| 摘要 |
<p>In the catalytic methanation of synthesis gas (essentially H2 + carbon oxides), the exotherm is moderated by adding recycled CO2 to the reactor feed. The CO2 is removed from the prod. in a physical or chemical scrubber, which may also remove S cpds. The required CO2 may be generated in the methanator by adding H2O to a CO-rich synthesis gas feed. The reactor may be isothermal or adiabatic. The concn. of CO2 required for reaction damping is less than the concn. of other diluents (H2O or prod. gases) in existing processes, leading to a smaller and cheaper reactor. In comparison with H2O as diluent, CO2 gives a reduced risk of soot formation and an increased yield of h.p. steam by heat exchange from the exit gases. S scrubbing after the reactor (requiring a S-resistant catalyst) is advantageous for synthesis gas contg. CO2. In the methanator, this yields CO2 and H2S, the H2S requiring a smaller scrubber for its removal than CO2 does.</p> |
