What are two types of clearance in a turbine?

1 Answer

Answer :

1. Radial - clearance at the tips of the rotor and casing.  
2. Axial - the fore-and-aft clearance, at the sides of the rotor and the casing.

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Description : What are four types of turbine seals?

Last Answer : 1. Carbon rings fitted in segments around the shaft and held together by garter or retainer springs. 2. Labyrinth mated with shaft serration's or shaft seal strips. 3. Water seals where a ... using woven or soft packing rings that are compressed with a gland to prevent leakage along the shaft.

Description : How many governors are needed for safe turbine operation? Why? Two independent governors are needed for safe turbine operation:

Last Answer : 1. One is an overspeed or emergency trip that shuts off the steam at 10 percent above running speed (maximum speed). 2. The second, or main governor, usually controls speed at a constant rate; however, many applications have variable speed control.

Description : Why is there a relief valve on a turbine casing?

Last Answer : The turbine casing is fitted with spring-loaded relief valves to prevent damage by excessive steam pressure at the low-pressure end if the exhaust valve is closed accidentally. Some casings on smaller ... -pressure of the exhaust end. A spring-loaded relic valve is needed to relieve high pressure.

Description : What is the safe maximum tripping speed of a turbine operating at 2500 rpm?

Last Answer : The rule is to trip at 10 percent overspeed. Therefore, 2500 x 1.10 = 2750 rpm.

Description : What is the remedy for a bent steam turbine shaft causing excessive vibration?

Last Answer : 1. The run-out of the shaft near the center as well as the shaft extension should be checked. 2. If the run-out is excessive, the shaft is to be replaced.

Description : What is the cause of turbine deposits?

Last Answer : The turbine deposits are steam-born foreign matters settled on turbine blades. Substances dissolved in the BFW transfer partly from the water to steam, during the process of evaporation. They get dissolved in the steam and are carried into the steam turbine.

Description : What are the possible causes of excessive vibration or noise in a steam turbine?

Last Answer : 1. Misalignment. 2. Worn bearings. 3. Worn coupling to driven machine. 4. Unbalanced coupling to driven machine. 5. Unbalanced wheel. 6. Piping strain. 7. Bent shaft.

Description : What are the main causes of turbine vibration?

Last Answer : 2. unbalanced parts 3. poor alignment of parts 4. loose parts 5. rubbing parts 6. lubrication troubles 7. steam troubles 8. foundation troubles 9. cracked or excessively worn parts

Description : How is the washing of turbine blades carried out with the condensate?

Last Answer : 1. The washing is carried out with the condensate at 100°C. 2. The turbine is cooled or heated up to 100°C and filled with the condensate via a turbine drain. 3. The rotor is ... level), the rotor is rotated and the condensate is drained after sometime. This process is repeated several times.

Description : How does the foreign-particle damage of turbine blades arise?

Last Answer : It occurs due to impact on blades by foreign particles (debris) left in the system following outages and become steam-borne later.

Description : How does deposit formation on turbine blades affect turbine efficiency?

Last Answer : About 500 g of deposits distributed more or less evenly all over the blading section can bring down turbine efficiency by 1%.

Description : How can the detection of deposits in a turbine be made during operation?

Last Answer : 1. Pressure monitoring. 2. Internal efficiency monitoring. 3. Monitoring exhaust steam temperature. 4. Monitoring specific steam consumption.

Description : What is an extraction turbine?

Last Answer : In an extraction turbine, steam is withdrawn from one or more stages, at one or more pressures, for heating, plant process, or feedwater heater needs. They are often called "bleeder turbines."

Description : What are some conditions that may prevent a turbine from developing full power?

Last Answer : 1. The machine is overloaded. 2. The initial steam pressure and temperature are not up to design conditions. 3. The exhaust pressure is too high. 4. The governor is set too low. 5. ... is clogged. 6. Turbine nozzles are clogged with deposits. 7. Internal wear on nozzles and blades.

Description : What is a stage in a steam turbine?

Last Answer : In an impulse turbine, the stage is a set of moving blades behind the nozzle. In a reaction turbine, each row of blades is called a "stage." A single Curtis stage may consist of two or more rows of moving blades.

Description : What are the two basic types of steam turbines?

Last Answer : 1. Impulse type. 2. Reaction type

Description : How many types of steam condenser are known?

Last Answer : 1. Jet Condensers - direct contact heat exchanger. 2. Surface Condensers - indirect contact heat exchanger using water. 3. Air Condensers - direct contact heat exchangers using air.

Description : What are four types of thrust hearings?

Last Answer : 1. Babbitt-faced collar bearings. 2. Tilting pivotal pads. 3. Tapered land bearings. 4. Rolling-contact (roller or ball) bearings.

Description : What is the purpose of a turning gear?

Last Answer : Heat must be prevented from warping the rotors of large turbines or high-temperature turbines of 400°C or more. When the turbine is being shut down, a motor-driven turning gear is engaged to the turbine to rotate the spindle and allow uniform cooling.

