A device and method for recovering C2 in refinery dry gas

Abstract

The invention discloses a device of recycling C2 from refinery dry gas, which includes a PSA unit, a compression unit and an oil absorption unit. The PSA unit includes a first-section PSA device. The compression unit includes a compressor and a liquid separation pot. An inlet of the first-section PSA device is communicated with the raw material dry gas and an outlet of the first-section PSA device is communicated with the inlet of the compressor. The outlet of the compressor is communicated with the inlet of the liquid separation pot. The invention is advantaged in that firstly the raw material dry gas is subjected to primary concentration in the first-section PSA device being low in energy consumption, and then the PSA concentrated gas is further concentrated through an adsorption / desorption method being high in recycle rate and product purity, wherein the temperature of fed gas material, an absorbent and top reflux are all 40 DEG C in the absorption unit. By means of circulated cooling water, the cooling condensation temperature can be achieved without any refrigerating device. By means of the compressed condensate as the absorbent, it is unnecessary to feed a C4 absorbent from other apparatus. The invention also discloses a method of recycling C2 from the refinery dry gas.

Description

technical field [0001] The present invention relates to a device and method for recovering C2 in refinery dry gas. Specifically, it relates to C2 and C2+ components in refinery dry gas. The oil absorption method further removes methane, hydrogen, nitrogen, oxygen and other light components in the enriched gas, and the finally obtained product is used as a raw material for ethylene production, and belongs to the technical field of tail gas recovery in petroleum refineries. Background technique [0002] At present, the methods for recovering C2 from dry gas in refineries mainly include two-stage PSA method and shallow cooling oil method. [0003] The two-stage PSA method has two stages of PSA, the first stage of PSA is the main adsorption unit, and the PSA enriched gas is used as the replacement gas to further replace the adsorbent bed after the adsorption step, so as to reduce the residual methane in the bed, etc. The concentration of non-ideal components is used to achieve ...

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Problems solved by technology

[0005] The two-stage PSA method has the advantages of low energy consumption and low operating pressure, but it also has the disadvantages of low recovery rate and low product gas purity. The C2 recovery rate is about 84% to 88%, and the methane content in the product gas is about About 10% (V)

[0006] The shallow cooling oil method has the advantages of high recovery rate (90% to 93%) and high purity of product gas (methane content in product gas is less than 5% (V)), but at the same time it has high energy consumption, high operating pressure, and lithium bromide needs to be installed. Refrigeration unit needs to introduce C4 absorbent from external devices and has a large degree of correlation with other devices

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