Method for recovering light hydrocarbon in refinery dry gas

Abstract

The invention provides a method for recovering light hydrocarbon in refinery dry gas. The method comprises the following steps: compressing, desulfurizing, decarbonizing, recompressing and cooling refinery saturated dry gas, and recovering light hydrocarbon in the refinery dry gas by adopting a combined sequential absorption process consisting of three-tower absorption and six-tower process flow. According to the invention, three absorbents are used, and absorption is carried out in sequence, wherein the first absorbent is used for absorbing C2+ components in refinery dry gas; the second absorbent is used for absorbing the first absorbent entrained in dry gas at the top of a first absorption tower; and the third absorbent is used for absorbing the second absorbent entrained in the dry gas from the top of a second absorption tower. According to the invention, while the recovery rate of light hydrocarbons (ethane and propane) in the refinery dry gas is increased, the problems of high energy consumption, large investment, insufficiently-dried dry gas and the like in existing light hydrocarbon recovery process for refinery dry gas can be effectively solved; and the content of heavy components in the recovered ethane-rich gas is low (wherein C4+ is not greater than 1.5 mol%), and the ethane-rich gas is suitable for being directly used as a raw material of a gas cracking furnace of an ethylene cracking device.

Description

technical field [0001] The invention relates to the recovery of light hydrocarbons in refinery dry gas, in particular to a method for recovering light hydrocarbons in refinery dry gas. Background technique [0002] Refinery dry gas mainly comes from the primary and secondary processing of crude oil, such as the by-product gas in the process of atmospheric and vacuum distillation, hydrocracking, catalytic reforming, disproportionation, etc., and the tail gas in the PSA unit. Refinery dry gas contains hydrogen, methane and ethane, propane, carbon four and other light hydrocarbon components. At present, the dry gas of most domestic refineries is mostly directly used as fuel for heating furnaces, resulting in a serious waste of light hydrocarbon resources. Ethane and propane can be used as raw materials for ethylene cracking units to produce ethylene and propylene, which can effectively reduce the cost of raw materials for ethylene cracking units and improve the economic benefi...

AI Technical Summary

Problems solved by technology

[0007] To sum up, the current refinery dry gas recovery method is mainly to separate and recover C2 and C3 from the saturated dry gas of the refinery, which has high energy consumption, large investment, low recovery rate of C2 and C3 and dry gas "not dry" ( It is generally required that the entrainment amount of components above C3 and above is not greater than 0.5mol%) and other issues

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