Abstract: The plant is used for producing oxygen by cryogenic air separation. The plant has a high-pressure column, a low-pressure column and a main condenser. An argon-elimination column is in fluid connection with an intermediate point of the low-pressure column and is connected to an argon-elimination column head condenser. An auxiliary column has a sump region, into which gas is introduced from the argon-elimination column head condenser. The head of the auxiliary column is connected to a return flow liquid line, in order to introduce a liquid stream from the high-pressure column or the head condenser. The liquid stream has an oxygen content which is at least equal to that of air. At least one part of the crude liquid oxygen from the sump of the high-pressure column is fed to the auxiliary column at a first intermediate point.

Abstract: The plant is used for producing oxygen by cryogenic air separation. The plant has a high-pressure column, a low-pressure column and a main condenser. An argon-elimination column is in fluid connection with an intermediate point of the low-pressure column and is connected to an argon-elimination column head condenser. An auxiliary column has a sump region, into which gas is introduced from the argon-elimination column head condenser. The head of the auxiliary column is connected to a return flow liquid line, in order to introduce a liquid stream from the high-pressure column or the head condenser. The liquid stream has an oxygen content which is at least equal to that of air. At least one part of the crude liquid oxygen from the sump of the high-pressure column is fed to the auxiliary column at a first intermediate point.

Abstract: For cooling a gas by direct heat exchange with a cooling liquid, the gas (1) to be cooled is introduced into the lower region of a direct contact cooler (2). A first stream of cooling liquid (8) is fed into the direct contact cooler (2) above the point of introduction of the gas (1). Cooled gas (5) is removed above the point of introduction of the gas (1) from the direct contact cooler (2). A liquid backflow (10) is drawn off from the lower region of the direct contact cooler (2). At least at times, a second stream of cooling liquid (13) with a temperature that is lower than that of the backflow (10) is fed into the liquid backflow (10) and combined with the latter to form a return flow (11).

Abstract: A process and device for evaporating an oxygen-enriched working fluid by indirect heat exchange include introducing an oxygen-rich working fluid into the evaporation passages of an evaporator where it is partially evaporated. A first oxygen-enriched gas and a portion of the oxygen-enriched working fluid that remains liquid are drawn off from the evaporation passages. At least a part of the portion that remains liquid is returned to the evaporation passages as a circulation liquid by a conveying device. The conveying device for the circulation liquid injects a lift gas.

Abstract: For cooling a gas by direct heat exchange with a cooling liquid, the gas (1) to be cooled is introduced into the lower region of a direct contact cooler (2). A first stream of cooling liquid (8) is fed into the direct contact cooler (2) above the point of introduction of the gas (1). Cooled gas (5) is removed above the point of introduction of the gas (1) from the direct contact cooler (2). A liquid backflow (10) is drawn off from the lower region of the direct contact cooler (2). At least at times, a second stream of cooling liquid (13) with a temperature that is lower than that of the backflow (10) is fed into the liquid backflow (10) and combined with the latter to form a return flow (11).

Abstract: The process and the apparatus serve for the low-temperature fractionation of air. Feed air (1) is introduced into a first rectification column (3). A transfer fraction (6, 7) of density &rgr; is withdrawn in the liquid state from a reservoir (24, 16) within the first rectification column (3), expanded (14, 14a, 18) and fed to a further process step (5, 23). The liquid level in the reservoir (24, 16) is in this case at a first level h1 and is at a first pressure p1. The expanded transfer fraction is fed to the further process step (5, 23) at a second, higher level h2 (h2 >h1) and at a second, lower pressure (p2 <p1). The difference between the two pressures &Dgr;p=p1−p2 is less than the hydrostatic pressure (Phydr=&rgr;·g·[h2−h1]) caused by a liquid column of the transfer fraction between the first level and the second level: &Dgr;p=p1−p2<&rgr;·g·[h2−h1] (g: acceleration due to gravity).