Novel ethane recovery process from natural gas using ZIF-8/water-glycol slurry: Techno-economic and energy consumption evaluation

Ethane recovery is a vital step in natural gas processing and can provide raw material for ethylene production. The widely used cryogenic separation process is energy intensive, and the absorption-adsorption coupling process based on porous ZIF-8 slurry (SorbPro I) has been proven to be more energy-efficient. To further reduce energy consumption, this paper proposes a novel process with two absorption-adsorption columns (SorbPro II) and establishes its mathematical model by equilibrium stage method. Taking the natural gas with an ethane content of 6.19 mol% at 300,000 Nm3/d as a case study, the operating parameters of SorbPro I and SorbPro II are optimized by sensitivity analysis, and ethane recovery ratio of both processes can reach 90 %. The technoeconomic/energy consumption evaluations of the two processes are conducted. Results show that the total annualized cost and the energy consumption per Nm3 feed gas of SorbPro II are 41.7 % and 47.7 % lower than those of SorbPro I, respectively. It indicates that SorbPro II has the same separation performance as SorbPro I, but is more economical.