GB721369A - Improvements in or relating to methods of and means for burning solid fuels - Google Patents

Abstract

721,369. Furnaces. YGNIS AKT.-GES. March 3, 1952, No. 5510/52. Class 51 (1). In a furnace having a low roofed combustion chamber and a V-shaped or inclined grate through which primary air is blown upwards, secondary air is blown into the chamber at such points and in such directions that through the interaction of the blown secondary and primary air one or two substantially spiral flames in which the gases rotate about a substantially horizontal axis which lies within the flame zone and is substantially parallel to the grate is or are produced. The furnace shown comprises a V-shaped grate, formed from water-cooled tubes 10, 11, the tubes 11 having transverse ducts 12 through which primary air, from tubes 13, is supplied to the fuel bed. The furnace chamber, comprising a water jacket 14, is traversed by a plurality of hairpin type water tubes 15, 16, 17, the tubes 15, 17, communicating with jacket 14 at the furnace front whilst tubes 16 communicate with the jacket at the rear. The water circulating through jacket 14, grate tubes 10, 11, and water tubes 15, 16, 17 is supplied at 18 and discharged hot at 19. T-bars 20 supported by the upper legs of tubes 15, 16, and bars 21 carried by both legs of tubes 17 form baffles such that combustion chamber 22 is formed above the grate from which combustion gases are upwardly conducted between the baffles in a circuitous path to the outlet 28. Above the grate a duct 23 is incorporated in the jacket 14 on both longitudinal furnace sides, each duct having a plurality of orifices 24 through which secondary air, preheated in the duct and supplied thereto from a container 30, enters the chamber 22 in the direction S. The ducts 23 are of such shape that the duct wall in which the orifices 24 are located is very narrow and is set back with respect to the vertical main face of the associated combustion chamber side wall. The walls 14a of jacket 14 serve to direct the secondary air in the direction S, and also tend to shield the narrow walls and their orifices against heat radiation from the fuel. Fuel is supplied to the grate from bunkers 25 through rotatable cylindrical controlling elements 27. The furnace air supply system comprises a fan discharging into a container 30 from whence the primary air for grate tubes 10, 11, leaves via valve controlled tubes 13, primary air for below the grate through tube 32 and primary air for the grate centre through tube 31. The secondary air to ducts 23 leaves the container 30 through valve controlled ports 33. Each coal bunker is connected by a tube 35 to the container 30 so that any gases issuing from the fuel are conducted to the bombustion chamber 22. The secondary air is supplied in such quantity to chamber 22 that a super-atmospheric pressure is produced therein.