Abstract: Oxygen and nitrogen are produced by low-temperature separation of air in a rectification system that has a pressure column (4) and a low-pressure column (5). Charging air (1, 3) is introduced into pressure column (4). An oxygen-containing liquid fraction (8, 10) is removed from pressure column (4) and fed into low-pressure column (5). Gaseous nitrogen (17) from low-pressure column (5) is at least partially condensed in a top condenser (7) by indirect heat exchange with an evaporating cooling fluid (15). A nitrogen product stream (19) is removed from low-pressure column (5) and/or pressure column (4). An oxygen product stream (61, 62, 63) is pulled off from low-pressure column (5). The cooling fluid for top condenser (7) of low-pressure column (5) is formed by an intermediate liquid (15) that is drawn off from an intermediate point on low-pressure column (5).

Abstract: The process and the apparatus serve for the low-temperature fractionation of air. Compressed and prepurified feed air (3, 5) is introduced into a rectification system for nitrogen-oxygen separation which has a pressure column (6). At least a part of the compressed and prepurified feed air is fed (5) to the pressure column (6). An oxygen-enriched fraction (13) is taken off from the pressure column (6) and passed (14) to a further working step (7) within the rectification system. The oxygen-enriched fraction (13) is taken off at least one theoretical or actual plate (15) above the point at which the compressed and prepurified feed air (5) is fed to the pressure column. From the bottom of the pressure column (6) a purge fraction (16) is removed in the. liquid state, fed in the liquid state to a purification stage (17), in which N2O is removed, and is taken off from the purification stage (17) as purified purge fraction (18).

Abstract: Oxygen and nitrogen are produced by low-temperature separation of air in a rectification system that has a pressure column (4) and a low-pressure column (5). Charging air (1, 3) is introduced into pressure column (4). An oxygen-containing liquid fraction (8, 10) is removed from pressure column (4) and fed into low-pressure column (5). Gaseous nitrogen (17) from low-pressure column (5) is at least partially condensed in a top condenser (7) by indirect heat exchange with an evaporating cooling fluid (15). A nitrogen product stream (19) is removed from low-pressure column (5) and/or pressure column (4). An oxygen product stream (61, 62, 63) is pulled off from low-pressure column (5). The cooling fluid for top condenser (7) of low-pressure column (5) is formed by an intermediate liquid (15) that is drawn off from an intermediate point on low-pressure column (5).

Abstract: The invention relates to a method for extracting xenon and eventually also krypton from a liquid oxygen (LOX) charge, as it accrues in a cryogenic air separation system (LZA) during a rectification of the air, mostly as a bottom product of a low-pressure, column, namely with xenon (Xe), krypton (Kr) and hydrocarbons (CxHy) in a small concentration and approximately 99 mol % oxygen (O2). According to the inventive method, the LOX charge is fed to a first column, the oxygen of the LOX charge is extensively removed by stripping with an inert gas, and is extracted in the top gas, whereas the inert gas is withdrawn in the form of a liquid from the bottom of the first column with little O2 and nearly the total mass of CxHy, Kr, Xe. According to the invention, the liquid discharge is fed to a second column without prior catalytic and/or adsorptive removal of CxHy. A Kr fraction is extracted as top gas of the second column, and an Xe fraction is withdrawn from the bottom of the second column.

Abstract: The process and the apparatus serve for the low-temperature fractionation of air in a rectification system that has at least one pressure column and one low-pressure column. Feed air is compressed to a first pressure p1 in a first compressor, purified in a purification stage, cooled and at least in part introduced into the pressure column. At least one liquid fraction from the pressure column is fed into the low-pressure column. A nitrogen-rich fraction from the low-pressure column is warmed and mixed with feed air. The warmed nitrogen-rich fraction is mixed with the feed air downstream of the feed air purification stage. The mixture of feed air and nitrogen-rich fraction is further compressed in a second compressor to a second pressure p2 which is higher than the first pressure p1.

Abstract: The invention relates to a process and a liquefier for the production of liquid air with an oxygen content of between 16 and 21 mol % in a low-temperature process, whereby atmospheric air is used as a feed gas; in a warm part of the process, H2O, carbon dioxide and contaminants entrained in the air are removed in a purification step, e.g. adsorption; cold is produced by compression and engine expansion of process streams. Liquid air is obtained as a liquid head product in a cold part of the process by low-temperature rectification in a column having less than four theoretical plates. In addition, a liquid bottoms product is obtained in the rectification, used exergetically and vented as a warm residual gas into the atmosphere or used at least partially in the purification step.

