Exergy Analysis of Silicon Metallurgy in 22.5 MVA Submerged Arc Furnaces

Different types of ore—thermal furnaces were studied and it was found that the large rated capacity have broad application prospects in energy saving. Different proportions of raw materials significantly affect the specific energy consumption and exergy efficiency in silicon production. The effects of raw materials on energy consumption, exergy efficiency, and direct recovery rate in the 22.5 MVA furnaces were analyzed and evaluated using statistical techniques. The 12.5 MVA furnaces produced by the same manufacturers were also evaluated. The calculated exergy efficiency was 0.32 for the 12.5 MVA furnace and 0.33 for the 22.5 MVA furnace. The fitting diagram for the direct recovery rate shows that when raw material is consumed beyond the critical point (A), the furnaces—ranked by the change in the direct recovery rate of silicon—is as follows: 22.5 MVA > 12.5 MVA > 8.5 MVA. Raw materials consumption varies within the same range, large-capacity furnaces exert a stronger effect on raw material fluctuations. Raw material consumption more strongly affects power consumption in the 22.5 MVA furnace than in the 12.5 MVA furnace, and power consumption increases with an increase in raw material consumption.