Interview Questions.

Question 1. What Is A Stage In A Steam Turbine?

Answer :

In an impulse turbine, the stage is a hard and fast of shifting blades at the back of the nozzle. In a reaction turbine, each row of blades is known as a "stage." A single Curtis stage may also encompass  or extra rows of transferring blade.

Question 2. What Is A Diaphragm?

Answer :

Partitions among strain levels in a turbine's casing are referred to as diaphragms. They preserve the vane-formed nozzles and seals between the levels. Usually labyrinth-kind seals are used. One-half of of the diaphragm is fitted into the pinnacle of the casing, the alternative half into the bottom.

Thermal Power Plant Interview Questions
Question three. What Is A Radial-glide Turbine?

Answer :

In a radial-float turbine, steam flows outward from the shaft to the casing. The unit is often a response unit, having both constant and shifting blades. They are used for unique jobs and are more common to European producers, such as Sta-Laval (now ABB).

Question four. What Are Four Types Of Turbine Seals?

Answer :

Carbon jewelry outfitted in segments across the shaft and held collectively by means of garter or retainer springs.
Labyrinth mated with shaft serration’s or shaft seal strips.
Water seals where a shaft runner acts as a pump to create a ring of water across the shaft. Use most effective handled water to avoid shaft pitting.
Stuffing container the use of woven or smooth packing jewelry which might be compressed with a gland to save you leakage along the shaft.
TurboGears Tutorial
Question five. In Which Turbine Is Tip Leakage A Problem?

Answer :

Tip leakage is a trouble in reaction mills. Here, each vane forms a nozzle; steam need to flow via the transferring nozzle to the fixed nozzle. Steam escaping throughout the recommendations of the blades represents a lack of work. Therefore, tip seals are used prevent this.

TurboGears Interview Questions
Question 6. What Are Two Types Of Clearance In A Turbine?

Answer :

Radial - clearance on the suggestions of the rotor and casing.
Axial - the fore-and-aft clearance, at the perimeters of the rotor and the casing.
Question 7. What Are Four Types Of Thrust Hearings?

Answer :

Babbitt-confronted collar bearings.
Tilting pivotal pads.
Tapered land bearings.
Rolling-contact (roller or ball) bearings.
Oil and Gas Interview Questions
Question 8. What Is The Function Of A Thrust Bearing?

Answer :

Thrust bearings hold the rotor in its accurate axial position.

Question 9. What Is A Balance Piston?

Answer :

Reaction turbines have axial thrust due to the fact pressure on the getting into facet is extra than stress at the leaving side of each stage. To counteract this force, steam is admitted to a dummy (stability) piston chamber at the low-pressure stop of the rotor. Some designers additionally use a balance piston on impulse generators which have a high thrust. Instead of piston, seal strips are also used to duplicate a piston's counter force.

Natural Gas Interview Questions
Question 10. Why Should A Steam Or Moisture Separator Be Installed In The Steam Line Next To A Steam Turbine?

Answer :

All multistage turbines, low-pressure turbines, and generators working at high pressure with saturated steam need to have a moisture separator in order to prevent fast blade wear from water erosion.

Question 11. What Are Some Conditions That May Prevent A Turbine From Developing Full Power?

Answer :

The machine is overloaded.
The initial steam pressure and temperature aren't up to layout situations.
The exhaust stress is just too excessive.
The governor is about too low.
The steam strainer is clogged.
Turbine nozzles are clogged with deposits.
Internal wear on nozzles and blades.
Gas Detection System Interview Questions
Question 12. Why Is It Necessary To Open Casing Drains And Drains On The Steam Line Going To The Turbine When A Turbine Is To Be Started?

Answer :

To keep away from slugging nozzles and blades in the turbine with condensate on start-up; this can ruin these additives from effect. The blades were designed to address steam, now not water.

Thermal Power Plant Interview Questions
Question thirteen. What Is Steam Rate As Applied To Turbo-generators?

Answer :

The steam rate is the pounds of steam that need to be furnished in keeping with kilowatt-hour of generator output at the steam turbine inlet.

Question 14. What Are The Two Basic Types Of Steam Turbines?

Answer :

Impulse kind.
Reaction kind.
Question 15. What Is The Operating Principle Of An Impulse Turbine?

