Phenomena and mechanism of slagging and corrosion in energy use of coal with a high content of salts

Abstract

Purpose. Determination of the main mechanisms of slagging and corrosion of heating surfaces when using coal or other raw materials with a high content of alkali and alkaline earth metals. Experimental determination of mineral phases of ash residues of burning composite raw materials with the participation of salty coal and the influence of component composition on the formation of refractory compounds. Methodology. Critical analysis and generalization of achievements in the developed theories of slagging and corrosion of surfaces during the combustion of problematic carbon raw materials (salty coal, biomass, some wastes, etc.). Determination of the main approaches to the problem of using coal with a high pollution factor. Selection of objects of experimental study on composite raw materials, including coal of different degrees of metamorphism and salinity. Identification of minerals of ash residues of individual fuels and their blends using X-ray phase analysis (X-ray diffraction). Semi-quantitative phase analysis of diffractograms was performed using MATCH! software. Findings. Modern views on the causes of slagging and corrosion processes during the combustion of fuel with a high salt content are highlighted. It has been determined that the process of intensive slagging is associated with a certain ratio of sodium, calcium and iron compounds. The composition and features of the mineral phases of ash residues of composite fuel with the participation of salty coal are experimentally established. The influence of the content of components on the formation of certain mineral phases of mixed ash was determined. Originality. For the first time, the prospects of using two-component blended fuel with the participation of Ukrainian salty coal have been studied. The analysis of minerals in ash residues of salty coal and its blends was carried out. It has been determined that the main part of Na in ash of salty coal of the Bohdanivske deposit in the Northern Donbas is in the form of sulfates and silicates. For the first time, the composition and ways of formation of new refractory mineral compounds in the ash formed during the combustion of composite fuel from coal of different metamorphism and salinity have been established. Practical value. Based on the analysis of literary sources and conducted studies, the dependence of the ash composition on the minerals of the initial fuel and on the ratio of various components in the blends was determined. The proposed approach has a predictive power, as it allows predicting the formation of the main refractory ash minerals. The expediency and prospects of involving salty coal in the fuel base of Ukraine as a component of blended fuels are shown.