A nitrogen liquefier configured to be integrated with an argon and nitrogen producing cryogenic air separation unit and method of nitrogen liquefaction are provided. The integrated nitrogen liquefier and associated methods may be operated in at least three distinct modes including: (i) a nil liquid nitrogen mode; (ii) a low liquid nitrogen mode; and (iii) a high liquid nitrogen mode. The present systems and methods are further characterized in an oxygen enriched stream from the lower pressure column of the air separation unit is an oxygen enriched condensing medium used in the argon condenser.

A moderate pressure nitrogen and argon producing cryogenic air separation unit is provided that includes a three distillation column system and turbine air stream bypass arrangement or circuit. The turbine air stream bypass arrangement or circuit is configured to improve argon and nitrogen recoveries in select operating modes by optionally diverting a portion of the turbine air stream to a nitrogen waste stream circuit drawn from the lower pressure column of the cryogenic air separation unit such that the diverted portion of the turbine air stream bypasses the distillation column system.

The invention relates to a method for a low-temperature air separation in which an air separation unit is used comprising a first rectification column and a second rectification column. The first rectification column is operated at a first pressure level, and the second rectification column is operated at a second pressure level below the first pressure level. Fluid which is oxygen-enriched compared to atmospheric air is drawn from the first rectification column in the form of one or more first material flows. At least one fraction of the fluid which has been drawn from the first rectification column in the form of the one or more first material flows is heated in a heat exchanger; a fraction of the fluid which has been heated in the heat exchanger is compressed using a compressor and is returned to the first rectification column.

A moderate pressure air separation unit and air separation cycle is disclosed that provides for up to about 96% recovery of argon, an overall nitrogen recovery of 98 percent or greater and limited gaseous oxygen production. The air separation is configured to produce a first high purity oxygen enriched stream and a second lower purity oxygen enriched stream from the lower pressure column, one of which is used as the refrigerant to condense the argon in the argon condenser, with the resulting vaporized oxygen stream used to regenerate the temperature swing adsorption pre-purifier unit. All or a portion of the first high purity oxygen enriched stream is vaporized in the main heat exchanger to produce the gaseous oxygen products.

A moderate pressure, argon and nitrogen producing cryogenic air separation unit and air separation cycle having a higher pressure column, a lower pressure column and an argon column arrangement is disclosed. The moderate pressure, argon and nitrogen producing cryogenic air separation unit is configured to take a first portion of an oxygen enriched stream from the lower pressure column, which together with an external source of liquid nitrogen is used as the boiling side refrigerant to condense the argon in the argon condenser. Use of the external source of liquid nitrogen in the argon condenser allows a second portion of the oxygen enriched stream from the lower pressure column to be taken as a liquid oxygen product stream.

A moderate pressure air separation unit and air separation cycle is disclosed that provides for up to about 96% recovery of argon and an overall nitrogen recovery of 98% or greater. The air separation is configured to produce a high purity oxygen enriched stream which is used as the refrigerant to condense the argon in the argon condenser, with the resulting vaporized oxygen stream used to regenerate the temperature swing adsorption prepurifier unit. Argon recovery is facilitated with the use of an argon superstaged column.

A moderate pressure air separation unit and air separation cycle is disclosed that provides for up to about 96% recovery of argon, an overall nitrogen recovery of 98 percent or greater and limited gaseous oxygen production. The air separation is configured to produce a first high purity oxygen enriched stream and a second lower purity oxygen enriched stream from the lower pressure column, one of which is used as the refrigerant to condense the argon in the argon condenser, with the resulting vaporized oxygen stream used to regenerate the temperature swing adsorption pre-purifier unit. All or a portion of the first high purity oxygen enriched stream is vaporized in the main heat exchanger to produce the gaseous oxygen products.

A moderate pressure air separation unit and air separation cycle is disclosed that provides for up to about 96% recovery of argon, an overall nitrogen recovery of 98 percent or greater and limited gaseous oxygen production. The air separation is configured to produce a first high purity oxygen enriched stream and a second lower purity oxygen enriched stream from the lower pressure column, one of which is used as the refrigerant to condense the argon in the argon condenser, with the resulting vaporized oxygen stream used to regenerate the temperature swing adsorption pre-purifier unit. All or a portion of the first high purity oxygen enriched stream is vaporized in the main heat exchanger to produce the gaseous oxygen products.

A moderate pressure air separation unit and air separation cycle is disclosed that provides for up to about 96% recovery of argon, an overall nitrogen recovery of 98% or greater and limited gaseous oxygen production. The air separation is configured to produce a first high purity oxygen enriched stream and a second lower purity oxygen enriched stream from the lower pressure column, one of which is used as the refrigerant to condense the argon in the argon condenser, with the resulting vaporized oxygen stream used to regenerate the temperature swing adsorption pre-purifier unit. All or a portion of the first high purity oxygen enriched stream is vaporized in the main heat exchanger to produce the gaseous oxygen products.

A moderate pressure air separation unit and air separation cycle is disclosed that provides for up to about 96% recovery of argon, an overall nitrogen recovery of 98 percent or greater and limited gaseous oxygen production. The air separation is configured to produce a first high purity oxygen enriched stream and a second lower purity oxygen enriched stream from the lower pressure column, one of which is used as the refrigerant to condense the argon in the argon condenser, with the resulting vaporized oxygen stream used to regenerate the temperature swing adsorption pre-purifier unit. All or a portion of the first high purity oxygen enriched stream is vaporized in the main heat exchanger to produce the gaseous oxygen products.