Mathematical modelling of erosion behaviour of impacted fly ash particles on coal fired boiler components at elevated temperature

Abstract

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 flow path. Such erosion can reduce significantly the operational life of the boiler components. A fundamentally-derived mathematical model embodying the mechanisms of erosion involving cutting wear, plastic deformation wear and effect of temperature on erosion behaviour, has been developed to predict erosion rates on the coal fired boiler components such as boiler tubes, economiser and air-preheater assemblies at room and elevated temperature. Various grades of steels commonly used in the fabrication of boiler components and published data pertaining boiler fly ash has been used for modelling the process. The model incorporates the tensile properties of the target metal surface at room and elevated temperatures, as well as the characteristics of the ash particle dynamics in the form of impingement angle, impingement velocity and composition of the ash particle in terms of the silica content. The mathematical model has been implemented in an user-interactive in-house computer code, (EROSIM-1) to predict the erosion rates at room and elevated temperature for various grades of steel normally used in boiler components. The model predictions have been found to be in good agreement with the published data. The model will be calibrated in future with the plant and experimental data generated from a high temperature air-jet erosion testing facility. It is hoped that the calibrated model will be useful to the power plant industry for erosion analysis of boiler components.