| 摘要 |
A process for separating butadiene from mixtures of butadiene and C4 unsaturates in an extractive distillation of the mixture in the presence of a polar solvent and recovering the butadiene from the fat solvent mixture is disclosed. The butadiene-containing hydrocarbon mixture is introduced to the intermediate portion of an extractive distillation zone wherein it is contacted with the polar solvent which flows downwardly in the zone. In this manner butadiene is recovered in the fat solvent from the bottom of the extractive distillation zone. This fat solvent is introduced to a flash zone, operated at a pressure lower than that of the extractive distillation zone wherein a major portion of the butadiene is vaporized. The remaining solvent, partially depleted in butadiene, is then transferred to a first stripping zone operated at a pressure lower than the extractive distillation zone where the remaining butadiene is stripped from the solvent. The butadiene rich vapor from this first stripping zone is then combined with the vapor obtained in the flash zone and the resulting mixture is compressed. A portion of the compressed vapor is returned to the bottom portion of the extractive distillation zone and butadiene is recovered from the remaining portion of the compressed vapor in a second stripping zone.
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