Apparatus for removing gases from an arc furnace

768,311. Electric furnaces. RESEARCH CORPORATION. April 4, 1955 [April 9, 1954], No. 9768/55. Class 39(3) In order to dispose of fume from the interior of an electric furnace having at least one electrode 18 extending through an opening 16, in its roof 14, a collar with air inlets and communicating with the opening between the electrode and the furnace roof is placed round each electrode adjacent the exterior of the roof, this collar forming a chamber into which outside air and fumes from the furnace interior are drawn; and a mixture of air and fumes is drawn from the chamber under reduced pressure through a pipe 30 by a fan or the like to a fume-disposal means such as an electric precipitator. The collar may comprise a ring 77 with an insulating cover 84 and air inlet apertures 72 in the wall regulated by valves or by a rotatable sleeve 78 with corresponding apertures around the ring so that angular adjustment of the sleeve by a rod 82 adjusts the air inlets thereby controlling the degree of cooling of the -fumes. The opening between the roof and the electrode may also be adjusted, e.g. by an iris diaphragm 74 with a controlling handle 76. The collar includes and is preferably mounted on an annulus 44 through which cooling water is circulated. The reduced pressure in the chamber may be further regulated by a valve 40 in the outlet tube 30. In Fig. 6 a single metal cover 60 extends over the furnace roof to form a single-fume-collecting chamher into which air passes between the water-cooling annulus 44 and the electrode and from which the fumes and air are removed through suction tubes 30. In Fig. 9 the suction tube 30 is connected to the vertical side 110 of an L-shaped ring 102 mounted on the furnace roof around the electrode and five superposed courses of bricks are arranged as shown in Fig. 12. By radial movement of wedge-shaped bricks 130 into gaps between spaced bricks 126 mounted on plates 104 around the electrode, the passage for air and fume to the suction pipe 30 are regulated: The furnace has side access doors, and the space within these doors may be connected by a pipe with a valve to the suction tube 30 so that when the doors are opened the valve is also opened and fume is removed through the tube 30. The furnace may have three vertical carbon electrodes each with a suction tube 30, and these tubes are connected to a single outlet duct, such connection being through a flexible coupling if the furnace is to tilt.