US2033094A - Method and apparatus for dispensing gas material - Google Patents

Description

Marsh 3, i936. M. P. DE MOTTE METHOD AND APPARATUS FOR DISPENSING GAS MATERIAL Filed March 28, 1934 2 Sheets-Sheet l mww IN V EN TOR.

A TTORNEYS.

March 3, 1936. M- p DE MOTTE 2,033,094

METHOD AND APPARATUS FOR DISPENSING GAS MATERIAL Filed March 28, 1934 2 Sheets-Sheet 2 Patented Mar. 3, 193e LIETHOD AND APPARATUS FOR ISHSPENS- ING GAS MATERIAL Maurice P. De Motte, Indianapolis, Ind., assignor to The Linde Air' Products Company, New York, N. Y.; a corporation of Ohio Application March 28, 1934, Serial N0. 717,712

This invention relates to a method and apparatus for dispensing gas material and particularly to a method and suitable apparatus for transferring liquefied gas from one container to r another.

The invention has for its object generally the provision of an improved method and apparatus of the character indicated which is efcient and economical and adapted for making a transfer wof a liquefied gas that has a boiling point at atmospheric pressure materially below 273 Kelvin, for example, liquid oxygen, at or near atmospheric temperature in a manner such that losses due to vaporization are relatively small.

More specifically, the invention has for its object the provision of steps and of suitable means for carrying the same into effect, whereby the liquefied gas being transferred is refrigerated so as to reduce the losses due to evaporization and 2U to facilitate the admission of the gas material to a second container.

It is another object to refrigerate the liquefied gas when transferred from a storage container to a portable container, so as to provide a subcooled 5 liquid for transport in the portable container.

It is also another object to provide an expansion device for expanding a portion of liquefied gas being transferred from the storage container to a second or portable container so as to produce the refrigerating effect by the utilization of the expansive properties of the liquefied gas being transferred.

It is still another object to provide a distributing system, having a storage container and an associated expansion device for subcooling the liquid being transferred by means of its own expansive properties, with compression means for recompressing the expanded gas material whereby the cost of providing subcooled'liquefled gas is reduced to substantially that of the power consumed in effecting recompression.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others, and the apparatus embodying features of construction, combinations of elements and arrangement of parts which are adapted to effect such steps, all as exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a, fuller understanding ofthe nature and objects of the invention.' reference should be had to the following detailed description talgen in connection with the accompanying drawings, in which:

Fig. l is a view mainly in vertical section, showing an arrangement of containers for transferring liquefied gas in accordance with the invention; 5

Fig. 2 is a view partly in section and partly diagrammatic, showing another arrangement of apparatus for transferring a liquefied gas in accordance with the invention; and

Fig. 3 is a fragmentary view, showing a modified 10 form of the apparatus shown in Fig. 2 for carrying out the invention.

In transferring liquefied gases of the character indicated at substantially the boiling point temperature corresponding to the existing pressure from storage containers to other containers, for example, to portable containers of the transport variety mounted on motor vehicles, it has been customary to discharge the liquefied gas into such other container directly from the first, a 2o differential of pressure between the two containers being provided, in order to maintain a fiow. This method of transfer, however, results in a certain amount of the gas material being initially vaporized when the liquefied gas is transferred from the storage container to the second container before the walls of the latter are brought substantially to the temperature of the liquefied gas being transferred. The liquefied gas thus vaporized entails losses unless retained in the second container by closing the same to the atmosphere. The back pressure which builds up in such cases results in decreasing the pressure differential depended upon to maintain flow and retards the filling operation.

In accordance with the present invention, the filling losses heretofore incident to the transfer of liquefied gases at substantially the boiling point temperature corresponding to atmospheric 4o pressure are avoided by refrigerating the liquefied gas being transferred, so that when it reaches the second or portable container, an appreciable temperature elevation is possible to cool the walls of the second container without flashing the 4 liquefied gas into vapor.. This refrigerating effect is preferably produced by utilizing the expansive properties of the liquefied gas to produce a lowered temperature and passing it in heat exchanging relation with the gas material that is to enter the second container. Accordingly, a' suitable expansion device, for example, an expansion valve, is provided to control a portion of the withdrawn gas material, in order to provide a medium, that has been cooled by self-expansion, in heat exchanging relation with the portion being passed into the second or portable container.

