METHOD AND DEVICE FOR PRODUCING COMPRESSED NITROGEN

摘要

The process and the apparatus serve to produce pressurized nitrogen by low-temperature fractionation of air in a rectification system which has a pressure column (4) and a low-pressure column (5). Feed air (1, 3) is passed into the pressure column (4). An oxygen-containing liquid fraction (11) is taken off from the pressure column (4) and fed into the low-pressure column (5). Gaseous nitrogen (18) from the low-pressure column (5) is at least partially condensed in a top condenser (17) by indirect heat exchange with an evaporating liquid (13). Nitrogen from the low-pressure column is produced as gaseous pressurized nitrogen product (24, 25, 29) at a pressure which is higher than the operating pressure of the low-pressure column (5). Liquid nitrogen (20) withdrawn from the low-pressure column is brought (21) in the liquid state to a pressure which exceeds the pressure of the low-pressure column (5). The pressurized liquid (22) is evaporated in a product evaporator (23) by indirect heat exchange with a heat-transfer medium (35) and is subsequently produced as gaseous pressurized nitrogen product (24, 25, 29). (FIG. 1)