Redesign of impact plates of ventilation mill based on 3D numerical simulation of multiphase flow around a grinding wheel

This paper presents results of the impact plate surface modification of the ventilation mill in the Kostolac B power plant (Serbia). The modification is based on 3D numerical simulation of multiphase flow around a grinding wheel. High velocity of sand particles in the ventilation mill causes strong wear of the impact plates. The multiphase flow simulations of dilute gas–solid are performed in order to obtain the sand particle paths and velocity vectors for a different surface geometry of the mill impact plates. The mixture model of the Euler–Euler approach is used. The results obtained in the numerical simulation serve for the selection of an optimal redesign of the impact plates. The experimental tests of the revitalized mill wearing parts in real exploitation conditions show that the proposed modification, surfacing technologies and (coating) materials give good results. The relative weight loss of the base plate after 1440h period of exploitation in real conditions is 8%, while the weight loss for the hardfaced plate is 5.9% for the second filler. The application of this approach can reduce the number of possible repairs and extends the period between them, resulting in significant economic effects. ► CFD simulations of the multiphase flow in a thermo power plant mill are performed. ► The impact plate parts, exposed to wear, due to sand movement, are defined. ► Distribution and velocity vectors of gas mixture and sand particles are presented. ► Optimal surfacing technology and material are used to optimize the surface hardness. ► Modified plates tested in exploitation conditions have reduced wearing.