| 摘要 |
Described is a process for producing methane-rich, pipeline-quality gas from raw gas produced by gasifying carbonaceous materials. Following any needed adjustment of its H2/CO ratio, which can be by a preconditioning water gas shift reaction or its reverse, the raw gas is fed to a direct methanation reaction (2H2 + 2CO-><- CH4 + CO2) which does not require substantial addition of steam. If needed, the intermediate product gas from the direct methanation reaction can be passed over a water gas shift catalyst to control its H2/CO ratio so that after removal of acid gases its methane content can be raised further over a nickel catalyst. This enables production of a very high heating value pipeline gas with only one acid gas removal step in the entire process sequence. In the alternative, the intermediate product gas can be subjected to cryogenic methane separation, with the separated H2 and CO fed back to the direct methanation and the separated methane used as SLNG. A preliminary direct methanation step can be carried out prior to any needed preconditioning step. |
