Power Plant Turbine Objectives Questions And Answers

Gas Turbine-Steam Power Plant Multiple Choice Questions And Answers

1. What part or % of power developed is utilised for driving the compressor?

a) 65 %

b) 70 %

c) 55 %

d) 80 %

Answer: 65 %

2. The heating value of gaseous fuels is about _____________

a) 500 kJ/litre

b) 30 kJ/litre

c) 100 kJ/litre

d) 10 kJ/litre

Answer: 30 kJ/litre

3. In the ____________ heat transfer takes place between the exhaust gases and cool air.

a) Intercooler

b) Re-heater

c) Regenerator

d) Compressor

Answer: Regenerator

4. The efficiency of multistage compressor is _____ than a single stage.

a) lower

b) higher

c) equal to

d) all of the mentioned

Answer: lower

5. The compressor has to be started _____________

a) Before starting the gas turbine

b) After starting the gas turbine

c) Simultaneously with starting of gas turbine

d) At any time during the operation

Answer: Before starting the gas turbine

6. Gas turbine is shut down by ____________

a) Turning off starter

b) Stopping the compressor

c) Fuel is cut off from the combustor

d) All of the mentioned

Answer: Fuel is cut off from the combustor

7. In gas turbine, intercooler is placed _____________

a) before low pressure compressor

b) in between low pressure compressor and high pressure compressor

c) in between high pressure compressor and turbine

d) none of the mentioned

Answer: in between low pressure compressor and high pressure compressor

8. The ‘work ratio’ increases with _____________

a) increase in turbine inlet pressure

b) decrease in compressor inlet temperature

c) decrease in pressure ratio of the cycle

d) all of the mentioned

Answer: all of the mentioned

9. In centrifugal compressor, power input varies as _________

a) directly as the speed ratio

b) the square of speed ratio

c) the cube of the speed ratio

d) all of the mentioned

Answer: the cube of the speed ratio

10. In centrifugal compressor, the diffuser converts _________

a) Kinetic energy into pressure energy

b) Pressure energy into Kinetic energy

c) Kinetic energy into Mechanical energy

d) Mechanical energy into Kinetic energy

Answer: Kinetic energy into pressure energy

11. In the centrifugal compressor, total pressure varies _____________

a) directly as the speed ratio

b) square of speed ratio

c) cube of the speed ratio

d) all of the mentioned

Answer: square of speed ratio

12. The ratio of heat actually released by 1kg of fuel to heat that would be released by complete perfect combustion is called ___________

a) Thermal efficiency

b) Combustion efficiency

c) Engine efficiency

d) Compression efficiency

Answer: Combustion efficiency

13. A Gas Turbine is which type of combustion plant?

a) external

b) open

c) internal

d) cannot say

Answer: internal

14. What is the air standard cycle for a Gas-Turbine called?

a) Reheat cycle

b) Rankine cycle

c) Brayton cycle

d) Diesel cycle

Answer: Brayton cycle

15. Which of these is not a part of a Gas Turbine Plant?

a) Compressor

b) Gas Turbine

c) Combustion chamber

d) Boiler

Answer: Boiler

16. The gas turbine power plant mainly uses which among the following fuels?

a) Coal and Peat

b) Kerosene oil and diesel oil and residual oil

c) Gas oil

d) Natural gas and liquid petroleum fuel

Answer: Natural gas and liquid petroleum fuel

17. Power is produced when the working fluid does some work on the?

a) Shaft

b) Fins

c) Blades

d) None of the mentioned

Answer: Blades

18. What is the difference between a Rankine cycle & a Brayton cycle?

a) working fluid in a Brayton cycle undergoes phase change while it doesn’t in Rankine cycle

b) working fluid in a Brayton cycle doesn’t undergo phase change while it does in Rankine cycle

c) both are same

d) none of the mentioned

Answer: working fluid in a Brayton cycle doesn’t undergo phase change while it does in Rankine cycle

