Method for separating isoprene by combined rectification

Abstract

The invention relates to a combined isoprene rectification and separation method, mainly aimed at solving the problems in prior art that when to separate and crack the diolefin in c_5 fraction, the raw materials have to enter a thermal dimerization reactor first, resulting in great losses of isoprene and cyclopentadienyl, and that because the boiling points of isoprene and cyclopentadienyl are nearly the same, the cyclopentadienyl affects the purity of the product isoprene and a part of cyclopentadienyl is lost, and particularly the problem that the isoprene knockout tower has high temperature and is energy-consuming. The invention makes the c_5 materials enter the isoprene knockout tower2 from the middle; after separation, material flow I containing isoprene comes out from the top of the tower and the material flow II containing cyclopentadienyl comes out from the bottom of the tower for later processing. Then the material flow I enters the cyclopentadienyl recycling tower from the middle part, after separation the material flow III coming out from the top of the cyclopentadienyl recycling tower enters the follow-up isoprene refining process and the cyclopentadienyl material flow coming out from the bottom of the cyclopentadienyl recycling tower circulates to the middle part of the isoprene knockout tower2. With such technique proposal, the invention solves the problems, thus the invention can be applied to the industrial production of separating the diolefin in c_5 fraction.

Description

technical field [0001] The invention relates to a method for separating isoprene by combined rectification. Background technique [0002] In the process of producing ethylene from petroleum cracking, a considerable amount of C5 fraction is produced by-product, and the C5 fraction is rich in dienes such as isoprene, piperylene and cyclopentadiene. These diolefins are chemically active and are important chemical raw materials. Due to the differences in raw materials, cracking depth and separation degree of petroleum hydrocarbon cracking, the content of diolefins in the C5 fraction is different, but the total amount is between 40% and 60%. Therefore, the separation and utilization of C5 fractions has far-reaching significance for improving the economic benefits of ethylene plants and comprehensively utilizing petroleum resources. [0003] The cracked C5 distillate is composed of more than 20 components with similar boiling points and easy to form azeotropes with each other. I...

AI Technical Summary

Problems solved by technology

This method can reduce the difficulty of separating isoprene and cyclopentadiene to a certain extent, but there is a disadvantage: all isoprene must pass through the thermal dimerization reactor

Both research and practical operation have shown that isoprene has high activity. In the thermal dimerization reactor, about 2-10% of isoprene self-polymerizes or copolymerizes with cyclopentadiene, which not only causes isoprene The loss of dicyclopentadiene also affects the purity of dicyclopentadiene to a large extent, reducing the use value of dicyclopentadiene

In addition, although a large amount of cyclopentadiene is separated by generating dicyclopentadiene, since the boiling points of isoprene and cyclopentadiene are similar, the separation energy consumption is large, and there are still a considerable amount of cyclopentadiene and isoprene Dienes enter the subsequent extraction, rectification and refining process together, which affects the purity of the product isoprene and causes the loss of cyclopentadiene

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