US2125355A - Load controlling apparatus - Google Patents

Description

Aug. 2, 1938. c. w. METZGAR 2,125,355

LOAD CONTROLLING APPARATUS Filed July 26, 1934 975 i l 7* 68 Q 6.9/ 6:9 15 5 9 68 5 y 65 68 65 if I 8110 fl u n 5 11175 tlygjl 71176 678176 x e 60 yyfp 6156.1 67562 fargli' j 7i, a; 8l- (8l l l 4 (f 95 84 82 -57 78 i 77 15 5f' A58d-Z5 95 74' I 1479 1a lz 5 J L 91.10 98 6, JJ 66 L v 111 i6 '55 2 42 5555 45 6 75 71 5 .72 ""5" 224 3 47 und.

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l j 1.11 4l? 12545 @fermi/M5157@ tza 255 BY :r :l I l \7 HIS ATTORNEY Patented Aug. 2,l 19,38

lUNITED STATES APli'rrzrl'rI OFFICE 2,125,355 LoAD ooN'rRoLLlNG APPARATUS Chesterl W. Metzgar, Easton, vPa., assigner to Infgersoll-Rand Company, Jersey City, N. J., acorporation of New Jersey Appneatign July 2s, 1934, serial N. '137,035 15 claims. (c1. 23o-21) 410 that of controlling the load of a compressor used for removingg gas under pressure from a tank or chamber containing a definite volume of gas sol that, as compression proceeds the pressure oi the duid supply is reduced. The several controlling elements of the apparatus may come into operation atpredetermined pressure values to cause additions to the load on the compressor and in that way assure a constant discharge pressure, irrespective of the value of the pressure 20 of the iluld constituting the source of supply.

One object of the invention is to eiect la regulation of the load on a compressor cylinder or cylinders in response to variations in the value of the suction pressure.

A further object of the invention is to provide a compressor with load-changing devices each having a separate regulator or controller therefor.

Another object is' to arrange such -separate regulators for the load-changing devices so that 30 one acts as a master regulator for the remaining ones.

Other`objects .will be in part obvious and in part pointed out hereinafter.

.One purpose which the invention can serve is 35. in regard to the coolingof petroleum and its distillates to cause the separationl of the parailin n therein, preparatory to the recovery o1' the parallln. Theoil containing the paramn, after such treatment as may be necessary, is conducted into o a suitable vessel or reservoir, and then a cooling medium such as liqueiled propane gas (CaHs) is mixed with it; the pressure and temperature within the reservoir containing the oil being so adjusted that the propane can readily be con- 45 verted back into gaseous form. When theproc- .ess ofmixing is complete, the propane is allowed to vaporlze in'said vessel; and, in the course of vaporization, the propane takes from the oil an A amount ofv heat corresponding to the specific 50 heat or vaporization of the propane. This heat becomes latent and the oil is thus cooled to the #required degree. During vaporization theV propane' bubbles out of the oil and collects above it,-

ing the propane from said vessel, and delivering it at constant pressure, as the pressure in the reservoir progressively drops..

The accompanying drawing illustrating one I form which the invention may assume in practice, is a diagrammatic view partly in section of a. load-controlling apparatus constructed in accordance with the practice of the invention and showing it connected to a compressor.

Referring more particularly to the drawing, the load-controlling apparatus, designated in general by 20, is shown applied to a multi-stage compressor 2| comprising low and high pressure cylinders 22 and 23, respectively.l Within the cylinders 22 and 23 are double acting pistons 24 and 25 which are driven by a motor 26.

The low pressure cylinder 22 is connected to a source of fluid supply, for example a tank or reservoir 21, by a conduit 28 and thev fluid passing from the cylinder y22 lflows directly through a conduit 29 into the high pressure cylinder 23. From the highrressurevcyllnder 23 the compressed fluid ows to the point 0I application' through a discharge conduit 38.

,The low pressure cylinder accordingly has a plurality of clearance chambers, four being shown for illustrative purposes. Those adjacent the crank end are designated 3| and 32, while those associated with the opposite endjoi the cylinder 22 are designated 33 and 34. Each clearance chamber communicates with the'adjacent end of `the cylinder 22 through -a port 35, and communication is afforded between pairsof. clearance chambers lying on each side oi the cylinder through a by-pass port 35.

