US 2848879 A
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Description (OCR text may contain errors)
J. c. HEssoN 2,848,879
2 Sheets-Sheet 1 /N VEA/TOR James 6I Hasso/7 m Aug. 26, 1958 SYSTEM FOR DISPENSING LIQUID CARBON DIOXIDE Filed Aug. 17, 1955 SYSTEM FOR DISPENSING LIQUID CARBON DIOXIDE Filed Aug. 17, 1955 J. C. HESSON Aug. 26, 1958 2 Sheets-Sheet 2 Nx ff..
United States Patent @hice p 2,848,879 Patented Aug. 26, 1958 SYSTEM FOR DISPENSING LIQUID CARBON DIOXIDE James C. Hessen, Riverdale, lll., assignor to Cardox Cor4 poration, Chicago, Ill., a corporation of illinois Application August 17, 1955, Serial No. 528,921
2 Claims. (Cl. 152-54) This invention relates to new and useful improvements in distribution systems for liquefied gases and deals more particularly with systems wherein liquid carbon dioxide is delivered from storage at a low temperature and a correspondingly low pressure to a point of use where the vapor formed during delivery is separated from the liquid, returned to storage and reliqueed.
There is, in modern industry, an ever increasing use of liquid carbon dioxide for purposes such as very low temperature refrigeration of cold test boxes, the refrigeration of tumbling drums for removing ash materials from articles of molded rubber or the like, and other similar purposes. For operations of this type, liquid carbon dioxide may be withdrawn from a supply or storage tank through an insulated pipeline to the point of use. Despite all normal precautions, however, the surrounding air will cause a certainv amount of heat to be transferred to the carbon dioxide which will vaporize a portion of the liquid. For example, liquid carbon dioxide withdrawn from storage, at a temperature of F., through a one-half inch pipe with a normal thickness of insulation, will evaporate at a rate of from ve to ten pounds of liquid for each one hundred feet of pipeline. per hour when the temperature of the air is 80 F. Further, an increase in the thickness of the insulation will increase its insulating value only in proportion to the natural logarithm of the increased thickness and does not offer a practical method for preventing the evaporation of some portion of the liquid.
Since the carbon dioxide vapor that is discharged with liquid carbon dioxide at a point of use has very little cooling effect, the discharged vapor may be considered to be almost a complete loss. In other words, the vapor will absorb very little heat whiley its temperature increases through a substantial range as compared to the heat absorbed by the liquid during its evaporation at the point of use. Further, the combined discharge of carbon dioxide vapor and liquid causes the discharge rate to be irregular and the sound of the escaping Vapor is disconcerting to the workers in the vicinity of the operation.
lt is the primary object of this invention to provide a distribution system for low temperature liquid carbon dioxide which will eliminate the delivery and loss of carbon dioxide vapor at the point of use and will return the vapor to a refrigerated storage container.
A further important object of the invention is to provide a low temperature liquid carbon dioxide distribution system in which the vaporized carbon dioxide delivered with the liquid to a location adjacent a discharge point is separated from the liquid, compressed and reliqueiied by its return to a refrigerated liquid storage container.
Still another important object of the invention is to provide a system for withdrawing low temperature liquid v carbon dioxide from storagev for delivery to a point of use, the evaporatedportionof the carbon dioxide reaching the point of use being separated from the liquid portion and returned to storage for reliquefaction.
Other objects and advantages of the invention will be apparent during the course of the following description.
In the accompanying drawings, forming a part of this specification and in which like reference characters kare employed to designate like parts throughout the same,
Figure 1 is a schematic view of a low temperature, low pressure liquid carbon dioxide distributing system embodying the invention, and
Figure 2 is a longitudinal sectional View of the iloat operated valve employed in the system of Fig. 1.
In the drawings, wherein for the purpose of illustration is shown the preferred embodiment of this invention, and first particularly referring to Fig. l, reference character 3 designates a supply or storage container surrounded by suitable insulating material 4. The' container 3`is charged with liquid carbon dioxide in any suitable manner and the temperature of the liquid is maintained at approximately 0 F. `by the coils 5 of a conventional mechanical refrigeration system, not shown. At this low temperature, the vapor pressure of the liquid carbon dioxide will bemaintained at approximately three hundred and ten pounds per square inch, gauge.
