Abstract

The production of high-purity synthesis gas for ammonia manufacturing demands precise removal of residual reactive and inert impurities - principally carbon monoxide (CO) and methane (CH₄ ) as reactive species, and argon (Ar) as an inert that accumulates in the ammonia synthesis loop - to levels acceptable for downstream catalytic conversion. Cryogenic nitrogen wash technology represents one of the most effective and industrially proven processes for achieving these stringent gas purity requirements. This paper presents the design basis, process configuration, and engineering philosophy underpinning a nitrogen wash unit (NWU) developed for ammonia synthesis gas preparation in an Autothermal Reforming (ATR)-based plant configuration.