GB616439A - Improvements in or relating to high temperature electric furnaces - Google Patents

Abstract

616,439. Electric furnaces. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Sept. 2, 1946, No. 26337. Convention date, Sept. 8, 1945. [Class 39 (iii)] [Also in Group XXVIII] An electric furnace comprising a cup shaped heating element of graphite surrounded on all sides by heat radiation shields, is enclosed in a vacuumtight metallic casing connected to a vacuum pump. The graphite heating element comprises a thick base 112, and a thin vertical cylindrical wall 114 formed with a plurality of narrow horizontal perforations 118 providing a tortuous current circuit. Heat losses are minimised by spaced apart heat radiation shields 124, 126, 128 below the heating element, by spaced apart cylindrically shaped shields 142, 134 around the heating element and by removable shields 146 arranged horizontally above the heating element, the latter shields having openings for the escape of gases and for observing the charge through a peep-tube 152 in the top plate 12 of the metallic casing. A central conductor 20 is electrically connected to the base of the heating element whilst other conductors 22, 24, &c., spaced around the central conductor 20 and insulated from the metallic casing, are electrically connected in parallel to the upper periphery of the heating element. Each conductor comprises a hollow water cooled metal rod 76, surmounted by a graphite member 38 recessed to accommodate a round graphite rod 42, 96 electrically connected to the heating element. Apertures are made in the heat radiation shields to accommodate the graphite rods. Water cooled coils 164 are arranged around and at the ends of the metallic casing.