Numerical Prediction of Erosion of Mild Steel Surfaces by Boiler Fly Ash Particles

Fly ash particles entrained in the flue gas from boiler furnaces in coal-fired power stations can cause serious erosive wear on steel surfaces along the downstream flow path. This paper describes research into fly ash impingement erosion on such surfaces, with particular reference to the heat transfer plates in rotary regenerative air heaters. The effect of the ash particle impact velocity and impact angle on the erosive wear of mild steel surfaces was determined through experimental investigations, using three different power station ash types. The experimental data were used to calibrate a fundamentally-derived model for the prediction of erosion rates. This erosion model was incorporated into a particle-tracking CFD flow simulation of the ash-laden flue gas flow through the complex channels between corrugated air heater plates. The predicted erosion rates were compared with measured erosion rates obtained using a large accelerated-erosion test facility located at a power station. Good agreement was obtained, the predictions generally being within 20 percent of the measured values.