| 摘要 |
<p>The present invention relates to a method of purification of ammonia synthesis gas subsequent to pre-purification. The pre-purified gas from a preceding unit is cooled from its process temperature to saturation temperature level and fed to a distillation column for separation of the gas into purified synthesis gas and vent gas containing the removed CH4, Ar and excess N2. The separation is performed at substantially the same pressure as in the preceding unit. The vent gas is heated to the final vent temperature with intermediate pressure release through a pressure relief valve and at least one expansion turbine. The purified synthesis gas is heat exchanged with the pre-purified synthesis gas. Most of the CH4 content of the vent gas can be removed in a second distillation column prior to final pressure release. H2 can be removed from the vent gas prior to CH4 removal.</p> |
