SAFE Syngas Associates FE LLC

Feedstock NG is desulfurized prior to steam reforming similarly to Hydrogen production. The desulfurized NG is conveyed to a combined reforming system ("CR")  consisting of steam reformer, i.e. the primary reformer with Reaction  (1), (3) and (4) and air blown ATR, i.e. the secondary reformer. with Reaction (5) in the combustion zone  and Reactions (3) and (4) in the catalyst bed. The air flow rate to the secondary reformer is determined usually with the stoichiometric N2 amount for NH3  synthesis.

Since carbon oxides in the produced syngas are not used but rather react as catalyst poisons for NH3  synthesis, these components shall be removed to the level of 0.1 vol ppm. Therefore, at first, CO is converted to CO2 by low temperature level of shift reaction where the stoichiometric steam is reduced to H2  at the same time. Then CO2 is removed by absorption solvent such as activated MDEA.  The treated syngas from CO2 absorber still contains 1000 vol ppm of CO2 and then final purification is executed by methanations in accordance with the following reactions or cryogenic separation. Produced methane is inert in NH3  synthesis loop and purged out from the loop for the use as fuel in the steam reformer.