# US 2004/0069016 A1 · Process and installation for separation of air by cryogenic distillation integrated with an associated process

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- Number: US 2004/0069016 A1
- Document ID: US20040069016A1
- Status: Published application
- Kind: A1
- Application number: 10/415,835
- Filed: 2003-04-30
- Published: 2004-04-15
- Earliest claimed: 2000-10-30
- Assignees: L'Air Liquide, Societe Anonyme a Directoire et Conseil de Surveillance pour l'Etude et l'Exploitation des Procedes Georges Claude
- Inventors: Alain Guillard
- Web page: https://patentgrep.com/patent/US20040069016A1

## CPC

- F25J 3/04218: {Parallel arrangement of the main heat exchange line in cores having different functions, e.g. in low pressure and high pressure cores (F25J3/04503 takes precedence)}
- F25J 3/04018: {of main feed air}
- F25J 3/04054: {of air}
- F25J 3/04121: {Steam turbine as the prime mechanical driver}
- F25J 3/04145: {Mechanically coupling of different compressors of the air fractionation process to the same driver(s)}
- 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 3/04296: {Claude expansion, i.e. expanded into the main or high pressure column}
- F25J 3/04539: {for the H2/CO synthesis by partial oxidation or oxygen consuming reforming processes of fuels}
- F25J 3/046: {Completely integrated air feed compression, i.e. common MAC}
- F25J 3/04612: {Heat exchange integration with process streams, e.g. from the air gas consuming unit}
- F25J 3/04618: {for cooling an air stream fed to the air fractionation unit}
- F25J 3/04824: {Stopping of the process, e.g. defrosting or deriming; Back-up procedures}
- 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 3/04963: {and inter-connecting equipment within or downstream of the fractionation unit(s) (F25J3/04393 takes precedence)}
- F25J 2215/02: Mixing or blending of fluids to yield a certain product
- F25J 2215/40: Air or oxygen enriched air, i.e. generally less than 30mol% of O2
- F25J 2215/50: Oxygen or special cases, e.g. isotope-mixtures or low purity O2
- F25J 2235/50: the fluid being oxygen
- F25J 2240/20: the fluid being oxygen
- F25J 2240/70: Steam turbine, e.g. used in a Rankine cycle
- F25J 2240/90: Hot gas waste turbine of an indirect heated gas for power generation
- F25J 2245/50: the recycled stream being oxygen
- F25J 2250/50: One fluid being oxygen
- F25J 2290/12: Particular process parameters like pressure, temperature, ratios
- 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

In a process for separation of air by cryogenic distillation integrated with an associated process, air is separated in a separation unit (1), fluid is sent from the separation unit to an associated process, steam (3) is derived from the associated process, at least part of the steam is used in the separation unit and at least one fluid stream (11) is sent from the air separation unit to the atmosphere, at least when the steam is used in the air separation unit.

## Claims

### Claim 1

Process for separation of air by cryogenic distillation integrated with an associated process comprising the steps of
a) cooling compressed and purified air to a cryogenic temperature in a heat exchanger (21) by heat exchange with fluids separated in an air separation unit
b) separating compressed, purified and cooled air in an air separation unit (1,101) to produce at least one fluid enriched in oxygen (23,43,123) and/or at least one fluid enriched in nitrogen (27,45)and possibly at least one fluid enriched in argon (31),
c) sending at least part of one said fluid (23,43,123) to an associated process,
d) deriving at least one stream of steam (3,103) from the associated process,
e) using at least part of the steam in the air separation unit, characterised in that it comprises operating the air separation unit with at least one of the following process features:
i) operating the heat exchanger to have a temperature difference between a warm stream entering the heat exchanger and a stream leaving the heat exchanger, having been warmed, of at least 5 K, preferably at least 10 K, at its warm end and/or
ii) producing the fluid enriched in oxygen with a yield of less than 95%, preferably less than 90% and/or
iii)sending at least first and second fluid streams (11,11A,11B,25,29,33,37) from the air separation unit to the atmosphere and/or
iv) warming a fluid stream separated in the air separation unit against a stream of steam
wherein in the case where features i), ii) and/or iii) are used, and optionally in the case where feature iv) is used, at least one steam turbine (7) is used to produce work and the work is used to supply at least part of the energy needs of at least one main compressor (5) compressing air treated in the air separation unit and/or an air booster (9) compressing air which has already been compressed to a superatmospheric pressure and/or a compressor (13,15) for gas enriched in oxygen or nitrogen.

### Claim 2 (depends on 1)

Process according to claim 1 comprising sending at least first and second fluid streams (11,11A,11B,25,29,33,37) from the air separation unit to the atmosphere wherein the first fluid stream (37)sent to the atmosphere is previously used to regenerate the purification unit used to purify the air and the second fluid stream or streams (25,29,33) sent to the atmosphere is/are enriched in oxygen, nitrogen and/or argon and is preferably at a pressure of at least 5 bar abs.

### Claim 3 (depends on 1, 2)

Process according to claim 1 or 2 comprising sending at least first and second fluid streams (11,11A,11B,25,29,33,37) from the air separation unit to the atmosphere wherein the second fluid stream or streams (11, 11A, 11B) is compressed air, removed before or after purification, preferably at a pressure of at least 5 bar abs.

### Claim 4

Process according to any preceding claim wherein at least two air separation units (1,101) supply fluid to the associated process, each air separation unit being dimensioned to produce N/N-1 multiplied by at least 80%, preferably 90% or even 100%, of the nominal flow, N being the number of air separation units supplying the associated process.

### Claim 5

Process according to any preceding claim comprising expanding at least part of the vapour (3,103) in at least one turbine (7) coupled to at least one compressor (5,9,13,15) of the air separation unit.

