Method for separating mixture of catalytic cracking rich gas and methanol-to-olefin reaction product

Abstract

The invention relates to a method for separating a mixture of catalytic cracking rich gas and a methanol-to-olefin reaction product. According to the method, a catalytic cracking unit, an absorption stabilization unit, a gas fractionation unit and a set of methanol-to-olefin device are provided; the device comprises a reaction unit, a compression unit and a separation hot region; the methanol-to-olefin reaction product is compressed and separated through a pre-depropanizing tower, C4 is non-clearly cut, C1-C4 at the top of the tower are mixed with the catalytic cracking rich gas to obtain a mixture, and the mixture is separated by virtue of the absorption stabilization unit and the gas fractionation unit; residual liquid is separated through the separation hot region to form C4 products, C4-C6 cyclic hydrocarbons and gasoline; all or part of C4 products (containing catalytic cracking byproducts C4) of the gas fractionation unit return to a methanol-to-olefin reaction unit. Compared with the prior art, the method is used for a catalytic cracking and methanol-to-olefin combined device, a separation cold region and a refrigeration unit of a conventional methanol-to-olefin device can be omitted, the treating capacity of a catalytic cracking device is increased to the maximum extent, the economy of the catalytic cracking byproducts C4 is improved through circular cracking, and the operating energy consumption of the methanol-to-olefin device is reduced.

Description

technical field [0001] The invention belongs to the technical field of light hydrocarbon separation, and relates to a catalytic cracking and methanol-to-olefin combined device, in particular to the separation of catalytic cracking rich gas and methanol-to-olefin reaction product mixture. Background technique [0002] Methanol to olefins technology is to convert methanol into low-carbon hydrocarbons under the action of catalysts, including fluidized bed technology and fixed bed technology: fluidized bed technology, DMTO technology of Dahua Institute, MTO technology of UOP company and Sinopec Represented by SMTO technology, etc., the main products of fluidized bed methanol to olefins technology are ethylene and propylene products, and by-product fuel gas and C4+ products. The fluidized bed removes heat quickly, uses steam as the dilution gas, and does not need to recycle hydrocarbons back to the reactor. Fixed bed technologies include Lurgi's MTP technology, Wison's WMTO tech...

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Problems solved by technology

However, this method does not take into account that the proportion of C4-C6 circulating hydrocarbons contained in the methanol-to-olefins reaction product is larger than that of catalytic cracking rich gas. If all the methanol-to-olefins reaction products are directly sent to the catalytic cracking rich gas compression and absorption stabilization system for separation, The operating conditions will be greatly changed from the original design value, the degree of equipment transformation will be relatively large, and the investment required for transformation will be relatively high

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