GB810477A - Improvements in or relating to the burning of solid fuels in furnaces - Google Patents

Abstract

810,477. Solid fuel furnaces. DEUTSCHE KOHLENBERGBAU-LEITUNG. May 4, 1955 [Jan. 26, 1955], No. 12886/55. Class 51 (1). Solid fuel is burnt in a furnace chamber, from which the ash is continually removed by agitation of the fuel bed, in the presence of a mixture of recycled gaseous combustion products and air, the oxygen content of which is about 15 to 17 per cent by volume. In a boiler, fuel from a hopper 1, Fig. 1, drops into a chamber 2 whilst primary air passes transversely through the fuel bed and secondary air is introduced at 6 into a chamber 5. Combustion products are drawn through a duct 9 having a valve 11 from a gas pass 8 by a fan 10 and recycled, via ducting 14, to the chamber 2, a duct controlled by a valve 12 feeding air to mix with the products. The recycled products may be automatically or manually varied by controlling the fan 10 or valves 11, 12, such control depending either upon the boiler exit temperature of the products or upon the boiler or furnace output given, e.g. by the amount of steam generated or hot water supplied and the primary air supplied, respectively. Control may also depend upon the oxygen content of the mixture either automatically under the control of an oxygen analyser or manually by use of an oxygen gauge. Water, thermostatically controlled, may be automatically injected into the recycled products when the temperature of the latter exceeds a predetermined amount. The furnace grate 3 may have fixed bars 16, Fig. 2, alternating with bars 17 which are shaken by being pivotally attached at 18, 19, to reciprocable bars 20, 21. A modified grate has alternate bars 22, Fig. 3, lifted by a lever mechanism 24, 25 about a pivot bar 23. The bars may be shaped as shown in Fig. 4.