Coalseam methane recovery by vacuum swing adsorption

Coalseam methane gas recovery using pressure and vacuum swing adsorption (P SA/VSA) processes were investigated both theoretically and experimentally. CO2 is more strongly adsorbed and also diffuses faster compared to methane and nitrogen in a carbon-based adsorbent. Hence such adsorbents are suitabl e for methane recovery. Carbon molecular sieve adsorbents were employed for testing the technical feasibility of the adsorption process. Numerical sim ulations indicate that the purity of methane gas recovered can be greater t han 90%, by switching from PSA to VSA operation. The effect of process cycl e time, purge pressure and feed flow rates were investigated. Both model pr edictions and laboratory experiments show promising separation performance. This study shows that a relatively untapped source of methane from coalsea m gas can be economically recovered for industrial applications. (C) 2001 E lsevier Science B.V. All rights reserved.