Method for separating catalytic dry gas in refinery by using shallow cold oil absorption method

Abstract

The invention discloses a method for separating catalytic dry gas in a refinery by using a shallow cold oil absorption method, which belongs to the technical field of separation and recovery of olefin and alkane. In order to solve the problems of large investment and high power consumption in the prior process of recovering the olefin and the alkane from the dry gas of the refinery, the inventionprovides a high-efficient method for separating the catalytic dry gas in the refinery by using the shallow cold oil absorption method. The method uses a C5 fraction as an absorbent, maintains an absorption temperature at shallow cold higher than 20 DEG C below zero, and adopts an expansion machine and a cold box to recover cold amount to significantly improve the recovery rate of the olefin and the alkane and simultaneously reduce the cycle amount and the loss amount of the absorbent so as to reduce the power consumption.

Description

technical field [0001] The invention relates to a method for separating and recovering olefins and alkanes, in particular to a method for separating and recovering olefins and alkanes from catalytic dry gas in a refinery. Background technique [0002] Catalytic dry gas in refinery comes from catalytic cracking process. Usually, the content of ethylene in the dry gas is about 12-20 mol%, the content of ethane is about 15-24 mol%, and it also contains alkenes and alkanes such as propylene, propane and butane. At present, catalytic dry gas in refineries is mainly burned as fuel, and its utilization value is low. If the olefins and alkanes in the catalytic dry gas are recovered and sent to the ethylene plant as the raw material for ethylene production, a large amount of cracked raw material oil can be saved, the cost of ethylene production can be greatly reduced, and the enterprise can obtain better economic benefits. [0003] At present, the methods for recovering ethylene fro...

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Problems solved by technology

[0011] In order to solve the problems of large investment and high energy consumption in the existing technology for recovering olefins and alkanes from refinery dry gas, the present invention proposes an efficient method for separating refinery catalytic dry gas by using shallow cold oil absorption method, the method Using C5 distillate as absorbent, keeping the absorption temperature at a shallow temperature (temperature higher than -20°C), using expander and cold box to recover cooling capacity, greatly improving the recovery rate of olefins and alkanes, and reducing the circulation of absorbents amount and loss, reducing energy consumption

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