Process and apparatus for separating gaseous mixtures by low-temperature rectification

Claim 1

IN A PROCESS FOR SEPARATING A GASEOUS MIXTURE CONTAINING HIGHER AND LOWER BOILING COMPONENTS BY LOW TEMPERATURE FRACTIONATION IN A FRACTIONATING COLUMN TO OBTAIN BOTTOM PRODUCT OF HIGHER BOILING ENRICHED LIQUID, THE STEPS COMPRISING: (A) DIVIDING SAID GASEOUS MIXTURE INTO HIGHER PRESSURE GAS MIXTURE PORTION AND LOWER PRESSURE GAS MIXTURE PORTION; (B) PASSING SAID HIGHER PRESSURE GAS MIXTURE PORTION IN INDIRECT HEAT TRANSFER RELATIONSHIP WITH SAID BOTTOM PRODUCT IN A ZONE EXTERNAL TO SAID FRACTIONATING COLUMN, SAID INDIRECT HEAT TRANSFER BEING CONDUCTED IN SUCH MANNER AS TO EVAPORATE SAID BOTTOM PRODUCT AT GRADUALLY INCREASING TEMPERATURES, AND TO COOL SAID HIGHER PRESSURE GAS MIXTURE PORTION AT GRADUALLY DECREASING TEMPERATURES TO AT LEAST PARTIALLY CONDENSE SAID HIGHER PRESSURE GAS MIXTURE PORTION; (C) PASSING RESULTANT CONDENSED HIGHER PRESSURE GAS MIXTURE PORTION TO SAID FRACTIONATING COLUMN; (D) PASSING SAID LOWER PRESSURE GASEOUS MIXTURE PORTION TO SAID FRACTIONATING COLUMN; AND (E) PASSING SAID LOWER PRESSURE GASEOUS MIXTURE PORTION IN SAID RECITIFICATION COLUMN IN INDIRECT HEAT TRANSFER RELATIONSHIP WITH SAID RESULTANG CONDENSED HIGHER PRESSURE GAS MIXTURE PORTION, SAID INDIRECT HEAT TRANSFER BEING CONDUCTED IN SUCH MANNER AS TO PARTIALLY VAPORIZE SAID RESULTANT CONDENSED HIGHER PRESSURE GAS MIXTURE PORTION AT GRADUALLY INCREASING TEMPERATURES, AND TO COOL SAID LOWER PRESSURE GAS MIXTURE PORTION AT GRADUALLY DECREASING TEMPERATURES TO AT LEAST PARTIALLY CONDENSE SAID LOWER PRESSURE GAS MIXTURE PORTION.