The gas distributing system of the present invention, which has anv expansion device associated with the storage container for the liqueed gas. has also an associated compression means for recompressing the expanded portion of the liquefied gas utilized to produce a refrigerating effect and return the same to the storage coni tainer, where it is conserved and utilized, for example, in providing the pressure differential depended upon to effect transfer of liquefied gas.

The present invention is particularly intended for use in connection with the dispensing and distribution of liquid oxygen when supplied for industrial uses, since by refrigerating the liquid oxygen as withdrawn from a storage container, it may be discharged in a subcooled condition to a transport container; the losses due to vaporization in the chilling of the transport container when the liquid is first introduced, being in such case materially reduced or avoided altogether. The heat which is absorbed in producing this cooling effect merely raises the liquid oxygen introduced into the second container from the temperature of a subcooled condition toward the boiling point temperature at atmospheric pressure or a pressure slightly thereabove. The invention also has extensive application in connection with other liquefied gases intended for industrial use, for example, in connection with the distribution of liquid hydrocarbons, such as liquid ethane or liquid propane. Such liquids are withdrawn from storage containers and by refrigerating a portion to reduce the liquid to a temperature below the boiling point temperature, it may be distributed through a manifold or otherwise to suitable portable containers such as gas receiving cylinders, which are used subsequently as the receptacles from which to supply directly the gas material in the gas phase to the place of use.

Referring now to the drawings and particularly to Fig. 1, I0 denotes a thick-walled vessel comprising the pressure vessel of a storage container for liquefied gas which is here shown as having a heat insulating envelope II and a supporting casing I2 for holding the insulation and vessel in place. The container is shown as provided with a filling connection I3 and with a liquid phase withdrawal connection I4, which serves as the conduit for conveying the liqueed gas being transferred to a second container. This latter is depicted as comprising a vessel I5 having heat insulation I6 and a casing I'l, the whole being mounted on a truck I8 for transport service. The conduit I4 exteriorly of the casing I2 is shown as comprising a ilexible, de tachable portion I4 which engages with a filling connection I9 for discharging the liquefied gas being transferred into the second vessel I 5,

In order to withdraw a portion of the liquid being transferred to expand the same and producea refrigerating effect in accordance with the invention, a branch conduit 20 is provided which leads from the conduit I4 at a point adjacent to where it connects with the vessel I0 and has an expansion valve 2|, from which the expanded fluid emerges and is conveyed to a heat exchanger 22. This latter may be in any convenient form, but is here shown as a counter-current cooling conduit disposed about a relatively long portion of the conduit I4, which is housed in the casing I2, this conduit being provided with one or more return bends in order to achieve housing the desired length within the space available within the casing I2. The gas material which has been utilized in producing the refrigerating effect upon the liquefied gas being transferred is preferably led from the high temperature end of the heat exchanger 22 through a coil 23 that is disposed in the heat insulating envelope about the vessel I 0 for the purpose of cooling it and preventing heat leakage vas far as practical through the insulating envelope to the vessel I0. The exteriorportion of this conduit or coil denoted 23' is enlarged to provide a heat exchanging casing which leads the expanded gas to a suitable recompressing device, for example, a turbine pump 24 driven by an electric motor at 25. From the pump the gas returns by way of connection 26 through the heat exchanger 23' into the vessel I0 after passing the expansion valve 26'. Another valved return connection 26" is also provided which communicates also with a relief -or safety valve as shown at 21. A valved gas phase vwithdrawal connection is shown at 28 leading from the gas space of the vessel I0 and communicating with the coil 23, in order that the accumulated pressure within the vessel I0 may be' regulated by withdrawing a portion of the gas in the gas phase when desired. Such withdrawn portion of the ,gas material in the gas phase may be further compressed if desired in the turbine 24 and discharged at 29 directly to a place of use.

