ELECTRICAL FURNACE FOR MELTING GLASS

摘要

An electrical furnace particularly suitable for melting thermoplastic material used in producing glass fibers includes a tank having side walls constructed of a refractory material having an electrical conductivity greater than the material being melted at furnace melting temperature. In order to minimize electrical conduction through the side walls, first and second sets of electrodes are arranged with one set centrally disposed in the tank and the other set surrounding the first. Electric power is applied between the first and second electrodes to generate a potential field with substantially continuous equi-potential lines between the second electrodes so as to shield the first electrodes from the side walls. An electrical control circuit limits the current flow between any two electrodes to prevent a runaway condition which might otherwise be caused by the steep negative temperature-resistivity characteristics of the glass. The control circuit includes a circuit which minimizes the DC component from current flow between the electrodes.