US1892155A - Process and apparatus for liquefying and rectifying air or other gaseous mixtures - Google Patents

Process and apparatus for liquefying and rectifying air or other gaseous mixtures Download PDF

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Publication number: US1892155A
Authority: US; United States
Prior art keywords: gas; cooling; compressing; expanded; air
Prior art date: 1929-08-03
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.): Expired - Lifetime

Application number

US472020A

Inventor

Isaac H Levin

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Individual

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Individual

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1929-08-03

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1930-07-31

Publication date

1932-12-27

1930-07-31 Application filed by Individual filed Critical Individual

1932-12-27 Application granted granted Critical

1932-12-27 Publication of US1892155A publication Critical patent/US1892155A/en

1949-12-27 Anticipated expiration legal-status Critical

Status Expired - Lifetime legal-status Critical Current

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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air

Definitions

This invention relates to improvements in the process of production of liquid air or similar gases and of separating air or other gaseous mixtures into their constituents by TI liquefaction and rectification by the air of two or several circuits.
the aim of the invention is to utilize to the maximum the relatively inexpensive source of cold as ammonia or other easily liquefiable gases.
air or other gaseous mixtures is compressed in a compressor 6 and is supplied to an interchanger 4 as through a pipe 5.
the air is compressed and purified in the usual manner before reaching 5.
interchanger 4 the air is cooled b heat transfer contact with a refrigerant sucii as ammonia or the like.
the refrigerating system is operated, for
a compressor 1 is used for compressing the ammonia.
the ammonia is condensed in coil 2 and expanded in valve 80 3.
the expanded ammonia enters into interchanger 4, and comes in heat transfer contact preferably by counter current with the air to be cooled and is then again compressed and the cycle is repeated.
a valve is provided at 7 to drain any moisture that is collected in the interchanger.
the air leaving the interchanger 4 may be expanded into expansion valve 8, or in the expansion engines 9 and/or 10, into the interchanger 11 as through pipe 12. While several ex anding means are shown, expansion can ta e place either through valve 8 without the use of either of the engines shown, or the expansion may take place through the engine without being previously expanded in the Serial 110. 472,020, and in France August 8, 1929.
the expanded air may connect to container 14, which is a collector for liquefied portions of the air or gas, as through pipe 13, and so deposit any liquefied portions that may have resulted from the expansion.
the interchangers 11 and 18 could be united into one. It is preferable to have two interchangers, which gives one the advantage of limiting the condensationof moisture and also of frost to practically interchanger 18 and the necessary defrosting can be done without disturbing interchanger 11.
the means for heating the interchanger for defrosting are not shown in the drawing.
Valve 21 may be used to drain moisture out of interchanger 18.
the air to be liquefied passes through the inter-changers 18 and 11. Before it is expanded it is quite warm relative to the cold vapors in pipe line 12. This permits of good heat transfer. If one utilizes both circuits of the air at 200 atmospheres, for example, in the proportion of 1 kilogram of air of the circuit cooled by the cold non-liquefied por- 5 tions of the air to 1.33 kilogram of the circuit cooled by ammonia or the like, the result will be that instead of getting about 8 calories in the form of liquid air per kilogram of air compressed by using the first circuit above (i. e. the liquefaction circuit alone), this process has a value of the order of 30 calories per kilogram of air compressed of the combined circuits.
T e process is not limited to the means of realizing same described but can be varied considerably.
the circuit for refrigerating is not limited to air even when air is to be liquefied but other ases could be used as nitrogen or hydrogen.
the gas used in the circuit for refrigerating is to be recuperated and is not the same as the gas to be liquefied
an additional interchanger or an additional set of tubes in interehangers 11 and 18 and the necessary piping changes will have to be provided to avoid contamination between the gas in the refrigerating circuit and the vapors of the gas that is liquefied.
the circuits need not be at the same pressure but the pressure and volumes should be chosen in such a manner as to obtain the necessary heat transfer and to bring the cold vapors to room temperature.
An apparatus for liquefying a gas comprising means for compressing a portion of the gas, means for compressing, cooling and expandin a refrigerant, means to bring the contact with the compressed gas whereby the cold expanded refrigerant into heat transfer gas will be cooled and the refrigerant will be sated to room temperature, means to expend the cooled gas in an expansion valve and/or expansion engine producing external work, means to employ the cooled gas as a refrigerant to cool by heat transfer contact an other portion of compressed gas whereby the refrigerant will be heated to room temperature and the compressed gas will be cooled, means to expand and partially liquefy the 2.
a process of liquefying gas comprising compressing one portion of gas, compressing a. second portion of gas, cooling said second portion by a refrigerant which is more easily liqueliable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, and using the cold expanded second portion to cool the first portion.
a process of liquefying gas comprising compressing one portion of gas, com ressing a second portion of gas, cooling sai second portion by a refrigerant which is more easily liqueliable than the gas which is to be liquefied, expanding said second portion with a productlon of a lower temperature, using the cold expanded second portion to cool the first portion, expanding and partially liquefyin said cold first portion, and using the noniquefied part of said first portion after expansion for cooling only the first of said portions before the first portion is expanded.
a process of liquefying gas comprising compressing one portion of gas, com I'essing a second portion of gas, cooling sai second portion by an external refrigerant, expandm said second portion with a production of a ower temperature, and using the cold expanded second portion to cool the first portion.
