Process system and process method for increasing yield of p-xylene

Abstract

The process system for increasing the yield of p-xylene comprises a xylene fractionation unit, a p-xylene purification unit, an isomerization reaction unit, a disproportionation and transalkylation unit and an alkylation unit. The xylene fractionation unit comprises a xylene tower and a heavy aromatics tower, the p-xylene purification unit comprises a crystallization separation unit and a membrane separator, and the isomerization reaction unit comprises an isomerization reactor and a heptane removal tower connected with the isomerization reactor. The disproportionation and transalkylation unit comprises a disproportionation and transalkylation reactor, a hydrogenation reactor and a hydrogenation reaction product separation tower which are connected in sequence, and the alkylation unit comprises a separation tower and an alkylation reactor. According to the invention, the conversion rate of toluene is improved, the conversion of the product benzene to p-xylene is fully utilized, and the purpose of separating reactants and reaction products in one tower is realized by adopting a divided wall tower technology, so that the energy consumption of the device is reduced, the removal efficiency of unsaturated hydrocarbons such as olefin and carbonyl in disproportionation and transalkylation reaction products is improved, and the production cost is reduced. The pollution of the waste carclazyte to the environment is avoided, the yield of the high value-added product p-xylene is improved, and the economic benefit and the social benefit are improved.

Description

technical field [0001] The present invention relates to the production technology of p-xylene, in particular to the production of C 8 + The invention discloses a process system and a process method for increasing the production of p-xylene by using mixed aromatic hydrocarbons as raw materials. Background technique [0002] Paraxylene is one of the important basic organic raw materials in the petrochemical industry. It is mainly used to prepare terephthalic acid (PTA) and dimethyl terephthalate (DMT). It is widely used in chemical fibers, synthetic resins, pesticides, pharmaceuticals , plastics and other production fields. According to statistics, in 2019, the production capacity of PX in my country increased significantly by 11.9 million tons, and the total production capacity reached 25.03 million tons, with a production capacity growth rate of 70.4%, which is the highest growth rate of PX production capacity in recent years. [0003] C 8 Aromatic hydrocarbons include f...

AI Technical Summary

Problems solved by technology

[0006] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a process system and process method for increasing the production of p-xylene, improve the selectivity of p-xylene, make full use of the product benzene and toluene to convert p-xylene, and adopt a dividing wall tower technology to achieve the purpose of separating reactants and reaction products in one tower, and adopt a combined process to increase the yield of high value-added product p-xylene, thereby reducing the energy consumption of the device, and at the same time improving the disproportionation and transalkylation reaction products of olefins, etc. The removal efficiency of impurities solves the problems of waste white clay polluting the environment and frequent replacement

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