GB761409A - Improvements in or relating to the production of glass by means at least partially of electrically generated heat - Google Patents

Abstract

761,409. Electric glass furnaces; current supply. PENBERTHY, H. L. July 5, 1954 [Jan. 8, 1954], No. 19641/54. Class 39(3) In making glass by passing current introduced from electrodes inserted into the body of the furnace at the rear end wall and side walls thereof so as to pass current through the glass in the melting zone below the added floating batch constituents, the currents are caused to flow so that more than half the heat is liberated in a zone of general U- or V-shape near the side and rear end walls of the furnace enclosing the glass, the zone being not wider than a quarter of the distance separating the side walls. The electrodes may be of molybdenum and constructed as in Specification 752,597, and are inserted either vertically, or horizontally or inclined up towards the centre at 45 degrees when inserted in the lowest fourth part or the bottom corner of the furnace wall. In Fig. 7, the electrodes 92 in the end wall and 91, 93 in the side walls are connected to the terminals of a 3-phase transformer 34. In Fig. 3 (not shown) the electrodes 91, 93 in the side walls are connected to the same terminal of a 3 phase transformer, and two electrodes 92 in the end wall are connected each to one of the other terminals thereof. Three single phase transformers or mains supply may be used. In Fig. 4 a pair of 3 phase transformers is used, having a common terminal connected to an electrode 46 in the end wall. and the other terminals connected as shown to electrodes 42-45 in the side walls, the transformers being so phased that the opposite electrodes 42, 43 are at equal potentials and the potentials of electrodes 44, 45 are also equal to each other. In Fig. 5 (not shown) the end wall carries two electrodes and each side wall carries three electrodes, each outermost side wall electrode being connected to one of the end wall electrodes; and current is supplied from a pair of 3 phase transformers. The end wall electrodes may be spaced to leave an unheated area between them, or an additional single phase transformer may be connected to them. In Fig. 6 (not shown) each side wall carries two electrodes; and two terminals of a 3 phase transformer are connected one to each of the electrodes near the end wall, while the outer electrodes are connected both to the third terminal of the transformer. In Fig. 10 (not shown) the end wall carries two electrodes and each side wall one electrode; and the supply is an open # 3 phase transformer, or three single phase transformers similarly connected, the open terminals of the transformers being conected to the electrodes in the side walls and the other two terminals being connected'each to one of the electrodes in the end wall. Unsymmetrical current distribution may' be created by varying the transformer voltages. In Fig. 9 two transformers or sets of transformers 123, 124 are connected, one terminal of each to one of two electrades 120 in the end wall; and two electrodes in each side wall are connected each to a different transformer as shown. Convection or stirring motion of the glass is stated to be largely avoided. The surface of the batch may be heated by gas flames.