... entering the lower column becomes liquid air due to consecutive cooling. Purified oxygen and nitrogen will be obtained after distillation ... consumption for O2 ~0.75KW.h/ m3 O22.7 Cooling water consumption 30t/h2.8 Temp difference at warm end ... whole ASP consists of an air compressor, sub-coolers, pre-cooling unit, purifiers, electric heaters, expanders, a distillation column, analyzing apparatus, ...