The latter ports are controlled by pressure l actuated spring-pressed clearance valves 31 which operate to controlthe by-passing of fluid between ends of the cylinder 22. Similar valves designated 38, 39, 40 and 4I are arranged in the chambers 3|, 32, 33 and 34, respectively, to control the associated ports 35.

The high pressure cylinder 23 is* likewise provided with a plurality of` clearance chambers, two designated 42 and 43 being located at the crank end of the cylinder and a like number designated 44 and 45 at the-opposite end of the cylinder. As in thel low pressure cylinder the clearance chambers lying on a side of the cylinder 23 also communicate with each other through ports 36 which are controlled by pressure actuated valve devices 46. Each clearance chamber in the high nisms 41, 48, 49 and 59 arranged inthe clear-- ance chambers 42, 43, 44 and 45, respectively.

The valve mechanisms controlling. the ports 35 and 36 may be of a Well kinown type comprising a` Acasingn5| andY apressure actuated springopposed plunger 52 adapted to seat into the ends of the ports 35. The valve mechanisms are preferably operated in pairs, that is, the pressure fiuid whereby the plungers 52 are actuated is simultaneously supplied to or exhaustedl from two valve mechanisms of a cylinder. The valves 31 controlling the by-pass portsg; 36 of the low pressure cylinder are accerdingly connected to a common conduit 53. In like manner the valve mechanisms 38 and 4I are connected to Ya. conduit 54 while thefpressure :fluid is simultaneously supplied to and discharged from the valve mechanisms and 49r through a conduit 55.

The valve mechanisms controlling the ioading ef the yhighpressure-cylinder 23 are similarly operated, the valve mechanisms 46 controliing the 'by-pass ports 36ibeing cennectedizo receive pressure fluid from a common supply conduit 5G. In order to simultaneously ,eiect partial loading or unloading of each end of the high pressure cylin der one valve mechanism'latV each end! of the cylindei 23, as for instance those designated 41 and 59, Yare connected to a supply conduit 5 1 and ,ithe valve mechanisms 48 vand 49 are cennectedv 53, 55 and 54, respectively.

structurally the controlling *devicesrare sub-v stantially identical so that a description of one will sumce forrall. Each contrelling device comprises a main casing65 havingY a valve chamber 66 closed at its lower and upper ends Yby heads 61 and 6B, respectively.Vi The head SB'haS a ared portion 69 anda cover 19 cooperates therewith to form a pressure chamber 1l which is in free cornmunicationwith a source of suction pressure, in this instance the tank 21'through a conduit 172, the header 291,1.V and a branch pipe 13. e l

' Thevalve chamber 66 contains a pilot. valve 14 of which the lower e@ extends into the head 61 and is seated upon aspring supported by a -cap 16 threaded on the head 61 for adjusting 'the force of the spring. 15. The opposite end 4of the valve 14 extends into the flared portion 69 of the head 68 and has afiixed thereto a head 11 which seats againsta diaphragm 18 clamped between the flared portion 69 of the headf-S and the cover 19. Y

The valve 14 serves as a pilot valve for controlling the admission of pressure uid to a main valve 19 reciprocable in theJcasing 65. `.Such pressure nuid issupplied to the valve chambers 66 by the supply conduit 56 which is connected to the valve chambers 65 by branch conduits 89. The pilot valve 14 admits pressure fluid selectively to the ends of the main valve19 for connecting the valve chamber 66 with a supply conduit leading to the clearance valve mechanisms or for v connecting a supply .conduit with discharge pipe 8| connected to the valve casing65.

As has been previously intimated, thehead 11: of each controlling device is constantly subjected to the pressure existing in thetank'21 and in order that the valves 14 wherewith they are associated may came into action at'rlifferent suction pressures said heads are of dilerent diameters.

