Patent ID: 8869564

Claim:
A method of refining a glass melt in the interior of a vessel formed by a bottom wall and side walls which comprise metallic components, the method comprising: a) providing molten glass in the interior of the vessel up to a molten glass surface; b) providing at least one pair of electrodes in the interior of the vessel in a distance of at least 1 cm from the metallic components and without direct contact with cooled bounding surfaces of the vessel; c) powering the at least one pair of electrodes to produce electrical current therebetween and to heat the molten glass by ohmic resistance heating up to at least 1700° C. in at least a restricted region between the electrodes, with the electrodes being used within a hot region of the glass melt; d) cooling the bottom wall and the side walls adjacent to the metallic components so as to cool the glass melt near the metallic components, such that all of the side walls are separated from the glass melt by a skull layer consisting of solidified material of the melt during operation, with the skull layer being isolated against ground and the electrodes; and e) producing a convective flow of molten glass in the interior of the vessel, driven by a temperature difference of the molten glass near the electrodes and near the cooled walls so as to make molten glass flow along the molten glass surface and help gas bubbles to escape through the molten glass surface by the electrodes all being arranged in the interior of the vessel and causing heating of the melt forming an upward flow of the melt between the electrodes in the vessel.