Process for separating higher hydrocarbons from gas mixtures containing acetylene and/or ethylene

Claim 1

A PROCESS FOR SEPARATING HIGHER HYDROCARBONS HAVING AT LEAST THREE CARBON ATOMS FROM CRUDE GAS MIXTURES CONTAINING A MEMBER SELECTED FROM THE GROUP CONSISTING OF ACETYLENE, ETHYLENE AND MIXTURES THEREOF, AND OBTAINED IN THE PYROLYSIS OF LIQUID HYDROCARBONS HAVING A BOILING RANGE OF ABOUT 35* TO ABOUT 107*C. WHICH COMPRISES PRECOOLING SAID GAS MIXTURE, INTRODUCING THE PRECOOLED GAS MIXTURE INTO A PURIFICATION STAGE CONTAINING IN THE UPPER SECTION A COOLING AND CONDENSATION ZONE, AN ABSORPTION ZONE IN THE MIDDLE SECTION, AND A DISCHARGE ZONE IN THE LOWER SECTION, SAID PRECOOLED GAS MIXTURE BEING INTRODUCED INTO THE PURIFICATION STAGE BETWEEN THE ABSORPTION ZONE AND THE DISCHARGE ZONE, DIVERTING ABOUT 30-60% OF A MAIN STREAM OF LIQUID HYDROCARBONS INTO A BRANCH CURRENT, WASHING SAID GAS MIXTURE IN A PURIFICATION STAGE WITH SAID BRANCH CURRENT OF LIQUID HYDROCARBONS RUNNING COUNTERCURRENT TO THE GAS MIXTURE ANDFLOWING INTO THE PRIFICATION STAGE BETWEEN THE CONDENSATION ZONE AND THE ABSORPTION ZONE AT A TEMPERATURE OF ABOUT -60* TO -80*C. AND UNDER A PRESSURE OF ABOUT 10 TO 20 ATMOSPHERES, MAINTAINING THIS TEMPERATURE INTHE ABSORPTION ZONE BY THE REFLUX OF ABOUT 10 TO ABOUT 30% BY VOLUME OF AT LEAST ONE SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF ACETYLENE AND ETHYLENE INTRODUCED INTO AND CONDENSING IN THE CONDENSATION ZONE, THE REFLUX COMBINED WITH THE BRANCH CURRENT WASHING LIQUID PRODUCING A COMPLETE SEPARATION OF HIGHER BOILING IMPURITIES FROM THE CRUDE GAS MIXTURE, DRAWING OFF AT THE HEAD OF THE PURIFICATION STAGE THE PRUIFIED GAS FREE OF HIGHER HYDROCARBONS WITH AT LEAST THREE CARBON ATOMS, EXPELLING DISSOLVED ACETYLENE AND ETHYLENE FROM THE BRANCH CURRENT WASHING LIQUID BY BLOWING THE SAME OUT WITH RESIDUAL GAS, DISCHARGING THE CONTAMINATED BRANCH CURRENT WASHING LIQUID FROM THE DISCHARGE ZONE, SUPERHEATING THE MAIN NON-BRANCHED PORTION OF THE PURE LIQUID HYDROCARBONS AT A TEMPERATURE OF 400 TO 500*C. AT ATMOSPHERIC PRESSURE, AND COMBINING SAID NON-BRANCHED PORTION WITH THE CONTAMINATED BRANCH CURRENT WASHING LIQUID PRIOR TO PYROLYSIS.