GB749682A - Improvements in and relating to pulverised fuel furnaces - Google Patents

Abstract

749,682. Pulverulent-fuel furnaces. WALTHER & CIE AKT.-GES. Nov. 11, 1952 [Nov. 20, 1951 ; Dec. 13, 1951 ; Feb. 9, 1952 ; Feb. 9, 1952], No. 28431/52. Class 51(1). In a boiler furnace fired by pulverised fuel having an ash-melting hopper and auxiliary burners arranged below the main burners, the air supply to the auxiliary burners is so regulated in relation to the fuel supply that a reducing atmosphere is produced in a zone below the layer of gases produced by the main burners, fly ash being blown into this lower zone. Figs. 1 and 2 show a construction in which the furnace 10 is fitted at the corners with vertically tiltable main burners arranged in three superposed rows 13, 14, 15, auxiliary burners 18 and fly ash delivery nozzles 19 being disposed in alternate side walls of the ash-melting hopper 11 which in this case is constituted by the lower part of the furnace chamber 10. Fig. 7 shows a modification in which the lower part of the combustion chamber slopes towards a slag outlet 33 below which is a separate melting hopper 37 having auxiliary burners 38, secondary air nozzles 40 and nozzles 39, of which only one is shown, for the supply of fly ash. The hopper 37 is surrounded by cooling water tubes and is mounted on rails 57 so that it may be readily replaced by a spare hopper. This arrangement of a separate hopper is suitable for conversion of existing furnaces. Slag from the hopper 37 drops into a water bath from which it is removed by a conveyer 43; and in a modification drops into an injector supplied with water under pressure and is carried away in the water stream. In a further modification the returned fly ash is injected into the auxiliary fuel nozzles so as to mix with the fuel before its ignition.