Method for saving energy and producing more propylene in absorption-stabilization system by catalytic cracking

Abstract

The invention relates to a method for saving energy and producing more propylene in an absorption-stabilization system by catalytic cracking. A liquid phase of a vapor-liquid equilibrium tank exchanges heat with stable gasoline on the bottom of a desorber T305 through a heat exchanger E301, exchanges heat with stable gasoline on the bottom of a stabilization tower T304 through a heat exchanger E302, and then enters a desorber T302; deethanized gasoline on the bottom of the desorber T302 exchanges heat with the stable gasoline on the bottom of a stabilization tower T304 through a heat exchanger E305, and then enters the stabilization tower T304; the stable gasoline on the bottom of the stabilization tower T304 is cooled by the heat exchanger E305 and the heat exchanger E302, a part of the stable gasoline enters a reaction-regeneration system for recycling, the rest stable gasoline is cooled by a heat exchanger E303, and a part of the rest stable gasoline enters an absorption tower T301; and the stable gasoline on the bottom of the desorber T305 is subjected to two-stage cooling of the heat exchanger E301 and a heat exchanger E304, serves as a stable gasoline product and is discharged from the device. The thermal load is reduced by 15.8 to 17.7 percent; and the alkene content in the stable gasoline product is reduced by 34.3 percent.

Description

technical field [0001] The invention relates to a method for saving energy and producing more propylene in a catalytic cracking absorption stabilization system. Background technique [0002] The catalytic cracking unit is one of the main refining units. It is an important device for lightening heavy oil and producing liquefied gas, gasoline and diesel. The absorption stabilization device is a post-processing system in the catalytic cracking unit, which separates the crude gasoline and rich gas from the top of the catalytic fractionation tower into product liquefied gas and stable gasoline, and at the same time obtains dry gas as a by-product. In recent years, with the acceleration of gasoline quality upgrading, it is necessary to cut gasoline into two fractions, light and heavy, so that the heavy fraction can be hydrodesulfurized separately, and the light fraction can be separately refined and converted to achieve the purpose of reducing olefins and producing more propylene...

AI Technical Summary

Problems solved by technology

The single-tower process mainly has the following disadvantages: the absorption and desorption processes are carried out in the same tower, and the mutual interference is relatively large; it is difficult to achieve a high absorption rate and desorption rate; it is difficult to control and adjust the device

[0006] The double-tower process overcomes the shortcomings of the above-mentioned single-tower process to a certain extent, but there are generally problems in the following aspects: (1) Excessive desorption of the desorption tower leads to a large amount of C3 and C4 components in the absorption tower and desorption tower cycle, increasing the energy consumption of the process

(2) Only raw crude gasoline and rich gas are separated into dry gas, liquefied gas, and stable gasoline products, making it difficult to adjust the olefin content in stable gasoline products

(3) The absorption effect of the absorption tower is not ideal, and the dry gas contains a large amount of liquefied gas components, resulting in the loss of liquefied gas

(4) The separation capacity of the stabilization tower is not enough, the high content of carbon five components in the liquefied gas makes the quality unqualified, and the gasoline yield decreases

(5) The content of C4 in stable gasoline products is high, resulting in unqualified gasoline vapor pressure

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