摘要 |
<p>When melting thermoplastic material, partic. glass, by heat developed by the passage of electric current between immersed electrodes, the fusion zone between batch and melt is controlled by using electrodes which penetrate into the melt to differing extents. These penetration depths may be varied when the compsn., resistivity temp. relationship, or IR absorption characteristic of the feed changes. In modification the power supply to the more deeply immersed electrodes may be increased, and the charging pattern may be varied to control the height of molten material adjacent to the wall above the uppermost electrodes. By controlling the shape and stability of the fusion zone the glass quality is improved and electrode and furnace life are extended. The arrangement makes it possible to have a temp. differential between the central and peripheral regions.</p> |