
53Oxygen Production
(Figure3.15). Air is compressed and cooled in a main
heat exchanger. The HP air is then used to boil the
liquid in an LP column. The air is condensed and
then transferred into the top of the LP column. As the
liquid ows down the column it contacts the vapor
generated in the reboiler and becomes richer in oxy-
gen. Product oxygen in a gaseous form is generated
at the bottom of the column at a purity dened by
the number of distillation stages in the column. Due
to the fact that there is not a rectication section in
this column, a pure nitrogen stream cannot be gen-
erated and the purity is limited to a vapor oxygen
concentra ...