GB848069A - Improvements in igniting means for fluent fuel fired furnaces and to surface discharge sparking plugs - Google Patents

Abstract

848,069. Sparking plugs. BABCOCK & WILCOX Ltd. April 9, 1957 [April 10, 1956], No. 10921/56. Class 7(4). In a surface discharge sparking plug having a part of insulating or semi-conducting material which affords a surface extending between electrodes, the distance between the electrodes is adjustable. In Fig. 1 spacing washers 17 are provided so that the distance between the electrodes may be varied by removing the nut 13 and washer 12 withdrawing the rod 5 from the ceramic tube 2 and removing or adding a washer 17 or washers or changing at least one washer for one of different thickness. The electrodes 1 and 7 are of stainless steel. If desired two spaced tubes of ceramic material may be used. The opposing faces of the electrodes may be radially outwardly convergent. Collar 15 serves to locate the sparking plug in a reciprocable tube of an igniter of the form described in Specification 780,653. In Fig. 2 the gap between the electrodes is varied by rotation of the nut 43. The sleeve 32 and plug 40 are of ceramic material. End 41 of sleeve 21 is threaded to engage a corresponding thread in a reciprocable igniter means shown in Specification 780,653. When the igniter assembly is used in conjunction with pulverised fuel-fired furnaces in which sparking is required continuously for long periods the plug illustrated in Fig. 2 is secured within the tube 215. The plug is of heavy construction so that it may be maintained at elevated temperatures. The ignition system comprises a capacitator associated with a charging circuit and switching device. The switching device comprises a motor driven cam operated switch, the electric motor for operating the switch device being arranged to be energized, on energizing the charging circuit.