# US 9,435,582 B2 · Method and apparatus for liquefying a gas or cooling a feed gas at supercritical pressure

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- Number: US 9,435,582 B2
- Document ID: US9435582B2
- Status: Granted
- Kind: B2
- Application number: 14/111,349
- Filed: 2012-04-12
- Published: 2014-01-30
- Granted: 2016-09-06
- Earliest claimed: 2011-04-14
- Assignees: L'Air Liquide, Societe Anonyme pour l'Etude et l'Exploitation des Procedes Georges Claude
- Applicants: Arthur Darde; Xavier Traversac
- Inventors: Arthur Darde; Xavier Traversac
- Web page: https://patentgrep.com/patent/US9435582B2

## CPC

- F25J 1/00: Processes or apparatus for liquefying or solidifying gases or gaseous mixtures {(recovering volatile solvents by condensation B01D5/00; vapor recovery systems combined with filling nozzles B67D7/54; solidification of carbonic acid C01B32/55; for ammonia in general C01C1/00)}
- F25J 1/0027: {Oxides of carbon, e.g. CO2}
- F25J 1/004: {by flash gas recovery (F25J1/0267 takes precedence)}
- F25J 1/0042: {by liquid expansion with extraction of work}
- F25J 1/0045: {by vaporising a liquid return stream}
- F25J 1/0202: {in a quasi-closed internal refrigeration loop (F25J1/0208, F25J1/0219, F25J1/0224 take precedence)}
- F25J 1/0262: {Details of the cold heat exchange system (constructional details F25J5/00, construction of cold-exchangers in general F28)}
- F25J 1/0263: {using different types of heat exchangers}
- F25J 1/0264: {Arrangement of heat exchanger cores in parallel with different functions, e.g. different cooling streams (F25J1/0272 takes precedence)}
- F25J 3/067: {separation of carbon dioxide (production of carbon dioxide in general C01B32/00)}
- F25J 2200/00: Processes or apparatus using separation by rectification
- F25J 2210/70: Flue or combustion exhaust gas
- F25J 2220/82: Separating low boiling, i.e. more volatile components, e.g. He, H2, CO, Air gases, CH4
- F25J 2230/30: Compression of the feed stream
- F25J 2230/42: the fluid being nitrogen
- F25J 2240/40: Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval
- F25J 2245/02: Recycle of a stream in general, e.g. a by-pass stream
- F25J 2270/02: Internal refrigeration with liquid vaporising loop
- F25J 2270/80: Quasi-closed internal or closed external carbon dioxide refrigeration cycle
- Y02C 20/40: of CO2
- 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 (cryogenic pumps F04B37/08; gas storage vessels, gas holders F17; filing vessels with, or discharging from vessels, compressed, liquefied or solidified gases F17C; refrigeration machines, plants, or systems F25B)}
- Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]

## Abstract

The invention relates to a method for liquefying a feed gas or cooling a feed gas at supercritical pressure, in which the feed gas mixed with a cycle gas is condensed or cooled in order to form a supercritical gas or liquid at the first pressure, the liquid at the first pressure is cooled in a first heat exchanger (E2), the cooled liquid is removed from the first exchanger and expanded up to a second pressure that is lower than the first pressure in order to form an expanded flow, at least one portion of the expanded flow is cooled in a second heat exchanger, the expanded flow is removed from the second heat exchanger (E2), said flow is split into at least two portions, including a first portion and a second portion, the first portion of the expanded flow constituting the liquefied product, the second portion and preferably a third portion being vaporized in the second heat exchanger and the thus-formed at least one cycle gas is then mixed with the feed gas and compressed in a compressor, before or after being mixed with the feed gas.

## Claims

### Claim 1

A method for liquefying a feed gas or cooling a feed gas at supercritical pressure, the method comprising the steps of:
cooling the feed gas mixed with a cycle gas in a first heat exchanger to form a cooled fluid at a first pressure, wherein the cooled fluid is condensed within the first heat exchanger if the first pressure is below the critical pressure of the feed gas mixed with the cycle gas, wherein the cooled fluid is a supercritical fluid if the first pressure is above the critical pressure of the feed gas mixed with the cycle gas, wherein the feed gas mixed with the cycle gas is cooled against a single vaporizing fluid within the first heat exchanger;
removing the cooled fluid from the first exchanger and expanding the cooled fluid to a second pressure lower than the first pressure to form an expanded flow;
cooling a first portion of the expanded flow in a second heat exchanger to form a cooled first portion of the expanded flow;
removing the cooled first portion of the expanded flow from the second heat exchanger;
dividing the cooled first portion of the expanded flow into at least a first fraction and a second fraction, wherein the first fraction forms a liquefied product; and
expanding the second fraction and vaporizing the expanded second fraction in the second heat exchanger to form at least a portion of the cycle gas that is then mixed with the feed gas and compressed in a compressor after or before being mixed with the feed gas;
wherein a second portion of the expanded flow cools in the second heat exchanger to a temperature between the temperature of a cold end and a warm end of the second heat exchanger prior to being expanded again to form an expanded second portion; wherein a third portion of the expanded flow is expanded again, heated in the first heat exchanger and then sent to the compressor.

### Claim 2 (depends on 1)

The method of claim 1, wherein the expanded second portion is heated in the second heat exchanger and is sent to the compressor.

### Claim 3 (depends on 1)

The method of claim 1, wherein only the feed gas mixed with the cycle gas and another fluid exchange heat in the first exchanger.

### Claim 4 (depends on 1)

The method of claim 1, wherein no flow sent to the second exchanger has a pressure that is greater than 60 bar.

### Claim 5 (depends on 1)

The method of claim 1, wherein flows sent to the first exchanger have a pressure that is greater than 40 bar.

### Claim 6 (depends on 1)

The method of claim 1, wherein the cooled fluid is formed in the first heat exchanger only by the exchange of heat with a single other fluid.

### Claim 7 (depends on 1)

The method of claim 1, wherein at least a portion of the expanded flow is cooled in the second heat exchanger by exchanging heat with several other fluids.

### Claim 8 (depends on 1)

The method of claim 1, wherein the expanded flow is at a sufficiently high pressure so as not to vaporize during expansion.