Separation method for mixed C4

Abstract

The invention discloses a separation method for mixed C4, which comprises the following steps of separating butene and butane from mixed C4 through extractive distillation, wherein the mixed C4 contains n-butane, iso-butane, 1-butylene and 2-butylene after removal of components such as C3, butadiene, alkyne, isobutene, C5 and the like, furthermore, separating to obtain iso-butane, 1-butylene and 2-butylene and the byproduct of crude n-butane through ordinary distillation, wherein the solvent for extractive distillation is publicly known in the industry, non clear-clear separation method is adopted in extractive distillation technology, namely, the combination of preextraction distillation and extractive distillation. Due to the adoption of the separation method, after the mixed C4 is processed, products of iso-butane, 1-butene and 2-butene of high concentration can be obtained simutaneously, therefore, the separation method has the advantages of being energy-saving, good in economic efficiency, high in resource utilization rate, and the like, reducing the cost and is of great significance in comprehensive utilization of mixed C4 resource.

Description

technical field [0001] The invention belongs to the technical field of mixed C4 separation, and in particular relates to a method for separating and obtaining isobutane, 1-butene and 2-butene from mixed C4 by-products of ethylene cracking, catalytic cracking, methanol-to-olefins and other devices. Background technique [0002] With the increase of ethylene production and refining processing capacity at home and abroad, as well as the continuous expansion of the scale of coal-to-olefins units, the amount of mixed carbon four produced by these units will increase significantly. At present, most of the mixed carbon four is used as liquefied gas fuel, and a small part is used as chemical raw materials. There is a problem of low utilization efficiency of carbon four resources, which reduces its utilization value. Make full use of this part of mixed carbon four resources to improve its economy Added value has become increasingly important. [0003] Traditionally, the main process...

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Problems solved by technology

[0008] The above-mentioned patents all propose to use ordinary rectification to remove the light components of the pretreated mixed C4 to obtain isobutane, and the heavy components to obtain 1-butene. Due to the combination of butene / butane in C4 The separation boiling points are similar, and the reflux ratio, high energy consumption, and high processing cost required for separation by ordinary distillation methods reduce its economic benefits

It is difficult to effectively separate n-butane and 2-butene (including cis-butene and trans-butene) by ordinary distillation methods, and cannot obtain 2-butene products with higher added value

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