Modeling and Simulation of the Primary Reformer

Abstract

The Primary Reformer is an integral unit of the ammonia synthesis plant. Ammonia is reacted with Carbon dioxide to create Urea fertilizer. And for the production of Ammonia, Hydrogen needs to be produced through the formation of syngas. The reformer is a packed tubular bed reactor with Ni-based catalyst. The volume of the chamber is 40 m3. Operating conditions are 600 oC and 36 kg/cm2g for the feed and 808 oC and 32 kg/cm2g for the exit with the burners operating at 1015 oC being fed fuel at 35 oC. There are two main reactions occurring in the reformer: CH4 + H2O CO + 3H2 ΔH295= 206 kJ/mol The above reaction is endothermic and is the major reaction taking place in the reformer, with an extent more than twice that of the second. This is the methane steam reforming. The second reaction is exothermic which provides some of the heat requirement of the first endothermic reaction. This is the water gas shift reaction. CO + H2O CO2 + H2 ΔH295= -41 kJ/mol The rest of the heat for the convective part of the primary reformer is provided by the radiant section. The heat in the primary reformer is supplied by combustion of natural gas in burners inside the reformer. The exhaust flue gases exit through the chimney after waste heat recovery.