Process and apparatus for obtaining low purity oxygen by fractionation of air at low temperatures

Claim 1

A PROCESS FOR PRODUCING LOW PURITY OXYGEN BY THE LOW TEMPERATURE FRACTIONATION OF AIR IN A DOUBLE RECTIFICATION COLUMN HAVING A HIGH PRESSURE ZONE AND A LOW PRESSURE ZONE, WHICH PROCESS COMPRISES: (A) CONDUCTING COMPRESSED AIR TO BE FRACTIONATED THROUGH REGENERATORS AND COOLING IT TO A LOW TEMPERATURE; (B) CONDUCTING THE COOLED GASEOUS AIR TO A WASHING ZONE AND WASHING THE AIR WITH LIQUID AIR ENRICHED IN OXYGEN; (C) CONDUCTING THE LIQUID FRACTION FROM THE WASHING ZONE TO AN INTERMEDIARY SECTION OF THE LOW PRESSURE ZONE OF THE DOUBLE RECTIFICATION COLUMN; (D) CONDUCTING ALL OF THE GASEOUS FRACTION FROM THE WASHING ZONE TO A HEAT EXCHANGE ZONE, IN INDIRECT HEAT EXCHANGE RELATIONSHIP WITH A LIQUID COMPRISING BOTTOMS FROM SAID LOW PRESSURE ZONE TO PARTIALLY CONDENSE SAID GASEOUS FRACTION INTO A LIQUID FRACTION ENRICHED IN OXYGEN AND A VAPOR FRACTION DEPLETED IN OXYGEN; (E) CONDUCTING THE LIQUID FRACTION OF SAID PARTIALLY CONDENSED GASEOUS FRACTION TO THE WASHING ZONE AS SOLE WASHING LIQUID; (F) CONDUCTING THE VAPOR FRACTION OF SAID PARTIALLY CONDENSED FRACTION TO THE HIGH PRESSURE ZONE OF THE DOUBLE RECTIFICATION COLUMN.