Fedorov S. Development of the Scientific Basis for Design of High-Temperature Furnaces based on Electro-Thermal Fluidized Bed for Carbon Materials Processing

The present thesis is devoted to resolving of the substantial scientific and applied problem – development of the scientific basis for design of high-temperature furnaces based on electro-thermal fluidized bed concept for carbon materials processing at temperatures of 2000-3000C and graphite production of more than 99,95% purity. Set tasks were resolved by combining methods of the theoretical and experimental analysis. Experimental research of the electric conductivity of particulate carbon materials in packed and fluidized bed was conducted via developed laboratory installations using the potentiometric measurement method and further verification of working hypotheses with a physical model of an electro-thermal furnace. Computational and theoretical research was conducted on the basis of mathematical models of: structural properties of random particles systems; electrical conductivity of heterogeneous structures along with a frame model of conductivity for an elementary volume; heat transfer in high-temperature electro-thermal furnaces based on double phase fluidization theory; heat and mass transfer in heat exchangers with fluidized and moving packed bed. Conducted research includes study of the electrical conductivity of the electrothermal bed with respect to: bed’s structures, contact interaction between material particles, working temperature and specific heat output per unit volume as well as a thermal work of high-temperature electro-thermal furnaces with fluidized bed. Verified and refined modern hypotheses comprise the concept of the phenomenon of the electrical conductivity as well as the development on their basis calculating method for the 5 electrical resistivity of the fluidized bed. In the issue, the determined results are: scientifically substantiated preconditions of reliable operation, particularities of material heating, patterns of power distribution and inhomogeneity of the temperature field as well as a calculation method of workspace dimensions for these furnaces. New efficient designs of for electro-thermal fluidized bed furnaces were developed. Their rational operation modes, that ensure required working temperatures, were substantiated. As a result, an industrial plant concept for carbon materials thermal processing at 2500-3000C for production of battery grade graphite of more than 99,95% purity was developed. Thesis’s outcomes include theoretical basis of enhancing thermal efficiency of an industrial plant for thermal processing of carbon materials based on the electrothermal fluidized bed technology by controlled modes of material moving and improved technical solutions for fluidizing agent inlets as well as utilizing of processed product waste heat for heating raw material. Keywords: carbon raw material, graphite, electro-thermal furnace, fluidized bed, graphitization, electrical resistivity, heat transfer, heat power, energy efficiency.