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 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 portion of feed air is expanded and cooled in front of a main heat exchanger, and is used as cold for precooling the remaining unexpanded feed air inside the main heat exchanger. A portion of the feed air precooled inside the main heat exchanger is removed to outside the main heat exchanger, expanded and cooled, and used as cold to cool the remaining unexpanded precooled feed air inside the main heat exchanger.

In a process for distilling a gas mixture of CO2 and at least one component lighter than CO2, a partially purified liquid CO2 stream is withdrawn at an intermediate level of the distillation column at least one theoretical plate below the top of the distillation column and at least one theoretical plate above the bottom of the distillation column and the stream extracted at the intermediate level of the distillation column is vaporized by heat exchange with the gas mixture, with which it is then compressed.

The distillation column system has a high-pressure column, a low-pressure column, a main condenser and a low-pressure-column top condenser. Feed air is cooled in a main heat exchanger and introduced into the high-pressure column. An oxygen-enriched liquid stream is withdrawn from the high-pressure column and introduced into the low-pressure column. A gaseous nitrogen stream is withdrawn from the high-pressure column, warmed in the main heat exchanger and withdrawn as gaseous pressurized nitrogen product. The high-pressure column has a barrier-plate section arranged immediately above the point at which the feed air is introduced. The oxygen-enriched liquid stream is withdrawn from the high-pressure column above the barrier-plate section. A purge stream is withdrawn below the barrier-plate section. The gaseous nitrogen stream, before being warmed in the main heat exchanger, is warmed in a counter-current subcooler in indirect heat exchange with the oxygen-enriched liquid stream from the high-pressure column.

A system and method for flexible production of argon from a cryogenic air separation unit is provided. The cryogenic air separation unit is capable of operating in a no-argon or low-argon mode when argon demand is low or non-existent and then switching to operating in a high-argon mode when argon is needed. The recovery of the argon products from the air separation unit is adjusted by varying the percentages of dirty shelf nitrogen and clean shelf nitrogen in the reflux stream directed to the lower pressure column. The cryogenic air separation unit and associated method also provides an efficient argon production/rejection process that minimizes the power consumption when the cryogenic air separation unit is operating in a no-argon or low-argon mode yet maintains the capability to produce higher volumes of argon products at full design capacity to meet argon product demands.

A SPECTRA process for low-temperature fractionation of air is proposed, in which bottoms liquid from an additional second rectification column used to obtain oxygen is evaporated in a second condenser evaporator arrangement. In this second condenser evaporator arrangement, gas that has been evaporated beforehand in a first condenser evaporator arrangement, which is used for condensation of tops gas from a first rectification column, is partially condensed after recompression. The invention also relates to a corresponding plant.

A system and method for cryogenic purification of a hydrogen, nitrogen, methane and argon containing feed stream to produce a methane free, hydrogen and nitrogen containing synthesis gas and a methane rich fuel gas, as well as to recover an argon product stream, excess hydrogen, and excess nitrogen is provided. The disclosed system and method are particularly useful as an integrated cryogenic purifier in an ammonia synthesis process in an ammonia plant. The excess nitrogen is a nitrogen stream substantially free of methane and hydrogen that can be used in other parts of the plant, recovered as a gaseous nitrogen product and/or liquefied to produce a liquid nitrogen product.