Patent GB-990528-A (GB)
Title: Improvements in or relating to quick-acting shut-down devices for gas-turbine plants
IPC: F02C9/24
Filed: 1962-04-24
Abstract: 990,528. Gas turbine plant. ESCHER WYSS A.G. April 24, 1962 [April 24, 1961], No. 15638/62. Heading F1G. [Also in Division G3] In a gas turbine plant having a closed circuit for the working fluid, a quick-acting shut-down device is provided, the device comprising an escape valve through which working fluid, say air, can escape from the high pressure part of the circuit into the atmosphere or into another space outside the closed circuit, and a by-pass valve through which working fluid can pass from the high pressure part of the circuit into the low pressure part thereof. One or more control elements are also provided and are so constructed and arranged that on quick-acting shutdown in the case when the plant is running on high power, the control element first opens the escape valve only and then after a period of delay opens also the by-pass valve, while in the case when the plant is running on low power, the control element first opens the by-pass valve only and then after a period of delay also opens the escape valve. The engine shown comprises a compressor 2, turbine 1 and generator 3 on a common shaft, air from the compressor being preheated in a heater 6 and then further heated in a heater 5, the heated air then passing into the turbine 1. After expansion in the turbine, the exhaust air passes into the heater 6 where it gives up heat to the air discharged from the compressor, the exhaust air then being further cooled in the cooler 7 before re-admission to the compressor. A second outlet 8 is provided from the compressor and air may be passed from this outlet through the escape valve 9 to atmosphere and through the by-pass valve 11 back to the low pressure part of the closed working fluid circuit. The escape valve 9 is controlled by a servo-device 12 and the by-pass valve 11 is controlled by a servo-device 16. A change-over valve is associated with the servo-devices 12, 16 and comprises a changeover valve 27 having valve members 28, 30 which co-operate with valve seats 29, 31 respectively. Fluid under pressure is supplied from the reservoir 21 through the line 23 to the change-over valve and then passes either through line 25 to the servo-device 12 or through line 26 to the servo-device 16 depending on the position of the change-over valve 27. The valve 27 comprises also a piston 32 and diaphragm 35, the left-hand side of the piston being acted on by pressure of fluid in the line 23 and the righthand side of the piston being acted on by a spring 34, also by pressure of working fluid in the low pressure part of the closed circuit which pressure is communicated by way of line 33. By-pass passages 36, 37 having restrictions 38, 39 are provided across the valves 28, 30, all respectively. The pressure fluid line 23 is also connected to an emergency pressure relief valve 24 which is connected to a speed governor 4 by connection 40. The valves 9, 11 and 24 are all closed in normal operation. At low pressure of the working fluid, the change-over valve occupies the position shown in which the valve 28, 29 is closed. If now the emergency relief valve 24 should open, the pressure fluid acting on the servo-device 16 will immediately escape whereby the by-pass valve 11 will open. The escape valve 9 will open after a certain delay since the pressure fluid from the servodevice 12 can escape only through the restriction 38. At high pressure of the working fluid, the valve 27 will be in its other, i.e. left-hand position, and should the emergency relief valve 24 then become open, the escape valve 9 will open immediately and the by-pass valve 11 will open only after a certain delay since pressure fluid can in this case escape from the servodevice 16 only through the restriction 39.