Patent GB-649893-A (GB)
Title: Improvements in or relating to fuel burning apparatus
IPC: F23N1/00
Filed: 1948-10-26
Abstract: 649,893. Lighting burners. SEE, W. G. Oct. 26, 1948, No. 27789. Convention date, Nov. 5, 1947. [Classes 75(i) and 75(iii)] A fuel burning apparatus comprising an electric igniter element having a negative temperature coefficient of resistance, is provided with an electrical system for actuating said igniter element and for controlling the delivery of fuel to the burner apparatus comprising a solenoid for controlling the fuel supply, a transformer for energizing said igniter element, and a current responsive relay responsive to current flow to said igniter element, including switch means for energizing said solenoid when current flow to said igniter element reaches a predetermined value. A gas burner for submerged combustion comprises coaxial tubes 31, 22, 21 and 15<SP>1</SP>. Fig. 2, connected, respectively, with a tube 30 supplying pilot fuel, a tube 27 supplying air for combustion of the pilot fuel, a tube 20<SP>1</SP> (not shown) supplying air for combustion of the main fuel, and a tube 18' supplying the main fuel; and an electric igniter element 32 having a negative temperature coefficient of resistance is disposed within the tube 22 in position to ignite the pilot fuel. The element 32 comprises a carbon compound as its principal constituent and consists, for example, of 85 per cent silicon carbide and 15 per cent silicon by weight, the silicon filling the interstices of a continuous reticular skeleton of minute cubic crystals of silicon carbide. The electric conductors 43 supplying the element 32 pass through the air conduit 27 and connect with a pair of conducting rods 33 supporting the ends of the element 32, and mounted in a star-shaped insulating member 35 through which the pilot burner tube 31 passes. The igniter element 32 is connected to the secondary winding of a transformer 44, Fig. 8, and is energized by the closing of a manually operable switch 47 which connects the transformer primary winding to supply lines 45 through protective means 46. When the element 32 has reached or exceeded the ignition temperature the current therethrough will have increased, due to its negative coefficient of resistance, thereby increasing the current through a relay coil in the transformer primary circuit to clcse a switch 49 and energize the solenoid 51 of a control valve or other flow control device in the pilot fuel conduit 30 to initiate the delivery of fuel to the pilot burner 31. After a further time delay the coil 48 closes a switch 52 to energize the solenoid 53 of a valve or other flow control device in the main fuel conduit 18<SP>1</SP> to initiate the main fuel supply. A relay coil 55 in parallel with the solenoid 53 then opens a switch 57 to de-energize the transformer 44 and the igniter element 32, whilst at the same time closing a switch 56 to energize a relay coil 58 to close switches 61, 62 to establish holding circuits through the solenoids 51, 53. Blower or compressor means, or both, may supply air under pressure to the conduits 20<SP>1</SP> (not shown) and 27, and fuel under pressure to the conduits 18<SP>1</SP> and 30; and such means may also be energized by the closing of the switch 49 or of both switches 49, 52. The transformer 44 may be of a current limiting type. An alternative electric supply circuit is described in which there is provided no relay switcn means for disconnecting the igniter element and transformer when the solenoid 53 has been energized.