Electric glass melting furnace

In a method of heating glass in a glass heating apparatus having a refractory lining which, at the apparatus operating temperature, has an electrical resistivity less than the resistivity of the glass being heated, the steps of:

• a. electrically heating the molten glass by electrodes inserted through the refractory lining of opposing walls of the apparatus, the electrodes of a given wall being of the same polarity and the electrodes of opposing walls being of different polarity;
• and
• b. maintaining the non-electrode bearing walls of the apparatus at a temperature less than the temperature of the molten glass and at which the resistivity of the refractory lining of the non-electrode bearing walls is substantially increased.

In a method of heating glass, the steps of:

• a. maintaining a body of molten glass in contact with opposing refractory walls pierced by heating electrodes and joined by a joining refractory wall having no electrodes, the electrodes of the opposing walls being of different polarity, the refractory of said walls having an electrical resistivity which is less than the resistivity of the glass at the temperature of the molten glass;
• and
• b. cooling the joining wall to a temperature (a) that is less than the temperature of the molten glass and (b) that materially increases the resistivity of the joining wall to a value at which appreciable short-circuiting through said joining wall does not occur.

In an apparatus for heating a body of molten glass, a heating space defined by side, end and bottom peripheral walls;

• heating electrodes of the same polarity carried by each of the side walls and projecting into said space, the electrodes of opposing walls being of opposite polarity;
• a refractory lining for said peripheral walls, the lining having an electrical resistivity (a) that varies inversely with the lining temperature and (b) that, at the operating temperature of the apparatus, is less than the resistivity of molten glass;
• and heat exchange means in heat exchange relation with the end and bottom peripheral walls for cooling the lining of said end and bottom walls.

The method of reducing short-circuiting in an electrically energized glass heating apparatus having spaced electrodes of opposite polarity and a refractory lining of relatively low electrical resistivity through which the electrodes extend comprising the step of cooling those portions of the refractory lining which are interposed between electrodes of opposite polarity to an extent sufficient to materially increase the electrical resistivity of said lining portions.

In a method of operating an electrically heated glass heating furnace having a heating space circumscribed by refractory walls less than all of which bear heating electrodes of opposite polarity, the improvement of cooling the non-electrode bearing refractory walls of said furnace to an extent sufficient (a) to materially increase the electrical resistivity of the cooled walls and (b) to reduce short-circuiting therethrough.

The method of heating glass comprising the steps of:

• a. confining a pool of molten glass in contact with side, end and bottom walls of a chromic oxide refractory;
• b. heating the pool by electrodes projecting through the side walls into said pool, the electrodes of each side wall being of the same polarity and the electrodes of the opposing side walls being of opposite polarity;
• c. cooling the chromic oxide refractory of said end walls and said bottom wall only to a temperature at which the electrical resistivity of said chromic refractory is materially increased.