Butadiene recovery process
An improvement is described on a process for recovery of butadiene from a C/sub 4/ hydrocarbon mixture containing minor amounts of C/sub 5/ saturated and unsaturated hydrocarbons, and being obtained as the overhead product of an initial fractionation to separate larger quantities of C/sub 5/ and heavier hydrocarbons. The hydrocarbon mixture is subject to extractive distillation in the presence of a polar solvent e.g., acetonitrile, in which butadiene is separated from the fat solvent bottoms of extractive distillation by sequential low pressure flashing and stripping, followed by compression of the combined vapors of flashing and stripping with part of the compressed vapors being recycled as reboiled vapor to the extractive distillation and the remainder being again stripped at a higher pressure to recover butadiene therefrom. Butadiene purification problems are avoided by condensing a portion of the combined and compressed vapor stream from low pressure flashing and stripping to obtain a condensed liquid stream relatively rich in C/sub 5/ hydrocarbons, which additionally contains butadiene and a small amount of polar solvent, followed by water washing of the condensed liquid stream to remove polar solvent therefrom and subsequent passing of the water-washed stream, substantially free of polar solvent, to the initial hydrocarbon fractionation employed to separate larger quantities of C/sub 5/ and heavier hydrocarbons, whereby C/sub 5/ hydrocarbons contained in the condensed liquid stream are substantially removed from the hydrocarbon mixture passed to extractive distillation. 8 claims, 1 figure.
- Assignee:
- Shell Oil Co.
- Patent Number(s):
- US 4038156
- OSTI ID:
- 7318395
- Resource Relation:
- Patent File Date: Filed date 21 Sep 1976
- Country of Publication:
- United States
- Language:
- English
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