Design Model for Selective Catalytic Reduction Process: Solution of Convective Diffusion and NO x Reaction

A simple model for the design of selective catalytic reduction (SCR) process is presented. The two-dimensional mass transfer equation shown in Bai and Chwu (1997) is simplified and the analytic solution is obtained. The analytic solution is verified by the solution of the numerical two-dimensional model as well as published experimental data. Then it is applied for the design of the SCR reactor. Effects of operating temperature, inlet molar ratio of NH3/NO, channel pitch, and gas flow rate on the SCR reactor volume are evaluated based on a designed NO removal efficiency. The NH3 slip problem of a given inlet ratio of NH3/NO also is discussed. It is shown that the injection ratio of NH3/NO must be slightly higher than the desired NO removal efficiency so that the reactor volume can be reduced and the problem of NH3 slip is not a major concern.