GB756803A - Improvements relating to the preparation and burning of moisture-containing solid fuel and to apparatus for preparing and burning such fuel - Google Patents

Abstract

756,803. Steam generator furnaces. BABCOCK & WILCOX, Ltd. July 5, 1954 [July 7, 1953 ; July 9,1953], No. 19610/54. Class 51(1). In a steam generator furnace fired by fuel containing a high proportion of moisture, e.g. brown coal, the fuel is pulverized in a grinding mill in which it is also dried by hot gases from the furnace, the arrangement being such that as the rate of firing of the furnace is varied over a range extending from a maximum value so is the final moisture content of the fuel changed so that the percentage of moisture in the fuel varies in the same sense as the rate of firing. In the construction shown in Fig. 1, the furnace comprises a combustion chamber 1 communicating through a throat 3 with an antechamber 4, both chambers being lined with cooling tubes connected into the boiler circulation system. The antechamber 4 is divided by vertical tube walls into three compartments having separate outlets to the combustion chamber 1 and separate slag outlets 20 which discharge through shafts 23 into a water trough 25 fitted with a scraper conveyer 26. At each side of the furnace is arranged a beater mill 30 fed with fuel from a hopper 27 through a shaft 29, the mill acting as a fan to draw hot gases from the furnace through aperture 31 and conduit 32. The aperture 31 is fitted with a control damper and the conduit 32 has an air inlet 37 provided with a damper 38 for controlling the admission of tempering air. The mill 30 is connected by pipes 42 to three centrifugal separators 43 each delivering the separated fuel through a burner nozzle 52 to one of the-compartments of the antechamber 4 ; gases and vapours with such fuel as is unseparated pass from the separators 43 through ducting 47 to burners 48 disposed in the wall of the combustion chamber 1. Treated air for combustion is supplied to the burners 48, 52 from a hot air duct 44. The hot air, in its passage to the burners 52, heats the separators 43 so that condensation therein is avoided and the degree of separation effected in each separator is controlled by supplying, through a nozzle 46<SP>1</SP>, agitating air the flow of which may be varied by operating a valve 45. The Specification also describes an automatic system applied to a plant in which the whole of the fuel is supplied to a cyclone furnace arranged to deliver to a secondary combustion chamber leading to the main radiation chamber of the steam generator.