International Journal of Energy Research, Vol.44, No.1, 438-447, 2020
Thermodynamic equilibrium analysis of steam methane reforming based on a conjugate solution of material balance and law action mass equations with the detailed energy balance
Thermodynamic equilibrium analysis of the steam methane reforming (SMR) process to synthesis gas was studied. For this purpose, the system equations of the material balance and the equations of law mass action were solved by dichotomy method. The investigation was performed for a wide range of operational conditions such as a temperature, pressure, and inlet steam-to-methane ratio. The results obtained, with the help of developed algorithms, were compared with the results obtained via different commercial and open-source programs. All results are in excellent agreement. The operational conditions for the probable formation of carbon were determined. It was established that for the temperature range above 1100 K, the probability of carbon formation is absent for steam-to-methane ratio above units. In order to determine the amount of heat supplied per 1 mol to the reformer, the heat balance equation was obtained to achieve a targeted degree of methane conversion. With the help of the heat balance equation, it was established that the resulting transformation of substances in the steam methane reformer can be presented as a sequential heating of feed streams of methane and steam from the inlet temperature T-1 to the outlet temperature T-2, heat for SMR reaction at the temperature T-2, and heat for transformation of the part of the produced carbon monoxide (CO) via the water-gas shift (WGS) reaction at the temperature T-2. The presented algorithm of thermodynamic analysis gives an appearance of the dependence of the product composition and the amount of required heat from operating conditions such as the temperature, pressure, and steam-to-methane ratio.