Since the portable container shown in Fig. 1 is of the insulated variety, it is generally desirable to provide the same with pressure building means for effecting relatively rapid discharge at the place of use. Accordingly, this portable container is shown as provided with a pressure building coil 30 exposed to the atmosphere and arranged to communicate with the container at points both above and below the liquid level of the container, as taught in Heylandt P atent Reissue No. 18,876, dated June 20, 1933; this container also has a liquid phase withdrawal connection at 3| and a gas phase withdrawal connection at 32.

In the arrangement shown, an optional additional expansion valve 2| is provided for withdrawing a portion of the liquefied gas after it has passed through the exchanger, instead of before such passage. Such construction may be used also as an alternate form of that provided by the valve 2I. A valve 33 is shown for controlling the outlet end and passage of liquefied gas through the conduit I4. A valve 33 is similarly shown for controlling the inlet end for the inlet connection I9 of the transport container. There is also a by-pass connection 34 controlled by a. valve 35 leading from a point just beyond the valve 33 in conduit I4 to the conduit 23', whereby gas in the gas phase remaining in the transport container may be withdrawn before a filling operation is begun, the withdrawn gas being compressed and supplied to the system through the conduit 26". The use of such bypass connection, while preferred, is not essential to the practice of the present invention.

In operation, when it is desired to withdraw liquefied gas from the container I0, for example, liquid oxygen, and transfer the same to a transport container I5, the conduit I4 is connected to the inlet I9 by the connection I4' and the outlet valve 33 from the storage container opened, as well as the inlet valve 33 on the transport container. Pressure in the vessel I 0 will cause the liquid oxygen to pass out through the conduit I4, this pressure being obtained by maintaining compressed gas in the gas space of the container I8. Or compressed gas may be added to the gas space by opening the passage 26" until the desired pressure is reached. Just before, simule taneous with, or soon after opening the valve 33, the expansion valve 2l is opened, in order that a portion of the withdrawn gas material may be passed into the heat exchanger 22 in an expanded condition and at a temperature below that of the liquid in the vessel I8; the temperature of the latter being close to that of the boiling point of liquid oxygen at normal atmospheric pressure, since the pressure in the vessel ID is not, as a rule, greatly in excess of atmospheric pressure,

for example, in the neighborhood of from 15 to 20 lbs. gage pressure. The gas material expanded to sub-atmospheric pressure, passing about the conduit I4 in a countercurrent direction in exchanger 22 refrigerates the liquid passing to the transport container, into which it is discharged through the inlet I9 in a sub-cooled condition.Y

The expanded gas passes from the exchanger 22 into the cooling coil 23 coiled about the vessel I0 and nally through the exchanger 23 into the turbine 24, this turbine being set into operation to maintain a sub-atmospheric pressure in exchanger 22 as soon as the expansion valve 2| is opened. The sub-atmospheric pressure maintained in exchanger 22 determines the degree of subcooling attained. When expansion valve 28' is opened, the compressed gas flowsA through conduit 26, being cooled by heat exchange in exchanger 23 and partially liqueiied when passing through expansion valve 26. The turbine may be run at other times where it is desired to withdraw gas through the connection 28 from the gas space in the vessel l0 to compress it and supply it to a place of use through the conduit 29.

In the modied arrangement shown in Fig. 2. a storage container is shown at 40 having a lling connection 4| and a withdrawal conduit 42 controlled by valve 43 and communicating with a heat exchanger 445. This heat exchanger is shown as an insulated vessel containing a coil 45 to the lower end of which a conduit 46 suppies a withdrawn portion of the liqueed gas, such gas having passed through an expansion valve 41 at the entrance to the coil. From Vthe coil 45, the expanded gas material is led by way of conduit 45 to a compressor 49 and returned to the system through the inlet at 58. A blow-back tank 5i for receiving and storing the expanded liquefied gas may be provided in communication with the conduit 48, if desired. Such tank is shown connected to the system and provided with a control valve 52, While the conduit 48 has a' cooperating valve 53.

