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

Abstract

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 the ventilation mill are exposed to very complex working conditions (high velocity of particles, presence of up to 40% sand and other mineral components). Using the CFD 3D numerical simulation of multiphase flow in a grinding mill, the speed, concentration, and flow angle of the mixture around working parts are analyzed. Analyzing the potential application of wear-resistant coating on the working parts of the ventilation mill has the goal of increasing the remaining working life of working elements. By analyzing the damaged parts of the ventilation mill and using the numerical simulation around working elements, a wide pallet of wear-resistant filler materials for experimental testing was created. 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 filler materials with different chemical compositions were used. The samples' structure is analyzed with SEMEDS and also by measurement and distribution of hardness in the samples' cross-sections. Verification of the analyzed result is done by experimental testing, performing simulation of wear in a ventilation mill on the samples in a sandblasting machine chamber. The medium for simulating wear is quartz sand, and the samples are positioned at a 20° angle. Application of this research can increase the working life of parts in thermo-energetic facilities, reduce the number of possible repairs, and extend the period between them. This achieves significant economic effects.