Method and system for catalytic cracking by using fast fluidized bed and dilute-phase conveying bed

Abstract

The invention relates to a method and system for catalytic cracking by using a fast fluidized bed and a dilute-phase conveying bed. The method comprises the following steps: preheated inferior heavy oil is introduced into a fast fluidized bed from the lower part of the fast fluidized bed to be in contact with a catalytic cracking catalyst, and a first catalytic cracking reaction is carried out from bottom to top, so that a first reaction product and a semi-spent catalyst are obtained; the obtained first reaction product and semi-spentcatalyst are introduced into the bottom of a dilute-phase conveying bed, and a second catalytic cracking reaction is carried out from bottom to top, so that a second reaction product and a spent catalyst are obtained; the obtained second reaction product are separated to obtain dry gas, liquefied gas, cracked gasoline, cracked diesel oil and cracked heavy oil; and the spent catalyst is sent to a regenerator for regeneration by coke burning, and the obtained regenerated catalyst is returned to the bottom of the fast fluidized bed as a catalytic cracking catalyst. Through catalytic cracking by the method and system provided by the invention, the yields of dry gas and coke are low, and product distribution is good.

Description

technical field [0001] The invention relates to a method and system for catalytic cracking using a fast fluidized bed and a dilute-phase transport bed. Background technique [0002] Low-carbon olefins represented by ethylene and propylene are the most basic raw materials in the chemical industry. Natural gas or light petroleum fractions are mostly used as raw materials at home and abroad, and low-carbon olefins are produced by steam cracking technology in ethylene complexes. 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. Although the steam cracking technology has been developed for decades and th...

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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

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