Problems with emergency shutdown of steam turbines
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Is it necessary to perform shaft turning after an emergency shutdown of the turbine? What should be done if the automatic shaft turner fails?
There’s no other choice; manual turning of the shaft is necessary.
It depends on the specific circumstances. In the case of a serious accident, turning the shaft may increase the extent of damage; generally, turning the shaft is done after shutting down the machine to prevent the shaft from bending or deforming
It depends on the specific circumstances. In the case of a serious accident, turning the shaft may increase the extent of damage; generally, turning the shaft is done after shutting down the machine to prevent the shaft from bending or deforming
Generally, it is necessary to turn the shaft by hand; if the shaft turning device is broken, manual turning is the only option. We usually remove the coupling guard in order to do this.
The turntable is broken; contact the fitter and electrical maintenance staff promptly to address the issue and restore the operation of the turntable； If it cannot be handled, the fitter will have to remove the coupling guard and turn the shaft manually ； In some current designs, even after removing the coupling guard, it is still not possible to rotate the component; in such cases, there is nothing but to wait and report the situation to higher-level management promptly.
Cranking the engine is a must. The shaft is kept rotating continuously during cooling by using a barring gear to prevent it from bending. Typically, the barring motor is equipped with a dual-power supply, one of which is powered by the battery. If even the battery is unreliable, there is usually a handwheel available for manual rotation. However, under normal circumstances, a handwheel is not installed on the barring motor; it is only fitted when the barring motor is not working properly and barring is required.
Cranking is necessary; by cranking, the shaft is kept rotating during cooling to prevent it from bending. Manual turning of the shaft should begin within five minutes after it stops rotating. Turn the shaft every 15–20 minutes during the first hour, every 30 minutes during the second hour, once per hour during the third hour, and every two hours after the fourth hour, until it reaches normal temperature
Except in cases of shutdown due to the lack of lubrication or shaft displacement interlock, it is required to start the shaft turning device; this allows the shaft to keep rotating during cooling to prevent it from bending.