Answer :

The fundamental idea of an impulse turbine is that a jet of steam from a hard and fast nozzle pushes against the rotor blades and impels them forward. The speed of the steam is set twice as fast as the rate of the blades. Only mills using constant nozzles are classified as impulse turbines.

Gas Analyzer Interview Questions
Question 16. What Is The Operating Principle Of A Reaction Turbine?

Answer :

A reaction turbine makes use of a jet of steam that flows from a nozzle at the rotor. Actually, the steam is directed into the moving blades by means of fixed blades designed to enlarge the steam. The result is a small boom in velocity over that of the shifting blades. These blades form a wall of transferring nozzles that further extend the steam. The steam flow is partially reversed by using the shifting blades, generating a reaction at the blades. Since the pressure drop is small throughout each row of nozzles (blades), the rate is relatively low. Therefore, more rows of moving blades are wished than in an impulse turbine.

Question 17. What Are Topping And Superposed Turbines?

Answer :

Topping and superposed mills arc excessive-pressure, non-condensing devices that can be brought to an older, moderate-pressure plant. Topping turbines receive high-stress steam from new excessive-strain boilers. The exhaust steam of the new turbine has the equal strain as the antique boilers and is used to deliver the antique mills.

Solar Thermal Interview Questions
Question 18. What Is An Extraction Turbine?

Answer :

In an extraction turbine, steam is withdrawn from one or more degrees, at one or greater pressures, for heating, plant system, or feedwater heater needs. They are frequently referred to as "bleeder turbines."

TurboGears Interview Questions
Question 19. What Is A Combination Thrust And Radial Bearing?

Answer :

This unit has the ends of the Babbitt bearing extended radially over the give up of the shell. Collars at the rotor face these thrust pads, and the magazine is supported within the bearing between the thrust collars.

Question 20. What Is A Tapered-land Thrust Bearing?

Answer :

The babbitt face of a tapered-land thrust bearing has a series of constant pads divided through radial slots. The leading aspect of each area is tapered, permitting an oil wedge to build up and convey the thrust among the collar and pad.

Wind Turbine Interview Questions
Question 21. What Is Important To Remember About Radial Bearings?

Answer :

A turbine rotor is supported with the aid of  radial bearings, one on each cease of the steam cylinder. These bearings have to be accurately aligned to hold the near clearance among the shaft and the shaft seals, and among the rotor and the casing. If excessive bearing put on lowers the he rotor, remarkable damage can be accomplished to the turbine.

Question 22. How Many Governors Are Needed For Safe Turbine Operation? Why?

Answer :

Two impartial governors are needed for secure turbine operation. One is an over pace or emergency experience that shuts off the steam at 10 percentage above walking pace (most speed). The 2d, or essential governor, generally controls velocity at a consistent price; however, many programs have variable pace manipulate.

Question 23. How Is A Flyball Governor Used With A Hydraulic Control?

Answer :

As the turbine accelerates, the weights are moved outward through centrifugal pressure, causing linkage to open a pilot valve that admits and releases oil on either facet of a piston or on one aspect of a spring-loaded piston. The movement of the piston controls the steam valves.

Solar Water Pumps Interview Questions
Question 24. What Is A Multi-port Governor Valve? Why Is It Used?

Answer :

In large generators, a valve controls steam go with the flow to organizations of nozzles. The number of open valves controls the number of nozzles in use in step with the load. A bar-raise or cam arrangement operated via the governor opens and closes these valves in sequence. Such a device is a multi-port valve. Using nozzles at complete steam pressure is greater green than throttling the steam.

Oil and Gas Interview Questions
Question 25. What Is Meant By Critical Speed?

Answer :

 It is the rate at which the device vibrates maximum violently. It is due to many reasons, consisting of imbalance or harmonic vibrations installation by means of the complete device. To minimize harm, the turbine need to be hurried through the recognized essential velocity as unexpectedly as viable. (Caution, make sure the vibration is as a result of critical pace and no longer by using some different problem).

Question 26. How Is Oil Pressure Maintained When Starting Or Stopping A Medium-sized Turbine?

