An olefin catalytic cracking system and method for improving the total conversion rate of olefins

Abstract

The invention discloses an alkene catalysis cracking system and a method for improving alkene total conversion rate. The system comprises a charging gasification unit, a reaction unit, a compression unit and a separation unit; the charging gasification unit comprises a charging buffer tank and a raw material evaporator; the reaction unit comprises a charging / discharging heat exchanger, a charging heater and a reactor; the compression unit comprises a compressor; and the separation unit comprises a depropanization tower and a debutylization tower, the middle-upper part of the sidewall of the debutylization tower is provided with an outlet pipeline, and the outlet pipeline is combined with the inlet of the raw material evaporator or an outlet pipeline and then connected with the charging / discharging heat exchanger. The method comprises that distillates containing C4 and C5 alkene obtained by performing side withdrawing at the middle-upper part of the debutylization tower are taken as a recycle material of the system. The system and the method help to improve the utilization rate of C4 and C5 alkene in the raw materials, and no equipment is additionally added.

Description

technical field [0001] The invention relates to the technical field of olefin catalytic cracking to produce propylene and ethylene product gas separation, and furthermore, relates to an olefin catalytic cracking system and method for improving the total conversion rate of olefins. Background technique [0002] Olefin catalytic cracking technology uses the mixed carbon four and carbon five by-products of ethylene plant, MTO plant or FCC plant as raw materials, and in the presence of molecular sieve catalysts, catalytically cracks the olefins contained in the raw material to obtain light molecular olefins propylene and ethylene. way. [0003] The typical process of this technology is as follows figure 1 shown. Freshly mixed carbon 4 and carbon 5 (F-1) is heated and vaporized in the raw material evaporator 2, mixed with the gas phase distillate F-8 from the top of the debutanizer tower (as a recycled C4 feed) and sent to the reaction The product enters and exits the heat exc...

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Problems solved by technology

[0004] This typical process has a low utilization rate of olefins in the raw material. There are two reasons: 1. This process uses the gas phase at the top of the debutanizer tower as the circulating material, and no measures have been taken to utilize the relatively higher boiling point of C4 olefins than C4 alkanes. The characteristics of enriching carbon tetraolefins, that is, the concentration of olefins in the recycled material is low, even lower than the concentration of olefins in the by-product crude butane, so there are more olefins that have not been converted and utilized

2. In order to ensure the quality of the by-product crude butane (that is, to meet the C5 content index), only C4 in the gaseous phase at the top of the debutanizer is used as a recycling material, resulting in C5 olefins that cannot be recycled, further reducing olefins in raw materials, especially C5 Olefin Utilization

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