Emergency response measures for lubricating oil system failure
Thread Content
A lubricating oil system generally includes a main oil pump for the turbine shaft, an AC lubricating oil pump, and a DC lubricating oil pump (without a high-level oil tank). In the event of an unexpected situation such as the main cable being severed, which causes the AC lubricating oil pump to stop working, and at the same time the DC lubricating oil pump also fails to start, what emergency measures can be taken to ensure the proper shutdown of the steam turbine generator set and prevent damage to the bearing shells? Some friends say that after shutting down the machine, steel wire ropes and a crane should be used to manually rotate the shaft in order to prevent the bearing shells from sticking together and getting damaged. But without lubrication, the temperature of the bearing shells will be high, leading to wear, won’t it?
In the event of a failure in the lubrication system, the following steps can be taken to address the situation: 1. Immediately reduce the speed of the turbine and bring it to a safe stop as soon as possible. Reducing the machine's operating speed can lower the load on the bearing shells and the rate of temperature rise. 2. Start the backup lubricating oil system (if available). Some units are equipped with a backup lubrication system that can be activated in case the main system fails. 3. If no backup lubrication system is available, a manual lubrication method should be employed. For example, a manual pump or other methods can be used to lubricate the bearings in order to reduce friction and wear. 4. Use a crane or manual winch to turn the shaft, to ensure that the bearing shells do not get stuck or damaged as a result of an abrupt stop. While this cannot completely prevent wear of the bearing shells, it can alleviate to some extent the direct damage caused by the lack of lubrication. 5. Throughout the entire process, closely monitor the temperature and vibration of the bearings to ensure they do not exceed the safety limits. 6. After shutdown, promptly inspect the DC lube oil pump and AC lube oil pump to restore the normal operation of the system. Through the above measures, although wear of the bearing shells cannot be completely avoided, the damage can be minimized and the safe shutdown of the equipment ensured. .
Apart from what was mentioned on the 2nd floor, under normal circumstances a return valve is used to increase oil pressure; the most effective way is to reduce the setting of this return valve, which will have some effect. As for by how much it should be reduced, I’m not sure.
Generally, oil pumps are not connected to the same power supply. For example, there are two AC-powered pumps; this is done to prevent both pumps from stopping working in case of a power outage. There is also a DC-powered pump that receives its own power supply. Unless all three cables are cut at the same time, and even if the cable supplying the AC oil pump is cut, it does not affect lubrication. Under normal conditions, it is the shaft-mounted oil pump that provides lubrication