Process and installation for separation of air by cryogenic distillation integrated with an associated process
AssigneeL'Air Liquide, Societe Anonyme a Directoire et Conseil de Surveillance pour l'Etude et l'Exploitation des Procedes Georges Claude
InventorAlain Guillard
Life of this patent
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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.
Claims21
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.
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.
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.
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.
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).
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.
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.
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.
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.
Process according to any preceding claim wherein steam is sent constantly or substantially constantly to the air separation unit (1,101,201).
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.
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.
Dependencies are inferred from the claim text.