Numerical analysis of ABS deposition and corrosion on a rotary air preheater

The Ammonium bisulfate (ABS), formed by the reaction of ammonia escaped from the selective catalytic reduction (SCR) system and sulfur oxides (SOx) in the flue gas, could cause serious blockage and corrosion of the rotary air preheater (RAPH) in coal-fired power plant due to the porous structure and the just appropriate temperature window. In this paper, a numerical investigation is performed by using porous media approach in FLUENT software to study the effects of operation conditions, i.e., the temperature difference, mass flow rate, distribution of inlet flue gas flow rate, and rotational speed, on overall performance, ABS deposition and corrosion of RAPH. A local non-equilibrium thermal model is adopted. Good agreement between the numerical results and measured data is achieved. The results show that it is necessary to strictly control the temperature difference, mass flow rate and rotational speed, which have a significant influence on the overall performance. In addition, the distribution of inlet flue gas flow rate could affect the matrix temperature remarkably and play a positive role to reduce the blockage and corrosion tendency.