Answer :

An auxiliary pump is supplied to maintain oil pressure. Some auxiliary pumps are grew to become by a hand crank; others are motor-driven. This pump is used whilst the fundamental pump is running too slowly to offer pressure, as whilst beginning or securing a medium-sized turbine.

Thermal Engineer Interview Questions
Question 27. Besides Lubrication, Which Are Two Functions Of Lubricating Oil In Some Turbines?

Answer :

In large gadgets, lube oil cools the bearings via carrying off warmness to the oil coolers. Lube oil in a few mills additionally acts as a hydraulic fluid to perform the governor speed-control gadget.

Natural Gas Interview Questions
Question 28. What Is Meant By The Water Rate Of A Turbine?

Answer :

Water fee is any other time period used for the steam charge.

Question 29. What Is The Difference Between Partial And Full Arc Admission?

Answer :

In multi-valve turbine inlets, partial arc ad undertaking permits the steam to enter consistent with valve establishing in a sequential manner, in order load is elevated, extra valves open to confess steam. This can purpose uneven heating on the excessive-strain annulus because the valves are individually opened with load boom. In complete-arc admission, all regulating valves open however best at a percentage of their full opening. With load increase, they all open greater completely. This offers extra uniform heating around the high-stress part of the turbine. Most modern-day controls start with complete-arc and transfer to partial arc to lessen throttling losses via the valves.

Gas Compressor Interview Questions
Question 30. At What Points Does Corrosion Fatigue Does Show Up?

Answer :

It assaults trailing edges, near the base of the foil and additionally the blade-root serration’s.

Question 31. Besides Lubrication, What Are Two Functions Of Lubricating Oil In Some Turbines?

Answer :

In larger devices, lube oil cools the bearings via sporting off heat to the oil coolers. Lube oil in some generators also acts as a hydraulic fluid to function the governor velocity-control gadget.

Question 32. Despite Preventive Measures, Damage Due To Moisture Impingement Has Been Found, In Certain Cases, In The Shield And Beyond. Why?

Answer :

Shields are designed and fabricated on the premise of predicted range of steam/water portions impacting the blades at precise angles.
Now if the working situations deviate significantly from layout parameters then the erosion harm will arise. And in some cases it can pass past nominal erosion put on and warrant restore.
Also the corrosion of casing can arise because of blockage/clogging of water drains or extraction thereby forcing the water back into the casing. If this condensate water is carried over to steam route and impacts the blade, thermal-fatigue failure can arise inside a quick duration.
Question 33. By Monitoring The Exhaust Steam Temperature, How Can The Blade Deposition Be Predicted?

Answer :

Immediately after the 1st commissioning, the special values of exhaust temperature for extraordinary steam drift rates are precisely decided and plotted in opposition to steam waft. This will produce the first actual graph. This is for a easy turbine.
Similar graphs are to be drawn at later periods for evaluating with the preliminary graph.
A upward push in exhaust steam temperature beneath the equal conditions refers to deposit formation.
An boom of exhaust steam temperature by greater than 10% in the variety of 70 to l00% steam flow, suggests inadmissible blade depositions. Shutdown is to be taken and blades are to be washed off deposits.
Gas Detection System Interview Questions
Question 34. Do The Radial Axial-bore Cracks Occur In The Lp Rotor/shaft Alone?

Answer :

These also are acknowledged to arise inside the HP as well as HP rotors.

Question 35. Do You Stop Cooling-water Flow Through A Steam Condenser As Soon As The Turbine Is Slopped?

Answer :

You must hold the cooling water circulating for about 15 mill or more so that the condenser has a risk to calm down regularly and evenly. Be certain to have cooling water flowing thru the condenser earlier than setting out so that you can prevent stay steam from entering the condenser except it's far cooled. Overheating can cause intense leaks and different headaches.

Question 36. Do You Think That Turbine Blade Failure Is The Only Cause Of Unreliability Of Steam Turbines? Does Upgrading Of Turbine Means Replacement Of Blades And/or Improvement Of Blade Design?

Answer :

Like the blades, the steam-turbine rotors are surprisingly careworn components. They are challenge to cracking by means of a selection of failure mechanisms. Rotor failures do occur. And after they arise the end result is catastrophic with the complete destruction of the unit and the total lack of generating potential.

