ISOMERIZATION WITH DISTILLATION AND PSA RECYCLE STREAMS

摘要

An isomerization zone process is disclosed that combines a deisohexanizer with a PSA separation section to provide a product stream comprising methylbutane and dimethylbutane. The process combines a methylpentane and normal hexane recycle stream, a normal pentane recycle stream and a fresh feedstream to provide a combined feedstream that is charged to an isomerization zone. The effluent from the isomerization zone is stabilized and passed to a deisohexanizer. A sidecut stream carries the methylpentane and normal hexane recycle stream from the deisohexanizer. Hydrocarbons having a higher boiling point than the sidecut stream are withdrawn as a bottoms stream from the deisohexanizer. An overhead carries normal pentane, methylbutane and dimethylbutanes to the PSA separation section. An extract stream is recovered as the normal pentane recycle stream. The raffinate from the PSA provides a high octane isomerate stream comprising mainly methylpentane and dimethylbutanes.