a process of liquefying gas comprising compressing one portion of as, com ressin a second portion of s, coo ing sai secon portion by an externa refrigerant, expanding said second portion with a production of a lower temperature, expanding and partially liquefymg said cold first portion. and using the non-liquefied part of said first ortion after ex ansion for cooling only the rst of said portions before the first portion is expanded.
a process of liquefying gas comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by non-regenerative cooling means, expanding said second portion with a production of a lower temperature, and using the cold expanded second portion to cool the first portion.
a process of liquefying gas campusing compressing one portion of gas, compressing a second portion of gas, cooling said second portion by nonregenerative cooling means, expanding said second portion with a production of a lower temperature, expanding and partially liquefyin said cold first portion, and using the non-liquefied part of said first ortion after expansion for cooling only the rst of said portions before the first portion is expanded.
a process of liquefying gas comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by a refrigerant which is more easily liqu'efiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, and cooling said first portion by heat exchange with said cold expanded second portion.
a procefs of liquefying gas comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, and cooling said first portion by countercurrent heat exchange with said cold expanded second portion.
a process of liquefying gas comprising compressing one portion of gas, comressing a second portion of gas, cooling said second portion by a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, and cooling said first portion by heat exchange with said cold expanded second portion in such manner that the second portion is brought to substantially the temperature of the entering first portion.
a process of liquefying gas comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, and cooling said first portion by heat exchange with said cold expanded secondportion while said first portion is at substantially room temperature.
a process of liquefying gas comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, and cooling said first portion by heat exchange with said cold expanded second portion while said first portion is at a substantially higher temperature than the temperature of the cooled expanded second portion before heat exchange.
a process of liquefyin gas comprising compressing one portion 0 gas, compressing a second portion of gas, cooling said second portion by an external refrigerant, expanding said second portion with a production of a lower temperature, cooling said first portion by a countercurrent heat exchange with said cold expanded second portion in such manner that the temperature of the first portion is reduced and the second portion is discharged at substantially the temperature of the entering first portion.
a process of liquefying gas comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by an external refrigerant, ex paneling said second portion with a production of a lower temperature, cooling said first portion by a countercurrent heat exchange with said cold expanded second portion in such manner that the temperature of the first portion is reduced to substantially that of the expanded second portion and the second portion is discharged at substantially the temperature of the entering first portion.
a process of liqucfying gas comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, cooling said first portion by a countercurrent heat exchange with said cold expanded second portion in such manner that the temperature of the first portion is reduced and the second portion is discharged at substantially the temperature of the entering first portion.
a process of liquefying gas comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, cooling said first portion by a countercurrent heat exchange with said cold expanded second portion in such manner that the temperature of the first portion is reduced to substantially that of the expanded second portion and the second portion is discharged at substantially the temperature of the entering first portion.
a process of liquefying gas comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, cooling said first portion by a countercurrent heat exchange with said cold expanded second portion in such manner that the temperature of the first portion is reduced to substantially that of the expanded second portion at the discharge end and the second portion is discharged at the other end at substantially the temperature of the entering first portion.
a process of liquefyin gas comprisingcompressingone p0 iono gas,compressing a second portion 0 gas, cooling said second portion bv a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, cooling said first portion by heat exchange with said cold expanded second portion, ex-
a process of Iiquefying gas comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by an external refrigerant, expanding said second portion with a production of a lower temperature, cooling said first portion by a countercurrent heat exchange with said cold expanded second portion in such manner that the temperature of the first portion is reduced to substantially that of the expanded second portion and the second portion is discharged at substantially the temperature of the entering first portion, expanding and partially liquefying said cold first portion, and using the non-liquefied part of the first portion after expansion for cooling only the rst of said portions before it is expan ed.
a process of liquefyin gas comprisingcompressingone p0 iono gas,compressing a second portion 0 gas, cooling said second portion bv a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, cooling said first portion by heat exchange with said cold expanded second portion, ex-
a process of Iiquefying gas comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by an external refrigerant, expanding said second portion with a production of a lower temperature, cooling said first portion by a countercurrent heat exchange with said cold expanded second portion in such manner that the temperature of the first portion is reduced to substantially that of the expanded second portion and the second portion is discharged at substantially the temperature of the entering first portion, expanding and partially liquefying said cold first portion, and using the non-liquefied part of the first portion after expansion for cooling only the rst of said portions before it is expan ed.

