An apparatus for separating air, comprising a double column, means for sending air to the purification unit at a pressure that is no more than 1 bar higher than atmospheric pressure, a pipe for sending a first air flow, the first air flow having been purified in the purification unit, to the heat exchanger at a fourth pressure that is no more than 1 bar higher than the second pressure, a pipe for sending the first purified air flow, which has been cooled in the heat exchanger, to the second column for separation, and a booster compressor, the apparatus not comprising any means for depressurizing the first flow.

A nitrogen production system that can produce high purity nitrogen containing a desired concentration of oxygen and ultrahigh purity nitrogen containing a desired concentration of argon in a single rectifying column while restraining increase in electric power consumption and a production process thereof are provided. The method can include the steps of rectifying a cooled and compressed air stream in the rectifying column; withdrawing the ultrahigh purity nitrogen stream from a top portion of the nitrogen rectifying column, warming the ultrahigh purity nitrogen stream in a heat exchanger, and then recovering the ultrahigh purity nitrogen stream from the heat exchanger; and withdrawing a high purity nitrogen stream from a rectification section of the nitrogen rectifying column, warming the high purity nitrogen stream in the heat exchanger, and then recovering the high purity nitrogen stream from the heat exchanger.

Process and apparatus for the separation of a compressed feed air stream to produce an oxygen product using a distillation column having a lower-pressure column and a higher-pressure column, a higher-pressure heat exchanger and a lower-pressure heat exchanger where the gaseous nitrogen expander receives a nitrogen-enriched fraction from a position intermediate the warmer end and the colder end of the higher-pressure heat exchanger.

The invention relates to a method for separating air by cryogenic distillation in a column system, comprising a first column operating at a first pressure and a second column operating at a second pressure, in which an argon-enriched flow is sent from an intermediate point of the first column to the tank of the second column and an argon-rich flow is drawn off at the top of the second column, wherein a nitrogen-enriched flow of the first column is compressed in a compressor, the compressed flow is sent to a head condenser of the second column after an expansion step and the vaporized flow is expanded in the condenser in a turbine where it at least partially liquefies.

Provided are a method and apparatus for producing nitrogen and oxygen by means of cryogenic distillation of air. Nitrogen products are extracted only from the top of a tower. If a customer needs nitrogen with lower pressure, part of pure nitrogen that is partially located at a first nitrogen product pressure is reheated in a main heat exchanger, then decompressed to a second nitrogen product pressure by means of a nitrogen expander, further reheated by means of the main heat exchanger, and output as a low-pressure nitrogen product. The nitrogen expander can be braked by an expander booster for compressing air. By means of the method, nitrogen with different pressures can be suitably produced, and the energy consumption for producing the pressurized air can be reduced by utilizing the expansion work of nitrogen.

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 method for separating air by cryogenic distillation, wherein air is compressed in a first compressor, cooled in a heat exchanger and then separated in a system of columns, liquid oxygen is vaporized in the heat exchanger countercurrent to a flow of pressurized gas which pseudo-condenses, a flow of gas which is air or a gas delivered from the system of columns is expanded in a cryogenic expansion turbine having a single wheel, the turbine having an inlet temperature lower than 100 C., a gas which is air or a gas delivered from the system of columns is compressed in a first booster compressor having a single wheel, with an inlet temperature higher than 50 C., a gas which is air or a gas delivered from the system of columns.

Process and apparatus for the separation of a compressed feed air stream to produce an oxygen product using a distillation column having a lower-pressure column and a higher-pressure column, a higher-pressure heat exchanger and a lower-pressure heat exchanger where the gaseous nitrogen expander receives a nitrogen-enriched fraction from a position intermediate the warmer end and the colder end of the higher-pressure heat exchanger.

A method and apparatus for producing compressed nitrogen and liquid nitrogen. A separation system has a high-pressure column, a low-pressure column with a top condenser and a main condenser. Air is compressed in an air compressor, purified, cooled in a heat exchanger and introduced into the high-pressure column. A first part of the gaseous top nitrogen from the low-pressure column becomes compressed nitrogen product. A second part of the gaseous top nitrogen is condensed in the condensing space of the top condenser and vapor is drawn off as a residual gas stream. The vapor is expanded in a first expansion machine. A second compressed nitrogen stream from the top of the high-pressure column is expanded in a second expansion machine and then drawn off as compressed nitrogen product. A part of the nitrogen condensed in the top condenser is drawn off as liquid nitrogen product.

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.