GB652667A - Improvements in fuel igniters - Google Patents

Abstract

652,667. Lighting burners. BAKER & CO., Inc. July 7, 1948, Nos. 18264 and 18265. Convention dates, Dec. 19, 1947. [Class 75(iii)] In an igniter for. organic fuels in a gaseous or finely divided state capable of being catalytically oxidized in a flowing fuel-air mixture in the presence of a catalyst, comprising an electrically heated helical closely spaced coil having a surface of catalyst metal, and a source of electrical power adapted to heat said coil to a temperature below the ignition temperature of said fuel in said fuel-air mixture and below the recrystallization temperature of said catalyst metal the coil consists of a wire having a diameter not greater than about 0.003 inch and not less than about 0.001 inch. The helical coil may be wound evenly, or, alternatively, wound so that the catalytic action occurs in two phases, e.g. as shown in Fig. 3 in which the coil 4 tapers from one end to the other and is wound more closely at the wider end. On supplying fuel-air mixture to the electrically heated coil 4 the closely wound end becomes heated sufficiently to initiate the catalytic reaction but flameless combustion only takes place at this part of the coil, ignition being initiated at the remaining part of the coil the heating of which is accelerated by conduction from the flameless combustion zone. Different forms of construction of the coil 4 as a two-phase catalyst may be employed, e.g. as a tapering or cylindrically helical coil having turns in the middle part more widely spaced than at the two ends, as a helical coil bent at right angles so that at the bend the turns are more widely spaced than at the two ends; or as shown in Fig. 6 in which an additional coil 4<SP>1</SP> of larger diameter is wound around the middle portion of a uniformly wound coil 4<SP>11</SP>. The coil 4<SP>1</SP> may consist of a coiled coil. In each case the catalyst may consist of platinum or of an alloy thereof with a metal of the platinum group, e.g. rhodium or iridium; or with another suitable metal, e.g. nickel, or it may contain refractory oxide or beryllium oxide. The wire may be formed wholly of the catalyst or may comprise a layer of the catalyst on a suitable core, e.g. of tungsten or molybdenum. The device is adapted particularly for igniting saturated hydrocarbons, e.g. methane, and for igniting finely divided kerosene. It may be used in stoves, furnaces &c. or in a cigarette lighter when gasoline may be used as fuel instead of the normal " lighter fuels." Alternatively, the device may be utilized for lighting a gas burner 1, Fig. 1, provided with a flash back port 2 and a flash back tube 3, whereby contact between the coil 4 and the fuel is terminated immediately after ignition. The electrical heating of the igniter 4 may be either continuous or controlled to coincide with the initiation of the fuel supply to the burner.