Technical method for recovering ethylene from ethylene containing mixed gas

Abstract

The invention provides a technical method for separating ethylene from ethylene containing mixed gas. The technical method comprises a gas pretreatment process, an absorption process, a desorption process and an ethylene refining process, wherein a novel absorbing agent of trimethylbenzene is adopted, the heat integration methods such as a desorption tower, a middle reboiler, refrigeration of poor ethylene current by pressure recovery turbine and refrigeration recovery are adopted, so that the recovery and the purity of the ethylene can reach more than 99 percent and 91 percent respectively. The technical method can lower power consumption of compression of a system as well as consumption of throttling and low-temperature cooling capacity. Compared with the common ethylene high-pressure cryogenic separation process, the technical method of the invention is easier and is suitably used for recovering and enriching the ethylene from the ethylene containing mixing gas such as refinery dry gas, and the like.

Description

technical field [0001] The invention proposes a process for recovering ethylene from ethylene-containing mixed gas. It is suitable for ethylene recovery and enrichment of dry gas or other ethylene-containing mixed gas produced by catalytic cracking in refineries. Background technique [0002] Ethylene and propylene are important organic chemical raw materials. Conventional ethylene high-pressure cryogenic separation process is not only complex, but also high energy consumption. The lack of suitable absorbents is an obstacle for the use of solvent absorption methods for the separation of ethylene. U.S. Patent No. 6,518,476 proposes the use of silver nitrate complexation method to absorb and separate ethylene in the reaction product gas of natural gas oxidative coupling method. Under the condition of a high pressure of about 5.86MPa, the process consists of a complex absorption / desorption process consisting of 7 compressors and 3 flash tanks with high energy consumption. U...

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Problems solved by technology

This patent solves the heat integration of the system including absorption, analysis, and waste heat recovery process of adjacent processes to reduce energy consumption, but the system directly vents the alkanes (olefin-depleted gas stream) at the top of the absorption tower when the olefins are separated, so it leaves the absorption tower The residual pressure of the olefin-depleted gas stream at the top of the tower has not been further utilized, and the energy utilization of the system needs to be further optimized, and the process does not include further separation of olefins, refining ethylene

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