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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. [ABSTRACT FROM AUTHOR]

In order to involve coal with a high content of alkaline and alkaline earth metals (so-called salty coal) in the fuel base of the Ukrainian energy sector and to solve problems in its use (formation of ash deposits and development of corrosion processes), studies were performed on the co-combustion of salty coal with traditional steam coal. The phase composition of the ash of the studied samples of salty coal and its blends with traditional steam coal was analyzed using X-ray diffraction (XRD). It was found that significant changes in the phase composition of the ash blends occur, namely the formation of new mineral phases such as Nepheline (NaAlSiO 4), Jadeite ( NaAlSi 2 O 6 ), Albite ( NaAlSi 3 O 8 ), and ultramarines such as Hauyne ( Na 6 Ca 2 (Al 6 Si 6 O 24) (SO 4) 2 ) and Nosean ( Na 8 Al 6 Si 6 O 24 SO 4 ), which have high melting points. In addition, using the optical and gravimetric methods, a significant decrease in corrosion activity during the combustion of composite fuel with the participation of salty coal was determined. It was found that the composite fuel involving the studied salty coal at its content of 20 to 50 % in the blend significantly reduces the effects of slagging (due to an increase in the melting point) and the corrosion activity of the fuel. • Possible ways to use coal with a high content of alkali and alkaline earth metals. • Formation of new mineral phases during co-combustion of salty and steam coal. • Reduction of corrosive properties of salty coal during co-combustion with steam coal. • Involvement of salty coal in the energy sector as a component of blended fuel. [ABSTRACT FROM AUTHOR]

The problems of reducing the slagging ability and corrosiveness of coal with a high content of low-melting salts (the so-called salty coal (SC) in the processes of its combustion) are considered. Salty coal is considered to be the coal, the ash of which contains Na2O>2 %. The object of study is the salty coal of Donbass and ways of solving the problems of its use. The influence of low-melting salts on the formation of ash deposits and the development of corrosion of the metal surface during the combustion of salty coal from different fields was determined. A noticeable decrease in the slagging ability and corrosiveness of the test coal was noted during the removal of salts by water extraction. The composition of corrosive compounds (oxides Fe2O3, Fe3O4 and iron sulfide FeS) has been determined, formed during the combustion of native coal, and their absence in the case of desalinated coal. Artificial fuel mixtures produced from more reactive salty and conventional low reactive coal have been studied. To create a mixed fuel, long-flame salty coal (low stage of metamorphism) from the Northern Donbas and unsalty lean coal (high stage of metamorphism) from Kuzbas were used. A significant deviation (to 9 %) was noted for the release of ash during the combustion of mixtures from the additivity, indicating a chemical interaction between the mineral components of the mixture. The formation of new refractory mineral phases of ash (nepheline, ultramarine, combeite) during the combustion of composite fuel from coals of different metamorphism and salinity was established. The obtained results will be useful in the development of recommendations for the preparation of model fuel mixtures and their accident-free combustion in industrial boiler units. Experimental data on the determination of new mineral compounds in the case of composite fuels can be used to create a general theory of slagging in the combustion of salty coal of different origins. [ABSTRACT FROM AUTHOR]

Ash in biomass is believed to damage biorefinery equipment due to its abrasive properties. All biomass contains at least some ash, or inorganic content, as a result of normal physiological processes. The concentration of biogenic ash in biomass is largely species dependent; however it can also be affected by weather patterns, irrigation, soil type, and fertilizer applications. Ash concentrations in harvested biomass can also be elevated due to the incorporation of soil and dust during the harvest and collection processes. While ash concentration in biomass is important, so also is the mineral form of the ash. Certain mineral forms of ash can be much harder than the steels used to construct biorefinery equipment and cause excessive wear. In this perspective, the relative concentrations of ash elements, mineral forms of ash, and the hardness of these minerals are considered to identify ash components of concern to biorefinery operators. Strategies are suggested to remove ash from harvested biomass to reduce the risk of excessive wear on biomass processing equipment.

Though commonly used in the dewatering of textile dyeing sludge (TDS) before its incineration, chemical conditioning has yet to be evaluated in terms of its impact on the reaction mechanisms, emissions, and ash minerals. This study combined experiments and equilibrium simulations to disentangle the interaction mechanism among the combustion behaviors, gas emissions, ash minerals of TDS conditioned with(out) three blend ratios of the AlCl 3 conditioner. The use of the AlCl 3 conditioner slightly improved the performance of the combustion stage of volatiles and chars. No significant effect of AlCl 3 conditioner was detected on the kinetic mechanism of its main combustion stage best elucidated by the n th-order and diffusion models. SO 2 was the main evolved gas whose reduction between 600 and 800 °C was attributed to its increased retention rate by CaO from the decomposition of CaCO 3. Aluminum compounds acted as a stimulator in SO 2 emission between 800 and 1000 °C since the formation of calcium aluminosilicates. At above 1060 °C, CaSO 4 decomposed rapidly, thus almost completely releasing inorganic S. This study supplies new insights into pollution 'controls on the combustion of TDS conditioned with Al salt coagulant. ga1 • The use of AlCl 3 improved the combustion performance of textile dyeing sludge. • Reaction mechanism changed from a n th-order model to a diffusion model. • SO 2 was the main gaseous pollutant. • Insights into emission control were provided combining experiments and simulations. • The formation of calcium aluminosilicates enhanced SO 2 emission. [ABSTRACT FROM AUTHOR]