A numerical study of expanded metal screens as applied to a coal-fired utility boiler

Coal-fired utility boilers suffer from catastrophic tube failures induced by flyash erosion. Flyash erosion is inevitable when burning coal to generate electric power, but the erosion is aggravated by local high velocities. Expanded metal screens can be used to control excessive erosion. The objective of this research is to provide tools for predicting screen behaviour for the design of boiler retrofits.;Numerical models for screens of various shapes were solved and good agreement with the experimental data was obtained. Numerical solutions were obtained for a two-dimensional model of the boiler both with and without screens in order to visualize the flow modification. Good agreement with the cold air velocity data was obtained except for large over prediction of the channeling velocity. A three-dimensional boiler model was created which was found to more realistically simulate local high velocities. Finally, a three-dimensional economizer model was created and the results were analyzed qualitatively.