Catalytic cracking method and system for producing propylene and light aromatic hydrocarbons

Abstract

The invention relates to a catalytic cracking method and system for producing propylene and light aromatic hydrocarbons. The method comprises the following steps that light raw material oil is introduced into adilute phase conveying bed from the lower part of the dilute phase conveying bed to be contacted with a first catalytic cracking catalyst and to be subjected to first catalytic cracking reaction from bottom to top to obtain a first reaction product and a semi-spent catalyst; the obtained first reaction product and the semi-spent catalyst are fed into a dense-phase fluidized bed to continue to be subjected to a second catalytic cracking reaction to obtain a second reaction product and a first spent catalyst; and preheated inferior heavy oil is introduced into a fast fluidized bed fromthe lower part of the fast fluidized bed to be contacted with a second catalytic cracking catalyst and to be subjected to a third catalytic cracking reaction from bottom to top to obtain a third reaction product and a second spent catalyst. By virtue of the catalytic crackingmethod and system, the yield of propylene and light aromatic hydrocarbons is high, and the yield of coke and dry gas is low.

Description

technical field [0001] The invention relates to a catalytic cracking method and system for producing propylene and light aromatic hydrocarbons. Background technique [0002] Propylene is an important organic chemical raw material. In 2016, the equivalent consumption of propylene in my country was 33.8 million tons, and the equivalent self-sufficiency rate was 75.2%. It is estimated that by 2020, the equivalent consumption of propylene in my country will reach 39 million tons, and there is still a certain space for its production capacity gap. Benzene, toluene and xylene (BTX) are important basic chemical raw materials, among which p-xylene (PX) accounts for about 45% of the total consumption of BTX. With the development of my country's polyester and other industries, it is expected that the demand for BTX will continue to grow at a high speed. About 90% of ethylene, about 70% of propylene, 90% of butadiene, and 30% of aromatics come from steam cracking by-products. Althou...

AI Technical Summary

Problems solved by technology

The reduction of coke yield can be achieved when the down-flow reactor is used, but the reaction conversion rate is relatively low, and a special catalyst is required

Images