From the lower end of the heat exchanger 44 a manifold connection 54 is led preferably through heat insulation and provided with a plurality of filling outlets 55; the latter have controlling valves 56 and are shown as discharging into receivers 51 which communicate therewith. If desired to maintain the liqueed gas cooler than the surrounding temperature, the receivers 51 and container 40 are preferably also provided with heat insulation.

In the modified arrangement shown in Fig. 3, the parts are generally similar to those in Fig. 2, with the exception that a modiiied form of heat exchanger is shown. Here the heat exchanger is denoted 44' and has the conduit 42 for gas material being distributed passing centrally through the same, the expanded gas material which is to cool the exchanger being arranged to enter at the bottom from the conduit 46 after having passed an expansion' valve 41'. In the arrangements shown in Figs. 2 and 3, it is advantageous to provide thermometers in the heat exchangers. Such thermometers are accordingly shown at 68 disposed in the heat exchangers 44 and 44'. It is also preferable, as indicated in the drawings, to locate the heat exchangers in close proximity to the inlets of the containers or receivers being filled, so as to maintain losses due to heat absorption from the atmosphere at as low a rate as practically possible.

In operation, when charging receivers such as shown at 51 with liquid propane or similar liquid of high vapor tension, the liquid is withdrawn from the storage container 48 through the conduit 42 and introduced into the heat exchanger 44. A portion of the liquid is withdrawn through the branch conduit 46 in Fig. 2 and caused to enter the coil 45 in the heat exchanger at the lower end after having passed under the control of the expansion valve 41. The expanded gas material passes into the coil and absorbs heat from the fluid surrounding the coil. In this manner, liquefied gas being passed to the' receivers 51 is refrigerated and brought to a relatively low temperature, preventing rapid vaporization thereof, but the cooling is accomplished without changing the pressure or loss of pressure. The expanded gas passes from the coil 45 through the conduit 48, either into the tank 5I or to the compresser 49, where it is recompressed and returned to the storage container 40. When the compressor is in operation, the valve 52 is gen.- erally closed, while the valve 53 is opened. If desired, however, both valves may be open so that the tank will act as a capacity chamber to provide an even flow of gas to the compressor. When the tank 5I- only is in use, the compressor is cut out of operation by closing the valve 53. Thus by reducing the temperature of the liquefied gas entering the heat exchanger and passing it to the manifold and thence into the receivers 51, any back pressure tending to develop as a result of the vaporization of liquid accumulates and builds up at a relatively low rate compared with the rate that obtains when supplying liquefied gas at a temperature at or near 'the boiling point at atmospheric pressure. The pressure differential between the storage container 40 and the portable containers or gas receivers 51 is thereby maintained for relatively long periods and the time of lling is thereby materially reduced in that the resistance which the vaporized gas material sets up against the incoming gas material is substantially reduced.

The operation of the arrangement shown in Fig. 3 is substantially like that shown in Fig. 2. It will be appreciated, however, that for the purpose of preventing atmospheric temperatures from adversely affecting the cooling process, the heat exchangers are preferably jacketed with suitable insulating material, for example, with porous asbestos. such jacket being preferably extended to include as much of the manifold and container as practical..

Since certain changes may be made in the above construction and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all rcatter contained in the above description or shown in the accompanying drawings shall be intil terpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is:

l. The method of dispensing liquefied gas material that has a boiling point at atmospheric pressure below 273 K., which comprises storing a body of said material in the liquid phase in a container, transferring liquid from said container by simultaneously withdrawing two portions from said body, one of which is conveyed directly to a second container while maintained substantially at the same pressure, expanding the other portion to produce a refrigerating effect, and cooling said first portion by utilizing the refrigeration produced in said other portion.

