Siberian Federal University

The use of solid fuel mixtures as an energy fuel requires comprehensive studies of the patterns and characteristics of their combustion processes, which may differ significantly compared to the patterns and characteristics of the combustion of energy coals. The combustion processes of solid fossil fuels (Balakhta brown coal), biomass (pine cones) and their mixtures (with different component ratios) were studied within the framework of synchronous thermal analysis.

During the study of the processes occurring during heating of fuel mixtures and their individual components, it was found that combustion of solid natural fuels, biomass and their mixtures occur in different temperature ranges of the heating source. Brown coal burns at 238–549⁰ C, pine cones require a temperature of 220–503⁰ C, and solid fuel mixtures based on them — 230–536⁰ C (depending on the concentration of components).

The coke residue of pine cones ignites at a temperature of 302⁰ С, which is 58⁰ С lower than the ignition temperature of the coal residue, which is 360⁰ С. In general, the addition of biomass to coal (25-75% in the solid fuel mixture) leads to a decrease of 21–56⁰ С in the temperature at which the coke residue of the solid fuel mixture ignites.

Scientists have found that predicting the main characteristics of the combustion process based on the additive properties of components is possible for fuel mixtures with the addition of no more than 25% of biomass. If there are more pine cones in it, the components will unevenly affect the characteristics of the combustion process of the fuel mixture when the temperature of the heating source varies.

"The results of the study indicate good prospects for the practical application of solid fuel mixtures based on coal and biomass (for example, pine cones). Such mixtures will reduce the consumption of fossil fuels, reduce environmental pollution by waste from biomass processing, reduce anthropogenic emissions into the atmosphere with flue gases and decomposition products of biomass, and also reduce the intensity of filling ash dumps. Among the fuel mixtures considered (75% coal + 25% biomass; 50% coal + 50% biomass; 25% coal + 75% biomass) the first one can be practically applied, literally along with widespread solid natural fuels," said the head of the laboratory of the Department of Thermal Engineering and Hydrogas Dynamics Andrey Zhuikov.

Dmitry Glushkov, co-author of the study, Director of the Research School of Physics of High-Energy Processes of TPU, also noted: "The relevance of studying the characteristics of biomass during combustion, both individually and together with other fuels, is reasoned by the need to reduce the consumption of solid fossil fuels and reduce harmful emissions during the production of thermal and electrical energy."

The results of the research are published in the journal «Coke and Chemistry». The research was covered by the grant of the Russian Science Foundation No. 23-23-00280.