Description : What is an air ejector?

Last Answer : An air ejector is a steam siphon that removes non-condensable gases from the condenser.

Description : What is a surface condenser?

Last Answer : It is a shell-and-tube heat exchanger in which steam is condensed on the shell-side while cooling water flows through the tubes. The condensate and cooling water leave the system separately.

Description : What are the effects of air leakage in the condenser?

Last Answer : 1. It increases the back pressure on the turbine with the effect that there is less heat drop and low thermal efficiency of the plant 2. The pressure of air in the condenser lowers ... steam, because air having poor thermal conductivity impairs the overall heat transfer from the steam-air mixture.

Description : What maybe the possible causes for the safety trip to trip at normal speed?

Last Answer : 1. Excessive vibration. 2. Leakage in the pilot valve. 3. Deposition of dirt in the safety trip valve.

Description : What are the basic causes of the problem of rotor failure?

Last Answer : 1. Normal wear. 2. Fatigue failure due to high stress. 3. Design deficiency. 4. Aggressive operating environment

Description : How will you detect that misalignment is the probable cause of excessive vibration?

Last Answer : 1. Coupling to the driven machine is to be disconnected. 2. The turbine is to be run alone. 3. If the turbine runs smoothly, either misalignment, worn coupling or the driven equipment is the cause of the trouble.

Description : What is the remedy to it?

Last Answer : The spring end cap as well as safety trip valve should be cleaned

Description : How does the dirty safety trip valve trip the safety trip at normal speed?

Last Answer : Dirt may find its way to the safety trip valve and get deposited around the spring end cap end. This will block the clearance between the safety trip valve and the spring end cap. As a result the steam pressure in the spring cap gets lowered allowing the valve to close.

Description : How can the speed variation be reduced by making a governor droop adjustment?

Last Answer : If the internal droop setting is increased, the speed variation will reduce.

Description : How can the deposits be removed?

Last Answer : 1. Water soluble deposits may be washed off with condensate or wet steam. 2. Water insoluble deposits are removed mechanically after dismantling the turbine. 3. Experience shows that water ... leaving a loose, friable skeleton of water-insoluble deposits which then break loose and wash away.

Description : The final pressure:

Last Answer : 16. Condensing. 17. Non-condensing.

Description : The inlet steam pressure:

Last Answer : 13. High pressure. 14. Medium pressure. 15. Low pressure.

Description : The direction of steam flow:

Last Answer : 7. Axial. 8. Radial. 9. Mixed. 10. Tangential. 11. Helical. 12. Reentry.

Description : The number of step reductions involved:

Last Answer : 4. Single stage. 5. Multi-stage. 6. Whether there is one or more revolving vanes separated by stationary reversing vanes.

Description : How can steam turbines be classified? By the action of steam:

Last Answer : 1. Impulse. 2. Reaction. 3. Impulse and reaction combined

Description : How can problems of "excessive vibration or noise" due to piping strain be avoided on steam turbines?

Last Answer : 1. The inlet as well as exhaust steam lines should be firmly supported to avoid strains from being imposed on the turbine. 2. Adequate allowance should be made for expansion of steam pipes due to heat.

Description : What is meant by critical speed?

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Description : What is a tapered-land thrust bearing?

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Description : What is a combination thrust and radial bearing?

Last Answer : This unit has the ends of the babbitt bearing extended radially over the end of the shell. Collars on the rotor face these thrust pads, and the journal is supported in the bearing between the thrust collars.

Description : What is a balance piston?

Last Answer : Reaction turbines have axial thrust because pressure on the entering side is greater than pressure on the leaving side of each stage. To counteract this force, steam is admitted to a dummy (balance) ... thrust. Instead of piston, seal strips are also used to duplicate a piston's counter force.

Description : What is the function of a thrust bearing?

Last Answer : Thrust bearings keep the rotor in its correct axial position.

Description : What is a diaphragm?

Last Answer : Partitions between pressure stages in a turbine's casing are called diaphragms. They hold the vane-shaped nozzles and seals between the stages. Usually labyrinth-type seals are used. One-half of the diaphragm is fitted into the top of the casing, the other half into the bottom.

Description : What Are Two Types Of Clearance In A Turbine?

Last Answer : 1. Radial – clearance at the tips of the rotor and casing. 2. Axial – the foreandaft clearance, at the sides of the rotor and the casing.

Description : What are types of steam turbine and why are they popular?

Last Answer : Answer: Condensing and non-condensing, Popular because can convert large amounts of heat energy into mechanical work very efficiently.

Description : What Are Four Types Of Turbine Seals?

Last Answer : 1. Carbon rings fitted in segments around the shaft and held together by garter or retainer springs. 2. Labyrinth mated with shaft serration's or shaft seal strips. 3. Water seals where a shaft ... using woven or soft packing rings that are compressed with a gland to prevent leakage along the shaft.

Description : Explain the Need of draft tube in reaction turbine .state the types of draft tube used in it

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Description : List the types of turbine used in hydro power plant.  

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