A method and apparatus serve for the cryogenic separation of air in an air separation plant which has a main air compressor, a main heat exchanger and a distillation column system with a high-pressure column and a low-pressure column. All of the feed air is compressed in the main air compressor to a first air pressure which is at least 3 bar higher than the operating pressure of the high-pressure column. A first part of the compressed total air flow, as first air flow at the first air pressure, is cooled and liquefied or pseudo-liquefied in the main heat exchanger, then expanded and introduced into the distillation column system. A second part of the compressed total air flow, as second air flow, is post-compressed in a turbine-driven post-compressor to a second air pressure.

A system and method for cryogenic air separation arrangement having a booster loaded liquid turbine for expansion of a liquid air stream or other fluid having liquid-like densities is provided. The disclosed booster loaded liquid turbines are relatively small to provide an aerodynamic and speed match between the turbine and the coupled gas compressor. The coupled gas compressor is a supplemental booster compressor and may be a dedicated warm booster compressor or alternatively a cold booster compressor.

A process for the production of at least liquid oxygen and/or liquid nitrogen in cryogenic rectification. During a first period, during which electrical power prices are low, a process stream utilized by the ASU is liquefied and stored. During a second period, during which electrical prices high, at least a portion of the stored, liquefied process stream is withdrawn and introduced into the ASU. Wherein the MAC has a discharge pressure of greater than 10 bara during the first period, a first molar flowrate (LF) and a first pressure (LP) during the first period, a second molar flowrate (HF) and a second pressure (HP) during the second period. Wherein C=(LF/HF)/(LP/HP). And wherein second molar flowrate (HF) is <90% of first molar flowrate (LF) and C is between 0.9 and 1.05.

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.

A process for producing liquid oxygen, including an offshore platform the system including cooling a high-pressure nitrogen gas stream in a main heat exchanger, thereby producing a cooled high-pressure nitrogen gas stream, expanding the cooled high-pressure nitrogen gas stream in a turbo-expander, thereby producing a cold low-pressure nitrogen gas stream, warming the cold low-pressure nitrogen gas stream by indirect heat exchange with a high-pressure gaseous oxygen stream, thereby producing a liquefied oxygen stream and a warm low-pressure nitrogen gas stream, wherein, at least a portion of the warm low-pressure nitrogen gas stream is vented to the atmosphere.

In a process for starting up an air separation unit, which is at a temperature of above 0° C., the air separation unit comprising a main air compressor for compressing the feed air, a booster driven by a turbine and a venting conduit connected downstream of the booster and upstream of the main heat exchanger wherein in order to start up the air separation unit, once the turbine is operating at said given speed, the venting conduit is opened to send at least part of the air compressed in the booster from the booster outlet to the atmosphere.

Method and device for generating gaseous compressed nitrogen by the low-temperature separation of air in a distillation column system, having a pre-column, a high-pressure column and a low-pressure column. The feed air is compressed, purified in a purification apparatus and cooled. A first sub-flow of the cooled feed air is introduced in a predominantly liquid state into the distillation column system. A gaseous fraction from the pre-column in introduced into the liquefaction chamber of a pre-column head condenser with liquid formed therein fed as reflux into the pre-column. A first gaseous nitrogen product fraction is drawn from the high-pressure column, heated, and obtained as first gaseous compressed nitrogen product. At least a part of the second sub-flow is introduced into the evaporation chamber of the pre-column head condenser. A third sub-flow of the cooled feed air is expanded to perform work and subsequently introduced into the liquefaction chamber.

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.

A method and the apparatus for obtaining a compressed gas product by means of cryogenic separation of air in a distillation column system which has a high-pressure column and a low-pressure column. All of the feed air is compressed in a main air compressor to a first pressure which is at least 4 bar higher than the operating pressure of the high-pressure column. A first partial flow of the feed air compressed in the main air compressor is cooled to an intermediate temperature in a main heat exchanger and is expanded so as to perform work in a first air turbine. At least a first part of the first partial flow expanded so as to perform work is introduced into 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.