GB741998A - Improvements in or relating to apparatus for burning liquid fuel in a ducted gas stream - Google Patents

Abstract

741,998 Vapour burners. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Oct. 6, 1953 [Oct. 7, 1952], No. 25153/52. Addition to 696,757. Class 75(1). [Also in Groups XII and XXVI] The apparatus for burning liquid fuel in a ducted stream of combustion supporting gas, forming the subject of the parent Specification, is modified in that a plurality of vaporizer bodies are arranged across the duct in a common imaginary surface, the relative dispositions of the bodies and the side walls of the duct being such that the total effective width per body of the zone at which flame propagation commences is greater than the total projected width of each of the several bodies and the effective free air space around it on a plane normal to the axis of the duct on the upstream side of the bodies so that the effective increase in width of the duct available for gas flow downstream of the vaporizer bodies is equally distributed between all the bodies to permit stable flame formation at each body. As illustrated in Fig. 1 vertical vaporizer rods 1 are disposed in a cylindrical formation in a divergent part 5 of the high velocity gas duct 2. The effective flow width of the substantially cylindrical zone 6 at which flame propagation commences is thus greater than the cross-sectional projected width XY of rods 1 and the gaps therebetween in a plane 8 normal to the.axis of the duct 2. The ends of the rods 1 may be mounted on chains or similar linkages passing through slots in the divergent side walls of the duct, so that the number of rods utilized may be varied and thus the radius of curvature of the cylindrical formation. In an alternative construction the vaporizer rods are of curved transverse section and serve as baffles for directing the gas stream through an angle of the duct. Fig. 5 illustrates a further construction in which baffles 12 are located between the vaporizer rods 1 to restrict the gaps for the gas flow, whilst providing for lateral expansion of the flames. The fuel may be fed to each rod 1 from a tank 14, Fig. 6, by a drip feed 13, the unburnt fuel being collected in a trough 15 and returned to the tank 14 through the air bleed pipe 16. A part 16a of the latter is disposed so as to be heated by the combustion whereby the return of excess fuel is facilitated. Alternatively the fuel may be fed from the tank 14 to a manifold 19, Fig. 9, to pass to each rod 1 through a metering orifice 20 and a pipe 18 into which fits a substantially rectangular tang 17 at the upper end of the rod 1. The pipe 18 has an air bleed hole 21 above the orifice 20. To avoid erratic fuel feed, turbulence in the gas flow around the upper end of the rod 1 is reduced by providing, immediately downstream thereof, a slope in the roof of the duct or an inclined baffle.