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Description

Dec. 27, 1932. H LEVlN 1,892,155

PROCESS AND APPARATUS FOR LIQUEFYING AND RECTIFYING AIR OR OTHER GA'SEOUS MIXTURES Filed July 51. 1930 Patented Dec. 27, 1932 PATENT OFFICE ISAAC H. LEVIN, OF PITTSBURGH, PENNSYLVANIA rnocnss AND nrrnnarus ron monnrxme AND nno-rrrme AIR on o'rann GASEOUS mrxrnnns Application fled July 81, 1930,

This invention relates to improvements in the process of production of liquid air or similar gases and of separating air or other gaseous mixtures into their constituents by TI liquefaction and rectification by the air of two or several circuits. The aim of the invention is to utilize to the maximum the relatively inexpensive source of cold as ammonia or other easily liquefiable gases.

The advantages of my invention and means for obtaining these advantages will be clearly set forth in the description of an apparatus that can be employed as a matter of example to carry out the invention. The accompany- 16 ing drawing shows schematically an apparatus in which the process may be practiced.

Referring to said drawing, air or other gaseous mixtures is compressed in a compressor 6 and is supplied to an interchanger 4 as through a pipe 5. The air is compressed and purified in the usual manner before reaching 5. In interchanger 4, the air is cooled b heat transfer contact with a refrigerant sucii as ammonia or the like.

i The refrigerating system is operated, for

example, by the apparatus represented in the drawing, in which a compressor 1 is used for compressing the ammonia. The ammonia is condensed in coil 2 and expanded in valve 80 3. The expanded ammonia enters into interchanger 4, and comes in heat transfer contact preferably by counter current with the air to be cooled and is then again compressed and the cycle is repeated.

The above refrigerating cycle is given only as a matter of example, and can be varied in many ways, so long as the desired refrigerating effects are produced upon the compressed air. A valve is provided at 7 to drain any moisture that is collected in the interchanger.

The air leaving the interchanger 4 may be expanded into expansion valve 8, or in the expansion engines 9 and/or 10, into the interchanger 11 as through pipe 12. While several ex anding means are shown, expansion can ta e place either through valve 8 without the use of either of the engines shown, or the expansion may take place through the engine without being previously expanded in the Serial 110. 472,020, and in France August 8, 1929.

valve. Furthermore, the work done by both engines may be combined in one unit or but a single stage engine need be used. The expansion can thus take place in either of the units shown or in the combination of all of them.

In addition to passing into pipe 12 the expanded air may connect to container 14, which is a collector for liquefied portions of the air or gas, as through pipe 13, and so deposit any liquefied portions that may have resulted from the expansion.

Another portion of air is compressed in 16 and passed into interchanger 18 as through pipe 17, then into interchanger 11, and '85 u its heat in counter current to cold air in pipe 12. The gas is then expanded in valve 20 and partially liquefied. The liquefied gas is stored in 14. The liquid can be removed by valve 15, and the non-liquefied portlon is sent into interchanger 11 through pipes 13 and 12 and then to interchanger 18 and by heattransfer with the gas entering as through 17, is brought to room temperature.

The interchangers 11 and 18 could be united into one. It is preferable to have two interchangers, which gives one the advantage of limiting the condensationof moisture and also of frost to practically interchanger 18 and the necessary defrosting can be done without disturbing interchanger 11. The means for heating the interchanger for defrosting are not shown in the drawing. Valve 21 may be used to drain moisture out of interchanger 18.

