Liquid ammonia requirements for ammonia cracker
In order to ensure the quality of production products and to prevent catalyst poisoning in the ammonia cracker, it has strict requirements on the quality of liquid ammonia or ammonia gas.
The oxygen content and water content in ammonia gas will directly affect the oxygen content and dew point of the mixed gas after dissociation, and even affect the quality of the final protective gas. Some impurities in the ammonia gas will be adsorbed on the catalyst surface, making part of the catalyst surface ineffective, which is the phenomenon of catalyst poisoning. Among them, H20, CO, CO2, O2 will cause temporary poisoning of the catalyst, which can be removed by regeneration. The oil and S, H2S, As, P, NH3 will cause permanent poisoning of the catalyst and cannot be recovered.
In China, the quality level of liquid ammonia has three grades: excellence, first-class, and acceptable. And the ammonia quality required for ammonia cracker is at least first-class product. The impurity indexes of different grades of ammonia are shown in the table: