Recovery of hydrogen fluoride from alkylation product effluent

Claim 1

IN THE ALKYLATION OF AN ISOPARAFFIN WITH AN OLEFIN IN THE PRESENCE OF HYDROFLUORIC ACID AS A CATALYST IN WHICH THERE IS OBTAINED AN ALKYLATION EFFLUENT CONTAINING DESIRED ALKALATE PRODUCT, GASES LIGHTER THAN PROPANE, PROPANE, ISOBUTANE, NORMAL BUTANE, AND HYDROFLUORIC ACID, THE STEPS IN COMBINATION COMPRISING: FRACTIONATING A HYDROCARBON PHASE OBTAINED FROM SAID ALKYLATION TO OBTAIN THEREFROM A FRACTION CONTAINING GASES LIGHTER THAN PROPANE, SOME PROPANE, AND AN EQUILIBRIUM PROPORTION OF HYDROGEN FLUORIDE; PLACING SAID FRACTION UNDER CONDITIONS TO OBTAIN LIQUID PROPANE THEREFROM, WHICH IS REMOVED AS A PRODUCT OF THE PROCESS, AND A FIRST GASEOUS PHASE CONTAINING PROPANE, HYDROGEN FLUORIDE, AND GASES LIGHTER THAN PROPANE; COOLING SAID FIRST GASEOUS PHASE TO OBTAIN THEREFROM A CONDENSATE OF HYDROCARBON AND HYDROGEN FLUORIDE AND TO FORM A SECOND GASEOUS PHASE CONTAINING SUBSTANTIALLY ONLY GASES LIGHTER THAN PROPANE, VENTING SAID SECOND GASEOUS PHASE FROM THE PROCESS; SEPARATING SAID CONDENSATE INTO A HYDROCARBON PHASE AND A HYDROGEN FLUORIDE PHASE AND RECOVERING SAID HYDROGEN FLUORIDE.