Steam Methane Reforming, or SMR, processes feedstocks, ranging from natural gas to light naphtha, mixed with steam to produce a hydrogen-rich syngas effluent, with a typical H2/CO ratio of 3:1 to 5:1. SMR based plants are most commonly used to produce a hydrogen product or a combination of a hydrogen stream and another syngas product. In an SMR based plant, a heated mixture of the hydrocarbon feedstock and steam flows through catalyst filled tubes within a fired furnace called a reformer. In the presence of nickel catalyst, the mixed feed reacts with steam to produce hydrogen and carbon oxides by the following reactions:
CnHm + nH2O → nCO + (m/2+n) H2
CO + H2O → CO2 + H2
The first reaction is the reforming reaction, and the second reaction is the water gas shift reaction. Both reactions produce hydrogen and are both limited by thermodynamic equilibrium. The exit equilibrium temperature from the reformer is typically in the range of 1500°F to 1700°F. The net reaction is highly endothermic, requiring significant heat. These reactions take place under carefully controlled external firing within the reformer furnace.