19. Which of the following method(s) can be used to improve the thermal efficiency of open cycle gas turbine plant?

a) Inter-cooling

b) Reheating

c) Regeneration

d) All of the mentioned

Answer: All of the mentioned

20. Which among these is the main component of a gas turbine plant?

a) Condenser

b) Compressor

c) Boiler

d) Both Compressor & Boiler

Answer: Compressor

21. What are the major field(s) of application of gas turbine?

a) Aviation

b) Oil and gas industry

c) Marine propulsion

d) All of the mentioned

Answer: All of the mentioned

22. Which of the following is a type of Gas Turbine Plant?

a) Single Acting

b) Double Acting

c) Open

d) None of the mentioned

Answer: Open

23. Which of the following is (are) the limitation(s) of gas turbines?

a) They are not self-starting

b) Higher rotor speeds

c) Low efficiencies at part loads

d) All of the mentioned

Answer: All of the mentioned

24. Which type of compressor is used in a gas turbine plant?

a) Reciprocating compressor

b) Screw compressor

c) Multistage axial flow compressor

d) Either Reciprocating compressor & Screw compressor

Answer: Multistage axial flow compressor

25. What is the percentage of total energy input appearing as network output of the cycle?

a) Thermal efficiency

b) Combustion efficiency

c) Engine efficiency

d) Compression efficiency

Answer: Thermal efficiency

26. Which of the following is (are) used as starter for a gas turbine?

a) An Internal combustion engine

b) A steam turbine

c) An auxiliary electric motor

d) All of the mentioned

Answer: All of the mentioned

27. In gas turbine, what is the function of Re-heater?

a) Heat inlet air

b) Heat exhaust gases

c) Heat air coming out of compressor

d) Heat gases coming out of high pressure turbine

Answer: Heat gases coming out of high pressure turbine

28. The air standard cycle for a Gas-Turbine called Brayton cycle

a) True

b) False

Answer: True

29. In gas turbine, intercooler is placed in between low pressure compressor and high pressure compressor

a) True

b) False

Answer: True

30. The efficiency of multistage compressor is higher than a single stage.

a) True

b) False

Answer: False

Steam Turbines Basics Multiple Choice Questions And Answers

1. The isentropic enthalpy drop in moving blade is two-third of the isentropic enthalpy drop in fixed blades of a turbine. The degree of reaction will be ___________

a) 0.67

b) 0.4

c) 0.5

d) 0.56

Answer: 0.67

2. Depending on whether the back pressure is below or equal to the atmospheric pressure, how many types of turbines do exist?

a) 1

b) 2

c) 3

d) 4

Answer: 2

3. The energy conversion occurring in a steam turbine is a ______ step process.

a) 1

b) 2

c) 3

d) 4

Answer: 2

4. What is the action of steam in a steam turbine?

a) neither static nor dynamic

b) dynamic

c) static

d) both dynamic & static

Answer: dynamic

5. A nozzle is said to be a convergent nozzle when?

a) the cross-section of the nozzle increases continuously from entrance to exit

b) the cross-section of the nozzle decreases continuously from entrance to exit

c) the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit

d) none of the mentioned

Answer: the cross-section of the nozzle decreases continuously from entrance to exit

6. A duct which decreases the velocity of fluid & causes a corresponding increase in pressure is called?

a) nozzle

b) diffuser

c) jet

d) orifice

Answer: diffuser

7. The ratio of total useful heat drop to the total isentropic heat drop is called?

a) Rankine efficiency

b) Stage efficiency

c) Internal efficiency

d) None of the mentioned

Answer: Internal efficiency

8. A ______ is a duct through which velocity of a fluid increases at the expense of pressure.

a) orifice

b) nozzle

c) jet

d) diffuser

Answer: nozzle

9. The overall steam turbine generator arrangement of a power plant is designated as ________ compound on the basis of shaft orientation.

a) tandem

b) cross

c) tandem & cross

d) none of the mentioned

Answer: tandem & cross

10. A steam turbine is basically an assemblage of ____________

a) nozzle & condenser

b) blades & condenser

c) nozzle & blades

d) nozzle & fans

Answer: nozzle & blades

11. The reheat factor is the ratio of the ____________

a) total useful heat drop to the total isentropic heat drop

b) cumulative heat drop to the isentropic heat drop

c) isentropic heat drop to the heat supplied

d) none of the mentioned

Answer: cumulative heat drop to the isentropic heat drop

12. A steam turbine converts the output from a steam generator into ____________

a) Shaft work

b) Turbine work

c) Mechanical work

d) None of the mentioned

Answer: Shaft work

13. Thermal equilibrium means that the flow of steam is ____________

a) hyperbolic

b) isothermal

c) isentropic

d) polytropic

Answer: isentropic

14. The ratio of the work done on the blades to the energy supplied to the blades is called ____________

a) gross or stage efficiency

b) blading efficiency

c) nozzle efficiency

d) mechanical efficiency

Answer: blading efficiency

15. Multi-stage steam turbines are of the ___________

a) reaction type

b) velocity compounded type

c) pressure compounded type

d) all of the mentioned

Answer: all of the mentioned

16. In a nozzle, whole frictional loss is assumed to occur between ___________

a) inlet and throat

b) throat and exit

c) inlet and outlet

d) none of the mentioned

Answer: throat and exit

17. The critical pressure gives the velocity of steam at the throat ___________

a) equal to the velocity of sound

b) more than velocity of sound

c) less than the velocity of light

d) none of the mentioned

Answer: equal to the velocity of sound

18. The flow through a nozzle is regarded as ___________

a) isothermal flow

b) isobaric flow

c) isochoric flow

d) isentropic flow

Answer: isentropic flow

19. A regenerative steam cycle renders ____________

a) decreased work output per unit mass of steam

b) increased thermal efficiency

c) increased work output per unit mass of steam

d) decreased work output per unit mass of steam as well as increased thermal efficiency

Answer: decreased work output per unit mass of steam as well as increased thermal efficiency

20. The impulse reaction turbine has its driving force ___________

a) partly as an impulsive force and partly as a reaction force

b) as an impulsive force

c) as a reaction force

d) none of the mentioned

Answer: partly as an impulsive force and partly as a reaction force

Turbine Efficiency and Flow Through Nozzles Multiple Choice Questions And Answers

