How do the problems of vibration and fatigue arise with steam turbine blades?
• These arise due to flow irregularities introduced because of manufacturing defects, e.g. lack of control over tolerances. • System operating parameter, e.g. low flow may excite various modes of vibration in the blades. • How does deposit formation on turbine blades affect turbine efficiency? Answer: About 500 g of deposits distributed more or less evenly all over the blading section can bring down turbine efficiency by 1%. • How does improper governor lubrication arise and Answers: • In the event of low governor oil level or if the oil is dirty or foamy, it will cause improper governor lubrication. What is the remedy to it? • The dirty or foamy lube oil should be drained off, governor should be flushed and refilled with a fresh charge of proper oil. • In the event of low level, the level should be built up by make- up lube oil. • How does pressure monitoring ensure detection of turbine deposits? Answers: • Pressure of steam expanding in the turbine is measured at characteristic point
