Alkylation of hydrocarbons

Claim 1

IN AN ALKYLATION PROCESS WHICH COMRISES CONTACTING ISOBUTANE WITH AN OLEFIN IN THE PRESENCE OF SULFURIC ACID IN AN ALKYLATION CONTACTOR TO PRODUCE A VAPOROUS HYDROCARBON EFFLUENT CONTAINING ISOBUTANE AND A LIQUID EFFLUENT CONTAINING SULFURIC ACID, ALKYLATE AND UNREACTED ISOBUTANE; SEPARATING THE VAPOROUS EFFLUENT FROM THE LIQUID EFFLUENT; SEPARATELY REMOVING SULFURIC ACID FROM THE LIQUID EFFLUENT; AND SUBJECTING THE RESULTING LIQUID ALKYATE MIXTURE TO DEISOBUTANIZATION; THE IMPROVEMENT WHICH COMPRISES: PASSING THE LIQUID ALKYLATE MIXTURE TO A DEISOBUTANIZATION ZONE; REMOVING ISOBUTANE AS A VAPOROUS FRACTION FROM SAID ZONE; COMPRESSING THE VAPOROUS FRACTION AND THE VAPOROUS EFFLUENT TO THE PRESSURE LEVELS WITHIN THE RANGE OF BETWEEN ABOUT 20 P.S.I.G. AND ABOUT 125 P.S.I.G. AT A CONDENSATION TEMPERATURE OF BETWEEN ABOUT 40*F. AND ABOUT 140*F.; MAINTAINING AS TWO DISTINCT AND SEPARATE STREAMS THE VAPORS COMPRESSED TO DIFFERENT PRESSURE LEVELS SUPPLYING HEAT NECESSARY TO EFFECT THE AFOREMENTIONED DEISOBUTANIZATION OF SAID LIQUID ALKYLATE MIXTURE IN SAID ZONE BY PASSING THE VAPOR COMPRESSED TO THE LOWER PRESSURE IN INDIRECT HEAT EXCHANGE WITH THE DEISOBUTANIZATION ZONE IN A FIRST HEAT EXCHANGER TO REBOIL SAID ZONE, AND PASSING THE VAPOR COMPRESSED TO THE HIGHER PRESSURE IN INDIRECT HEAT EXCHANGE WITH THE DEISOBUTANIZATION ZONE AT A POINT BELOW SAID FIRST HEAT EXCHANGER TO REBOIL SAID ZONE IN A SECOND HEAT EXCHANGER CONDENSING THE LOW PRESSURE VAPOR IN SAID FIRST HEAT EXCHANGE OPERATION; RECYCLING THE RESULTING LIQUID TO THE ALKYLATION CONTACTOR AS PART OF THE ISOBUTANE FEED THERETO; CONDENSING THE HIGHER PRESSURE VAPOR AND FLASHING THE RESULTING CONDENSE IN A THIRD HEAT EXCHANGER TO PRODUCE A VAPOROUS PHASE AND A LIQUID PHASE; RECYCLING THE VAPOROUS PHASE TO SAID COMPRESSION STEP; RECYCLING THE LIQUID PHASE TO THE ALKYLATION CONTACTOR AS PART OF THE ISOBUTANE FEED THERETO AND RECOVERING A DEISOBUTANIZED ALKYLATE MIXTURE FROM THE DEISOBUTANIZATION ZONE.