Equipment and Operation Results of 30t DC Arc Furnace at Topy Toyohashi Works
1991 Volume 77 Issue 4 Pages 520-527
Details
1991 Volume 77 Issue 4 Pages 520-527
With aim of reducing production costs, in January 1988, one of 30 t conventional AC furnaces at Toyohashi Works of Topy Industries, Ltd., was changed to a Direct Current (DC) arc furnace which was the first DC melter in Asia. It was jointly developed by M.A.N.GHH and BBC, and then designed and made by NKK.
For reconstruction from AC to DC furnace, thyristor-controlled rectifier, DC reactor and bottom electrode were put additionally to 30 t arc furnace equipment. Electrode control equipment becomes simple, because only one electrode is used. The transformer and other furnace equipments were not changed.
The DC arc furnace operation have brought us the following merits,
1) The flicker of DC arc furnace was reduced to under 50%, compared with that of AC arc furnace.
2) The problem of harmonics caused by the rectifier was solved by installing harmonic filters, which restrained harmonic component of the current under 5%.
3) Any abnormal wear did not occur on the bottom and 330 heats of bottom electrode life was stably achieved in the intermittent operation.
4) The decrease in melting cost of 900 yen/t was achieved, which was mainly due to a reduction in the consumption of graphite electrode, furnace refractory and so on.
