Interview Questions on Steam Turbines | Interview Questions In Thermal Engineering
Series of questionnaires and answers for Mechanical and chemical engineering students on thermal engineering. Heat transfer, thermodynamics, energy conversion and heat wave solutions are all about thermal engineering. Mechanical engineers and chemical engineers might have been engaged in thermal engineering. A mechanical engineer ‘s job is to have solid academic knowledge through hard work, strong heat transfer knowledge, fluid flow and thermal control and outstanding communication ability. Different industries seek graduates in mechanical or chemical engineering as thermal engineers, thermal systems engineers, thermal technicians, chemical engineers and more. So get ready for the forthcoming interview by taking a peek at the questions and answers from the thermal engineer interview.
How many governors are needed for safe turbine operation? Why?
Two independent governors are needed for safe turbine operation:
One is an over speed or emergency trip that shuts off the steam at 10 percent above running speed (maximum speed).
In which part of the steam turbine does stress corrosion cracking (SCC) occur?
In the wet stages of the low-pressure turbine.
In which zone of steam turbines has temperature-creep rupture been observed?
Damage due to creep is encountered in high temperature (exceeding 455°C) zones. That is, it has been found to occur in the control stages of the high-pressure and intermediate-pressure turbines where steam temperature sometimes exceed 540°C. In the reheat stage, it has been observed that creep has caused complete lifting of the blade shroud bands.
Carbon rings fitted in segments around the shaft and held together by garter or retainer springs.
Labyrinths mated with shaft serrations or shaft seal strips.
Water seals where a shaft runner acts as a pump to create a ring of water around the shaft. Use only treated water to avoid shaft pitting.
Stuffing box using woven or soft packing rings that are compressed with a gland to prevent leakage along the shaft.
What are the basic causes of the problem of rotor failure?
Fatigue failure due to high stress.
Aggressive operating environment
What are the differences between impulse and reaction turbines?
The impulse turbine is characterized by the fact that it requires nozzles and that the pressure drop of steam takes place in the nozzles.
The reaction turbine, unlike the impulse turbines has no nozzles, as such. It consists of a row of blades mounted on a drum. The drum blades are separated by rows of fixed blades mounted in the turbine casing. These fixed blades serve as nozzles as well as the means of correcting the direction of steam onto the moving blades.
In the case of reaction turbines, the pressure drop of steam takes place over the blades. This pressure drop produces a reaction and hence cause the motion of the rotor.
Question And Answer For Steam Turbine | Interview Questions in Steam Turbines
Steam Turbine has been a device that derives thermal energy from the pressurized steam, which is used to carry out rotation work on a revolving drive shaft. The generator rotates and produces energy as the steam engine rotates. It is ideal for running a generator electrically. The thermal efficiency of steam turbines continues to increase as the average energy supply temperature increases with heat transfer. After that pursue these question and answer for Steam Turbine interview questions for steam Turbine Engineer, Supervisor, manufacturer, power plant operator, instrument engineer, senior process flow engineer, facility and machinery manager etc.
These questions and answers support those who have worked in Steam turbine-based thermal engineers who want to know more about the operation of the turbine. Since Turbine is an extra careful critical feature. These questions and answers will help you learn more about the operations of steam turbines.
How can problems of “excessive vibration or noise” due to piping strain be avoided on steam turbines?
The inlet as well as exhaust steam lines should be firmly supported to avoid strains from being imposed on the turbine.
Adequate allowance should be made for expansion of steam pipes due to heat.
How the deposits in turbine be removed? | Question and Answer for Steam Turbine
Water soluble deposits may be washed off with condensate or wet steam.
Water insoluble deposits are removed mechanically after dismantling the turbine.
Experience shows that water soluble deposits are embedded in layers of water-insoluble deposits. And when the washing process is carried out, water soluble parts of the deposit dissolve away leaving a loose, friable skeleton of water-insoluble deposits which then break loose and wash away.
How the fatigue damage on high pressure blades be corrected?
Fatigue-damage on high-pressure blades arises due to vibration induced by partial-arc admission. This can be corrected by switching over to full arc admission technique.
How the misalignment of Flanges be rectified? | Question and Answer for Steam Turbine
The bolts holding the flanges together are to be tightened. The coupling is to be checked for squareness between the bore and the face. At the same time axial clearance is to be checked.
How the problem of excessive speed variation due to throttle assembly friction be overcome?
The throttle should be dismantled. Moving parts should be checked for free and smooth movement. Using very fine-grained emery paper, the throttle valve seats and valve steam should be polished.
How the problems of vibration and fatigue arise in steam turbine blades? | Question and Answer for Steam Turbine
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 solid-particle erosion occur? | Question and Answer for Steam Turbine
Solid-particle erosion, i.e. SPE occurs in the high-pressure blades. And it takes place when hard particles of iron exfoliated by steam from super heater tubes, re-heater tubes, steam headers and steam leads strike on the surface of turbine blades.
How does the internal efficiency monitoring lead to the detection of turbine deposits? | Question and Answer for Steam Turbine
Process heat drop.
Adiabatic heat drop.
The process heat drop and adiabatic heat drop are obtained from a Mollier-Chart for the corresponding values of steam parameters – pressure and temperature – at initial and final conditions.
How is a fly ball governor used with a hydraulic control? | Question and Answer for Steam Turbine
As the turbine speeds up, the weights are moved outward by centrifugal force, causing linkage to open a pilot valve that admits and releases oil on either side of a piston or on one side of a spring-loaded piston. The movement of the piston controls the steam valves.