Patent GB-780653-A (GB)
Title: Improvements in electric igniters for use with fluent fuel burners
Inventor: DRYDEN THOMAS FERLIE
IPC: F23Q3/00
Filed: 1954-05-11
Abstract: 780,653. Igniting burners. BABCOCK & WILCOX, Ltd. May 11, 1955 [May 11, 1954], No. 13797/54. Classes 75(1) and 75(3). [Also in Groups XXVII and XXXV] An electric igniter for a burner comprises a sparking plug 1 arranged to be projected to and retracted from an operative position and comprising an inner electrode 3 and a surrounding outer electrode 5 separated by insulating material such as a mica tube 7 and extending in the direction of movement of the plug, the insulating material providing an annular spark-traversing surface 13 at the forward end of the outer electrode 5: or an electric igniter for a burner comprises a sparking plug 1 arranged to be projected to and retracted from an operative position, a capacitance 241, Fig. 7. charging and discharge circuits therefor, the discharge circuit including in series the sparking plug and a switch 243 arranged to close periodically. The inner electrode 3 is a rod and extends forwardly beyond the outer electrode 5. The outer electrode 5 is a tube and its forward portion 11 is reduced to compress the mica tube 7 between the electrodes. The enlarged rear end of the sparking plug fits loosely inside a tubular holder 35 and is retained therein by a ring 37 welded to the holder and engagimg a ring 15 soldered to the sparking plug. The rear end 31 of the rod electrode 3 abuts a terminal 63 on the end of a rod 53 extending through the holder 35 and urged forwardly by a coil spring 71 located in a housing 69 disposed within a tubular member 47 welded on to the rear end of the holder 35. The housing is formed by four annular insulating elements held in end to end abutment by a union nut 101 screwed on to the end of the tubular member 47. The igniter holder 35 is secured withim a tube 215, Fig. 3, extending through an oil-fired burner for igniting a pulverized fuel burner (not shown) and connected at its rear end to a piston associated with a double acting air cylinder 225 mounted on the rear plate 147 of the burner. The oil burner comprises an outer tubular casing 187 having an air inlet 188 and a fuel atomizing unit 133 adapted to be projected and retracted relative to the casing 187 by two pistons associated with two double-acting cylinders 143 mounted on the rear plate 147 of the burner. Towards its forward end the barrel 135 of the atomizing unit 133 is secured by a spider 165 to a tubular casing 163 having rollers on its sides engaging horizontal rails 181 on arcuate plates disposed outside the casing 163 and secured at their forward ends to an annular support 185 resting on the inner surface of the outer casing 187 and at their rear ends to a member 195 bolted to the rear end of the outer casing 187. Vanes 177 for whirling the air surround the atomizer head 137 and are connected to the forward end of the casing 163. An aperture 229 is provided in the vanes for the sparking plug and a further aperture is formed in the spider 165 to support the tube 215 containing the igniter. The burner is provided with doors which when the casing 163 is moved rearwardly close to prevent flow of air forwardly and to protect the movable parts of the burner from heat radiation from the furnace. The switch 243 in the discharge circuit of the condenser 241 comprises a four lobe cam 263 mounted on the shaft of an electric motor and a pivoted follower 267 adapted to open spring closed contacts 271, 273. The charging circuit of the condenser includes an adjustable resistance 245, a step down transformer 249, a switch 255 and a voltage doubling unit 247 comprising two rectifiers 259 and two condensers 261. The electric motor drivimg the cam is energized on closure of switch 255. The Provisional Specification describes an electrical circuit similar to that described above but in which the switch in the discharge circuit is operated by an electromagnet energized by a surge of current in the charging circuit to open the contacts of the switch. Upon reduction of the charging current the contacts close to discharge the condenser through the sparking plug and a further surge of charging current ensues. The Provisional Specification also states that the sparking plug may be reciprocated in the burner by hydraulic means.