Experimental and Computational Study of the Formation of Composite Granular Fuel

Currently, the topical trend in the development of energy complexes in a number of countries is the expansion of the solid fuel use, which is largely provided by the use of various types of local renewable fuels. The latter often have high thermal properties (heat of combustion, ash content, etc.), but have low or poorly predicted physical and mechanical characteristics (strength, granulometric composition, etc.). These circumstances practically make stable and efficient operation of automation systems, mechanization of transportation of pellets, and technological processes of boilers impossible. The formation of a composite fuel with specified physical and mechanical properties provides a solution to this problem. The structure of the composite fuel based on peat, sawdust, cellulose and modifier was established at the previous stages of our work. However, in case of a given composition, the physical and mechanical characteristics depend on the operating and technological conditions for obtaining granules. In this paper, a statistical and experimental study was carried out aimed at finding rational technological conditions for granulating and drying composite fuel particles with a given mass ratio of components. To prepare fuel pellets of a given size from the initial fine-fraction components, a laboratory installation was used, the main elements of which were a Z-shaped mixer, a screw granulator, and a fixed bed dryer. The influence of independent variables on the strength and final moisture content of finished pellets of composite fuel was determined within the framework of a full factor experiment. The paper presents graphical images of response surfaces characterizing the specified influence of variable factors. The obtained regression dependences describing the influence of factors on the target properties of granules are linear in nature. The latter limits the possibility of using gradient optimization methods and creates the need to search for rational conditions, taking into account the limitations caused by the technical and economic parameters of obtaining finished fuel pellets.

1. Korsak E. P. (2019) Formation of the System of Threats to Energy Security of the Republic of Belarus. Enеrgеtika. Izvestiya Vysshikh Uchebnykh Zavedenii i Energeticheskikh Ob’edinenii SNG = Energetika. Proceedings of CIS Higher Education Institutions and Power Engineering Associations, 62 (4), 388–398. https://doi.org/10.21122/1029-7448-2019-62-4-388-398 (in Russian).

2. Fortov V. E., Popel’ O. S. (2014) The Current Status of the Development of Renewable Energy Sources Worldwide and in Russia. Thermal Engineering, 61 (6), 389–398. https://doi.org/10.1134/S0040601514060020.

3. Pekhota A. N., Filatov S. A. (2022) Investigation of Energy Properties of Briquetated Multicomponent Fuel by Thermo-Analytical Methods. Enеrgеtika. Izvestiya Vysshikh Uchebnykh Zavedenii i Energeticheskikh Ob’edinenii SNG = Energetika. Proceedings of CIS Higher Education Institutions and Power Engineering Associations, 65 (2), 143–155. https://doi.org/10.21122/1029-7448-2022-65-2-143-155 (in Russian).

4. Laitinen S., Laitinen J., Fagernäs L., Korpijärvi K., Korpinen L., Ojanen K., Aatamila M., Jumpponen M., Koponen H., Jokiniemi J. (2016) Exposure to Biological and Chemical Agents at Biomass Power Plants. Biomass and Bioenergy, 93, 78–86. https://doi.org/10.1016/j.biom bioe.2016.06.025.

5. Tabakaev R., Shanenkov I., Kazakov A., Zavorin A. (2017) Thermal Processing of Biomass into High-Calorific Solid Composite Fuel. Journal of Analytical and Applied Pyrolysis, 124, 94–102. https://doi.org/10.1016/j.jaap.2017.02.016.

6. Maryandyshev P. A., Mukhreva I. I., Lyubov V. K., Schonnenbeck C., Trouve G., Brillard A., Brilhac J.-F. (2019) Thermal Decomposition and Combustion of Peat Fuel. Solid Fuel Chemistry, 53 (5), 283–288. https://doi.org/10.3103/S0361521919050094.

7. Grammelis P. (ed.) (2011) Solid Biofuels for Energy. A Lower Greenhouse Gas Alternative. London – Dordrecht – Heidelberg – New York, Springer-Verlag. 242. https://doi.org/10.1007/ 978-1-84996-393-0.

8. Mikhailov A. V. (2016) Coal-Peat Composition for Co-Combustion in Local Boilers. Journal of Mining Institute, 220, 538–544. https://doi.org/10.18454/pmi.2016.4.538.

9. Makeyenko А. А., Naumova G. V., Khmyzov I. A., Solov’yeva T. V. (2018) Strengthening Additives for Formatted Wood Fuel. Trudy BGTU. Seriya 2: Khimicheskie Tekhnologii, Biotekhnologiya, Geoekologiya [Proceedings of BSTU. Ser. 2], (2), 51–54 (in Russian).

10. Tabakaev R. B., Kazakov A. V., Zavorin A. S. (2014). Solid Composite Fuel from Low-Grade Raw (Technological Aspect). Izvestiya Tomskogo Politekhnicheskogo Universiteta. Tekhnika i Tekhnologii v Energetike = Bulletin of the Tomsk Polytechnic University. Engineering and Technology in the Energy Sector, 325 (4), 56–64 (in Russian).

11. Christoforou E., Fokaides P. A. (2019) Advances in Solid Biofuels. Cham, Springer. 130. https://doi.org/10.1007/978-3-030-00862-8.

12. Thomson A. E., Naumova G. V. (2009) Peat and its Processed Products. Minsk, Belaruskaya Navuka Publ. 328 (in Russian).

13. Naumovich V. M. (1984) Artificial Drying of Peat. Moscow, Nedra Publ. 222 (in Russian).

14. Arshadi M., Gref R., Geladi P., Dahlqvist S.-A., Lestander T. (2008) The Influence of Raw Material Characteristics on the Industrial Pelletizing Process and Pellet Quality. Fuel Processing Technology, 89 (12), 1442–1447. https://doi.org/10.1016/j.fuproc.2008.07.001.

15. Holm J. K., Henriksen U. B., Wand K., Hustad J. E., Posselt D. (2007) Hustad and Dor the Posselt. Experimental Verification of Novel Pellet Model Using a Single Pelleter Unit. Energy and Fuels, 21 (4), 2446–2449. https://doi.org/10.1021/EF070156L.

16. Ovchinnikov L. N. (2017). Investigation of Process of Obtaining Complex Granulated Organo-Mineral Fertilizers of Prolonged Action Based on Peat. Izvestiya Vysshikh Uchebnykh Zavedenii. Khimiya i Khimicheskaya Tekhnologiya = ChemChemTech, 60 (9), 100–104 (in Russian).

17. Mitrofanov A., Mizonov V., Camelo A., Tannous K. (2019) Application of the Theory of Markov Chains to Theoretical Study of Processes in a Circulating Fluidized Bed. Particulate Science and Technology, 37 (8), 1032–1038. https://doi.org/10.1080/02726351.2018.1525459.

18. Akhnazarova S. L., Kafarov V. V. (1978) Optimization of Experiment in Chemistry and Chemical Technology. Moscow, Vysshaya Shkola Publ. 319 (in Russian).

19. Adler Yu. P., Markova E. V., Granovsky Yu. V. (1976) Experiment Planning in the Search for Optimal Conditions. Moscow, Nauka Publ. 279 (in Russian).