In this process, where a current of air is compressed then refrigerated b ammonia or ither vapors of easily liquefiabih gases and is expanded in an engine doing external work, the result from the point of view of production of liquid air is small but the heat content is by this means vcry much lowered in the order of kilocalories per kilogram. The refrigerated air is used as a refrigerant on another current of air capable of absorbing this cold by heat transfer contact.

The air to be liquefied passes through the inter-changers 18 and 11. Before it is expanded it is quite warm relative to the cold vapors in pipe line 12. This permits of good heat transfer. If one utilizes both circuits of the air at 200 atmospheres, for example, in the proportion of 1 kilogram of air of the circuit cooled by the cold non-liquefied por- 5 tions of the air to 1.33 kilogram of the circuit cooled by ammonia or the like, the result will be that instead of getting about 8 calories in the form of liquid air per kilogram of air compressed by using the first circuit above (i. e. the liquefaction circuit alone), this process has a value of the order of 30 calories per kilogram of air compressed of the combined circuits. These quantities are not absolute but can vary largely according to the dimensions of the installation and the nature of the insulation and other conditions. The energy necessary for the production of cold by ammonia is very small in comparison with the energy necessary for the total compression of the air, the result being that one not only produces an unusual quantity of liquid air per kilogram of air treated, but also the energy to produce a kilo ram of liquid air is very much reduced relative to the present ractice.

T e process is not limited to the means of realizing same described but can be varied considerably.

The circuit for refrigerating is not limited to air even when air is to be liquefied but other ases could be used as nitrogen or hydrogen.

f the gas used in the circuit for refrigerating is to be recuperated and is not the same as the gas to be liquefied, an additional interchanger or an additional set of tubes in interehangers 11 and 18 and the necessary piping changes (which are not shown in the drawing) will have to be provided to avoid contamination between the gas in the refrigerating circuit and the vapors of the gas that is liquefied. The circuits need not be at the same pressure but the pressure and volumes should be chosen in such a manner as to obtain the necessary heat transfer and to bring the cold vapors to room temperature.

I claim:

1. An apparatus for liquefying a gas comprising means for compressing a portion of the gas, means for compressing, cooling and expandin a refrigerant, means to bring the contact with the compressed gas whereby the cold expanded refrigerant into heat transfer gas will be cooled and the refrigerant will be sated to room temperature, means to expend the cooled gas in an expansion valve and/or expansion engine producing external work, means to employ the cooled gas as a refrigerant to cool by heat transfer contact an other portion of compressed gas whereby the refrigerant will be heated to room temperature and the compressed gas will be cooled, means to expand and partially liquefy the 2. An apparatus for liquefying a gas com- 65 prising means for compressing a portionl of the gas, means for compressing, cooling and expanding a refrigerant, means to bring the cold expanded refrigerant into heat transfer contact with the compressed gas whereby the gas will be cooled and the refrigerant will be heated to room temperature, means to expand and partially liquefy the cooled gas in an expansion valve and/or expansion engine producing external work, means to employ the non-liquefied portion of the gas as a refugerant to cool by heat transfer contact another portion of compressed gas whereby the refrigerant will be heated to room temperature and the compressed gas will be cooled, means to expand and partially liquefy the gas.

3. A process of liquefying gas, comprising compressing one portion of gas, compressing a. second portion of gas, cooling said second portion by a refrigerant which is more easily liqueliable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, and using the cold expanded second portion to cool the first portion.

4. A process of liquefying gas, comprising compressing one portion of gas, com ressing a second portion of gas, cooling sai second portion by a refrigerant which is more easily liqueliable than the gas which is to be liquefied, expanding said second portion with a productlon of a lower temperature, using the cold expanded second portion to cool the first portion, expanding and partially liquefyin said cold first portion, and using the noniquefied part of said first portion after expansion for cooling only the first of said portions before the first portion is expanded.

5. A process of liquefying gas, comprising compressing one portion of gas, com I'essing a second portion of gas, cooling sai second portion by an external refrigerant, expandm said second portion with a production of a ower temperature, and using the cold expanded second portion to cool the first portion.

6. A process of liquefying gas, comprising compressing one portion of as, com ressin a second portion of s, coo ing sai secon portion by an externa refrigerant, expanding said second portion with a production of a lower temperature, expanding and partially liquefymg said cold first portion. and using the non-liquefied part of said first ortion after ex ansion for cooling only the rst of said portions before the first portion is expanded.

7. A process of liquefying gas, comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by non-regenerative cooling means, expanding said second portion with a production of a lower temperature, and using the cold expanded second portion to cool the first portion.

