Combustion of bituminous coal and semicoke with copper salts

• Published in: Fuel processing technology Vol. 213; p. 106706
• Main Authors: Larionov, K.B., Mishakov, I.V., Slyusarskiy, K.V., Tsibulskiy, S.A., Tabakaev, R.B., Bauman, Yu.I., Vedyagin, A.A., Nalivaiko, A.Yu, Gromov, A.A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-03-2021; Elsevier Science Ltd
• Subjects: Activating additive; Additives; Bituminous coal; Coal; Combustion; Combustion chambers; Combustion products; Copper; Delay time; Explosions; Fuels; Gas analyzers; Heating; High-speed video recording; Ignition; Ignition temperature; Oxidation; Reduction; Semicoke; High-speed video recording; Activating additive; Semicoke; Combustion; Bituminous coal; Ignition
• ISSN: 0378-3820; 1873-7188
• DOI: 10.1016/j.fuproc.2020.106706

This paper examines combustion of coal and semicoke modified by 5 wt% of Cu(NO3)2, CuSO4 and Cu(CH3COO)2. The additives were introduced using the wet impregnation method. Ignition and combustion experiments were performed in a combustion chamber at temperatures of the heating medium varying from 500 °C to 700 °C. The gas-phase combustion products were analyzed using an in-line gas analyzer. It was found that, on average, the use of activating additives contributed to a reduction of the ignition delay time by 1.8 times and a decrease in the minimum ignition temperature by 54–135 °C. An increase in the heating medium temperature resulted in a significant ignition delay decrease (by ~270%). The maximum difference in the ignition delay time between the reference sample and the modified coal (3.4 s) and semicoke (10.4 s) samples was observed at 500°С while using copper nitrate. In the initial stage of combustion, formation of micro-explosions on the samples modified with copper nitrate and acetate was observed. The use of additives contributed to reducing the content of unburnt carbon in the fuel. Addition of copper salts resulted in a significant reduction in the CO production volume and better fuel oxidation to CO2.
•Addition of copper salts decreases the delay time and temperature of the ignition.•Microexplosions occur at early stages of the coal combustion process with additives.•The content of unburnt carbon in ash residue was averagely reduced by 3.1 times.•CO content in the gaseous combustion products was diminished by 40%.•The CO-formation peak is shifted into earlier stages of combustion due to additives.