High-gravity assisted coal mine gas separation based on clathrate hydrates: Implication for methane recovery

Hydrate-based gas separation offers a promising approach for coalbed methane recovery, reaching energy conservation and emissions reduction. This study innovatively applied high-gravity technology to enhance hydrate formation in separating 25%CH 4 /67%N 2 /8% O 2 for achieving rapid and efficient methane recovery. Systematic investigations were conducted at 283.2 K and 3.0 MPa with tetrahydrofuran at a molar concentration of 5.56% and L-tryptophan at a mass concentration of 0.5% additives, first evaluating liquid flow rate effects (0–20 mL/min) on mixed hydrate kinetic performance and separation efficiency, followed by rotating speed optimization (0–1200 r·min −1 ) under the optimal liquid flow rate. The high-gravity system amplified the gas–liquid contact area by ∼1155 times through cascaded liquid supply and secondary shear effects, methane molecules entered the hydrate phase rapidly under the highest driving force with the significantly intensified mass transfer. Optimal conditions (20 mL/min, 600 r·min −1 ) yielded an exceptional initial hydrate growth rate of 58.59 mmol/(mol·h) and methane recovery of 50.76%, about 71.33 and 0.58 times higher than the static system, respectively. Gas chromatography and Raman spectrometer analyses revealed superior methane enrichment in hydrate phase at 90% gas uptake completion, with a concurrent 41.17% reduction in process duration. These findings demonstrate the efficacy of high-gravity-enhanced hydrate technology for coalbed methane separation, offering valuable insights for optimizing clean energy utilization.