Process to produce moderate purity oxygen using a double column plus an auxiliary low pressure column

摘要

(a) Air feed is supplied to the bottom of a high pressure(HP) column (b) nitrogen enriched overhead is removed from the column top and condensed in a first reboiler/condenser disposed in the bottom of an auxiliary low pressure(LP) column (c) condensed overhead is supplied as reflux to an upper location in the HP column (d) crude liquid oxygen bottoms are removed from the HP column and it's pressure reduced followed by supply to the top of the auxiliary LP column (e) crude nitrogen overhead is taken from the auxiliary LP column and fed directly as vapour to an intermediate location in the main LP column (f) an oxygen enriched stream is removed from a lower location of the main LP column as a vapour or liquid and supplied to an intermediate section in the main LP column below the intermediate location of the crude nitrogen overhead in stage (e). Then (g) nitrogen enriched overhead is removed from the top of the main LP column as waste and (h) oxygen product removed from a lower location of the main LP column as a vapour or liquid.