The plant is used for producing oxygen by cryogenic air separation. The plant has a high-pressure column, a low-pressure column and a main condenser. An argon-elimination column is in fluid connection with an intermediate point of the low-pressure column and is connected to an argon-elimination column head condenser. An auxiliary column has a sump region, into which gas is introduced from the argon-elimination column head condenser. The head of the auxiliary column is connected to a return flow liquid line, in order to introduce a liquid stream from the high-pressure column or the head condenser. The liquid stream has an oxygen content which is at least equal to that of air. At least one part of the crude liquid oxygen from the sump of the high-pressure column is fed to the auxiliary column at a first intermediate point.

An air separation unit and associated method for separating air by cryogenic distillation using a distillation column system including a higher pressure column, a lower pressure column, an intermediate pressure kettle column, and an argon column arrangement is provided. The disclosed air separation unit and method is particularly suited for production of an argon product as well as several nitrogen products wherein a portion of the nitrogen overhead intermediate pressure kettle column is taken as an intermediate or elevated pressure nitrogen product. The present air separation unit and associated method employs a once-through kettle column reboiler, a once-through kettle column condenser while the argon condenser condenses an argon-rich vapor stream against a pumped oxygen stream from the bottom of the lower pressure column.

A cryogenic air separation method and apparatus in which first and second liquid streams are produced. The first liquid stream has a higher oxygen content than air and can consist of a higher pressure distillation column bottoms and the second liquid stream, for instance, air, has a lower oxygen content than the first liquid stream and an argon content no less than the air. The second liquid stream is subcooled through indirect heat exchange with the first liquid stream and both of such streams are introduced into the lower pressure column. The second liquid stream is introduced into the lower pressure column above that point at which the crude liquid oxygen column bottoms or any portion thereof is introduced into the lower pressure column to increase a liquid to vapor ratio below the introduction of the second liquid stream and therefore, reduce the oxygen present within the column overhead.

A method for the cryogenic fractionation of air, in which a liquid volume present in a vaporization chamber in a distillation column system of an air fractionation plant is fed by means of a cryogenic liquid and in which a proportion of the liquid volume is continuously transferred into the gas phase by vaporization, wherein, in addition to oxygen, the cryogenic liquid contains components, including xenon, which are higher-boiling than oxygen. The content of xenon in the cryogenic liquid is determined and used as a measure of any enrichment of the components which are higher-boiling than oxygen in the cryogenic liquid. A corresponding air fractionation plant is also described.

The invention relates to a plant for low-temperature air separation, having a rectification column system comprising a high-pressure column, a divided low-pressure column and a divided argon column, and a cold box system comprising a first cold box and a second cold box. The high-pressure column is arranged beneath the lower section of the low-pressure column. The high-pressure column together with the lower section of the low-pressure column is located in the first cold box, and the top section of the low-pressure column in the second cold box. It is proposed to arrange the base section of the argon column in the first cold box and the top section of the argon column in the second cold box, or vice versa. The present invention likewise provides a corresponding method.

The invention relates to a plant for low-temperature fractionation of air, having a rectification column system comprising a high-pressure column, a divided low-pressure column and an argon column, and a coldbox system comprising a first coldbox, a second coldbox and a third coldbox. The high-pressure column is disposed beneath the lower section of the low-pressure column. The high-pressure column together with the lower portion of the low-pressure column is disposed in the first coldbox, and the top portion of the low-pressure column in the second coldbox. It is proposed that the argon column or one or more sections of the argon column be disposed in the third coldbox. The pure oxygen column is disposed in the second coldbox. The present invention likewise provides a corresponding process.

The plant is used for producing oxygen by cryogenic air separation. The plant has a high-pressure column, a low-pressure column and a main condenser. An argon-elimination column is in fluid connection with an intermediate point of the low-pressure column and is connected to an argon-elimination column head condenser. An auxiliary column has a sump region, into which gas is introduced from the argon-elimination column head condenser. The head of the auxiliary column is connected to a return flow liquid line, in order to introduce a liquid stream from the high-pressure column or the head condenser. The liquid stream has an oxygen content which is at least equal to that of air. At least one part of the crude liquid oxygen from the sump of the high-pressure column is fed to the auxiliary column at a first intermediate point.

A cryogenic air rectification system comprising a high pressure column, a low pressure column and an argon removal unit coupled to a condenser evaporator, wherein the system is configured to pass gas from a position above an oxygen section of the low pressure column as an argon removal feed gas to a lower region of the argon removal unit, wherein the system is configured to condense gas from an upper region of the argon removal unit in the condenser evaporator to form a condensate, wherein the system is configured to pass further gas from the top of the upper region of the argon removal unit out of the system, and wherein the system is configured to pass at least a part of the condensate as a reflux to the upper region of the argon removal unit.