Leading from the bottom of the container 3 is a pipe 6 which provides a flow path for the liquid carbon dioxide 'withdrawn from the container. The pipe 6 is surrounded by suitable insulating material 7 to minimize the absorption of heat by the cold liquid carbon dioxide and a manually operated valve 8 is provided adjacent the container 3 to control the iiow of liquid through the pipe.
The pipe 6 leads from the container 3 to one or more points of use of liquid carbon dioxide and at each of such points the pipe 6 is connected to the inlet port 9 of a float valve 11 by an insulated branch pipe 12. During the flow of the liquid carbon dioxide from the container 3 to the iloat valve 11, through the pipe 6 and branch pipe 12, heat will be absorbed by the very cold liquid and will convert a portion of the liquid to Vapor. Also, there will be a reduction in the pressure on the liquid due to the release of liquid from the system and this reduction in pressure will contribute to the conversion of a portion of the carbon dioxide entering the iioat valve 11 to vapor. Since the carbon dioxide vapor has a very low heat absorbing capacity, the float valve 11 is provided to separate the vapor from the liquid before the latter ows through the outlet 13 o'f the valve and through the insulated pipe 14 to the point of use 15 for the liquid.
It is to be understood that the purpose for which the liquid carbon dioxide is employed at the point of use 15 may be in connection with any conventional lcooling operation and does not form a part of this invention. A manually operated valve 16 is provided for the pipe l adjacent the point of use 15 to control the discharge of the liquid.
Referring now to Fig. 2 for a detail description of the float valve 11 and the manner in which it functions to separate the carbon dioxide vaporfrom the liquid flowing to the point of use 15, it will be noted that the mixture of liquid and vapor flowing through the pipe 12 enters the iioat chamber i7 through the inlet port 9 at the t'op of the valve. After entering the chamber 17, the liquid and vapor will separate and the liquid will occupy the bottom portion ofthe chamber from which it may iiow through the outlet port 13 into the pipe 14. The carbon through the latter.
, splines 21 Vwhich slidably engage the bore of the valve guide 22 to limit movement of the Valve to an axial direction. At .the outer end of the valve 18 there is provided an apertured valve seat 23 and the valve 18 is provided with a conical seating surface 24 which is movable into engagement with the valve seat to close the aperture Movement of the valve 18 away from the valve seat 23, on the other hand, will open the aperture through the `valve seat so that vapor may ow between the splines 21 and through the valve seat to the vapor outlet port 19. At the inner end. of the valve 18 there is provided an operating stem 25 which is threadedly connected to the valve 18.
Axial movement is imparted to the valve 18 to control the ow of vapor from the chamber 17 to the vapor outlet port 19 by an elongated oat 26 which is positioned in the chamber 17 and is mounted for pivotal movement about the pin 27 which lpasses through the block 28 that is rigidly. connected to the oat stem. One end portion of the block 28 is pivotally connected to the valve stem 25 by a pin 29 and the opposite end portion of the block is provided with a lug 31 for engaging the adjustable stop 32 to limit the pivotal movement of the block about the pin 27. Of course, some lost motion must be provided at the pin 29 to permit pivotal movement of the block 28 to eiect the straight line movement ofthe valve 18 in its guide 22.
It will be readily apparent that the'float 26 Will be raised and lowered in accordance With the level of the liquid in the bottom portion of the chamber 17 and such movement of the float will effect pivotal movement of the rigidly connected block 28 about the pin 27 to open and close the valve 18. In other words, as the level of the liquid carbon dioxide in the chamber 17 rises, the float 26 will be moved upwardly to effect pivotal movement of the block 28 in a clockwise direction, as illustrated in Fig. 2, and will cause the valve 18 Vto move toward the valve seat 23 so that the seating surface 24 will close the aperture through the valve seat. The flow of vapor yfrom the upper portion of the chamber 17 to the outlet port 19 will thereupon stop and vapor will accumulate in the upper portion of the chamber until the level of the liquid is lowered. No liquid, therefore, will be permitted to escape through the vapor outlet port 19. Conversely, when the level of the liquid carbon dioxide in' the chamber 17 drops, the float 26 will be lowered and the block 28 will beppivoted in a counter clockwise direction, as viewed in Fig. 2, to eiect ymovement of the valve 18 away from the valve seat 23 so that vapor will be free to ow from the upper portion of the chambery 17 between the splines 21 of the valve and through the apertured valve seat 23 to the vapor outlet port 19. This discharge of vapor from the chamber 17 will continue until the liquid level again rises by a suflicient amount to cause the float 26 to reclose the valve 18.
