ANALYSIS OF THE INFLUENCE OF DIFFERENT TYPES OF COATINGS ON INCREASING THE WORKING LIFE OF CONSTRUCTIONAL ELEMENTS OF THE VENTILATION MILL AND REDUCING THE WEAR OF WORKING SURFACES

Research presented in this paper analyzed the possibilities of increasing the wear resistance of the ventilation mill parts for coal grinding in power plants, analyzing with multidisciplinary research. The parts of ventilation mill are exposed in very complex working condition (high velocity of particles, presence of sand up 40% and other mineral components). Using the CFD 3D numerical simulation of multiphase flow in grinding mill, is analyzed the speed, concentration and flow angle of mixture around working parts. Analyzing the potential application of wear resistance coating on the working parts ventilation mill have goal to increase remaining working life of working elements. By analyzing the damaged parts of ventilation mill and using the numerical simulation around working elements, are selected wide pallet of wear resistance filer materials for experimental testing. To analyze possibilities to improve surface properties, the wear-resistant coatings were deposited by various technologies: manual metal arc welding, HVOF depositions and plasma welding and also are used filler materials with different chemical compositions. Samples structure is analyzed with SEM-EDS and also by measurement and distribution of hardness in the samples cross-sections. Verification of analyzed result is done by experimental testing, performing simulation of wear in ventilation mill on the samples in sandblasting machines chamber. Medium for simulating wear is quartz sand and the samples are positioned at angle 20 o. Application of this research can increase working life of parts in termoenergetic facilities, reduce the number of possible repairs and extends the period between them. This achieves significant economic effects.