Experimental study on the medium-pressure separation characteristics of coal seam gas hydrate

Coal seam gas (CSG) significantly contributes to global energy consumption as a conventional energy resource with an abundant and large reserve scale. Gas hydrate technology is a technique for separating and purifying methane from CSG that offers great application prospects in energy recovery development. However, its slow separation rate and low methane recovery rate limit this technique's application. Therefore, the present study explores the low-pressure separation characteristics of CSG hydrate to realize an improved CSG hydrate separation process. Herein, 5.56 mol% of tetrahydrofuran solution was used as a promoter, and various initial liquid phase saturations, initial pressure gradients, and temperatures. Furthermore, CSG hydrate was obtained in a tube-shaped reactor using two different porous media systems—zeolite 5 A and SBA-15 mesoporous zeolite. Temperature and pressure characteristics, gas consumption amount, gas consumption rate, and methane gas storage rate were analyzed during the CSG hydrate separation experiments. Results show that the proposed CSG hydrate formation reaction had the greatest promotion and separation effect when the initial liquid saturation was 37.5%. The promoting effect increased with increasing initial pressure and decreasing temperature, respectively. Moreover, the ordered porous media improved CSG separation efficiency through methane hydrate formation, with the SBA-15 mesoporous molecular sieve outperforming zeolite 5 A.