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.

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 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 method for obtaining one or more air products, in which method an air fractionation plant is used which has a column system with a pressure column, wherein air is fedto the column system and is fractionated in the column system, wherein at least 90% of the total amount of air supplied to the column system is compressed, wherein nitrogen-rich gas is extracted from the pressure column, and wherein, at least in a first operating mode, further air is compressed to a pressure level above the base pressure level, is expanded, and is warmed without fractionation in the column system. It is provided that, at least in the first operating mode, a proportion of the nitrogen-rich gas extracted from the pressure column is fed to the further air upstream of the expansion.

A hydrogen feed stream is introduced into a primary refrigeration system of a precooling system and cooling the hydrogen stream to a first precooling temperature. From there, the precooled hydrogen stream is then introduced to a secondary refrigeration system of the precooling system and cooling the precooled hydrogen stream to a second temperature. Next, the cooled hydrogen stream is then liquefied in the liquefaction system to produce liquid hydrogen.

An integrated industrial unit is provided, which can include: a nitrogen source configured to provide liquid nitrogen; a hydrogen source; a hydrogen liquefaction unit, wherein the hydrogen liquefaction unit comprises a precooling system, and a liquefaction system; and a liquid hydrogen storage tank, wherein the precooling system is configured to receive the gaseous hydrogen from the hydrogen source and cool the gaseous hydrogen to a temperature between 75 K and 100 K, wherein the precooling system comprises a primary refrigeration system and a secondary refrigeration system, wherein the liquefaction system is in fluid communication with the precooling system and is configured to liquefy the gaseous hydrogen received from the precooling system to produce liquid hydrogen, wherein the liquid hydrogen storage tank is in fluid communication with the liquefaction system and is configured to store the liquid hydrogen received from the liquefaction system.

A hydrogen feed stream is introduced into a primary refrigeration system of a precooling system and cooling the hydrogen stream to a first precooling temperature. From there, the precooled hydrogen stream is then introduced to a secondary refrigeration system of the precooling system and cooling the precooled hydrogen stream to a second temperature. Next, the cooled hydrogen stream is then liquefied in the liquefaction system to produce liquid hydrogen. The refrigeration is provided by expansion of a pressurized gaseous nitrogen stream and vaporization of a liquid nitrogen stream that is sourced from a nearby air separation unit.

A method for flexible production of argon from a cryogenic air separation unit is provided. The disclosed 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.

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.