Recovery of HF from an alkylation unit acid stream containing acid soluble oil

A method of recovering hydrofluoric acid, said method comprising:

• stripping a mixture containing at least HF, water and acid soluble by contacting the mixture with vaporous hydrocarbon in a fractionation column;
• recovering as an overhead product from said column a first mixture of HF and vaporous hydrocarbon;
• collecting a second mixture of HF, water and acid soluble oil in a lower portion of said column;
• removing a portion of said second mixture from said column and cooling the thus removed portion of said second mixture by indirect contact with a cooling hydrocarbon to a temperature no higher than about 125.degree. F.;
• phase separating the thus cooled portion of said second mixture into a first continuous acid soluble oil phase portion containing acid soluble oil which is substantially free of HF, and a second continuous acid soluble oil phase portion containing a major portion of the HF contained in the second mixture and acid soluble oil, with said acid soluble oil in the second phase portion being up to about 90 percent of the acid soluble oil contained in the thus cooled portion of said second mixture;
• separating said first phase portion from said second phase portion;
• returning the thus separated second phase portion containing HF to said column;
• and
• introducing at least a portion of the cooling hydrocarbon into said column as at least a portion of said vaporous hydrocarbon after the portion of cooling hydrocarbon has been used for cooling said portion of said second mixture.