Patent GB-760832-A (GB)
Title: An improved control and ignition system for liquid fuel combustion apparatus
Inventor: TROWBRIDGE DAVID ROY
IPC: F23N5/22
Filed: 1954-03-26
Abstract: 760,832. Gas turbine plant. PLESSEY CO., Ltd. Feb. 11, 1955 [March 26, 1954], No. 8903/54. Addition to 720,267. Class 110 (3). [Also in Group XI] The control equipment for liquid fuel combustion apparatus 9 comprising a time switch device 17 which controls an electromechanical fuel supply means 4 wherein a low-pressure switch 21/22 is closed by the pressure set up in the flow to the fuel atomizer and so effects ignition and wherein a high-pressure switch 23/ 10/24 actuated by the higher pressure arising due to combustion acts as a safety device whereby on failure of the high-pressure switch to close if ignition is not effected the time-switch device shuts off the power to the electromechanical fuel supply means, as claimed in the parent Specification, is arranged so that when the highpressure switch operates it cuts out the ignition circuit and provides an alternative electric supply path to the electromechanical fuel supply means. The combustion apparatus 9 may supply a starter turbine A' driving a shaft A<SP>2</SP> through reduction gearing A<SP>3</SP>; an overspeed governor 15 opens contacts 14 to shut down the system when the pre-set speed is reached. The time switch device 17 comprises contacts 3, 5, 16, 18 operated by a motor 2 energized at starting by a push-button 1 and, when the latter is released, through the contacts 3. A pump and blower motor 4 is then energized through contacts 3, 5 to circulate fuel from a tank 6 in conduits a, b, c and to deliver scavenging air through a conduit d to the combustion chamber 9. At the same time delay relay 12 is energized through contacts 3, 5, contacts 10 of the high-pressure switch 23 and contacts 11 of the low-pressure switch 21 and closes contacts 13 to provide an alternative electric supply to the pump and blower motor 4 via contacts 14 actuated by the overspeed governor 15 of the starter turbine A<SP>1</SP> driven by the combustion gases, contacts 13 and contacts 16 of the time switch 17. An alternative electric supply to the delay relay 12 is also provided via contacts 14,13, 16, 10, 11. After a pre-set time contacts 18 of the time-switch 17 close to energize a solenoid valve 19 which diverts the fuel along a conduit e leading to the combustion chamber 9 and containing the high-pressure and lowpressure switches 23, 21. The low-pressure switch 21 moves when the fuel pressure is sufficient for atomization by atomizers in the combustion chamber and opens contacts 11 to de-energize the delay relay 12 and closes contacts 22 to energize the ignition unit 25. The contacts 13 of the delay relay however remain closed for a pre-set time to maintain the fuel supply. Ignition of the fuel increases the pressure in the fuel supply line to operate the high-pressure switch 23 which opens contacts 10 to de-energize the ignition unit and closes contacts 24 to supply the pump and blower motor 4 and the solenoid valve 19 when the contacts 13 of the delay relay open. The highpressure in the combustion chamber closes a non-return valve 8 in the air conduit d and the increase in the fuel pressure opens an air valve 4b connecting the conduit d to atmosphere.