aspirator, and each of which includes its own actuating mechanism for the valve and three-way valve system, the pressure responsive devices of the different three-way valve systems being constructed to operate at difierent pressures from one another and each of the mixers including an air inlet passage which is relatively short to reduce flow resistance, and a light-weight, swing check valve in the air inlet passage operated entirely by the suction of the aspirator.

5. The air-gas mixing apparatus described in claim 1, and in which the actuating mechanism for the threeway valve system includes a conduit connected with one of the headers for supplying gas pressure to said actuating mechanism, and the pressure-responsive device includes a pilot valve for controlling the flow of gas through said conduit to the actuating mechanism of the three-way valve system.

6. The air-gas mixing apparatus described in claim 5, and in which the pressure responsive device includes an energy-storing element operated by the pressureresponsive device, a holder resisting movement of the pressure-responsive device, and connections through which said device operates the pilot valve with a snap action when the stored energy overcomes the resistance of said holder.

7. The air-gas mixing apparatus described in claim 1, and in which the apparatus is a self-contained unit enclosed within a housing having bed members on which the housing and its contents are supported and movable as a unit, the gas supply header being enclosed within the housing and extending through a wall of the housing and having means for connecting with a source of gas, the gas distributing header being also enclosed within the housing and having at least one end extending through a wall of the housing with means outside the housing for connecting with a distributing line, the con nections between the header being enclosed within the housing and including a plurality of parallel mixers connected with a common air supply passage, and a single inlet through a wall of the housing for flow of air from the ambient atmosphere to the common air supply passage.

References Cited in the file of this patent UNITED STATES PATENTS 718,049 Dally Jan. 6, 1903 1,074,266 Jones Sept. 30, 1913 1,287,139 Thompson Dec. 10, 1918 1,803,240 Fenzel Apr. 28, 1931 2,077,493 Rossi et a1. Apr. 20, 1937 2,366,322 Foster Jan. 2, 1945 2,570,373 Peacock Oct. 9, 1951

Claims (1)

1. AIR-GAS MIXING APPARATUS INCLUDING IN COMBINATION OF GAS SUPPLY HEADER FOR HIGH PRESSURE GAS, A DISTRIBUTING HEADER FOR AN AIR-GAS MIXTURE AT LOWER PRESSURE, CONNECTING MEANS THROUGH WHICH GAS FLOWS FROM THE SUPPLY HEADER TO THE DISTRIBUTING HEADER, SAID CONNECTING MEANS INCLUDING A PRESSURE REGULATOR AND A MIXER, AN ASPIRATOR IN THE MIXER OPERATED BY FLOW OF GAS THROUGH THE MIXER TOWARD THE DISTRIBUTING HEADER, AN AIR INLET COMMUNICATING WITH THE ASPIRATOR AND THROUGH WHICH AIR IS DRAWN BY THE ASPIRATOR, A VALVE FOR CONTROLLING THE FLOW OF THE GAS THROUGH THE ASPIRATOR, ACTUATING MECHANISM FOR THE VALVE OPERATED BY GAS PRESSURE, GAS

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