Catalytic cracking method and its apparatus

Abstract

The invention discloses a catalytic cracking method and its apparatus, which belongs to the petrochemical technical field. The process of catalytic cracking is carried out in a reactor which is at least provided with a first reaction zone, a conveyer pipe and a second reaction zone, a regenerated catalyst from a regenerator is contacted and reacted with raw oil in the first reaction zone of the reactor, a reaction mixture is flowed upwards and separated to a catalyst through a diverter, the separated catalyst directly flows into a stripping stage, the reaction oil gas flows upwards along the conveyer pipe and is introduced in the second reaction zone of the reactor, a part of cooling regenerated catalyst is introduced in a catalyst additional area, and then introduced in the second reaction zone from the catalyst additional area, mixed with reaction oil gas from the first reaction zone, thereby oil gas is continuously reacted, the separated oil gas after finishing the reaction is conveyed to a subsequent fractionation system, the catalyst flows into the stripping stage, combined with the separated catalyst through the diverter in the first reaction zone, stripped and then introduced in the regenerator for regeneration. The catalytic cracking method and its apparatus reinforce the selectivity of the catalytic reaction in the reactor, and the investment can be reduced by sharing stripping.

Description

Technical field [0001] The invention relates to the technical field of petrochemical industry, in particular to a method and device for the catalytic cracking of petroleum hydrocarbon feedstocks. Background technique [0002] The catalytic cracking unit is the most important gasoline production unit. Most of the world's automotive gasoline comes from catalytic cracking units, and conventional catalytic cracking uses riser reactors. [0003] The biggest drawback 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 been sharp. Decrease, the catalytic effect becomes worse, the thermal cracking reaction and other unfavorable secondary reactions increase, which not only limits the improvement of the single-pass conversion rate, but also causes the olefin content of catalytic gasoline to reac...

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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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