Method for removing C4 through rectification and hydrogenation coupling in cracked C5 separation process

Abstract

The invention relates to a method for removing C4 through rectification and hydrogenation coupling in a cracked C5 separation process. The method adopts C4 fraction obtained from the top of a C4 removing tower for a selective hydrogenation treatment so as to make the content of butadiene in a reflux material of the C4 removing tower greatly reduced, thus solving the self polymerization problem of butadiene inside the C4 removing tower, and providing technical guarantee for stable operation of the C4 removing tower. Compared with prior art, the method of the invention solves the tower blocking problem caused by self polymerization of butadiene inside the C4 removing tower, and also avoids bringing about adverse effects on petroleum resin production in next step due to the use of a polymerization inhibitor. Besides, a C4 hydrocarbon material removed from the C4 removing tower top has substantially reduced C5 diene content, thus creating a condition for improving the recovery rate of C5 diene.

Description

technical field [0001] The invention relates to a method for removing C4 from the by-product C5 fraction of petroleum cracking ethylene, and more specifically relates to a method for removing C4 by coupling rectification and hydrogenation in the cracking C5 separation process. Background technique [0002] In the process of petroleum cracking ethylene, by-products containing a large amount of carbon five fractions will be produced, and its output is generally about 10% to 20% of the ethylene output. The C5 fraction contains more than 30 kinds of hydrocarbon components, among which the most valuable are three diolefins: piperylene, isoprene, and cyclopentadiene. These diolefins are important chemical raw materials due to their active chemical properties. Due to differences in petroleum hydrocarbon cracking raw materials, cracking depth and separation degree, the content of diolefins in the C5 fraction will vary, but the total amount is usually between 40% and 60%. Therefore...

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Problems solved by technology

However, in the practical application of the decarburization tower, since the C4 fraction contains a large amount of butadiene, if the butadiene content in the decarburization tower exceeds its self-polymerization concentration, white polymers will be produced. The pollutants will accumulate on the surface of the metal components in the tower, causing the decarburization four towers to fail to operate normally

In order to avoid the butadiene in the carbon four cuts to produce white polymers in the fourth decarburization tower, the prior art generally adopts the following two methods to avoid the self-polymerization of butadiene in the fourth decarburization tower: 1, increase the decarburization C5 content in the C4 fraction obtained at the top of the C4 tower, to reduce the occurrence of butadiene self-polymerization, but this operation will inevitably cause the loss of C5 cuts, which will affect the recovery rate of C52 olefins; 2, to C5 Adding polymerization inhibitors in the separation device, but these polymerization inhibitors have a very adverse effect on the subsequent production of petroleum resins from the diolefins separated from the carbon five cuts. This is because the first process of petroleum resin production is cationic catalytic polymerization. After adding these polymerization inhibitors, it will lead to increased consumption of resin polymerization catalyst and instability of polymer molecular weight distribution (resin performance)

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