Features of Ash and Slag Formation During Incomplete Combustion of Coal from the Karazhyra Deposit in Small- and Medium-Scale Power Plants
Seraya N. Litvinov V. Daumova G. Shaikhov M. Ramazanova R. Aubakirova R.
August 2025Multidisciplinary Digital Publishing Institute (MDPI)
Processes
2025#13Issue 8
The study presents a comprehensive assessment of the combustion efficiency of low-grade coal from the Karazhyra deposit in small- and medium-capacity boiler units of the energy workshops operated by Vostokenergo LLP (East Kazakhstan Region, Kazakhstan). It was found that the average annual thermal energy output amounts to 2,387,348.85 GJ with a coal consumption of 164,328.5 tons. Based on operational data from 2016 to 2017, the average thermal efficiency (boiler efficiency) was 66.03%, with a maximum value of 75% recorded at the Zhezkent energy workshop. The average lower heating value (LHV) of the coal was 19.41 MJ/kg, which is below the design value of 20.52 MJ/kg, indicating the use of coal with reduced energy characteristics and elevated ash content (21.4%). The unburned carbon content in the ash and slag waste (ASW) was determined to be between 14 and 35%, indicating incomplete combustion. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses revealed the presence of microspheres, porous granules, and coal residues, with silicon and aluminum oxides dominating the composition (up to 70.49%). Differences in the pollutant potential of ash from different boiler units were identified. Recommendations were substantiated regarding the adjustment of the air–fuel regime, modernization of combustion control systems, and utilization of ASW. The results may be used to develop measures aimed at improving the energy efficiency and environmental safety of coal-fired boiler plants.
ash , ash and slag waste , coal , low-grade solid fuel , underburning
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International School of Engineering, D. Serikbayev East, Kazakhstan Technical University, Ust-Kamenogorsk, 070001, Kazakhstan
Proektno-Ekologicheskoe Bjuro LLP, Ust-Kamenogorsk, 070001, Kazakhstan
School of Earth Sciences, D. Serikbayev East Kazakhstan Technical University, Ust-Kamenogorsk, 070000, Kazakhstan
Vostokenergo LLP, Ust-Kamenogorsk, 070001, Kazakhstan
Higher School of IT and Natural Sciences, S. Amanzholov East Kazakhstan University, Ust-Kamenogorsk, 070001, Kazakhstan
International School of Engineering
Proektno-Ekologicheskoe Bjuro LLP
School of Earth Sciences
Vostokenergo LLP
Higher School of IT and Natural Sciences
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