| abstract |
A process for the synthesis of ammonia, where: a front-end produces a make-up syngas ( 10 ) having a substantial excess of nitrogen, the H 2 /N 2 ratio being less than 3; hydrogen is separated from a purge stream (15) taken in the high-pressure synthesis loop, with a molecular sieve or a cryogenic device, obtaining a hydrogen-rich gaseous stream ( 16 ); said hydrogen-rich gaseous stream ( 16 ) is returned to the ammonia synthesis loop, thus obtaining that the H 2 /N 2 ratio of the gas feed (12) actually converted into ammonia is close to 3 and preferably in the range 2.9-3.1. |