Investigating the Possibility of Coke Formation in Midrex Reformer

For the production of synthesis gas utilized in Midrex direct reduction plants, catalytic steam/CO2 reforming of hydrocarbons in tubular reactor is commonly used. Owing to the high heat flux through the wall of reformer tube, the endothermic nature of reforming reactions, low mass velocity of feed gas and large tube diameter, the catalyst bed is exposed to the considerable axial and radial temperature gradients. These radial gradients of concentration and temperature may create local areas with potency of carbon formation. In this investigation, a two dimensional model is developed for simulating the operation of a Midrex reformer. In this model, a thermodynamic approach is used to recognize zones inside the reformer tubes in which the risk of carbon formation is high. The simulation results are in good agreement with available data of Mobarake Plant, in Esfahan, Iran. The results show that the first half of tubes, both in center and near the wall, is critical in point of view of carbon formation.