Method for separating butane and butylenes, and dedicated installation

This invention discloses method and apparatus for separating butane and butylene. The method comprises: (1) pretreating the raw materials; (2) extraction-rectifying the heavy fractions separated from step 1; (3) extraction-rectifying the light-heavy fractions separated from step 1; (4) separating the heavy fractions and the extractant in a degasification column. The apparatus comprises a raw material pretreatment rectification column, a heavy fraction extraction rectification column, a light-heavy fraction extraction rectification column, and a degasification column. The method can effectively increase the yields and purities of the fractions separated from C4 raw materials, lower the consumption of the extractant, and effectively reduce the foaming in the extraction rectification columns. Besides, the operation is stable. When used to separate butane and butylene from C4 raw materials in oil refinery plant, the method can realize high yield and purity of butylene product, low consumption ...