Catalytic cracking method and apparatus

Abstract

The invention discloses a catalytic cracking method and an apparatus and belongs to the technical field of petrochemical processing. The catalytic cracking is carried out in a main reactor and a minor reactor. A regeneration catalyst of a first regenerator contacts and reacts with raw oil in a first reaction zone of the main reactor, and a reacted mixture goes upwards and is separated by a diverter into a catalyst; the separated catalyst directly flows into a first stripping stage, is treated with stripping and returns to the first regenerator for regeneration. Reacted oil goes up wards along a conveyer pipe and enters a second reaction zone. A spent catalyst in the minor reactor first enters a catalyst additional area, then enters the second reaction zone through the catalyst additional area and is mixed with the reacted oil gas from the first reaction zone, so that the oil gas continues to react; and the catalyst enters into a second regenerator for regeneration after the reaction. According to the invention, catalyst displacement is realized in the second reaction zone to reinforce catalytic selectivity of the main reactor; the first regenerator and the second regenerator control different regeneration conditions to reduce side reactions; and a connected design of the apparatus reduces investment.

Description

technical field [0001] The invention relates to the field of petrochemical technology, in particular to a method and device for catalytic cracking of petroleum hydrocarbon raw materials. Background technique [0002] Catalytic cracking unit is the most important gasoline production unit. The vast majority of motor gasoline in the world comes from catalytic cracking unit. Conventional catalytic cracking uses riser reactor. [0003] The biggest disadvantage of the existing riser reactor is that the riser is too long, and the catalyst activity at the outlet of the riser is only about 1 / 3 of the initial activity. Therefore, in the second half of the riser reactor, the catalyst activity and selectivity have sharply increased Decrease, catalytic effect worsens, thermal cracking reaction and other unfavorable secondary reactions increase, which not only limits the improvement of single-pass conversion rate, but also causes the olefin content of catalytic gasoline to be as high as 4...

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Problems solved by technology

However, in this technology, the catalyst separated from the first zone must be stripped before entering the regenerator. At the same time, the regenerated catalyst must be transported by the conveying medium before entering the second stage. The stripping steam and conveying medium will all enter the second stage, which will inevitably affect The reaction to the second stage; if the amount of stripping steam is limited, the stripping effect will be affected, and then the regeneration process will be affected; and this technology requires two settlers and two stripping sections, which greatly increases the investment

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