Wash liquid production by heat exchange with low pressure liquid oxygen

Claim 1

A PROCESS FOR PRODUCING GAS OF 70-98% OXYGEN PURITY IN AN DOUBLE RECTIFIER HAVING A HIGH PRESSURE COLUMN AND A LOW PRESSURE COLUMN, COMPRISING THE STEPS OF: (A) CONDUCTING COMPRESSED AIR TO BE FRACTIONATED THROUGH REGENERATORS IN INDIRECT HEAT EXCHANGE WITH FRACTIONATION PRODUCTS; (B) CONDUCTING COOLED GASEOUS AIR TO A PREWASHING COLUMN AND WASHING THE AIR WITH LIQUID AIR ENRICHED IN OXYGEN; (C) WITHDRAWING LIQUID PRELIMINARY PRODUCT FROM THE SUMP OF THE LOW PRESSURE COLUMN TO AN INTERMEDIATE PARTIAL VAPORIZATION ZONE AND PARTIALLY VAPORIZING SAID PRELIMINARY PRODUCT INTO A FIRST LIQUID FRACTION AND A FIRST VAPOR FRACTION; (D) RECYCLING SAID FIRST VAPOR FRACTION TO THE BOTTOM PORTION OF THE LOW PRESSURE COLUMN; (E) CONDUCTING SAID FIRST LIQUID FRACTION TO A FINAL PARTIAL VAPORIZATION ZONE SEPARATE AND DISTINCT FROM SAID INTERMEDIATE PARTIAL VAPORIZATION ZONE TO PARTIALLY VAPORIZE SAID FIRST LIQUID FRACTION TO OBTAIN A SECOND LIQUID FRACTION AND A SECOND VAPOR FRACTION; (F) CONDUCTING PARTIAL VAPORIZATION OF AT LEAST ONE OF STEPS (C) AND (E) IN INDIRECT HEAT EXCHANGE WITH WASHED COLD GASEOUS AIR FROM STEP (B) TO PARTIALLY CONDENSE SAME; (G) RECYCLING RESULTANT LIQUID FROM PARTIALLY CONDENSED AIR AS WASHING LIQUID TO SAID PREWASHING COLUMN; AND (H) CONDUCTING RESULTANT LOADED WASHING LIQUID TO THE LOW PRESSURE COLUMN.