Patent GB-659328-A (GB)
Title: Improvements in ignition apparatus
IPC: F23C99/00
Filed: 1949-03-15
Abstract: 659,328. Furnace-lighter burners. BABCOCK & WILCOX, Ltd. March 15, 1949, No. 7019. Convention date, March 17, 1948. [Class 75 (i)] The main burner of a furnace is lit from a lighting torch having its own ignition means and having associated mechanical interlocking means for the control of fuel and air to ensure that the fuel supply line to the torch is purged of fuel over a length thereof following on the shutting down of the fuel supply to the torch. A torch 22 provided with ignition electrodes 23, 24 is guided within a housing 26 and projected to a position to light the main burner 14 and retracted therefrom by an air cylinder and piston device 25, the ignition circuit being completed only when the torch in projected position has closed a switch 30 by an arm 39 at the rear end of the torch. Rotary plug valves 72, 83, 105, 102 for the supply and exhaust of air to and from the cylinder 25 and for the supply of fuel to the torch and of air for purging a length of the supply line are shown diagrammatically in Fig. 8 in the shut down position while the mechanical interlocking gear therefor is shown in Fig. 7. The valves 72, 83 are connected by a 2/1 chain and sprocket gear, the valves 102, 105 by a 1/1 chain and sprocket gear while the valves 83, 105 are provided with interlocking circular discs 85, 110 respectively arcuately recessed at 120, 115. When the torch is to be used the operator moves valve 72 (anti-clockwise in Fig. 8) to a 90 degrees position until an arm 77 on the valve stem is stopped by a solenoid plunger 81. In this 90 degrees position, Fig. 9, the valve 72 in conjunction with valve 83 (moved by the 2/1 chain gear to the 45 degrecs position) supplies air to one end of the cylinder 25 and exhausts the other whereby the torch is moved to the projected position and the switch 30 is closed to energize the solenoid and withdraw plunger 81. The valve 72 can now be turned to the 180 degrees position and valve 83 to the 90 degrees position, Fig. 10. The arcuate recess 120.of the circular interlocking disc 85 on valve 83 is now in position to allow movement of the associated interlocking disc 110. The operator accordingly moves valve 102 (and valve 105 through the 1/1 chain gear) and at the 90 degrees positions of these valves, Fig. 10, air is admitted for purging the line 56 to the torch. On the movement of valves 102, 105 being continued to the 180 degrees position, Fig. 11, the purging air is shut off by valve 105 and fuel is supplied to the line 56. Stops 113 limit the movement of the valves 102, 105 to this 180 degrees range. After the main burner 14 has been lit the valves 102, 105 are returned (in reverse directions) to the 0 degrees position to shut off the fuel and to give a purging at the 90 degree position. The arcuate recess 115 of the interlocking disc 110 is thus returned to 'the position allowing disc 85 to be moved. Disc 85 and valves 83, 72 are accordingly moved forward, a pivoted arm 90 co-operating with a series of pins 89 on the underside of the disc 85 acting as a ratchet to prevent rearward movement. At the 270 degrees position of valve 72 (and 135 degrees position of valve 83), Fig. 13, air is admitted to and exhausted from the cylinder 25 in the sense to retract the torch. The valves 72, 83 are thereafter moved forward to the 0 degree position for valve 72 (180 degrees for valve 83). A contact 125, Fig. 14 (not shown), closed only when the furnace draught apparatus has been put in operation controls the main fuel valve and the supply of current to the ignition and solenoid circuits.