Deep cooling and film coupled ethylene cyclic refrigeration system non-condensed effluent gas separating and recycling technology

Abstract

The invention provides a deep cooling and film coupled ethylene cyclic refrigeration system non-condensed effluent gas separating and recycling technology, and belongs to the technical field of petrochemical engineering. According to the technology, starting from the characteristics of an ethylene cyclic refrigeration system, deep cooling conditions formed through ethylene throttling expansion areutilized for conducting liquidation and rectification on non-condensed effluent gas, most of ethylene is recycled in the form of the liquid state, then, a gas film is used for separating and enriching ethylene left in deep cooling tail gas, and low-pressure ethylene-rich gas obtained on the permeation side returns to a compressor of the ethylene cyclic refrigeration system. Deep cooling and filmseparation coupling is adopted for treating the non-condensed effluent gas, and ethylene losses are obviously reduced while oxygen and nitrogen accumulation is avoided. Taking a butyl rubber device of60,000 tons / year as an example, by adoption of the provided efficient non-condensed effluent gas separating and recycling technology, the ethylene content of the tail gas exhausted towards a torch islower than 5.0 vol%, the ethylene recycling rate reaches 99%, about 210 tons of ethylene can be recycled every year, and the annual economic benefits exceed 2 million yuan.

Description

technical field [0001] The invention relates to a process for separating and recovering non-condensable exhaust gas from an ethylene circulation refrigeration system coupled with cryogenic and membrane, and belongs to the technical field of petrochemical industry. The process first uses the cryogenic conditions formed by ethylene throttling and expansion to liquefy and rectify the non-condensable exhaust gas, recover most of the ethylene in liquid form, and then separate and enrich the residual ethylene in the cryogenic tail gas through gas membrane separation and enrichment. On the permeation side The obtained low-pressure ethylene-rich gas is returned to the compressor of the ethylene cycle refrigeration system. The non-condensable exhaust gas is treated through the coupling of cryogenic and membrane separation, which significantly reduces the loss of ethylene while avoiding the accumulation of oxygen and nitrogen. Background technique [0002] Ethylene is an important ba...

AI Technical Summary

Problems solved by technology

Simple cryogenic separation mainly has the following limitations: the impact of cryogenic temperature fluctuations is large, when the cryogenic temperature is not low enough, the recovery effect is not obvious, and when the cryogenic temperature is too low, total condensation is prone to occur, which is not conducive to non-condensable gas emissions

Simple gas membrane separation is also limited: the ethylene concentration in the non-condensable exhaust gas is as high as 97%, the enrichment effect of membrane separation is not obvious, and there is also obvious accumulation of non-condensable gas

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