摘要 |
In an ammonia production process a hydrocarbon steam mixture (16) is preheated (18, 24) and reacted in an adiabatic catalyst bed (22, 26), the resulting methane-containing gas is reacted (30) with air (32) to introduce more than 1 N2 per 3H2 and purified (44, 48, 54) the purified gas is passed to ammonia synthesis (66) in admixture with a hydrogen-rich stream (82) separated at 80 from reacted synthesis gas, and the rate of flow of that stream is controlled so that the H2:N2 ratio of the gas entering the synthesis catalyst is in the range 1.0 to 2.5. Preferably methane is purged at 86 to the extent of 5-15% of the hydrocarbon feedstock. |