A certain power plant steam turbine shaft lock event study

A certain power plant steam turbine shaft lock event study 2020 - 02 - 01 1. Incident on November 25, 2017, comes to a certain power plant unit # 4 due to the condenser titanium pipe leakage and the condensate fine treatment, mixed bed resin failure leads to the deterioration of the water and boiler feed water quality, decided to load down the leak. Operators will auxiliary steam steam source by smoke cutting machine for the occasion requires steam source. Therefore # 4 of 350 mw unit load, the condensate water quality exceeds bid badly, stop manually. # 4 unit idle away since the launch of jacking oil pump and in the process of turning, electromagnetic valve, since open interlock correct each bearing shell temperature and vibration is normal. 21:02 idle speed to 0 r/min. Hydraulic turning into is not successful, on-site manual plates car can't move. Check the shaft bearing on top oil pressure and oil pressure value, and comparison with data of debugging stage, confirm the jacking oil, lubricating oil system working properly. By the analysis meeting think: 1) Caused by shaft seal for the steam temperature is low, the shaft sleeve contraction, seal and shaft lock; 2) Finishing the condenser leakage, leakage damage immediately after vacuum, to no. 4 steam turbine adopt boring cylinder processing; 3) Formulate boring cylinder measures, and put in place. 2. 1 event reason analysis. Turbine speed after lee go to zero speed, check the bearing lubricating oil and jacking oil pressure is normal, ruled out because the oil system failure caused by the possibility of large crankshaft lock. 2. A preliminary analysis of large shaft entertains the direct cause of death for the shaft seal steam temperature is low. To play before the gate, when the normal operation of the shaft seal temperature about 300 ℃, idle away in the process, because the shaft seal steam temperature drop, shaft seal steam temperature to 140 ℃, the lowest cold vapor into the shaft sleeve, cause the shaft sleeve cooling contraction, shaft seal lock. 3. Steam steam source unit manual before the downtime, auxiliary by smoke cutting machine for the occasion requires steam source, because during normal operation, the auxiliary steam contact mother tube steam was basically not flow state, steam temperature in saturation temperature around; To play before the gate, contact mother pipe warm enough, lead to the cold vapor in contact mother tube into steam, auxiliary shaft seal steam temperature fell sharply. 4. Downtime is undergoing in the process of titanium condenser pipe leak check, shaft seal steam temperature drop to normal operation after the lower limit value for failing to destroy the vacuum, shut down the shaft seal. 3. 1. Mother native contact occasion requires auxiliary steam pipe drain the imperfection of the system design, the contact mother tube not set temperature monitoring, causes between adjacent units auxiliary steam could not form the real hot standby, advice in front of the steam occasion requires for auxiliary steam electric add drain all the way to the condenser, normal operation often open, guarantee the spare steam supply temperature, and adding temperature monitoring station. 2. When a unit is in normal operation of the emergency stop, if the occasion requires auxiliary steam hot standby need has not been achieved, the machine shaft seal can be supplied by the machine cold again for the time being. 3. Stop working conditions if there is no effective way to improve shaft seal for the steam temperature, should be decisive destruction of vacuum, shut down the shaft seal. 4. Rev. Stop, pay attention to the high water reduction by the valve opening, to avoid a large amount of water that cold steam temperature fell sharply again. （ Source: QinYang power)