GB595295A - Improvements in or relating to methods of and apparatus for producing a gas or mixture of gases suitable for use in the heat-treatment of metals - Google Patents

Abstract

595,295. Gaseous mixtures; maintaining special atmospheres in furnaces. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. July 3, 1947, No. 17542. Convention date, June 19, 1942. [Classes 51 (ii) and 55 (ii)] An atmosphere of carbon monoxide, nitrogen and hydrogen with possibly some methane and small amounts of water vapour and carbon dioxide and suitable for use in the heat treatment of metals is obtained by continuously reacting fuel gas, particularly town's gas, and oxygen-containing gas in the presence of heat and a catalyst, the relative proportions of the gases being varied in response to variations in pressure in the reaction chamber so that free carbon is alternately separated from and taken up by the reacting gases. Apparatus may comprise an electrically heated chamber 3 containing nickel shot or other catalyst 12 to which the supply gases mixed in a chamber 22 are fed through a pipe 9 having constant pressure pump equipment 24 and constant flow equipment 27, the product gas issuing through a pipe 10, cooler 32 and water separator 33. A bye-pass 40 under the control of a solenoid operated valve 41 admits additional air to the supply mixture when the pressure at the inlet to the reaction chamber, increasing owing to carbon deposition, reaches a preset value. The chamber is initially primed by utilising a rich supply mixture and the product gas may be vented through a pipe 47. In an example rich and lean supply mixtures of air and town's gas air in the ratios of .6 to 1 and 1 to 1 yielded product gases of the following constituents respectively; carbon monoxide 16.8 and 21.4 per cent., hydrogen 60.6 and 44.7 per cent., methane 2 and 1.8 per cent., the balance being nitrogen, and the reaction temperature being about 1,950‹F. A modified apparatus provides a reversal of flow at each variation in the supply mixture which is brought about by a device responsive to the differential pressure between the supply and outlet pipes.