GB797532A - Combustion apparatus - Google Patents

Abstract

797,532. Preventing incrustation; generating combustion products under pressure. POWER JETS (RESEARCH & DEVELOPMENT), Ltd. May 10, 1956 [May 17, 1955; May 17, 1955; May 17, 1955; July 27, 1955; Jan. 18, 1956], Nos. 14203/55, 14204/55, 14205/55, 21681/55 and 1688/56. Class 51 (1). In a combustion apparatus, droplets of ashforming liquid fuel of various sizes are discharged into a region leading to the combustion zone, and droplets outside a predetermined range of size are separated from the remainder of the droplets which are carried into the combustion zone and partially burnt so that the combustion products contain a proportion of unburnt carbon. A conical spray of atomized fuel is fed into a precombustion chamber 31, Fig. 2, from an injector 41 of known type mounted in an axial duct 40 opposite the outlet 17. Air under pressure is admitted to the chamber 31 from the cooling jacket through a frusto-conical inlet 37 leading to a restricted throat 35. An inner wall 38 supported from the wall 37 by splitters carries the duct 40. A liner 51 with a short cylindrical part within the throat 35 and a diverging part forms an annular passage with the inlet wall 37 provided with swirlers so that the air flows outwardly over the end wall 36 of the chamber 31 and sets up a recirculation along the axes of the chamber. The remote end of the duct 40 is connected to a lower pressure region so that fuel droplets below a predetermined size are carried away from the chamber 31, separated from the air in a device 47 and returned to the fuel tank 45. The burning fuel from the chamber 31 passes in a generally tangential direction into a vortex chamber 12, Fig. 1, which has an axial outlet duct 16 connected to a gas turbine 2 driving an air compressor 1. Butterfly valves 25, 26 control air from the compressor entering the cooling jacket of the vortex chamber 12 and a separate jacket 23 surrounding the outlet duct 16. An axial inlet 18 controlled by a valve 27 admits air to the vortex chamber 12, and holes in the outtlet duct 16 admit air to the gases leaving the vortex chamber so that combustion is stopped before all the carbon is consumed, so that free carbon in the gases prevent deposition of ash on the turbine blades. In a modification, Fig. 6 (not shown), the duct 40 and convectional injector 41 are replaced by a duct 81, Fig. 7, open at both ends to allow air to enter the chamber 31 from the air jacket. An injector 82 of known type is supported in the duct 81 to direct a spray of fuel drops away from the chamber 31. Injector 82 is carried by a hollow strut 83, and a ring 85 spaced from and coaxial with the injector 82 delivers jets of air in a direction normal to the conical fuel spray. The smaller droplets of fuel are collected by a pipe 88 coaxial with the injector 82, while the larger drops are carried into the chamber 31 by air passing down the duct 81. In another embodiment, Fig. 3, a tubular vaporizing duct 62 is connected to the restricted throat of the combustion chamber 31 by a frusto conical wall 61, and an annular air with swirl vanes is formed in the end of the duct. At the other end of the duct 62 is an annular air inlet with between frusto-conical walls 64, 65, the inner wall 65 supporting a tube 71 admitting further air. Telescoping liners 67 are mounted within the vaporizing duct 62. Within the tube 71, Fig. 5, a fuel injector 75 is mounted in a faired shroud 76 within a tube 73 leading to a separator and fuel tank, and a tube 72 facing the injector 75 encloses a fairing 78. Air from the jacket of the chamber 31 entering the pipe 72 is deflected by fairing 78 to cross the conical fuel spray from the injector 75, diverting the smaller droplets into the tube 73. The larger droplets pass through the gap between tubes 72, 73 into the vaporizing duct 62, where the volatile constituents are vaporized before reaching the combustion chamber 31. The precombustion chamber may form part of a flame tube, instead of feeding a vortex chamber. Specifications 639,468, 719,379 and 719,380 are referred to.