Secondary Reformer Reactions and Heat Effects

Most steam reformers are process furnaces, transferring the required endothermic heat from a firebox to the process inside catalyst-packed tubes. Some steam reformers are auto-thermal , getting their heat from oxidation reactions occurring within the eatalyst bed. Secondary reformers in ammonia plants are an example of auto-thermal steam reformers. 

There are several categories of reactions and heat effects calculated in the secondary reformer model. First, the primary reformer effluent is mixed with the process air. Then, Ihe effect of consuming the oxygen that is admitted with the process air is determined. This effect was investigated by simulating several possible reaction pathways. The results were insensitive to the pathway chosen, so Ihe simplest, and also the most thermodynamieally 

The reactor bed is not assumed to be adiabatic, but loses heat from its walls. Presently a constant heat flux from the walls is assumed. A flux profile can easily be imposed, based on heat transfer driving force, but its effect will be negligible. In fact, if the reactor were assumed adiabatic the results would be essentially unchanged. The heat loss from the reactor walls was retained, so that the effects of the heat losses can be easily demonstrated. 

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