Techno-economic evaluation of gas separation processes for long-term operation of CO₂ injected enhanced coalbed methane (ECBM)

Energy source diversification through development of coalbed methane (CBM) resources is one of the key strategies to make a country less dependent on simple energy resources (e.g., crude oil, natural gas, nuclear energy etc.). Especially, enhanced coalbed methane (ECBM) technology can be expected to secure the resources as well as environmental benefits. However, the raw CBM gas obtained from CO₂ ECBM contains a considerable amount of CO₂, and the CO₂ content increases depending on the operation time of the facility. Considering the changes of the CBM composition, we developed process simulations of the CBM separation & purification processes based on the amine absorption to meet the design specifications (CH₄ purity of product stream: 99%, CH₄ recovery rate: 99%) with different CBM feed gas conditions. Using the developed simulation model, we performed an economic evaluation using unit methane production cost (MPC) considering coal-swelling types and facility operation time, and established an operation strategy under different natural gas market scenarios.