GB1369144A - Electric furnace - Google Patents

Abstract

1369144 Internal resistance heating OWENSCORNING FIBERGLAS CORP 17 May 1972 [17 May 1971] 23243/72 Heading H5H In order to protect low electrical resistance refractory walls of a glass furnace Fig. 4, a plurality of grounded interconnected electrodes 47, 47<SP>1</SP> are arranged between the side walls of the furnace and the "hot" electrode formed by two interconnected electrodes 46. In the single-phase furnace of Fig. 4, one electrode 47 is arranged to be adjacent the entrance of the throat 48 to insure that convection currents are created to prevent batch material (unmelted glass), floating on top of the melt, from being drawn out of the furnace. The furnace side walls may be chromic oxide and the floor of dense fused silica. Water jackets 34, Fig. 3 (not shown), may be provided around the electrodes to cool the furnace floor. The cool batch material distributed over the melt surface, prevents the escape of fluorine, (added as a flux) and boron from the molten glass. In multiphase arrangements, e.g. three phase furnaces, Fig. 5, electrode pairs 56, 57, 58 are connected to a phase of the supply and secondary grounded electrodes 59<SP>1</SP>, 59 lie between the individual electrode pairs and between said pairs and the side walls of the furnace.