EP0259070A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Air separation
Assignee: BOC Group Ltd
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Filing: 1987-08-21
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Granted: —
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Expires: 2007-08-21
Abstract
Abstract Purified air typically at its dew point is passed into distillation column 10 through inlet 2. Oxygen-rich liquid is withdrawn through outlet 6 and is passed to the top of a mixing column 20. Nitrogen-rich vapour passes from the top of the distillation column 10 to the bottom of the mixing column 20. In the mixing column, there is a downward flow of liquid that becomes progressively richer in nitrogen and an upward flow of vapour that becomes progressively richer in oxygen. Liquid nitrogen is withdrawn from the mixing column 20 through outlet 16 and is returned to the distillation column 10 to provide reflux for the distillation column 10. In addition a mixed stream 28 comprising oxygen and nitrogen is withdrawn from the column 20 as product or waste. The mixing column 20 is provided with a first condenser 30 at its top and a second condenser 40 which takes a vapour stream from intermediate the outlet 28 and the top of the column 20 and returns liquid to the column 20. The second condensation is effected by heat exchange with boiling liquid taken from and returned to the column 10. An argon-enriched oxygen stream is withdrawn (in 4) from the column 10 and is separated in a second distillation column 50 to yield an argon product.
Inventors
- 👤 Timothy David Atkinson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 12:19
CPC Classifications
F; F25; F25J; F25J3/00; F25J3/02; F25J3/04; F25J3/04642; F25J3/04648; F25J3/04654; F25J3/0466; F25J3/04248; F25J3/04284; F25J3/04309; F25J3/04333; F25J3/04351; F25J3/0446; F25J3/04521; F25J3/04527; F25J3/04533; F25J3/04563; F25J3/04575; F25J3/04581; F25J3/04709; F25J3/04715; F25J2200/00; F25J2200/02; F25J2200/04; F25J2200/50; F25J2205/00; F25J2205/02; F25J2235/00; F25J2235/50; F25J2235/52; F25J2235/58; F25J2240/00; F25J2240/80; Y; Y10; Y10S; Y10S62/00; Y10S62/923; Y10S62/924
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
262 words
A method of separating air, comprising the steps of: a) passing a stream of air into a first distillation column; b) withdrawing an oxygen-rich liquid from a bottom region of the first distillation column and passing it to a top region of a mixing zone; c) passing nitrogen-rich vapour from the first distillation column to a bottom region of the mixing zone; d) establishing through the mixing zone a downward flow of liquid that becomes progressively richer in nitrogen in the direction of liquid flow and an upward flow of vapour that becomes progressively richer in oxygen in the direction of vapour flow; e) passing liquid nitrogen from the mixing zone to the first distillation column to act as reflux; f) withdrawing as product or waste a mixed stream comprising oxygen and nitrogen from a chosen level of the mixing zone; g) providing condensation for oxygen-rich vapour at the top of the mixing zone; h) withdrawing from the first distillation column a stream of argon-containing fluid whose argon concentration is greater than that of the air stream, and separating an argon product from the argon-containing stream in a second distillation column; and i) withdrawing a vapour stream from a level of the mixing zone above that of the level from which said mixed stream is withdrawn but below the top of the mixing zone, condensing said vapour stream in heat exchange with a stream of boiling liquid from one of the distillation columns, returning a stream of thus-formed condensate to the mixing zone, and returning boiled liquid to its respective distillation column.
Claim 2
Independent Claim
262 words
A method of separating air, comprising the steps of: a) passing a stream of air into a first distillation column; b) withdrawing an oxygen-rich liquid from a bottom region of the first distillation column and passing it to a top region of a mixing zone; c) passing nitrogen-rich vapour from the first distillation column to a bottom region of the mixing zone; d) establishing through the mixing zone a downward flow of liquid that becomes progressively richer in nitrogen in the direction of liquid flow and an upward flow of vapour that becomes progressively richer in oxygen in the direction of vapour flow; e) passing liquid nitrogen from the mixing zone to the first distillation column to act as reflux; f) withdrawing as product or waste a mixed stream comprising oxygen and nitrogen from a chosen level of the mixing zone; g) providing condensation for oxygen-rich vapour at the top of the mixing zone; h) withdrawing from the first distillation column a stream of argon-containing fluid whose argon concentration is greater than that of the air stream, and separating an argon product from the argon-containing stream in a second distillation column; and i) withdrawing a vapour stream from a level of the mixing zone above that of the level from which said mixed stream is withdrawn but below the top of the mixing zone, condensing said vapour stream in heat exchange with a stream of boiling liquid from one of the distillation columns, returning a stream of thus-formed condensate to the mixing zone, and returning boiled liquid to its respective distillation column.
Claim 3
Dependent Claim
57 words
A method as claimed in claim 1, in which in step (i) the stream of liquid is taken from the first distillation column at a level below that at which the air stream is introduced, and the boiled liquid is returned to the column at a level below that from the said stream of liquid is taken.
Claim 4
Dependent Claim
53 words
A method as claimed in claim 1 or claim 2, in which the second distillation column operates at a lower pressure than the first distillation column, and the said argon-containing stream is withdrawn from the first column as a liquid, is sub-cooled and is passed into the second column through a throttling valve.
Claim 5
Independent Claim
55 words
A method as claimed in any one of the preceding claims, in which a stream of nitrogen vapour is taken from the mixing zone, is employed to reboil liquid in or from a bottom region of the second distillation column, is thereby condensed and resulting condensate is introduced into the first distillation column as reflux.
