| 摘要 |
A relatively easily soluble hydrocarbon is separated from a hydrocarbon mixture by extractively distilling the hydrocarbon mixture in an extractive distillation apparatus composed of two stages of a unit consisting of an extractive distillation column DA or DE and a stripping column DC or DF using a polar extractive solvent, a first-stage extractive distillation column DA being operated at a higher bottom pressure than the bottom pressure of a second- stage extractive distillation column, a pre-stripping column DB being provided between the first-stage extractive distillation column DA and a first-stage stripping column DC and operated at a pressure equal to or lower than the bottom pressure of the first-stage extractive distillation column DA and equal to or higher than the bottom pressure of the second- stage extractive distillation column DE, a gas of the relatively easily soluble hydrocarbon generated in the pre-stripping column DE being directly sent to the second-stage extractive distillation column DE without going through the first-stage stripping column DC and a compressor K or pump. <IMAGE> |