2. The method of dispensing liquefied gas material that has a boiling point at atmospheric pressure materially below 273 K., which comprises storing and conserving a body of said material in the liquid phase in a container, substantially excluding the entry of heat from an external source into said container, transferring liquid from"said storage container by simul.- taneously withdrawing two portions from said body, one of which is conveyed directly to a second container while being maintained substantially at the same pressure, expanding the other portion to produce a refrigerating effect, and passing said expanded portion in heat exchanging relation with said rst portion whereby said first portion is subcooled before deposition in said second container.

3. The method of dispensing liquefied gas material that has a boiling point at atmospheric pressure materially below 273 K., which comprises storing and conserving a body of said material in the liquid phase in a container, substantially excluding the entry of heat from an external source into said container, transferring liquid from said storage container by simultaneously withdrawing two portions from said body, one of which is conveyed directly to a second container while being maintained substantially at the same pressure, expanding the other portion to produce a refrigerating effect, passing the expanded portion in heat exchanging relation with said first portion, substantially excluding heat of external origin from said portions when passing in h`at exchanging relation, and recompressing and returning vapor resulting frorn said expansion to said storage container.

4. The method of dispensing liquefied gas material that has a boiling point at atmospheric pressure materially below 273 K., which comprises storing and conserving a body of said material in the liquid phase in a container, substantially excluding the entry of heat from an external source into said container, transferring liquid from said storage container by simultaneously withdrawing two portions from said body, one of which is conveyed directly to a second container while being maintained substantially at the same pressure, expanding the other portion to produce a refrigerating effect, passing the expanded portion in heat exchanging relation with said first portion, selectively collecting and conserving vapor resulting respectively from said expansion and from evaporation in said second container.

5. The method of transferring liquefied gas from a storage container into a portable container, which comprises simultaneously withdrawing two portions of the liquid from the storage container,

passing one of said portions directly into the portable container to be held therein while maintaining the pressure therein at a value not greatly different from that of said;V storage container, expanding the other portion;A to a relatively low pressure so that it is cooledwto a relatively low temperature, and subcooling the portion passed to the portable container before deposition therein by effecting heat exchange with the expanded portion.

6. T he method of transferring liquefied gas from a storage container into a portable container, which comprises simultaneously withdrawing two portions of the liquid from the storage container, passing one of said portions directly into the portable container to be held therein while maintaining the pressure therein at a value not greatly different from that of said storage container, expanding the other portion to a relatively low pressure, and recompressing and returning a suiiicient amount of said expanded portion to the storage container to raise the pressure therein to a desired value.

7. The method of transferring liquefied gas from a storage container into a portable container, which comprises simultaneously withdrawing two portions of the liquid from the storage container, passing one of said portions directly into the portableI container to be held therein while maintaining the pressure therein at a value not greatly different from that of said storage container, expanding the other portion to a pressure which is lower than the pressure of the gas material held in the portable container whereby the expanded portion is cooled to a relatively low temperature, subcooling the portion being passed to the portable container by effecting heat exchange with the expanded portion, and recompressing the expanded portion to a desired pressure for use.

8. The method of transferring liquefied gas from a storage container into a portable container, which comprises simultaneously withdrawing two portions of the liquid from the storage container, passing one of said portions directly into the portable container to be held therein while maintaining the pressure therein at a value not greatly different from that of said storage container, expanding the other portion to a pressure which is lower than the pressure of the gas material held inthe portable container whereby the expanded portion is cooled to a relatively low temperature, subcooling the portion being passed to the portable container by effecting heat exchange with the expanded portion, raising the pressure acting on the liquid in the storage container by compressing and passing into said stor` age container desired volumes of gas drawn selectively from the portable container and from the expanded portion.

