The analysis of acoustic noise in a submerged arc furnace
Master Thesis
1977
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University of Cape Town
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Abstract
This project deals with Acoustic Noise Analysis in a submerged Arc Furnace. Operators and Metallurgists believe that the acoustic noise coming from the furnace conveys information as to the operating conditions of the furnace. This submerged arc furnace reduces ferrochrome ore to the metal. A carefully made-up mixture of ore and slag producing materials is continually fed into the furnace. Three large carbon electrodes provide the heat to melt the ore by means of resistance heating and/or arcing. The exact mechanism is unknown. The furnace is rated at 48 MVA maximum and the electrodes carry currents of the order of 100 kiloamperes. The metal is tapped approximately every four hours. The term submerged arc is used because the furnace is completely enclosed and the arc occurs below a layer of ore mix. This differs from an open arc furnace which does not have a roof and where the operators can actually see into the top of the furnace. The operation of the submerged arc furnace is also different from that of a scrap melting electric arc furnace. A scrap furnace has set melting cycles and has acoustic noise changes determined by falling metal, melting and initial arcing. Higgs, Papadakis and Sheets (Ref .1) performed signature analysis on acoustic noise from a scrap furnace to differentiate between different operating conditions in the furnace. The aim of the present project was to collect and analyze data records of acoustic noise and operating conditions from the number four furnace at Ferrometals 1 Witbank. The data was recorded on analogue and computer magnetic tape and analyzed at UCT. The analysis was aimed at explaining the operators' theory of the acoustic noise relating to operating conditions of the furnace. This procedure is different from that of Reference 1 in that they did their analysis with an on-plant analyzing computer, and that their furnace had a set defined cycle whereas the submerged arc furnace is a continuous feed system. Reference 1 is the only known information relating to the analysis of noise in the electric arc furnaces, and their furnace operation is largely different to that of the furnace used in this project.
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Bibliography: page 123.
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Reference:
Chadowitz, J. 1977. The analysis of acoustic noise in a submerged arc furnace. University of Cape Town.