Abstract: In a process for the production of a pressurized gaseous product by low-temperature separation of air, which is at times done in a gas operation and at times in a combined operation, whereby in the gas operation and in the combined operation (a) purified charging air is cooled under pressure, partially liquefied, and subjected to rectification to produce gaseous and liquid fractions, (b) extremely cold liquid of at least one of the liquid fractions from the rectification is evaporated under elevated pressure by indirect heat exchange with feed air, heated, and obtained as a pressurized gaseous product, whereby in combined operation, (c) the cold that is required for this purpose is generated in an air-refrigeration cycle, by air being compressed in the refrigeration cycle and work expanded, in which case heat is removed from the air, and the actively depressurized air that is partially in countercurrent is heated again with the charging air that is to be cooled and then repressurized, (d) extremely cold liqui

Abstract: The process and the apparatus are used for low-temperature separation of air in a rectifying column system that has a preliminary separation column (10) and a low-pressure column (20). Feed air (1, 3) is introduced (4, 6, 7, 8, 41) into preliminary separation column (10) and is separated into a nitrogen-enriched overhead fraction and an oxygen-enriched bottom fraction. At least a portion (19) of the oxygen-enriched bottom fraction is introduced into the low-pressure column (20), in which liquid oxygen and gaseous nitrogen are produced. The pressure in preliminary separation column (10) is essentially equal to the pressure of low-pressure column (20). The reflux for the columns can be obtained by one or two cyclic processes operated with overhead gas (11, 23) from one or two columns (10, 20).

Abstract: A process and apparatus are used for liquefying a low-boiling gas, 1, 507, particularly nitrogen. Gas to be liquified is cooled 12 under an increased pressure, is expanded 14 and is then obtained as a liquid product 16. In a refrigeration cycle, cycle medium is compressed to a first pressure 4, 6, 8, 10. A first partial flow 101 of the cycle medium is expanded while carrying out work in a first expansion machine 102. A second partial flow 201 of the cycle medium is cooled 12a and is expanded while carrying out work in a second expansion machine 202. In addition, a third partial flow 301 of the cycle medium is cooled and is expanded in a third expansion machine 302 while carrying out work. All three expansion machines 102, 202, 302 have essentially the same inlet pressure. The cooling of the gas to be liquified is carried out at least partially by the indirect heat exchange with expanded cycle medium 103, 203, 17 in a cycle heat exchanger 12.

Abstract: The process and apparatus are based on a triple-column system, having at least a high-pressure column (7), a medium-pressure column (8) and a low-pressure column (9). Feed air (1) is compressed to a first pressure (2). A first partial stream (101, 103, 104) of the resultant air feed (3) is sent into high-pressure column (7) after it has been compressed to a second pressure (5, 102), which is at least equal to the operating pressure of the high-pressure column (7). A second partial stream (201, 202) of the compressed air feed (3) is fed into the medium-pressure column (8). A third partial stream (301, 303, 304) of the compressed air feed (3) is engine-expanded (305) and then fed (306) into the low-pressure column (9). Fractions (18; 26) from the high-pressure column (7) and the medium-pressure column (8) are introduced at least partially into low-pressure column (19, 20; 28, 29). Nitrogen-enriched top fractions (10; 21) from high-pressure column (7) and medium-pressure column (8) are condensed (11; 22).

Abstract: For the method, air (103, 104) is fractionated in a medium-pressure column (6) and a low-pressure column (5). The sump heating (3) of the low-pressure column (5) is carried out with a second airflow (204), which is liquefied at the same time. An intermediate fraction (18) is taken from the low-pressure column (5) and evaporated in the head condenser (10) of the medium-pressure column (6). The thereby resulting vapor (19) is returned to the low-pressure column. In the event that impure oxygen is obtained, the second airflow (203, 204) is recompressed (202) upstream from the sump heating (3), external energy being supplied, to a pressure above that of the medium-pressure column, the pressure being relieved downstream from the sump heating (3) in a first pressure relief valve (208) to the pressure of the medium-pressure column (6).