# US 8,769,985 B2 · Low temperature air separation process for producing pressurized gaseous product

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- Number: US 8,769,985 B2
- Document ID: US8769985B2
- Status: Granted
- Kind: B2
- Application number: 11/572,048
- Filed: 2005-07-12
- Published: 2009-01-08
- Granted: 2014-07-08
- Earliest claimed: 2004-07-14
- Assignees: L'Air Liquide, Societe Anonyme a Directoire et Conseil de Surveillance pour l'Etude et l'Exploitation des Procedes Georges Claude
- Applicants: Jean-Renaud Brugerolle; Bao Ha
- Inventors: Jean-Renaud Brugerolle; Bao Ha
- Web page: https://patentgrep.com/patent/US8769985B2

## CPC

- F25J 3/04012: {by compression of warm gaseous streams; details of intake or interstage cooling (F25J3/04048 takes precedence; operation of compressors F25J3/04781; particular layout of compressors used in air fractionation units F25J3/04866)}
- F25J 3/04: for air
- F25J 3/04018: {of main feed air}
- F25J 3/04024: {of purified feed air, so-called boosted air}
- F25J 3/04054: {of air}
- F25J 3/04084: {of nitrogen}
- F25J 3/0409: {of oxygen}
- F25J 3/04109: {Arrangements of compressors and /or their drivers (using work extraction by mechanical coupling of compression and cold expansion F25J3/04381)}
- F25J 3/04187: {Cooling of the purified feed air by recuperative heat-exchange; Heat-exchange with product streams (arrangements of cold exchangers F25J5/002)}
- F25J 3/042: {having an intermediate feed connection}
- F25J 3/04254: {using the cold stored in external cryogenic fluids (closed loop F25J3/04278)}
- F25J 3/04296: {Claude expansion, i.e. expanded into the main or high pressure column}
- F25J 3/04381: {using work extraction by mechanical coupling of compression and expansion so-called companders}
- F25J 3/04393: {using multiple or multistage gas work expansion}
- F25J 3/04412: {in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column}
- F25J 3/04496: {for compensating variable air feed or variable product demand by alternating between periods of liquid storage and liquid assist}
- F25J 3/04812: {Different modes, i.e. "runs" of operation (F25J3/04472 takes precedence)}
- F25J 3/04836: {Variable air feed, i.e. "load" or product demand during specified periods, e.g. during periods with high respectively low power costs (F25J3/0483 takes precedence)}
- F25J 2200/06: in a classical double column flow-sheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column
- F25J 2210/06: Splitting of the feed stream, e.g. for treating or cooling in different ways
- F25J 2210/40: Air or oxygen enriched air, i.e. generally less than 30mol% of O2
- F25J 2210/42: Nitrogen
- F25J 2210/50: Oxygen
- F25J 2230/08: Cold compressor, i.e. suction of the gas at cryogenic temperature and generally without afterstage-cooler
- 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)}

## Abstract

A compressed air stream is cooled in an exchanger to form a compressed cooled air stream. The stream is then cryogenically compressed in a first compressor to form a first pressurized gas stream. The first pressurized gas stream is further cooled in the exchanger, cryogenically compressed in a second compressor, and then it is cooled and partially liquefied. The cooled and partially liquefied product is then fed to a system of distillation columns. A liquid product is removed from the system of distillation columns. This product is then pressurized, vaporized and warmed in the exchanger to yield pressurized gaseous product.

## Claims

### Claim 1

An apparatus which may be used for producing pressurized gaseous product comprising:
a heat exchanger configured to cool a compressed air stream thereby producing a cooled compressed air stream, the heat exchanger having a warm side, a cool side, a first intermediate point, and a second intermediate point;
a first compressor in fluid communication with the heat exchanger, the first compressor configured to receive a fluid from the first intermediate point of the heat exchanger, compress the fluid, and then introduce the compressed fluid to the warm side of the heat exchanger;
a second compressor in fluid communication with the heat exchanger, the second compressor configured to receive a second fluid from the second intermediate point of the heat exchanger, compress the second fluid thereby producing a compressed second fluid, and then introduce the compressed second fluid back to the heat exchanger;
a first column in fluid communication with the cool side of the heat exchanger, the first column configured to receive the cooled compressed air stream and the compressed second fluid;
a second column in fluid communication with the first column, the second column comprising a liquid oxygen extraction port, the liquid oxygen extraction port disposed proximate a bottom portion of the second column, wherein the liquid oxygen extraction port is in fluid communication with the cool side of the heat exchanger; and
a liquid storage tank in fluid communication with a liquid outlet of the first column, wherein the liquid storage tank is operable to receive a liquid from the liquid outlet of the first column when electricity costs are below a predetermined level wherein the liquid storage tank is also in fluid communication with a liquid inlet of the second column such that the liquid storage tank is operable to introduce the liquid from the liquid storage tank into the second column when electricity costs are at or above a predetermined level.

### Claim 2 (depends on 1)

The apparatus as claimed in claim 1, further comprising:
a warm booster compressor configured to compress a portion of the compressed air stream, wherein the warm booster compressor is in fluid communication with the heat exchanger;
a first turbo expander in fluid communication with the warm booster compressor, the first turbo expander configured to reduce the pressure of a warm fluid stream received from the warm booster compressor, the first turbo expander in fluid communication with heat exchanger, wherein the first turbo expander is operable to provide cooling to the apparatus; and
a second turbo expander in fluid communication with the heat exchanger, wherein the second turbo expander is configured to receive a cold fluid from the heat exchanger that has been compressed by the warm booster compressor, wherein the second turbo expander is operable to provide cooling to the apparatus.

### Claim 3 (depends on 1)

The apparatus as claimed in claim 1, wherein liquid air is disposed within the liquid storage tank.