GB1433744A - Electric furnaces - Google Patents

Abstract

1433744 Resistance furnaces EXCEL HEAT Ltd 31 July 1973 [1 Aug 1972] 35780/72 Addition to 1354292 Heading F4B [Also in Division H3-H5] A furnace comprises ceramic (sintered alumina) brackets 7 for supporting radiant electric resistance heating elements 8 adjacent the internal wall of the furnace, each bracket 7 having a hooked end 17 for supporting an element 8 and a stem 16 extending through the furnace lining 3, 4, 5, 6 with its end located in a mounting 15 secured to the furnace casing 1. As shown, the mounting is a hollow cylindrical boss 15 welded directly to casing 1, but such a boss could be mounted on a bracket, strap or post secured to the casing 1. The bracket stem 16 has locating notches 18 or holes engageable by a transverse pin secured to the boss 15 to prevent axial movement of the bracket 7. When notches 18 are provided, the bracket 7, which is of rectangular cross-section, is inserted in the boss 15 in a horizontal position and then rotated 90 degrees to engage the transverse locating pin in the boss 15. A circular ceramic washer 20 is trapped between shoulders on the bracket 7 and the flexible inner layer 6 of the lining to seal the aperture in the lining through which the stem 16 passes and prevent heat transfer to casing 1. The brackets 7 serve also to secure the lining 3, 4, 5, 6 to the casing 1. Layer 3 comprises mineral wool slab, layer 4 a calcium silicate block, layer 5 a calcium silicate block, and layer 6 a flexible blanket of ceramic fibres. The brackets 7 can be of circular cross-section and the holes in the furnace lining of rectangular cross-section. For use in suspending elements from the furnace roof, the hook portions of the brackets may be modified with element retaining re-entrant portions in the U-shaped surface shown.