Numerical simulation of glass melting with radioactive waste in induction furnaces with a cold crucible and bottom heating

Presents the results of a numerical study of the electrical parameters dependence of induction melting furnaces in a cold crucible (IMCC) furnaces with bottom heating (IMCC-BH) on the presence of an electric circuit of the bottom sections in the peripheral zone of the crucible. The study was conducted using three-dimensional numerical simulation of the electromagnetic field (3D EM models). A number of calculations have been performed for IMCC-BH furnaces with a cold crucible made of copper and stainless steel and bottom sections of various types. It was found that the power factor of the inductor decreases by 19−31 % when the copper bottom sections of the crucible are connected to the straight closing bus, whereas the electrical efficiency of the inductor changes slightly by 2.0−3.6 %. When the bottom sections of the copper crucible are closed to the side wall, the electrical efficiency of the inductor decreases by 10 %, and the cos φ of the inductor decreases by 48 %. For stainless steel cold crucibles used for radioactive waste vitrification, connecting the bottom sections of the crucible to the side wall, contrary, leads to a slight decrease in the power factor of the inductor by 2.5−8 %, while the electrical efficiency of the inductor significantly decreases by 15−30 %. Considering that the electric power in the melt pool is proportional to the result of multiplication of the power factor by the electric efficiency of the inductor, it can be assumed that the change in the efficiency of induction heating when closing the bottom sections of the crucible slightly depends on the material of the cold crucible. With an increase in the diameter of the cold crucible at constant inductor sizes, the effect of closing the bottom sections of the crucible on the electrical parameters of the furnace is significantly weakened, which compensates for the negative effect of closing the bottom sections. It was found that in order to increase the electrical efficiency and cos φ of the inductor, the inductor dimensions should be chosen such that the distance between the outer coil of the inductor and the side wall of the crucible is in the optimal range of 120−150 mm. The influence of the perimeter of the cross-section of the bottom sections on the electrical efficiency and cos φ of the inductor is determined. Based on the data obtained, a conclusion is formulated on the expediency of using the IMCC-BH design with electrically closed bottom sections in the peripheral zone of the cold crucible in order to increase the reliability and tightness of the furnace at the cost of a slight decrease in the electrical parameters of the inductor.

Authors: A. A. Horshev, D. B. Lopukh, A. V. Vavilov, I. N. Skrigan, A. P. Martynov, P. V. Vysotsky

Direction: Electrical Engineering

Keywords: induction melting, cold crucible, vitrification of radioactive waste, numerical modeling, furnace reliability


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