Thus with the head 11 ci the controlling device 59 of larger area shan the other heads 11 it will yield toY a lower suction pressure, at equal pres=l 'sures ed the springs 15, than will the heads or? the heads of the other controlling devices areof increasing areas from that of the controlling dy vice 66 to the head 11 of the controllingjdevice 64 whichlatter head constitutes that of maximum area of the group of controlling devices 60 to 64, inclusive. 1 f

Preferably the pressure uid supplied to thecontrolling devices 69 to 64 and distributed thereby to the valve mechanisms wherewith they are associated passes through thercontrolling device v 59 which is, in eiect, the master Controller. ',o

this end the controllingdevice 59 is connectedto the conduit 12 and 'reservoir 21 by alconduit "62 having interposed therein a manuali@7 operable valve 83. The valve 83 is othe two-way type and serves togestablish communication between the several sections ef the conduit 82 connected to the valve 83 or between that section of the conduit 82 leading from the valve casing 65 to the valve 83 and an exhaust pipe 84.

The operation of the device is as follows: Let it be assumed that it is intended to remove gas under pressure, as say 125 pounds, frcm the tank 21 and compress'it to a final discharge pressure of 200 pounds and that it beV desired to maintain a predetermined load on the compressor through'- out the compressions period.Y As a rst step of operation intended te meet these conditions the valve 83 is opened to supply 'pressure uid from thefvessel .21 to the valve chamber 66 offgthe controlling device 59. It is, of course, understood that each pilot valve 14 of `the warious controlling devices is depressed, those the group of controlling devices 69 te 64 being in a position to ,admit pressure fluid to the main valves 19v for positioning them so that the main con-4 duits Whichj they cchtrol are connected with'the adjacent discharge'pipes 8l'.

With the several valves of the controlling devices 69 to 64 in the position described, and the valves 14 depressed; and before valve 83 connects the device 59 to the tank 2?i no pressure fluid will, therefore, pass te the associated valve mechanisms inthe compressor cylinders andthe valve mechanisms will, in consequence, remain open to connect the ends of the cylinders with the clearance chambers. Upon the admission of pressure uid into the controlling device 59, how'- ever, its main valve 19 rises and assumes a p0- sition to pass pressure uid through the pipe 56 tothe valve chambers 66 of the other controlling devices and also to the valve mechanisms 46 inl the high pressure cylinder. The valve mechanisms 46 will then close the ports '36 to prevent the by-passing of iiuid and the high :sey

tially loaded.

. The valve chamber upperport 5 and a lower port I with passages 1 and 8 respectively, connecting these ports tothe top and bottom of the space containing the main valve 19. This valve moves a sliding valve 9 -having a recess III which is capable of connectingports II and I2 leading respectively to the pipe 56 and the exhaust pipe 8|, so as to put these pipes intocommunication with each other. The supply pipe I2 connects with the inside of the `chamber' B5 through a port VI3 and a duct I4 connects this chamber to the middle of l the space containing the' valve 19. The valve 14 has two heads I5 thereon to control the ports 5 and 6, and the valve 19 has at its ends heads i6 connected by a reduced part I1. Hence, when the diaphragm' 19 is depressed, the upper port 5 will be cut ou by the upper head I5 or the valve 14 while the lower head I5 will expose the port 6. Fluid from the pipe 42 passing into the chamber 68 -ilows through the port 5 and passage .9 to lift the valve 19. The slide valve 9 then. exposes port 'II to the pipe 55. but closes the outlet port I2 to exhaust pipe BI. Pressure iluid then flows past the portion .I1 of thevalve 19 into the pipe 8l is closed.y

The fluid intended to be compressed passes directly through the low pressure cylinder and the conduit 29 into the high pressure cylinder 23 and, with the' various valve mechanisms of the low pressure cylinder occupying their openA positions, the pressure of the fluid passing through the low pressure cylinder will not be increased.

The compressor will continue to operate in this manner until the suction pressure drops to a In the new position of the valve-19 of the controlling device 5l pressure fluid ows through the conduit 59 to the valve mechanisms 48 and 49 to close them. thus increasing the load of the compressor by, s. one-quarter, depending upon the capacities of the clearance chambers.-

.As the operation of compression proceeds and the pressure value ofthe iluid in the tank 21, in.` consequence, decreases, the. spring 15 of the controlling device 4I will raise its associated valve 14 andcause the valve 19 oi thatl controlling device to be shifted. Pressure fluid then ilows through the supply' conduit l1. to the valve mechanisms 41 and 5I'for closing them. The high pressure cylinder 22 will then be fully loaded. When the suction pressure drops. sumciently to allow the spring 15 of the controlling device-42 Lto lift its va1ve'14lpreuure iluid'is admitted to the valvemechanisms l1 ot theV low 4pressure cylinder to close the ports 34 and thus cause the low pressure cylinder to operate at 'part load.