8. A process of liquefying gas, campusing compressing one portion of gas, compressing a second portion of gas, cooling said second portion by nonregenerative cooling means, expanding said second portion with a production of a lower temperature, expanding and partially liquefyin said cold first portion, and using the non-liquefied part of said first ortion after expansion for cooling only the rst of said portions before the first portion is expanded.

9. A process of liquefying gas, comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by a refrigerant which is more easily liqu'efiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, and cooling said first portion by heat exchange with said cold expanded second portion.

10. A procefs of liquefying gas, compris ing compressing one portion of gas, compressing a second portion of gas, cooling said second portion by a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, and cooling said first portion by countercurrent heat exchange with said cold expanded second portion.

11. A process of liquefying gas, comprising compressing one portion of gas, comressing a second portion of gas, cooling said second portion by a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, and cooling said first portion by heat exchange with said cold expanded second portion in such manner that the second portion is brought to substantially the temperature of the entering first portion.

12. A process of liquefying gas, comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, and cooling said first portion by heat exchange with said cold expanded secondportion while said first portion is at substantially room temperature.

13. A process of liquefying gas, comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, and cooling said first portion by heat exchange with said cold expanded second portion while said first portion is at a substantially higher temperature than the temperature of the cooled expanded second portion before heat exchange.

14. A process of liquefyin gas, comprising compressing one portion 0 gas, compressing a second portion of gas, cooling said second portion by an external refrigerant, expanding said second portion with a production of a lower temperature, cooling said first portion by a countercurrent heat exchange with said cold expanded second portion in such manner that the temperature of the first portion is reduced and the second portion is discharged at substantially the temperature of the entering first portion.

15. A process of liquefying gas, comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by an external refrigerant, ex paneling said second portion with a production of a lower temperature, cooling said first portion by a countercurrent heat exchange with said cold expanded second portion in such manner that the temperature of the first portion is reduced to substantially that of the expanded second portion and the second portion is discharged at substantially the temperature of the entering first portion.

16. A process of liqucfying gas, comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, cooling said first portion by a countercurrent heat exchange with said cold expanded second portion in such manner that the temperature of the first portion is reduced and the second portion is discharged at substantially the temperature of the entering first portion.

17. A process of liquefying gas, comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, cooling said first portion by a countercurrent heat exchange with said cold expanded second portion in such manner that the temperature of the first portion is reduced to substantially that of the expanded second portion and the second portion is discharged at substantially the temperature of the entering first portion.

18. A process of liquefying gas, comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, cooling said first portion by a countercurrent heat exchange with said cold expanded second portion in such manner that the temperature of the first portion is reduced to substantially that of the expanded second portion at the discharge end and the second portion is discharged at the other end at substantially the temperature of the entering first portion.

19. A process of liquefyin gas, comprisingcompressingone p0 iono gas,compressing a second portion 0 gas, cooling said second portion bv a refrigerant which is more easily liquefiable than the gas which is to be liquefied, expanding said second portion with a production of a lower temperature, cooling said first portion by heat exchange with said cold expanded second portion, ex-

pending and partially liquefying said cold first portion and using the non-1i uefied part of said first ortion after expansion for cooling only the rst of said ortions before the first portion is expander.

20. A process of Iiquefying gas, comprising compressing one portion of gas, compressing a second portion of gas, cooling said second portion by an external refrigerant, expanding said second portion with a production of a lower temperature, cooling said first portion by a countercurrent heat exchange with said cold expanded second portion in such manner that the temperature of the first portion is reduced to substantially that of the expanded second portion and the second portion is discharged at substantially the temperature of the entering first portion, expanding and partially liquefying said cold first portion, and using the non-liquefied part of the first portion after expansion for cooling only the rst of said portions before it is expan ed.

In testimony whereof I aifix my si ature.

ISAAC H. L VIN.

CERTIFICATE OF CORRECTION.

Patent No. I, 892. 155.

December 27, I932.

ISAAC I'I. LEVIN.

it is hereby certified that error appears above numbered patent requiring correction as l, strike out the words "cold expanded refrigerant into sort the same to follow "the" in line 50; should be read with this correction therein record of the case in the Patent Office.

in the printed specification of the Page 2, line 52. claim follows:

heat transfer" and inand that the said Letters Patent that the same may conform to the Signed and sealed this 21st day of February, A. D. 1933.

(Seal) M. 1.. Moore, Acting Commissioner of Patents.

charged at the other end at substantially the temperature of the entering first portion.