Patent GB-552747-A (GB)
Title: Improved combustion apparatus for burning solid fuels containing ash
IPC: F23C3/00
Filed: 1941-10-20
Abstract: 552,747. Pulverulent fuel combustion appara tus. BABCOCK & WILCOX, Ltd. Oct. 20. 1941, Nos. 13465, 13466 and 13467. Convention dates, March 7. [Class 75 (i)] [Also in Group XII] Combustion apparutus for burning granular fuel comprises a combustion chamber of circular or substantially circular cross section having fluid cooled walls lined with refractory material, means for supplying at high velocity at one end a mixture of fuel and air, which moves in a helical path towards an outlet at the other end and means for admitting a further supply of air for combustion between the ends of the chamber, molten slag being withdrawn from the bottom of the chamber. As shown in Fig. 3, the cylindrical combustion chamber 28 has one end of reduced cross section to the part 30 of which solid fuel and air are fed tangentially before passing through the section 29 to the enlarged portion of the chamber. Air is also fed tangentially to an axial passage 38 which also serves as an inspection opening and for the insertion of an oil burner for starting up The gases pass through the chamber in the form of a helical path and are supplied with secondary air, as shown in Fig. 5, through a long narrow port 50 controlled by a damper 54. The walls of the chamber are fluid cooled by studded tubes 31 covered wtih refractory material 33. The tubes are coiled and formed with gaps to provide for the secondary air inlet 50 and also for the escape of molten ash at 63. The gases are discharged from the chamber through a tapered throat 62 the walls of which also are cooled. The wall of the combustion chamber 28 and chamber 30 adjacent the inlets is of involute form: Fig. 11 shows a boiler with one of a number of combustion chambers 28 arranged side by side and delivering gases through a tubular screen 80, 81, to a space 75 beneath the boiler tubes 67, 68. Molten slag from the combustion chamber 28 falls down into a pit 85. The cooling tubes of the combustion chamber are connected to headers 71, 72, 73 as shown in Fig. 12, and to the circulation system of the boiler. According to a modified form of the combustion chamber the fuel and air are not introduced into a part of reduced cross section as shown in Fig. 3, but adjacent to the front end wall which is provided with a passage such as 38. Figs. 21, 22 show a vertical combustion chamber 28 from which molten slag is removed through an aperture 63. Solid fuel and air are supplied to the lower end 103 of the combustion chamber through an adjustable nozzle 97 located in the tapering end 93 of an air trunk 89. Further air is fed tangentialy into the combustion chamber at an intermediate zone between the fuel inlet and throat 62. Fig. 24 shows a vertical combustion chamber in which fuel and air are supplied tangentially through vertical slots in the walls. Fuel falls down the pipe 90 and is delivered laterally into a current of air supplied by a conduit 154 under the control of a plate damper which is capable of adjustment in such a manner that it lies parallel to the wall of the inlet pipe 122 in all positions. Air inlets 123, 124 provided below the inlet 122, have dampers hinged at their outer ends and are supplied from the conduit 155. The combustion products pass from the throat into a slag collecting chamber and thence to a flue arranged in a water tank. As shown in Fig. 33, a boiler is heated by a number of vertical combustion chambers from which the gases and slag pass into a chamber 174 communicating with the space 75 beneath the boiler tubes 67, 68. The walls of the combustion chamber are provided with vertical tubes connected to upper and lower headers in the circulation system of the boiler. Fig. 38 shows a device for introducing fuel into the air stream adjacent the furnace inlet. Fuel is supplied by a pipe 90 to a conduit 186 mounted on the air conduit 184 and provided with a telescopic extension 188 having an extension 194 for receiving various types of fuel tips 196 which may be provided with a tongue. The telescopic extension 188 is of substantially of the same width as the air conduit and controls the air flow around its lower end where the fuel meets the air stream. Fig. 41 shows a modification in which the fuel passes from a pipe 90 into a vertical adjustable pipe 200 arranged at the side of the air conduit 184 so that fuel may be delivered through the nozzle 201 at various positions in the air conduit the cross sectional area of which is controlled by a damper 207 in accordance with the position of the fuel inlets.