Patent GB-144763-A (GB)
Title: Improvements in apparatus for firing furnaces with powdered fuel
IPC: F23K3/00
Filed: 1919-03-11
Abstract: 144,763. Brand, J. J. C. March 11, 1919. Fuel, feeding.-In an air-current apparatus for supplying pulverulent fuel to furnaces, fuel is fed from a hopper to a fuel circuit, whence it passes to a screw conveyer, is mixed with a fraction of the air from an air-main, and is fed by the conveyer to a pipe in which it is mixed with another current of air, and through which it is conducted to the furnace. The screw conveyer is enclosed in a casing, and is of such length that a seal is formed between its feed and delivery. Fig. 1 shows the general arrangement of the plant in a steamship. The fuel is withdrawn from the bunkers 21, 22 by a pump 33 and pipes 34, 35, and is delivered to a separator 32 and a hopper 29, whence it falls into a sump 46, Fig. 6, and is removed by an endless rope 48, with disks 49, which move in a fuel circuit pipe 47, whence it is distributed to the various furnaces. From this pipe 47 the dust passes into pockets 54, Fig. 2, forming parts of the separate feeders for each furnace. It is discharged from these pockets by screws 64 to pipes 65; part of the air in the main 28 passes by pipes 55 to the conveyers 64, and part to the pipe 65, forming a dilute mixture of air and dust in the pipes 53 which convey it to the burners 79 and the furnace 90. The air blast in the main 28 is supplied by a fan 27 through a tubular heater 26 in the smoke stack 25. The bunkers 21, 22 are fitted with pneumatic conveyers 36, which may have mechanical or pneumatic agitators for aerating the dust. In the pneumatic apparatus shown on the left-hand side of Fig. 1, air entering by a valved hood 39, or preferably furnace gases entrained by a hood 40 and cooled by a water-cooled apparatus 41, are supplied by the pipe 38 to the pipe conveyer 36, which has at intervals vents controlled by shutters 37. The conveyer 42 has a shaft fitted with screw vanes 43 which agitate the coal and move it towards the sump 45, whence it passes to the pipe 34, the hopper 29, fuel pipe 47, and the furnace fittings shown in Fig. 2. The bunkers also have mechanical stirrers 58. The screw conveyer 64, Fig. 2, is driven by friction gearing 67, 70, the wheel 70 being adjustable on its spindle to vary the feed. The wheel 67 is pressed against the wheel 70 by springs 69, and may be lifted by a handle 71. The front end of the furnace flue is brought outwards, as shown in Fig. 2, and is fitted with doors 57, which embrace the burner 79, and close the front of an air chamber 77, to which air is supplied. The air passes through a tapering collar 82, in which apertures 83 are cut so as to give a whirling movement to the air passing through them into the annulus 85 surrounding the burner. The burner is waterjacketed, and has a cone 80, forming an annular 'burner mouth. A helical vane 88 imparts a whirl to the fuel current. The flames play on checker work 91. The wire-rope conveyer in the pipe 47 may be replaced by a chain conveyer with offset claws carrying scrapers. Fig. 8 shows a modification wherein a fan 102 maintains a fuel-andair current through a hopper 29, a conduit 98 fitted with a long screw conveyer 97, a sump pipe 100, and a return pipe 101. The fan delivers to a cyclone separator 31 with a filter 32, and the hopper has a bag filter. Hot air is supplied by a fan through a heater 26, and pipe 28 to pipes 108, 107, and thence from the pipe 107 by pipes 104 to the conduit 98, and through the pockets 54 to the furnace feed-pipes. The pipe 108 supplies air to the air chambers 77, Fig. 2, surrounding the burners. An injector fitting 212, Fig. 8, facilitates the circulation in the fuel and air pipes.