,Referring once again to Fig. l, it will be seen that the carbon dioxide Vapor flowing from the oat valve V11 through the vapor outlet port 19 will enter an insulated branch pipe 33 for iiow into the vapor return pipe 34 which may oe connected to one or more branch pipes 33 depending upon the number of points of use of liquid carbon dioxide. The branch pipe 33 and vapor return pipe 34 provide a flow path for the vapor from the oat valve l1 to the inlet port of a compressor 35 and a vapor accumulator cylinder 36 is arranged in open communication with the pipe 34 to increase the volume of the vapor yavailable for flow to the compressor. A pressure operated electric switch 37 is also mounted in open communication with the pipe 34 and may be adjusted, `for example, to close at a pressure of two hundred and seventy-ve pounds per square inch, gauge, and to open at a pressure of, two hundred and twenty-five pounds per square inch, gauge. The compressor 35 is driven by an electric motor 38 which is connected in a circuit includ- '4 ing wires 39 and 40 and the switch 37 so that the compressor will be operated when the switch is closed and will be stopped when the switch is opened.
The compressed carbon dioxide Vapor owing from the compressor 35 enters a pipe 41 and passes through two oil traps 42 into the upper portion of the container 3. The pressure of the vapor entering the container 3 from the pipe 41 is greater than the storage pressure of the liquid carbon dioxide so that the 4compressed Vapor will be reconverted to liquid as its temperature is reduced by the refrigerator coils 5.
To summarize the operation of the system described above, liquid carbon dioxide is withdrawn from the container 3 and flows through the pipe 6 to a float valve 11, a portion of the liquid being evaporatedby the absorption of heat during its ilow through the pipe. The oat valve v 11 functions to separate the vapor from the liquid, the liquid being permitted to iiow to the point of use and the vapor being discharged into a returnV pipe 34. Vapor will accumuate in the return pipe 34 and the accumulator cylinder 36 until the pressure therein reaches a value of, for example, two hundred and seventy-live pounds per square inch, gauge, at which time the pressure operated switch 37 will close to actuate the motor 38 which drives the compressor 35. Vapor is thereupon withdrawn from the pipe 34 and accumulator 36 and is compressed 'to a pressure at which the vapor will flow through the pipe 41 into the container 3 where it will be reliquefied at the storage temperature. When a suicient quantity of vapor has been withdrawn from the pipe 34 and accumulator cylinder 36, the pressure operated switch 37 will open the circuit to the motor 38 to stop the compressor 35 until additional vapor has again accumulated in the pipe 34 and accumulator cylinder. It will be readily apparent thatV the system described above provides for the discharge of liquid carbon dioxide to ay point of use 15, the discharged liquid being substantially free of vapor and the evaporated portion of the liquid being returned to a storage container 3 for reliquecation and subsequent use.
It is to be understood that the form of this invention herewith shown and described is to be taken as a pre.
'to a point of use, comprising an insulated chamber adjacent said point of use for containing a supply of liquid carbon dioxide, said chamber having an inlet and a vapor outlet in the upper portion thereof, said inlet and vapor outlet each being located above the level of the liquid carbon dioxide normally contained in said chamber, means forming an insulated iiow path from the bottom portion of said storage container to said chamber inlet, means forming an insulated ilow path from the bottom portion of said chamber to said point of use, iloat actuated valve means for opening and closing said vapor outlet in response to changes in the liquid level in said chamber to prevent the ow of liquid from said vapor outlet and to release the vapor from said flow path, a compressor having an inlet port, means forming a flow path from said vapor outlet to said compressor inlet port, means for controlling the actuation of said compressor in response to changes in the pressure in said last mentioned flow path, means for returning the compressed vapor from said compressorto said storage container, and means for lowering the temperature of the vapor returned to said storage container to reliquefy the same and to maintain the low temperature and pressure of the liquid in the storage container.
2. Apparatus as deiined in claim l further characterized by accumulator means arranged in open communication fell with said vapor flow path to the compressor to increase the volume of vapor available for flow to said compressor.
References Cited in the le of this patent ASA UNITED STATES PATENTS Wade Nov. 19, 1935 Cantacuzene Mar. 31, 1942 Benz et a1. Aug. 4, 1942 FOREIGN PATENTS France July 19, 1927