| 摘要 |
Ammonia synthesis processes are disclosed which provide enhanced recovery of hydrogen from ammonia synthesis purge streams by selective permeation. The enhanced recovery of hydrogen can provide increased conversion of hydrogen values to ammonia. In the processes, a purge stream from an ammonia synthesis loop at a superatmospheric pressure is passed to at least two permeator stages in series. Each permeator stage contains a separation membrane which exhibits selective permeation of hydrogen as compared to the permeation of each of methane and argon. A total pressure differential is maintained across the thickness of the separation membrane to provide a driving force for the permeation of hydrogen across the separation membrane of each of the permeator stages. Hydrogen permeates through the membrane, and a hydrogen-rich permeating gas is obtained on a permeate exit side of each of the permeator stages. The permeating gas from each of the permeator stages is recycled to the ammonia synthesis reaction zone. Between permeator stages, the non-permeating gas from one permeator stage is passed to the feed side of the next permeator stage. |