Thereafter, as the value of the suction pressure decreases the controlling devices 59"' and 44 will come successively. into action to close the valve ts' of the device n has an 55, while the outlet I2 to the pipe are connected tively. 4The compressor will then4 be completely loaded.

In order to prevent the creation of a sub-atmospheric pressure in the tank 21 the spring 15 of the controlling device 59 is adjusted to act at approximately atmospheric pressure. Thus when the pressure in the tank 21 reaches that value the valve 14 is raised to exhaust the holding pressure li'rom the adjacent valve 19. Hence, the lower head I5 on this valve rises above the lower port 5 and associated passage 8 and the upper head I5 uncovers the upper port 5. Pressure fluid fromthe pipe 82 now passes through the passage 1 andl reaches the top of the valve 19, and depresses it. The uid below this valve then i'iows through the passage 8 and the port 5 into the lower portion of .the casing 6 5, whence it may escape tothe atmosphere through a suitable port in the casing 55. The valve 19 will then move down to connect the conduit with the discharge pipe BI through the `valve 9. All the valve mechanisms in the compressor are then connected through their respective supply conduits and controlling devices with the discharge pipe 5I of .the controlling device 59, thereby completely unloading the compressor. 'I'he valve 83 may then be placed in the position for connecting the pipes 82 and 84 with each other and incidentally cutting oiT communication between the tank 21 and the'valve chest 66 o! the controlling device 59.

From the foregoing it will be apparent to those skilled in the art that the device will operate to compensate i'or the decrease in suction pressure resulting upon removal oi' gas ata definite rate from the tank 21 and that the load on the compressor will thus become gradually increased until the pressure in the tank 21 has been reduced to approximately atmospheric pressure, whereupon lthe master controller will act to effect complete l unloading of the compressor.

lWhen the invention is employed in the manner above described, to extract propane from paraffin bearing oil, the propane can be removed from the reservoir at a uniform rate and the envtire quantity can be exhausted in a given time.`

Also, with the suction pressure high at the start and gradually dropping, and the compression pressure maintained constant by the pumping mechanism, there is a considerable saving -in power over what would be required if the gas in the tank 21 were iirst allowed to decrease in presi sure'and then supplied through suitable appliances at a constant suction pressure to the cylina ders 22 and 23. From the compressor the propane can be conducted to acondenser to be again liqueiled.

0f course, the invention can be put to use to extract and compress other gases than propane. and the description herein is ior purposes of explanation only.v In practice many changes in structural details and mode of proceeding might be made and the scope of the invention is setV forth in the broad terms in which the claims appended hereto are expressed.

I claim: l

1. The combination of a compressor, a plu` rality of clearance chambers, clearance valves for' each chamber connected to operate in pairs, a plurality o i' control devices each directly controlling operation oi a pair of clearance valves and each acting in response to a difierent predetermined pressure, and a master control device directly controlling operation of one pair of clearance valves and indirectly controlling operation of the remaining clearance valves by controlling 2. The combination of a compressor, a pluralityA of clearance chambers, clearance valves for the chambers, by-pass valves to control communication between the chambers, a plurality of devices for controlling the clearance valves and connected to act one after another in response to decrements in the value of the suction pressure vfor effecting gradual loading of the compressor, and a controlling device for the by-pass valves connected to act responsively to suction pressure to effect closing of the by-pass valves and to a predetermined minimum suction pressure to effect opening of the by-pass valves.

3. The combination of a compressor, a plurality of clearance chambers, clearance valves for the chambers, by-pass valves to control communication between the chambers, a plurality of devices for controlling the clearance valves and connected to act one after another in response to decre- `ments in the value or the suction 'pressure for eiecting gradual loading of the compressor; and a controlling device for the by-pass valves connected to act responsively to suction pressure for effecting closing of the by-pass valves and to supply pressure fluid to the rst mentioned controlling devices for closing the clearance valves, said last mentioned controlling device connected to act responsively to a predetermined minimum suction pressure for effecting complete unloading of the compressor. i

4. The combination of a plurality of compressors, a plurality of load controlling devices for eachv compressor, a plurality of devices for enabling the load controlling devices to be operated and connected to-act one after the other in response to variations in the value of the suction pressure for eiiecting gradual loading of the compressors according as the value vof the suction pressure decreases, one of said second mentioned devices operating to effect complete unloading of all the compressors.

