GB718632A - Turbine driven fluid supply unit - Google Patents

Abstract

718,632. Gas turbine plant. GARRETT CORPORATION. March 27, 1952, No. 7859/52. Class 110(3) A gas turbine plant comprising a compressor supplying air to a combustion chamber feeding a gas turbine driving the compressor, has means for bleeding air from the compressor outlet and hot gas from the turbine inlet and leading them to a duct for external use and a fuel control valve actuated by variations in the compression ratio of the compressor due to changes in demand for fluid distributed by the duct. Air compressed by a compressor 13 is supplied to a combustion chamber 18 feeding a gas turbine 14 driving the compressor. A distribution duct 24 supplying compressed air for external use is connected to the turbine inlet through a conduit 25 and to the compressor outlet through a conduit 26. The temperature of the air supplied to the duct 24 is controlled by actuation of the valve 27. The valve 27 is actuated by the air pressure in the conduit 102 which is controlled by thermally operated valves 97 and 101 located in the duct 24 and compressor intake respectively so that a given temperature difference between these two points is maintained. Fuel is supplied to the combustion chamber 18 by a pump 30 through a conduit 21 and solenoid operated shut off valve 40. The fuel supply is controlled by a bypass valve 41 which is actuated by the air pressure in the conduits 83, 84. This pressure is controlled by a governor 43 which is arranged to maintain a substantially constant compression ratio over the normal load range and is compensated for changes in ambient air temperature. An orifice 85 prevents the build up of pressure in the conduit 84. In the event of an excessive temperature occurring in the turbine exhaust, a vent valve 86 is opened and the pressure in the conduit 84 reduced. This allows the valve 41 to open further and so reduce the fuel supply to the combustion chamber. To reduce the fuel supply during acceleration of the engine, an acceleration control valve 88 is provided. This valve allows air to pass from the conduit 83 through a restricted orifice 89 and an atmospheric vent 90 when no load is on the engine. Control air is also taken from the compressor outlet through a conduit 92 and a solenoid operated cut off valve 93 to a distribution duct 94. When it is desired to supply air for external use, the valve 93 is opened. This causes the valve 88 to close and increase the fuel supply to the engine. The unloading valve 29 is also closed. A load limiting valve 96 which is spring loaded to the closed posi- -tion is opened by the air pressure in a conduit 98. This conduit is vented to atmosphere by the vent valve 86 when a predetermined turbine exhaust temperature is reached. To start the engine, the switch 49 is closed, current then flows from the source 67 through contacts 50b conductor 68, contacts 64b, conductor 69, contacts 52, conductor 70, contacts 50a and conductor 71 to the coil 55 of the starting relay 54. Relay 54 closes contacts 56a and 56b. The closing of contacts 56a energizes the starter motor 36. The relay 56 which is energized at the same time as the relay 54 will close contacts 57 and enable the starting switch 49 to be released. The starter motor will now accelerate the unit and when the compressor discharge pressure reaches a predetermined value the pneumatic switch 63 will close contacts 64a and open contacts 64b. The closing of contacts 64a will energize the solenoid of the valve 40 to open the valve and energize the spark plug 23. After further acceleration of the engine the pneumatic switch 63 will open the high pressure contacts 65a, 65b which will break the circuit of the starting relay 54 and ignition coil 79. When the compressor discharge pressure reaches a very high value, the switch 63 closes the contacts 66 and lights a warning lamp 53. During normal operation, if an overspeed should occur, the contacts 60 would be opened by the governor 61 and the circuit of the coil 58, of the relay 56 broken. The contact 57 will then be opened which will cause the shut off valve 40 to close. Operation of the stop switch 51 will have the same effect. The engine is lubricated by a pump 31 which draws oil from the tank 34. The oil is returned' to the tank by a scavenge pump 32. A relief valve 48 limits the oil pressure. The fuel pump 30, oil pump 31 and scavenge oil pump 32 are driven by gearing 33 from the turbine shaft.