| 摘要 |
In separating gas(es) from a gaseous mixture using at least two permeator stages, the feed sides of which are in series, each stage containing a separation membrane which exhibits selective permeation of the gas(es) and a pressure differential being maintained across each membrane, the ratio of total pressure on the feed side to total pressure on the permeate exit side of the membrane for at least one permeator stage is less than the corresponding ratio for at least one subsequent permeator stage. The process may be employed to treat an ammonia synthesis purge stream (30) from an ammonia synthesis loop (20 to 28). The membranes in the permeators (36, 42) are selective to the permeation of hydrogen as compared to inert contaminants such as methane and argon. The permeates from the first and second permeator stages are recycled (38, 44) to the ammonia synthesis feed 10 downstream and upstream, respectively of a compassion stage (12) thereof. Alternatively, the second stage recycle stream may be compressed and mixed with the first stage recycle stream. <IMAGE> |
