Low temp. sepn. of argon, oxygen and nitrogen from air - using intermediate liq. oxygen fraction as cooling medium for the argon finishing column

摘要

Low temp. sepn. of air comprises cooling compressed pre-purified air (4) before feeding to a single stage sepn. column (8) to yield oxygen (9, 10) and nitrogen (11, 12) streams and an Ar enriched oxygen fraction (27) from a central take-off in the column, which is then further fractionated in a second column (28) to produce a crude Ar stream (29) and a liq. bottoms residue (30). The upper section of column (28) is cooled by indirect heat exchange with a crude oxygen stream (33) tapped from the middle reach of column (8). USE/ADVANTAGE - Reduced cost process for sepn. of nitrogen, oxygen and argon from air, obviating the requirement for a separate cooling system for operating the argon finishing column, by using a liq. oxygen off-take from column (8) as the coolant.