An improved catalytic cracking process

Abstract

The invention relates to an improved catalytic cracking technology method. In the method, oil gas at the top of a fractionation column in a catalytic cracking device passes through a condensation cooler to decrease the temperature to 30-60 DEG C. Rich gas being not condensed is compressed by a two-stage gas compressor, wherein the rich gas is firstly fed into a first stage of the gas compressor and is compressed under an absolute pressure of 0.02-1.0 MPa. The compressed rich gas is cooled to 30-60 DEG C and is separated in a gas-liquid separator. A separated inter-stage condensate is fed into a propylene removal column and is subjected to desorption under the absolute pressure of 1.4-1.8 MPa to remove low-carbon olefins being not more than 3 in carbon number. Oil from the bottom of the column, as recycle condensed oil, is fed into a riser for performing recycle, wherein the composition and the flow rate of the recycle condensed oil are controlled by adjusting the temperature of the oil gas at the top of the fractionation column before the oil gas being fed into the gas compressor and after the condensation cooling. By means of recycle of the inter condensed oil in the gas compressor, the content of olefin in catalytic gasoline can be reduced, the yield of the low-carbon olefin can be increased and meanwhile the energy consumption of the catalytic cracking device is effectively reduced.

Description

technical field [0001] The present invention relates to a new catalytic cracking technology integrating refining and chemical industry, more specifically, it is a new technology for improving the traditional catalytic cracking process, increasing the yield of low-carbon olefins (especially propylene), improving the quality of gasoline products, reducing the Process method of energy consumption. Background technique [0002] Since the first set of industrial units began to operate in the 1930s, as one of the core units in oil refineries, catalytic cracking technology has played a pivotal role in ensuring the supply of high-quality gasoline. However, with the increasingly stringent environmental protection standards, the quality requirements of catalytic gasoline products, which are the main components of finished gasoline, are getting higher and higher, especially the requirements for olefin content are getting lower and lower. [0003] At the same time, as an important basi...

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Problems solved by technology

Patents CN1279270, CA2186744, CN1237477, CN1031834, US4980053, CN1069054, US6569316 and CN101074392A respectively describe a variety of light hydrocarbons such as C4-C8 using conventional catalytic cracking unit riser reactors to increase light olefins (especially propylene) However, most of these technologies have the problem of high energy consumption of the device, which restricts their wide-scale application

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