### Claim 6

Process according to any preceding claim wherein at least one steam turbine (7) is coupled to at least one main compressor (5) compressing air treated in the air separation unit and/or to an air booster (9) compressing air which has already been compressed to a superatmospheric pressure and/or to a compressor (13,15) for gas enriched in oxygen or nitrogen.

### Claim 7

Process according to any preceding claim comprising warming a fluid stream separated in the air separation unit against a stream of steam wherein vapour (103) from the associated process is sent to at least one heat exchanger (17) forming part of the air separation unit, at least one cryogenic liquid (143) produced in the air separation unit is sent to the at least one heat exchanger, the at least one cryogenic liquid vaporises at least partially in the heat exchanger and is sent to the atmosphere and/or to an associated process in gaseous form (125).

### Claim 8

Process according to any preceding claim comprising warming a fluid stream separated in the air separation unit against a stream of steam wherein vapour (203) from the associated process is sent to at least one heat exchanger (117) of the air separation unit (201), at least one cryogenic fluid produced in the air separation unit is sent to the at least one heat exchanger wherein it is warmed and the warmed cryogenic fluid is then expanded in a turbine (227) before being sent to the atmosphere.

### Claim 9 (depends on 1, 2, 3, 4, 5, 6, 7, 8)

Process according to any of claims 1 to 8 wherein at least one fluid stream (11,11A,11B,25,29,33,125), preferably an oxygen enriched gaseous stream, is sent to the atmosphere from the air separation unit constantly or wherein at least one second fluid stream (11,11A,11B,25,29,33,125) is sent to the atmosphere from the air separation unit substantially constantly.

### Claim 10 (depends on 1, 2, 3, 4, 5, 6, 7, 8)

Process according to any of claims 1 to 8 wherein at least one fluid stream (11,11A,11B,25,29,33,125), preferably an oxygen enriched gaseous stream, is sent to the atmosphere from the air separation unit when the amount of steam derived from the associated process exceeds a given value or wherein at least one second fluid stream (11,11A,11B,25,29,33,125) is sent to the atmosphere from the air separation unit when the amount of steam derived from the associated process exceeds a given value.

### Claim 11

Process according to any preceding claim wherein the fluid sent to the associated process is an oxygen rich gas (23, 123) and the associated process is a partial oxidation process associated with a catalytic conversion process producing excess steam.

### Claim 12

Process according to any preceding claim wherein the at least one fluid stream (11,11A,11B,25,29,33,125) is not used or is only partly used to regenerate a unit (35) used to remove humidity and carbon dioxide from the feed air for the air separation unit or another air separation unit and is not used or is only partly used in a water chilling unit.

### Claim 13

Process according to any preceding claim wherein a fluid sent from the air separation unit to the associated process and a fluid sent from the air separation unit to the atmosphere have the same principal component, the fluid sent to the associated process being less pure or purer than the fluid sent to the atmosphere.

### Claim 14

Process according to any preceding claim wherein steam is sent constantly or substantially constantly to the air separation unit (1,101,201).

### Claim 15

Installation for separation of air by cryogenic distillation integrated with an associated process including:
i) at least one air compressor (5) for compressing air to be treated in an air separation unit
ii) an air separation unit comprising a purification unit (35), at least one heat exchanger (21), and at least one cryogenic distillation column (41)
iii) means for supplying compressed air from the main air compressor to the air separation unit
iv) means for removing a fluid enriched in a component of air from the air separation unit and sending it to an associated process
v) means for transferring steam (3) from the associated process to the air separation unit and
vi) means for sending at least one fluid stream (11,11A,11B,25,29,33,125) from the air separation unit to the atmosphere, without previously sending the fluid stream to regenerate the air purification unit.

### Claim 16 (depends on 15)

Installation according to claim 15 wherein the means for sending at least one fluid stream (11,11A,11B) from the air separation unit to the atmosphere is connected to the main air compressor (5).

### Claim 17 (depends on 15, 16)

Installation according to claim 15 or 16 wherein the means for sending at least one fluid stream (25,29,33,125) from the air separation unit to the atmosphere is connected to a column of the air separation unit.

### Claim 18 (depends on 15, 16, 17)

Installation according to any of claims 15 to 17 comprising at least one steam turbine (7) producing work and means to use the work for the energy needs of the main air compressor (5) and/or an air booster (9) of the air separation unit and/or a gaseous product compressor (13,15) of the air separation unit and means for feeding at least part of the steam (3) from the associated process to the steam turbine(s).

### Claim 19

Installation for separation of air by cryogenic distillation integrated with an associated process including:
i) at least one air compressor (5) for compressing air to be treated in an air separation unit
ii) an air separation unit comprising a purification unit, at least one heat exchanger (17,117), and at least one cryogenic distillation column
iii) means for supplying compressed air from the main air compressor to the air separation unit
iv) means for removing a fluid enriched in a component of air from the air separation unit and sending it to an associated process
v) means for transferring steam from the associated process to the air separation unit,
vi) means for sending at least part of the steam (103) from the associated process to the heat exchanger and
vii) means for sending a cryogenic fluid (143) from a column of the air separation unit to the heat exchanger to be warmed by indirect heat exchange with the steam, said heat exchanger being connected to the means for sending at least one fluid stream from the air separation unit to the atmosphere and/or to the associated process.

### Claim 20 (depends on 19)

Installation according to claim 19 comprising means for expanding the fluid stream downstream of the heat exchanger (117).

### Claim 21 (depends on 19, 20)

Installation according to claim 19 or 20 wherein the cryogenic fluid is a liquid, supplied from the air separation unit and, possibly, from at least one other air separation unit and wherein the cryogenic liquid is stored in a tank (155) before being sent to the heat exchanger (17).