9. The method of transferring 'liquefied gas that has a boiling point at atmospheric pressure below 273 K. from a place of supply to a place of use, which comprises storing and conserving a body of gas material in a heat insulated container at the place of supply, delivering gas material withdrawn from said body in a subcooled condition when at atmospheric pressure to a heat insulated transport container, sealing said delivered material in said transport container, transporting said delivered material without substantial change in its condition to a place of use, and then discharging one or more portions of tsaid delivered material from said transport conamer.

i0. Apparatus for dispensing gas material which comprises the combination with a heat insulated storage container arranged to retain liquefied gas material in the liquid phase, which material has a boiling point at atmospheric pressure materially below 273 K., of a one-way conduit means for withdrawing two portions from said body provided with a through passage for one of said portions, means for expanding the other portion and passing the same in heat exchanging relation with the first portion, said conduit means being associated with said storage container and insulated against the entry of heat of external origin, and a second container arranged to be connected to said conduit means and to receive the through conveyed portion in a subcooled condition.

11. Apparatus for dispensing gas material which comprises the combination with a heat insulated storage container arranged to retain liquefied gas material in the liquid phase, which material has a boiling point at atmospheric pressure materially below 273 K., of a one-way conduit means for withdrawing two portions from said body provided with a through passage for one of said portions, means for expanding the other portion and passing the same in heat exchanging relation with the first portion, said conduit means being associated with said storage container and insulated against the entry of heat of external origin, a portable container arranged to be disconnectively connected to seid conduit means for receiving the through conveyed portion, and means for collecting and conserving the vaf' pers produced from the expansion of said second portion.

12. Apparatus for dispensing gas material which comprises the combination with a heat insulated storage container arranged to retain liquefied gas material in the liquid phase, which material has a boiling point `at atmospheric pressure materially below 273 K., of a one-way conduit means for withdrawing two portions from said body provided with a through passage for one of said portions, means for expanding the other portion and passing the same in heat exchanging relation with the first portion, said conduit means being associated with said storage container and insulated against the cntry of heat of external origin, a portable container arranged to be disconnectively connected with said conduit means for receiving the through conveyed portion, and means associated with said container for selectively collecting and compressing the vapors resuliing respectively from said expansion and from evaporation in said portable container.

13. In apparatus for transferring liquefied gas in a subccolcd condition, the combination with a storage container, of a second container, a oneway conduit means for establishing communication between said containers whereby liquefied gas may be conveyed from said storage container into said second container, a heat exchanger associated with said withdrawal conduit, an expansion device connected to receive a withdrawn portion of liquefied gas from said storage container and pass the same into said heat exchanger, and means for conserving and compressing the expanded portion after passing through said heat exchanger.

14. In apparatus for transferring liquefied gas in a subcooled condition, the combination with a storage container, of a second container, a single conduit for withdrawing liquefied gas from said storage container and conveying the same into said second container, a heat exchanger associated with said withdrawal conduit, an expansion device connected to receive a withdrawn portion of liquefied gas from said storage container and pass the same into said heat exchanger, and means associated with said storage container for conserving and compressing said expanded portion after having passed through said heat exchanger.

l5. In apparatus for transferring liquid oxygen, the combination with an insulated storage container. of a portable insulated container of the transport type, a liquid phase withdrawal conduit associated with said storage container having a portion adapted to introduce the withdrawn material into said portable container, a heat insulated heat exchanger associated with said withdrawal conduit, an expansion valve connected to divert a portion of the liquefied gas from said withdrawal conduit into said heat exchanger,

a return conduit leading from said heat exchanger to the gas space of said storage container having a portion coiled about said storage container, and means in said return conduit for recompressing the expanded portion to a desired pressure before admission to the gas space of said storage container.

16. In apparatus for charging receivers with liquid propane', the combination with the storage container, of a vessel provided with a primary passage for the passing of fluid therethrough having an inlet and an outlet, a conduit for supplying fluid from said storage container to said inlet, a secondary passage through said vessel arranged in heat exchanging relation with Q the first-named passage. fluid expansion means associated with said second-named passage and connected to introduce a supply of fluid to be expanded from said storage container, manifold means for filling said receptacles from the outlet

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