The invention relates to an installation for producing liquefied gas comprising a circuit for supplying feed gas, a set of heat exchangers, a refrigerator for cooling some or all of the set of heat exchangers, the supply circuit comprising, between the set of heat exchangers and the downstream end thereof, a final expansion turbine for expanding the feed gas in liquid state, the supply circuit comprising a bypass line of the final expansion turbine fitted with a first expansion valve, a second expansion valve disposed in series upstream or downstream of the first expansion valve and of the final expansion turbine, an additional heat exchange line designed to exchange heat with a heat exchanger of the set of heat exchangers when the feed gas is expanded by the first expansion valve via the bypass line, the additional heat exchange line carrying out this heat exchange with said heat exchanger between the expansion carried out by the first expansion valve and the expansion carried out by the second expansion valve, the additional heat exchange line being located upstream or respectively downstream of the expansion carried out by the first expansion valve.

A system and method for the liquefaction and densification of oxygen for use in space vehicle applications is provided that uses high pressure air or synthetic air as the refrigerant source. The disclosed system and method employs a heat exchanger arrangement comprising a first heat exchange device configured to liquefy the high pressure gaseous oxygen stream and at least a portion of the high pressure gaseous air stream via indirect heat exchange with a refrigerant stream to yield a liquid oxygen stream and a liquid air stream. The heat exchanger arrangement also includes a second heat exchange device configured to densify the liquified oxygen stream via indirect heat exchange with the liquid air stream which yields the densified liquid oxygen and a cold vaporized air stream. The refrigerant stream comprises a mixture of the exhaust streams from one or more turbines with the cold vaporized air stream.

A method for supplying CO.sub.2 gas to a site comprising a facility (20) that requires CO.sub.2 or a mixture comprising CO.sub.2, such as an abattoir or a greenhouse for cultivating plants, comprises the following steps: a boiler (4) capable of supplying hot water to the site is arranged within the site, the boiler carrying out the process of oxycombustion between a fuel (14) and pure oxygen (1), the oxygen that supplies the boiler being obtained from a liquid oxygen source present on the site; and some or all of the CO.sub.2 contained in the flue gas produced by the boiler is recovered by transferring heat between the flue gas and the liquid oxygen in an exchanger (2).

An integrated industrial unit is provided, which can include: a nitrogen source comprising an air separation unit that is configured to provide pressurized gaseous nitrogen and 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 70K and 100K, 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.