PROCESS AND APPARATUS FOR HEATING OXYGEN TO HIGH TEMPERATURE

1,212,848. Arc heating of gases. FARBENFABRIKEN BAYER A.G. 27 Nov., 1967 [1 Dec., 1966], No. 53779/67. Heading H5H. Oxygen or an oxygen/inert gas mixture is heated by an electric arc discharge between cooled electrodes, at least one of which is a composite of silver or gold, or certain silver/gold alloys, with carbon or graphite, the composite containing 10 to 50% of the metal or alloy, the metal oxides of which are unstable above 500‹ C. and the thermal conductivity of which, as measured at 20‹ C., is greater than 0À33 cals./ cm. sec. ‹ C. The arc is moved rapidly over the electrodes either by a magnetic field or by introducing the gas tangentially. The insulator mountings for the electrodes are hexagonal boron nitride, silicon nitride, quartz or quartz glass. The gas to be heated may be pre-heated in an oil or gas-fired heater before entering the arc. The heated oxygen-containing gases are reacted with titanium tetrachloride to produce finely divided titanium dioxide.