Improvements in or relating to gas pilot burners for igniting combustible mixtures of fuel and air

摘要

676,892. Valves. PEABODY, Ltd. Oct. 27, 1949 [Dec. 17, 1948 ; Feb. 16, 1949], Nos. 27557/49 and 27558/49. Class 135 [Also in Group XI] A gas pilot burner for igniting fuel burners comprises a pair of valves controlling the supply of gas and air, respectively, to one end of a burner tube having an electric igniter therein, and operating means for the valves and a switch controlling the igniter whereby the air valve is both opened and closed to purge the tube before the gas valve is opened, and the latter cannot be opened before the switch is closed, so that when the gas is supplied ignition is effected when the interface of gas and air in advance of the gas reaches the igniter, the gas flow carrying the flame to the burner opening. The pilot burner tube 21, Fig. 2, contains sparking electrodes 25 energized by a transformer 29 mounted in a housing 41 secured to a casing 24 containing an electric switch controlling the primary supply to the transformer 29, and actuating means for air and gas valves 50, 51, respectively, operable by a single handle 120. The latter is maintained by a spring 112, Fig. 6, in a position in which both valves 50, 51 are closed and the electric switch 100 is open, and on turning clockwise a cam 60 on a shaft 81 engages a valve rod 59 to open the air valve 50 to allow air to pass through openings 56, into a chamber 53 and the tube 21 to purge the latter of residual gas. On continued clockwise rotation of the handle 120 the valve 50 closes and the cam 60 engages the valve rod 74 to open the gas valve 51 to allow gas to the tube 21, where it is ignited on reaching the electrodes 25, and the flame passes to the pilot burner head 32. The handle 120 is maintained in the latter position by the engagement of a spring-pressed pin 126 in an aperture in an index plate 111 at the side of the housing 24. The switch 100 has an actuating arm 101, Fig. 5, which engages a further cam 102 on the shaft 81 and rests in recessed portions 103 and 104 to allow the switch 100 to remain open when the handle 120 is at both ends of its normal arc of travel. Between said positions the arm 101 is engaged by a cam portion 105 so that the switch 100 is closed and the sparking electrodes 25 are energized. The pilot burner head 32 comprises a wall 33 of U-shape provided with end plates 34 and, inset in the mouth thereof, a plate 35 inclined to the axis of the tube 21 and provided with a burner opening 36, at which a flame may be maintained in an air stream by the shield provided by the extended edges of the walls 33, 34 and by flanges 46, 47 on two sides of the burner opening, the flange 47 being provided with a lip 48. For igniting a forced draught burner comprising a fuel atomizer 17, Fig. 1, and an additional fuel burner 16, mounted in an air supply conduit 10, the igniter tube 31 is disposed in an outer tube 43 and slidably mounted in a stuffing box 44 bolted to the front plate 13 of the wind-box. The head 32 extends into the conduit 10 and may be withdrawn into the tube 43 after ignition has been effected.