Method and system for extracting and separating CO2-C2H6 azeotrope from associated gas

Abstract

The invention discloses a method and a system for extracting and separating a CO2-C2H6 azeotrope from associated gas containing CO2. The separating method comprises the following steps: I, pretreatingthe associated gas; II, removing methane from the associated gas pretreated in the step I in a demethanizer; III, introducing a mixture flowing out of the bottom of the demethanizer into an extractive distillation column to obtain a high-purity carbon dioxide from the top of the extractive distillation column and a mixture of ethane and a C3+hydrocarbon substance outflowing from the bottom of theextractive distillation column; IV, making the mixture of the ethane and the C3+hydrocarbon substance pass through a dethanizer to obtain ethane from the top of the dethanizer. In an extractive distillation process, an extracting agent is a subsequent product in a flow, and is a homologous compound of the ethane. Dual recovery of the carbon dioxide and an ethane product is realized according to the similar dissolve mutually theory without introduction of foreign impurities. Moreover, an extracting agent separation flow does not need to be designed, and the energy consumption is lowered.

Description

technical field [0001] The invention relates to the technical field of separation of carbon dioxide in associated gas, in particular to the separation of CO in associated gas 2 -C 2 h 6 Azeotrope extraction and separation method and system. Background technique [0002] In today's environment where fossil energy is increasingly depleted and the ecological environment is deteriorating, people's demand for energy in production and life is increasing rapidly, and the contradiction between supply and demand is becoming more and more prominent. For oil field extraction, CO 2 As the third oil recovery technology, oil flooding can not only enhance oil recovery (Enhanced Oil Recovery, referred to as EOR), but also realize CO 2 The effective storage has shown good economic and environmental benefits, and has achieved good recovery results in Shengli Oilfield, Jilin Oilfield, Zhongyuan Oilfield and other oilfields. But the ensuing problem is that the CO in oilfield associated gas...

AI Technical Summary

Problems solved by technology

[0003] When the low-temperature cryogenic process is used for the recovery of associated gas light hydrocarbons, due to the low refrigeration temperature, there is CO in the top of the demethanizer. 2 Freeze plugging and the presence of CO in the deethanizer 2 -C 2 h 6 The phenomenon of azeotrope formation leads to the problem that the ethane product cannot meet the purity requirements and the recovery rate of ethane is low

And with the associated gas CO 2 The problem becomes more serious as the content of

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