GB770563A - Improvements in or relating to compressor output pressure control valve - Google Patents

Abstract

770,563. Gas turbine plant. GARRETT CORPORATION. Nov. 25, 1954 [Dec. 28, 1953], No. 34177/54. Class 110 (3). [Also in Group XXIX] In plant of the kind comprising a gas turbine 12 driving a compressor 11 which feeds the combustion chamber 16 of the turbine and also has an outlet 14 for a supply of compressed air, valve means 20 is provided to stabilize the operation of the turbine when variations in the demand for compressed air occur. The valve 20 is actuated by a flexible diaphragm 23 and is normally urged towards its closed position by a spring 28. A solenoid operated valve 49 is normally positioned as shown so that compressed air taken from a chamber 15 into which the compressor discharges and led through a conduit 56 including a pressure regulator 71 is directed by the valve 49 into a chamber 26 to assist the spring 28 in closing the valve 20 whilst the chamber 27 on the opposite side of the diaphragm 23 is vented by the valve 49 to atmosphere through a restriction 46 and an opening 53. Energization of the solenoid 55, which may be effected automatically by compressor pressure or other means or manually, causes the valve 49 to vent the chamber 26 through an opening 52 and to connect the chamber 27 to the pressure from the conduit 56 whereby the diaphragm 23 opens the valve 20. In the event of a sudden increase in demand for compressed air, e.g. by the opening of a valve 70, the pressure in the conduit 14 and consequently in a chamber 34 which is connected by a conduit 38 to the conduit 14 falls and causes movement of a diaphragm 30 against a spring 36 to open a valve 29 to vent the chamber 27 and cause the diaphragm 23 to move the valve 20 towards closure. Owing to a restricted passage 37, however, between the two sides of the diaphragm 30 the pressures on the two sides will ultimately be equalized to allow the valve 29 to close but in the meantime the normal fuel supply control means for the turbine responsive to compressor discharge pressure and turbine temperature will have re-adjusted the fuel supply to take account of the new conditions. In the event of overheating of the turbine a temperature-responsive element 19 in the turbine exhaust opens the passage 61 to atmosphere thereby reducing the pressure in the chamber 27 to cause the valve 20 to close. To release the pressure from the downstream side of the valve 20 when that valve is closed a passage 62 controlled by a valve 63 is provided. When pressure is effective in the chamber 27 the valve 63 is held closed by that pressure acting on a diaphragm 64. When, however, the valve 49 is in the position shown the chamber 66 is vented to atmosphere to allow a spring 67 to open the valve 63. In a modification the restricted passage 37 is variable by a needle valve adjusted by a bellows responsive to ambient air temperature and pressure, and in further modifications the temperature-responsive element 19 controls the pressure on one side of the diaphragm 30.