Process and plant for removing methane and argon from crude ammonia synthesis gas.

摘要

A process for removing methane and argon from crude ammonia synthesis gas, which method comprises the steps of:-
<UnorderedLists id="ula01" listStyle="none"><ListItem>a) cooling said crude ammonia synthesis gas in a heat exchanger;</ListItem><ListItem>b) distilling the cooled crude ammonia synthesis gas to provide purified ammonia synthesis gas and a liquid fraction containing methane, argon and nitrogen;</ListItem><ListItem>c) expanding said liquid fraction containing methane, argon and nitrogen;</ListItem><ListItem>d) introducing at least part of the liquid from step (c) into indirect heat exchange with vapour from the top of said distillation column to condense part of said vapour and provide reflux for said distillation column whilst simultaneously separating said liquid into a liquid stream rich in methane, and a gaseous stream rich in nitrogen;</ListItem><ListItem>e) warming said gaseous stream from step (d);</ListItem><ListItem>f) compressing at least part of the warmed gaseous stream from step (e);</ListItem><ListItem>g) cooling at least part of the compressed gaseous stream from step (f);</ListItem><ListItem>h) expanding at least part of the cooled gaseous stream from step (g); and</ListItem><ListItem>i) passing the expanded gaseous stream from step (h) through said heat exchanger.</ListItem></UnorderedLists>

There is also provided a plant in which the said process can be carried out.