5. The combination oi a plurality of compressors, a plurality o f load-controlling devices for each compressor, a plurality oi devices for enabling the load controlling devices to be operated and connected to act one after the other in response to decrements in the value of the -suction pressure for eiiecting first a gradual loading of one compressor and subsequently a gradual loading of another compressor according as ythe value of the suction pressure decreases, one of 'said second mentioned devices operating at a predetermined minimum suction pressure to effect complete unloading of all the compressors. A

6. A load controlling apparatus for a compressor having a plurality of clearance chambers,

'pressure medium while controlling its respective loading device. I/

' 7. The combination with a compressor and loading means therefor of al plurality of controlling devices each controlling a loading device, and a common source of pressure medium connected to said controlling devices through which said loading devices are actuated.

8. The combination of acompressor having loading devices, a plurality of controlling devicesl connected individually to certain -of the loading de vices and one of which controlling devices is a master controlling device and serves to control the remaining controlling devices, each controlling device comprising a separate casing containing a main valve and a pilot valve, and a source -of pressure medium connected to said casings to actuate said loading devices, said connection including means for passing said medium through the casing of the master controlling device to the casings of the remaining controlling devices.

9. The combination of a compressor having loading devices, a plurality of controlling devices for the loading devices, connections for convey.

ing pressure medium from each controlling device to a loading device, and connections for conveying pressure medium from one of said controlling devices to the remaining controlling devices.

10,. The combination of a compressor having loading devices, a plurality of controlling devices for the loading devices, connections connecting each controlling device with a pair of loading de-A vides to convey pressure 4medium thereto, a master controlling device, and connections to conveyy pressure medium from the master controlling device to the first mentioned controlling devices and to a pair of loading devices.

1l. The combination of a compressor having loading devices, a plurality of controlling devices each controlling a pair of loading devices, and a master controlling device controlling operation of said plurality of controlling devices while control-- ling a pair of loading devices.

l2. The combination of a compressor having loading devices, a plurality of controlling devices each controlling a loading device, and a master controlling device controlling said plurality of devices and a loading device substantially simultaneously.

13. The combination of a compressor having loading means, separate means each controlling a separate means and a loading means substantially simultaneously.

14. The combination of a compressor having loading means, a plurality of means each controlling a loading means, and master means controlling a plurality of means and a loading means substantially simultaneously, said master means and each said separate means being actuated by a diierent pressure.

15. A 'compressorcomprisi'ng loading devices, controlling devices for the respective loading devices to increase theload on the compressor step-by-step as the compressor discharge pressure decreases, each of said controlling devices comprising a casing having a pilot valve therein and an additional mechanism to enable the respective loading devices to be actuated, a head aixed to said valve, a diaphragm to engage the head, means for subjecting the diaphragm to the pressure of a fluid medium, and a spring to oppose the force of the pressure fluid acting against the diaphragm, said head for each controlling device being of a different size whereby dierent pressures actuate each device to affect step-by-step loading of the compressor.

CHESTER W. METZGAR.

' CERTIFICATE oF CORRECTION.

August 1958.

CHESTER W. HETZGARQ Itis hereby certified that error appears yin the printed specification A" of the above numbered patent requiring correction as follows: Page h, first column, lines bfto 68 vinclusive ,claim 6, strike out the comma and words one of said controlling devices serving tocontrol actuation of the re- 1`maining controlling devices bythe pressure medium while controlling its y respective loading device and insert ,the same after "act'ated" and before the period in second colin-nn, line 2, claim 7; line 26-27, claim 10, for

"devides". read devices; and that the said Letters Patent should be read4 with this correction therein that the 'sane may conform to the record of the case in the Patent Office;

Signedfand sealed this lst day of November, A. D. 1958.

' Henry Van Arsdale (seal) 'Ating commissioner or Patenti?.l

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