A process and system to capture ammonia from a purge gas of a urea plant

1) A process for removing ammonia from ammonia-containing purge gas of a urea plant, the process comprising:

• a) said ammonia-containing purge gas is contacted with a stream of carbon dioxide;
• b) at least one of:
• said ammonia-containing purge gas prior to contacting said stream of carbon dioxide,
• said stream of carbon dioxide prior to contacting the ammonia purge-gas,
• the mixture of purge gas and carbon dioxide resulting from the contacting step a), is refrigerated;
• c) in the so obtained refrigerated mixture of purge gas and carbon dioxide, at least some of the ammonia contained in the purge gas reacts to form one or more ammonium salts and a multiphase mixed stream containing the ammonium salts is obtained, and
• d) said ammonium salts are removed from said mixed stream.