Claim 6
Independent Claim
45 words
A method as claimed in any one of the preceding claims, in which nitrogen is employed as a working fluid, to reboil liquid at or from the bottom of the first column, and to condense oxygen at or from the top of the mixing zone.
Claim 7
Independent Claim
61 words
A method as claimed in any one of the preceding claims, additionally including the step of condensing argon at or from the top of the second distillation column, employing one portion of the condensed argon as reflux for the second column and taking a second portion of condensed argon as product, wherein nitrogen working fluid is employed to condense the argon.
Claim 8
Independent Claim
72 words
A method as claimed in any one of the preceding claims, in which low volatility impurities are removed from the air stream in reversing heat exchanger(s) upstream of the first distillation column, and in which the reversing heat exchanger is cleaned by said mixed stream from the mixing zone and additionally including the step of expanding a part of the mixed stream, so as to give cleaning gas at two different pressures.
Claim 9
Independent Claim
37 words
A method as claimed in any one of the preceding claims, in which a stream of liquid oxygen is taken from the bottom of the second column and is introduced into the top of the mixing zone.
Claim 10
Independent Claim
37 words
A method as claimed in any one of claims 1 to 6, in which the mixed stream has a ratio of oxygen to nitrogen greater than that of the incoming air stream and is taken as product.
Claim 11
Independent Claim
40 words
A method as claimed in any one of the preceding claims, in which the composition of the liquid nitrogen at the top of the first distillation column is such that it contains from 1 to 10% by volume of oxygen.
Claim 12
Independent Claim
82 words
A method as claimed in any one of the preceding claims, additionally including the step of taking a stream of vapour from a level of the second distillation column intermediate that at which the argon-containing stream is introduced into the second distillation column and the top of the second column, condensing the stream of vapour and returning it to the second column, wherein nitrogen is employed to condense the stream of vapour withdrawn from said intermediate level of the second distillation column.
Claim 13
Dependent Claim
292 words
Apparatus for separating argon from air, comprising: a) means for passing a stream of air into a first distillation column; b) means for withdrawing an oxygen-rich liquid from a bottom region of the first distillation column and passing it to a top region of the mixing zone; c) means for passing nitrogen rich vapour from the first distillation column to a bottom region of the mixing zone; d) liquid-vapour contact means for establishing through the mixing zone a downward flow of liquid that becomes progressively richer in nitrogen in the direction of liquid flow and an upward flow of vapour that becomes progressively richer in oxygen in the direction of vapour flow; e) means for passing liquid nitrogen from the mixing zone to the first distillation column to act as reflux; f) means for withdrawing of product or waste mixed stream comprising oxygen and nitrogen from a chosen level of mixing zone; g) a condenser for condensing oxygen-rich vapour at the top of the mixing zone; h) means for withdrawing from the first distillation column a stream of argon-containing fluid whose argon concentration is greater than that of the air stream, said means communicating with a second distillation column for separating an argon product from the argon containing stream; and i) means for withdrawing a vapour stream from a level of the mixing zone above that of the level from which said mixed stream is, in operation, withdrawn, but below the top of the mixing zone, means for condensing said vapour stream in heat exchange with a stream of boiling liquid from one of the distillation columns, and means for returning a stream of thus formed condensate to the mixing zone, and means for returning boiled liquid to its respective distillation column.
Claim 14
Dependent Claim
292 words
Apparatus for separating argon from air, comprising: a) means for passing a stream of air into a first distillation column; b) means for withdrawing an oxygen-rich liquid from a bottom region of the first distillation column and passing it to a top region of the mixing zone; c) means for passing nitrogen rich vapour from the first distillation column to a bottom region of the mixing zone; d) liquid-vapour contact means for establishing through the mixing zone a downward flow of liquid that becomes progressively richer in nitrogen in the direction of liquid flow and an upward flow of vapour that becomes progressively richer in oxygen in the direction of vapour flow; e) means for passing liquid nitrogen from the mixing zone to the first distillation column to act as reflux; f) means for withdrawing of product or waste mixed stream comprising oxygen and nitrogen from a chosen level of mixing zone; g) a condenser for condensing oxygen-rich vapour at the top of the mixing zone; h) means for withdrawing from the first distillation column a stream of argon-containing fluid whose argon concentration is greater than that of the air stream, said means communicating with a second distillation column for separating an argon product from the argon containing stream; and i) means for withdrawing a vapour stream from a level of the mixing zone above that of the level from which said mixed stream is, in operation, withdrawn, but below the top of the mixing zone, means for condensing said vapour stream in heat exchange with a stream of boiling liquid from one of the distillation columns, and means for returning a stream of thus formed condensate to the mixing zone, and means for returning boiled liquid to its respective distillation column.
Claim 15
Dependent Claim
18 words
Apparatus as claimed in claim 12 wherein said one of the distillation columns is the first distillation column.
Claim 16
Dependent Claim
35 words
Apparatus as claimed in claim 12 or claim 13, including means for sub-cooling said argon-containing stream and a throttling valve through which in operation said sub-cooled argon-containing stream is passed into said second distillation column.
Claim 17
Dependent Claim
65 words
Apparatus as claimed in any one of claims 12 to 14, in which the second distillation column is provided with a reboiler for boiling liquid in or from the bottom of that column, said reboiler having an inlet in communication with an outlet of the bottom of the mixing zone and an outlet in communication with an inlet for reflux to the first distillation column.
Claim 18
Dependent Claim
56 words
Apparatus as claimed in any one of claims 12 to 15, additionally including a condenser associated with the top of the second distillation column, said condenser being adapted to return one portion of argon condensed therein to the second column as reflux, there also being an outlet for liquid argon product in communication with said condenser.
References Cited (Backward Citations)
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