A process for providing an oxygen product using an air separation plant having a distillation column system, in which a cryogenic liquid is withdrawn from the distillation column system, wherein a first portion of the cryogenic liquid is subjected to a pressure-increasing evaporation by evaporating a second portion of the cryogenic liquid, and the oxygen product is provided using at least part of the first portion of the cryogenic liquid. At least part of the evaporated second portion of the cryogenic liquid, after the increase in pressure, is made available for further utilization, for the provision of the oxygen product. The present invention also relates to a corresponding air separation plant.

A cryogenic air separation apparatus comprises: a heat exchanger, a first rectification column, a first condenser, a second rectification column, a third rectification column, a second condenser, a high-purity oxygen rectification column, a third condenser, a nitrogen compressor, and a compressed recycled gas line L52 for introducing product nitrogen gas compressed by the first nitrogen compressor into a warm end (heat source) of an ultra-high-purity oxygen vaporizer as a compressed recycled gas.

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 gas production system that can supply liquefied gas obtained by rectifying source gas as product gas continuously with high heat efficiency without using a machine that has a risk of contamination like a pump. A gas production system includes a single pressure device having a single pressurized container to which liquefied gas extracted from a rectification unit is supplied, a pressure line for extracting and vaporizing a part of the liquefied gas in the pressurized container and returning the part of the liquefied gas to the pressurized container, and a second heat exchange unit that is disposed in the pressure line, and a liquefied gas storage unit that stores liquefied gas which is led out from the pressurized container.

A SPECTRA process for low-temperature fractionation of air, in which bottoms liquid from an additional second rectification column used to obtain oxygen is evaporated in a second condenser-evaporator. In this second condenser-evaporator, gas that has been evaporated beforehand in a first condenser-evaporator, which is used for condensation of tops gas from a first rectification column, is condensed at the pressure level of the previous evaporation. The invention likewise provides a corresponding plant.

One object of the present invention is to provide a compact multistage liquid storage-type condenser-evaporator capable of producing two kinds of gases having different compositions without increasing power, and a nitrogen production device using the multistage liquid storage-type condenser-evaporator without increasing the power for producing nitrogen, and the present invention provides a multistage liquid storage-type condenser-evaporator including a bottom liquid storage section which is configured to store the liquid supplied into the bottom evaporation passage without circulating, and a fluid collection section which is configured to collect the fluid which flows out from the bottom evaporation passage and discharge to the outside without returning into the bottom liquid storage section.

An apparatus for the separation of air by cryogenic distillation comprises three columns, including two concentric columns, the external diameter of the third column being at most equal to that of the second distillation column, a pipe for feeding the third column with air, a reflux pipe connected to an intermediate level of the upper section of the first distillation column in order to withdraw a liquid enriched in nitrogen, the pipe being connected to the head of the second distillation column and passing through a region of the third column devoid of heat exchange means and of mass exchange means, and an intermediate pipe for withdrawing a liquid at an intermediate level of the first distillation column.

An apparatus for the distillation of air by cryogenic distillation is provided. The apparatus can include an enclosure; a first distillation column configured to operate at a first pressure; a second distillation column configured to operate at a second pressure that is lower than the first pressure, the second distillation column being placed above the first distillation column and forming therewith a double column; a subcooling heat exchanger configured to cool at least one liquid from the first distillation column upstream of the second distillation column and configured to warm a gaseous nitrogen stream from the second distillation column; and an argon column configured to separate an argon enriched stream from the second distillation column and configured to produce an argon rich stream. In certain embodiments, the first distillation column, the second distillation column, the argon column and the subcooling heat exchanger are disposed within the enclosure, and/or the subcooling heat exchanger is disposed directly underneath the first distillation column or the argon column.

A cryogenic air separation apparatus comprises: a heat exchanger, a first rectification column, a first condenser, a second rectification column, a third rectification column, a second condenser, a high-purity oxygen rectification column, a third condenser, a nitrogen compressor, and a compressed recycled gas line L52 for introducing product nitrogen gas compressed by the first nitrogen compressor into a warm end (heat source) of an ultra-high-purity oxygen vaporizer as a compressed recycled gas.

A gas production system that can supply liquefied gas obtained by rectifying source gas as product gas continuously with high heat efficiency without using a machine that has a risk of contamination like a pump. A gas production system includes a single pressure device having a single pressurized container to which liquefied gas extracted from a rectification unit is supplied, a pressure line for extracting and vaporizing a part of the liquefied gas in the pressurized container and returning the part of the liquefied gas to the pressurized container, and a second heat exchange unit that is disposed in the pressure line, and a liquefied gas storage unit that stores liquefied gas which is led out from the pressurized container.