Patent ID: 7557257
Filing Date: 2009-07-07
Classification: C07C

Abstract:
1. A process for fractionating a crude C 4 fraction comprising butanes, butenes, 1,3-butadiene and small amounts of other hydrocarbons including C 4 -acetylenes, 1,2-butadiene and C 5 -hydrocarbons by extractive distillation using a selective solvent, the process comprising feeding the crude C taking off a gaseous side stream from the first extractive distillation column at a point below the feed point for the crude C taking off an overhead stream comprising components of the crude C feeding the gaseous side stream to a first side column in which the gaseous side stream is separated into an overhead stream and a bottom stream, wherein the overhead stream comprises the C a part of the condensed overhead stream is returned as runback to the first side column, and returning the bottom stream which comprises the selective solvent to the first extractive distillation column.