What issues should be considered in operational procedures to prevent static and dynamic friction in steam turbines?

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Pay attention to the following points: (1) Before each start-up, it is necessary to carefully check the deflection of the main shaft; startup may only proceed once it is confirmed that the shaft’s deflection is within the allowable range. (2) The temperature difference between the upper and lower cylinders must remain within the specified range. If the temperature difference between the upper and lower cylinders is too large, it will cause significant thermal bending of the cylinders. Practice has shown that a large temperature difference between the upper and lower cylinders is often the initial cause of shaft bending. (3) During the hot start of the unit, the state changes are relatively complex; operators should pay special attention to controlling and monitoring issues such as the steam inlet temperature and the steam supply for shaft seals. Most past accidents involving shaft bending occurred during hot starts. (4) Strengthen the monitoring of unit vibration. When static and dynamic friction occurs below the first critical speed, it poses the greatest threat of shaft bending; therefore, when the bearing vibration of the turbine reaches 0.03 mm at speeds below medium speed, the machine must be shut down immediately. It is absolutely forbidden to reduce the speed to warm up the machine while the vibration is increasing. When the machine is shut down due to an abnormal condition, it is necessary to check the rotor’s coasting time; if a significant change compared to normal conditions is observed, efforts should be made to determine the cause. (5) After the turbine is shut down, make sure to cut off all water sources connected to the utility systems to prevent water from entering the cylinders. To enhance the monitoring of equipment after it is shut down, it is necessary to continue with the regular routine inspection system; any abnormal conditions detected should be analyzed and addressed immediately.