GB1446071A - Furnaces for solid fuel - Google Patents

Abstract

1446071 Solid fuel furnace C O A EKMAN 17 April 1973 [17 April 1972] 18561/73 Heading F4B In a solid fuel fired furnace of the kind having an inlet shaft in which coal is degassed and which communicates with a main combustion chamber above a grate through a restricted opening below a wall of the shaft, a duct leads the gases from the lower part of the shaft to the combustion chamber, and the shaft wall nearest the combustion chamber is inclined downwards and outwards to allow the coal to swell. Coal is fed to a shaft 11 through a rotary feeder valve 63, and the coal passes down the shaft 11 below the lower edge of a rearwardly inclined wall 16 to the grate 13. A dead plate 12 extends rearwardly only as far as the upper edge 16b of the wall 16, and gases from the shaft 11 pass through ducts 40 to partition 20 in the ash pit for distribution below the grate. In normal operation, combustion air enters through front louvres 25, but for standby operation these louvres are closed and a normally closed flap 92 is opened to pass air directly to the combustion chamber. The flap 92 is held closed by a solenoid against spring pressure so that this flap is opened when the electricity supply fails. Ash from the forward part of the grate falls to a pit 77, and two pocketed rotary valves 72, Fig. 2, feed ash to a screw conveyer 26 below the rear part of the grate. The grate is formed of bars 27 with a slight rearward inclination and three abutments 28, 30, 29 to form two regions having gaps for the passage of air and gases through the grate. Alternate bars 27 are drawn forwardly by the action of lugs 43 on cam surfaces 44 at the end of each bar, all the bars being returned together by a bar 52 linking the two outermost grate bars. In a modification, alternate bars are linked to form two sets, each set having a cam surface at either side, the links between the bars of each set being such that both sets are returned to the rearmost position together.