Patent ID: 6660066
Filing Date: 2003-12-09
Classification: B01D

Abstract:
A process for removal and subsequent recovery of ammonia from a purge gas stream comprising ammonia, hydrogen, nitrogen, argon, helium and methane from an ammonia synthesis loop, comprising the steps of(a) introducing the purge gas stream into a first ammonia adsorber comprising a selective ammonia adsorbing agent, (b) adsorbing ammonia in the purge gas on the ammonia adsorbing agent at the same pressure as the pressure of the synthesis loop, (c) withdrawing an ammonia free purge gas from the first ammonia adsorber, (d) introducing a make-up gas stream comprising hydrogen, nitrogen and traces of at least one of argon, helium and methane to a second ammonia adsorber comprising a selective ammonia adsorbing agent saturated with ammonia, (e) removing ammonia from the ammonia adsorbing agent saturated with ammonia by the make-up gas at the same pressure as the pressure in the synthesis loop, (f) withdrawing an ammonia containing effluent from the second ammonia adsorber and introducing the effluent to the ammonia synthesis loop at the make-up gas addition point, and (g) introducing after a pre-set period of time the purge gas to the second ammonia adsorber as steps (a) to (c) and simultaneously introducing the ammonia free make-up gas to the first ammonia adsorber as steps (d) to (f).