Air separation
AssigneeThe BOC Group, Inc.
InventorTimothy D. Atkinson
Life of this patent
Estimating the term…
Abstract
In a process for the separation of argon from air by distillation in a plurality of distillation columns, liquid oxygen and gaseous nitrogen, withdrawn from a distillation column, are introduced into opposing ends of a mixing zone and there are created opposing flows of liquid and vapor that become progressively richer in nitrogen and oxygen, in the direction of flow. A mixed stream containing both oxygen and nitrogen is withdrawn as waste or product from an intermediate point in the mixing zone. The mixing zone also provides for condensation and reintroduction of oxygen-rich vapor and return of liquid nitrogen to the distillation column. The distillation column further provides an intermediate condenser which provides intermediate reboil for the distillation column.
Claims14
In a process for the separation of argon from air comprising introducing a stream of air into a first distillation column, withdrawing therefrom a stream of argon-containing fluid having an argon concentration greater than said stream of air and separating an argon product from said fluid in a second distillation column, wherein oxygen-rich liquid is withdrawn from said first distillation column and introduced into one end of a mixing zone, a nitrogen-rich vapor is withdrawn from said first distillation column and introduced into the opposite end of the mixing zone, a liquid flow and an opposed vapor flow are established through said mixing zone which become progressively richer in nitrogen and oxygen, respectively, a mixed stream comprising oxygen and nitrogen is withdrawn from an intermediate point in said mixing zone and said oxygen-rich vapor is condensed and returned to the mixing zone, the improvement wherein liquid nitrogen is passed from the mixing zone to the first distillation column, and a vapor stream is withdrawn from the mixing zone at a point intermediate in the direction of a vapor flow between the point of withdrawal of said mixed stream and the end of the zone, said vapor stream is condensed in heat exchange with a stream of boiling liquid from one of said distillation columns, said condensed stream is returned to the mixing zone and said boiled liquid is returned to said distillation column.
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 a mixing zone;
- (c) means for passing nitrogen-rich vapor from the first distillation column to a bottom region of said mixing zone;
- (d) liquid-vapor 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 vapor that becomes progressively richer in oxygen in the direction of vapor flow;
- (e) means for passing liquid nitrogen from the mixing zone to the first distillation column to act as reflux;
- (f) means for withdrawing a mixed stream comprising oxygen and nitrogen from an intermediate level of mixing zone;
- (g) condensing means for condensing oxygen-rich vapor 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 vapor 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;
- (j) means for condensing said vapor stream heat exchange with a stream of boiling liquid from one of the distillation columns and returning a stream of thus-formed condensate to the mixing zone;
- and
- (k) means for returning said boiled liquid to its respective distillation column.
Dependencies are inferred from the claim text.