RECOVERY OF HYDROGEN FROM 5500 nm3 /hr AMMONIA PURGE GAS USING MEMBRANE TECHNOLOGY

Abstract

Every atomic element ever in the history of the universe began as a H2 atom that had undergone nuclear fusion within a star. In other words, every one of us is a byproduct of H2. It is mainly used in the synthesis of nitric acid, which is used in fertilizers and explosives. There are many processes from which we can produce NH3 including Haber process, Cryogenic process, NH3 from natural gas, Electrolysis, Partial oxidation, Adiabatic reforming, Coal gasification. In this project, we have separate H2 from NH3 purge gas using Poly Sulfone Membrane Technology. In ammonia production, hydrogen and nitrogen are reacted at high pressure to form ammonia. Since the conversion per pass is not 100%, the reactor is operated in loop mode. In the processes, a purge stream from an ammonia synthesis loop, which purge stream contains NH3, is contacted at a super atmospheric pressure with the feed side of a separation membrane which exhibits selective permeation of each of hydrogen and ammonia as compared to the permeation of each of methane and argon. A total pressure differential across the membrane is maintained to provide a driving force for the permeation of H2 and NH3 through the membrane. A H2-rich permeating gas which contains ammonia is obtained on the permeate exit side of the membrane. The permeating gas is combined with the gas in the ammonia synthesis loop and passed to the ammonia synthesis reaction zone for conversion to ammonia. A non-permeating gas is removed from the feed side of the separation membrane at substantially the same pressure at which the purge stream is contacted with the separation membrane. Some benefits of Membrane Separation are: recovers valuable hydrogen in ammonia plant purge gas, Increases ammonia production by 4-5%, Less gas consumed per kg ammonia produced, Requires no additional rotating equipment, Easy to operate, passive system and Ambient temperature operation.