Single column process and assembly with turbine for fractional distillation

摘要

In a process and assembly to extract nitrogen from air (1) by fractional distillation in a single column (8), the air is compressed (2) to a first pressure. A first portion of this compressed air (4) is tapped (5) and cooled (7) approximately to the dew point and released into the column. The second portion (6) of compressed air is then raised to a higher pressure and then allowed to expand (10) surrendering energy on release into the column. The head gas (15) within the column is liquefied within a head condenser (14), the condensate (16) being partly (17) returned to the column, with nitrogen (19,20) being removed from the column.