METHOD OF SEPARATING C OR C HYDROCARBONS Russian patent published in 1999 - IPC

FIELD: chemical industry, more particularly, separation of mixtures of lower hydrocarbons. SUBSTANCE: in order to separate mixture of C₃ or C₄ hydrocarbons, extractive rectification is used in the presence of high-boiling polar agent. Less saturated hydrocarbons are separated from extractive agent in distillation-rectification zone where auxiliary desorption agent is present in amount of 2-35 wt %. Desorption agent is hydrocarbon and/or ether which have normal boiling temperature by 30-85 C higher than desorbable hydrocarbons. Part of desorption agent is withdrawn together with extracting agent stream followed by distillation thereof from extracting agent in additional column operating at lower pressure, preferably close to atmospheric pressure. Or part of desorption agent is withdrawn together with stream of desorbable hydrocarbons followed by separation of mixture by distillation. Desorption agent may be simultaneously withdrawn together with stream of extracting agent and with stream of desired hydrocarbons. It is preferable to recycle stream in condensed state of recoverable desorption agent into middle or lower portion or still of extractive rectification column and/or distillation- rectification zone. EFFECT: lower power consumption of hydrocarbon separation process. 9 cl, 3 dwg, 2 tbl