Question 710Steam Plants - Assistant Engineer70% to pass
The most critical period of main turbine operation is during cold start-up, rather than hot shutdown because _______________.
AI Explanation
The correct answer is D) differential expansion can result from the temperature difference between the rotor and rotor casing.
During a cold start-up, the temperature difference between the rotor and the rotor casing can be significant, leading to differential expansion. This differential expansion can cause stresses on the turbine components and increase the risk of damage. In contrast, during a hot shutdown, the temperatures are more uniform, and the risk of differential expansion is lower.
The other options are incorrect because:
A) Harmonic vibrations are more likely to occur during steady-state operation, not specifically during start-up.
B) Blade erosion damage from dry steam impingement is a concern during both start-up and shutdown, not specifically during start-up.
C) Lubricant film thickness is a concern during both start-up and shutdown, not specifically during start-up.
Related Questions
#708 During normal operation of a main propulsion turbine, the lube oil supply temperature to the bearings should be maintained at approximately _______________.#709 Operating a steam turbine propulsion unit at medium-speed, in an area with extremely cold sea water and the main circulating pump providing full cooling water flow to the condenser will result in _______________.#711 After properly lining up the main propulsion turbine for warm up, steam should first be admitted to the rotor through the _______________.#712 Which of the listed procedures should be followed when raising vacuum on the main propulsion plant prior to getting underway? #713 Prior to rolling the main turbines in preparation for getting underway, you should _______________.