4. Flame ovens with electric backup

The melting capacity of flame furnaces is limited by the heat transfer between the flame and the glass bath surface. This melting capacity can be increased by the addition of electric boost heating (also known as "boosting"). The electrodes are mounted either in the walls or in the bottom of the furnace. Their location is chosen to create glass currents that promote glass refinement.

The advantages of auxiliary heaters are as follows:

• increased furnace output with no drop in quality, to meet higher demand (particularly appreciated in the container glass industry, where seasonal increases in demand are frequent);

• fusion of coloured glass in a furnace normally designed for white glass;

• improved quality for special glasses that are difficult to melt and...