Under what circumstances is it generally prohibited to start or operate a steam turbine?
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Generally, it is prohibited to operate or start the turbine under the following conditions: (1) Abnormal operation of the emergency safety device. (2) The automatic main steam valve, control steam valve, and extraction check valve are sticky and cannot close tightly; the tightness tests for the automatic main steam valve and control steam valve fail. (3) The speed control system is unable to maintain the turbine operating at no load (or it cannot keep the speed within the range that triggers the emergency shutdown device after the unit loses load). (4) The bending value of the turbine rotor exceeds the specified limit. (5) The temperature difference between the upper and lower sections of the high-pressure inner cylinder is greater than 35°C, while the temperature difference between the upper and lower sections of the high and low-pressure outer cylinders is greater than 50°C. (6) When obvious friction sounds are heard inside the unit during shaft rotation. (7) When any oil pump or barring device fails. (8) The oil pressure is insufficient or the oil temperature is below the specified value. (9) When the oil level in the tank is below the specified value after the oil system has been filled. (10) There are severe leaks in various systems of the turbine. (11) When the insulation equipment is substandard or incomplete. (12) In the event of failure of the protection devices (low oil pressure, low vacuum, axial displacement protection, etc.) and failure of the main electric valves (such as the electric main steam valve, high-pressure heater feed valve, water inlet valve, etc.). (13) Failure of the main instruments, including the tachometer, deflection meter, vibration meter, thermal expansion meter, differential expansion meter, axial displacement meter, speed control and lubricating oil pressure gauges, seal oil pressure gauge, temperature gauges for thrust and seal bearings, hydrogen-oil pressure difference gauge, hydrogen pressure gauge, cooling water pressure gauge, main steam or reheat steam pressure and temperature gauges, cylinder metal temperature gauge, vacuum gauge, etc.
① The speed control system is unable to maintain the turbine at no-load operation, nor to raise the speed to the level at which the emergency shutdown device activates in the event of a sudden loss of all load. ② The automatic main steam valve, throttle valve, and extraction check valve are sticky or not tight. ③ When any safety device fails. ④ The oil return for any bearing is abnormal. ⑤ The pneumatic and electric oil pumps are faulty, failing to maintain normal oil pressure. ⑥ The oil system has severe leakage. ⑦ The quality of the turbine oil is unsatisfactory. ⑧ The tachometer is missing or not functioning properly. ⑨ There is an obvious friction noise between the moving and stationary parts of the turbine or at the shaft seal. ⑩The machine being dragged is faulty.
The static test failed; the required process conditions are not available