Patent ID: 7803979

Claim:
A method for removing water from an alkylation process system, said method comprising the steps of: alkylating an olefin with a first isoparaffin in the presence of an alkylation catalyst mixture comprising HF and water in an alkylation reactor thereby producing an alkylate product and an ASO reaction by-product; passing an alkylation reaction effluent comprising said alkylate product, said ASO reaction by-product and said alkylation catalyst mixture from said alkylation reactor to a separator for separating said alkylation reaction effluent into a hydrocarbon phase comprising said alkylate product, and an alkylation catalyst mixture phase comprising said alkylation catalyst mixture and at least a portion of said ASO reaction by-product; passing at least a portion of said alkylation catalyst mixture phase to a re-run column for contact with an upwardly flowing gas stream comprising a hydrocarbon selected from the group consisting of a second isoparaffin, a paraffin, and combinations thereof, to provide a re-run column bottoms stream comprising at least a portion of said ASO reaction by-product, and a re-run column overhead stream comprising HF, at least a portion of said gas stream and water; passing a portion of said re-run column overhead stream to said separator; providing a water removal column comprising a bottom section, an intermediate section, and a top section; using a portion of said re-run column overhead stream as a bottoms feed to said bottom section of said water removal column; upwardly flowing a stripping stream comprising the vaporous portion of said bottoms feed up to said intermediate section and said top section; condensing water out of the material entering into said top section to form a condensed stream comprising water; downwardly flowing said condensed stream from said top section to said intermediate section and said bottom section; contacting said upwardly flowing stripping stream with said downwardly flowing condensed stream in said intermediate section and said bottom section to thereby strip HF and hydrocarbons from said condensed stream into said stripping stream; and to thereby condense and transfer water contained in said stripping stream to said condensed stream; passing a water removal column overhead stream comprising hydrocarbons and HF from said top section to said separator; removing a water removal column bottom effluent comprising water from said bottom section.