Therefore, special attention ought to take delivery of to rotor upgrading and repairing strategies.

BLADE FAILURES

Unknown 26%
Stress-Corrosion Cracking 22%
High-Cycle Fatigue 20%
Corrosion-Fatigue Cracking 7%
Temperature Creep Rupture 6%
Low-Cycle Fatigue five%
Corrosion four%
Other reasons 10%
Besides, many damage mechanisms function in mixture of, poor steam/water chemistry, certain blade design elements that vary from one turbine manufacture to different, device working parameters.

Gas Analyzer Interview Questions
Question 37. How Can Damaged Tenons Be Repaired?

Answer :

By adopting contemporary welding techniques, tenons may be rebuilt This in a few cases outcomes in extended blade life.

Question 38. How Can Problems Of "immoderate Vibration Or Noise" Due To Piping Strain Be Avoided On Steam Turbines?

Answer :

The inlet in addition to exhaust steam traces need to be firmly supported to avoid lines from being imposed at the turbine.

Adequate allowance ought to be made for enlargement of steam pipes due to heat.

Question 39. How Can Steam Turbines Be Classified?

Answer :

By the action of steam:

Impulse.
Reaction.
Impulse and reaction mixed.
The range of step discounts worried:

Single level.
Multi-stage.
Whether there may be one or more revolving vanes separated by stationary reversing vanes.
The course of steam float:

Axial.
Radial.
Mixed.
Tangential.
Helical.
Reentry.
The inlet steam strain:

High strain.
Medium pressure.
Low strain.
The very last stress:

Condensing.
Non-condensing.
The supply of steam:

Extraction.
Accumulator.
Question 40. What Are The Disadvantages Of Velocity Compounding?

Answer :

Steam velocity is too excessive and that is answerable for considerable friction losses.

Blade efficiency decreases with the boom of the range of levels.

With the increase of the range of rows, the strength evolved in successive rows of blade decreases. For as much as, the identical space and material are required for each degree, it means, consequently, that each one stages aren't economically efficient.

Solar Thermal Interview Questions
Question 41. What Are The Factors That Contribute To Bearing Failure In A Steam Turbine?

Answer :

Improper lubrication. Only the endorsed lubricant need to be used.
Inadequate water-cooling.
The jacket temperature must be maintained within the variety of 37-60°C
The drift of cooling water ought to be adjusted as a result.
Misalignment:It is applicable that ball bearings should fit at the turbine shaft with a light press fit. If the proper is too tight, it's going to motive cramping. On the opposite hand, if the right is too unfastened it's going to motive the inner race to show at the shaft. Both conditions are undesirable. They result in wear, immoderate vibration and overheating. And bearing failure turns into the last result.
Bearing in shape.
Excessive thrust.
Unbalance.
Rusting of bearing.
Question forty two. What Are The Advantages Of Welded Rotors?

Answer :

Welded rotor is a composed frame built up through welding the character segments. So the limitations on forgings ability do not practice.
Welding discs collectively results in a lower stress stage. Therefore, greater ductile materials may be chosen to withstand SCC attack.
There aren't any keyways. So areas of high stress concentrations are eliminated.
Wind Turbine Interview Questions
Question forty three. What Are The Basic Causes Of The Problem Of Rotor Failure?

Answer :

Normal wear.
Fatigue failure due to high stress.
Design deficiency.
Aggressive working environment
Question forty four. What Are The Causes Of Radial Axial-bore Cracks On Hp/ip Rotors/shafts?

Answer :

The foremost reason is creep, which might also act with or without low cycle fatigue.
Also the cracks result due to bad creep ductility because of faulty heat remedy manner.
Question forty five. What Are The Differences Between Impulse And Reaction Turbines?

Answer :

The impulse turbine is characterised by means of the reality that it requires nozzles and that the stress drop of steam takes region within the nozzles.
The reaction turbine, unlike the impulse mills has no nozzles, as such. It consists of a row of blades hooked up on a drum. The drum blades are separated through rows of fixed blades hooked up in the turbine casing. These fixed blades serve as nozzles as well as the approach of correcting the direction of steam onto the shifting blades.
In the case of response generators, the strain drop of steam takes region over the blades. This stress drop produces a response and for this reason reason the movement of the rotor.