Aerodynamic Study For Air To Gas Leakage Reduction In A Typical Rotary Regenerative Air Preheater Of Coal-Fired Steam Generators

L. Ferravante[1], C. Zagano[1], and V. Marra[2]
[1]RSE S.p.A. - via Rubattino, Milano, Italy
[2]COMSOL S.r.l. - Via Vittorio Emanuele II, Brescia, Italy

The present study relates to the reduction of the amount of air to gas leakage in a typical rotary regenerative air preheater of coal-fired steam generators, by means of computational thermo-fluid-dynamics. Due to the gaps, or clearances, required for rotation, there is a significant amount of leakage of the higher pressure air to the lower pressure gas stream. This paper presents a turbulent CFD 2D model, taking into account heat transfer also, of the preheater. Modeling and simulations have been carried out using COMSOL Multiphysics. In order to reduce the driving force that pushes the air through the seals, flow patterns close to the seals were investigated to find an appropriate deflector. Different solutions have been studied, the one with the deflector has shown, in comparison to the original system, an effective leakage reduction of about 26%.