The Effect of the Conductive Walls of the Melting Tank of an Electric Furnace on the Distribution of Energy Flows
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Vol. 61, No. 2, July, 2020
THE EFFECT OF THE CONDUCTIVE WALLS OF THE MELTING TANK OF AN ELECTRIC FURNACE ON THE DISTRIBUTION OF ENERGY FLOWS N. N. Shustrov,1 V. G. Puzach,1 and S. A. Bezenkov2,3 Translated from Novye Ogneupory, No. 4, pp. 13 – 18, April, 2020.
Original article submitted December 16, 2019. A method for modeling the electric glass melting process, which allows obtaining information about the commonality of electric and thermal processes occurring in the glass mass inside an electric glass-melting furnace, has been developed. The melting tank of the furnace is made of electrically conductive chromium oxide. The study was performed by way of modeling using an EHDA integrator, which resulted in the construction of two versions of pilot electric furnaces with different orientation of the electric field lines and a pilot-commercial furnace capable of melting 7 t/day of E-glass, widely used in the fiberglass manufacturing. Keywords: electric glass melting furnace (EGMF), electrical conductivity, electric field lines, modeling, equipotential lines, equigradient lines.
The duration of the furnace campaign is mainly sustained by the use of more corrosion-resistant refractory materials with respect to the glass melts of different chemical composition. Along with the open-flame glass-melting furnaces, electric glass-melting furnaces (EGMFs) are used, which have a number of advantages compared to the open-flame furnaces [1], such as: – higher efficiency of electric melting, which allows increasing the productivity to 40 – 60% compared to 18 – 20% in the open-flame furnaces; – lower capital costs due to increased furnace dimensions, elimination of recuperative (regenerative) heat exchangers, flue gas stacks, etc.; – improved working conditions; – significantly reduced harmful atmospheric emissions. Despite its undisputed benefits, electric glass-melting came short of becoming widely used in the industry. One of the reasons for this is a low corrosion resistance of the refractory materials (e.g., Bacor) against glass melts. According to [3, 4], the melting tanks of both electric and open-flame furnaces are made of the refractory materials based on chro1
2 3
mium oxide. However, specific electrical resistivity (() of the chromium oxide-based refractory materials (e.g., C 1215, KhSU, KhTs-45, etc.) is comparable to that of the alkali glasses, and significantly exceeds that of the alkali-free glasses [5, 6]. Figure 1 shows the temperature dependence of specific electrical resistivity (r) of the chromium oxide-containing refractory materials (curves 1 – 4 ) in comparison with the high electrical resistivity refractories (curves 2, 3, 7 ), alkali-free E-glass (curve 6 ) and alkali A-glass (curve 5 ) [2]. The analysis of the curves shows that the r-value of the chromium-containing refractory materials is significantly lower than that of alkali-free glass, and is at about the same level as alkali glass. This causes issues when using them in the EGMFs and during additional electric heating. According to the data cont
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