1. What is the critical pressure ratio for initially wet steam?

a) 0.582

b) 0.546

c) 0.577

d) 0.601

Answer: 0.582

2. The value of the reheat factor varies from ____________

a) 1.08 to 1.10

b) 1.2 to 1.6

c) 1.6 to 2

d) 1.02 to 1.06

Answer: 1.02 to 1.06

3. Parson’s reaction turbine is a __________ reaction turbine.

a) 40%

b) 50%

c) 60%

d) 70%

Answer: 50%

4. A turbine is said to have an axial discharge when the steam leaves the blade tip at __________ to the direction of the blade motion.

a) 90°

b) 60°

c) 270°

d) 180°

Answer: 60°

5. When the back pressure of a nozzle is below the designed value of pressure at exit of nozzle, the nozzle is said to be ____________

a) overdamping

b) underdamping

c) chocked

d) none of the mentioned

Answer: underdamping

6. The supersaturated flow of steam through a nozzle as compared to a stable flow, the available heat drop ____________

a) increases

b) decreases

c) is unpredictable

d) remains same

Answer: decreases

7. The steam leaves the nozzle at a ____________

a) low pressure and a high velocity

b) high pressure and a high velocity

c) high pressure and a low velocity

d) low pressure and a low velocity

Answer: low pressure and a high velocity

8. The Parsons’ reaction turbine has ____________

a) only moving blades

b) only fixed blades

c) fixed and moving blades of different shape

d) identical fixed and moving blades

Answer: identical fixed and moving blades

9. The ratio of the useful heat drop to the isentropic heat drop is called ____________

a) condenser efficiency

b) nozzle efficiency

c) vacuum efficiency

d) boiler efficiency

Answer: nozzle efficiency

10. When the cross-section of a nozzle increases continuously from entrance to exit, it is called a ____________

a) convergent-divergent nozzle

b) divergent nozzle

c) convergent nozzle

d) none of the mentioned

Answer: divergent nozzle

10. Rateau turbine is ____________

a) pressure-velocity compounded turbine

b) simple reaction turbine

c) velocity compounded turbine

d) pressure compounded turbine

Answer: pressure compounded turbine

11. The difference in supersaturated temperature and saturation temperature at that pressure is called ____________

a) degree of super saturation

b) degree of superheat

c) degree of undercooling

d) none of the mentioned

Answer: degree of undercooling

12. The flow of steam is super-sonic ____________

a) in the convergent portion of the nozzle

b) at the entrance to the nozzle

c) at the throat of the nozzle

d) in the divergent portion of the nozzle

Answer: in the divergent portion of the nozzle

13. De-Laval turbine is a ____________

a) multi rotor impulse turbine

b) impulse reaction turbine

c) single rotor impulse turbine

d) none of the mentioned

Answer: single rotor impulse turbine

15. Parson’s turbine is a ____________

a) simple impulse turbine

b) impulse-reaction turbine

c) simple reaction turbine

d) none of the mentioned

Answer: simple reaction turbine

16. The variation of steam pressure in the nozzle depends upon ____________

a) dryness fraction of steam

b) specific volume of steam

c) velocity of steam

d) all of the mentioned

Answer: all of the mentioned

17. Steam turbines are used for ____________

a) electric power generation

b) large marine propulsion

c) direct drive of fans, compressors, pumps

d) all of the mentioned

Answer: all of the mentioned

18. The steam enters the nozzle at a ____________

a) low pressure and a low velocity

b) high pressure and a low velocity

c) low pressure and a high velocity

d) high pressure and a high velocity

Answer: high pressure and a high velocity

19. The impulse turbine rotor efficiency will have a maximum value of 0.5 cos2 α, where α is the nozzle exit flow angle, if the ____________

a) blades are equiangular

b) blade velocity coefficient is unity

c) blade solidity is 0.65

d) blades are equiangular and frictionless

Answer: blades are equiangular and frictionless

20. Curtis turbine is a ____________

a) pressure compounded turbine

b) velocity compounded turbine

c) simple reaction turbine

d) pressure-velocity compounded turbine

Answer: pressure-velocity compounded turbine

21. The diagram efficiency is the ratio of ____________

a) work done on the blades to the energy supplied to the blades

b) energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam

c) work done on the blades per kg of steam to the total energy supplied per stage per kg of steam

d) none of the mentioned

Answer: work done on the blades to the energy supplied to the blades

22. In a reaction turbine, when steam flows through the fixed blades ____________

a) pressure decreases while velocity increases

b) pressure increases while velocity decreases

c) pressure and velocity both increases

d) pressure and velocity both decreases

Answer: pressure decreases while velocity increases

23. A binary vapour plant consists of ____________

a) mercury boiler

b) steam turbine

c) steam condenser

d) all of the mentioned

Answer: all of the mentioned

24. In reaction turbines, the axial thrust is due to ____________

a) pressure drop across the rotor

b) change in axial velocity

c) both pressure drop across the rotor and change in axial velocity

d) none of the mentioned

Answer: both pressure drop across the rotor and change in axial velocity

25. Which of the following statement is correct?

a) The expansion of steam in a nozzle follows Rankine cycle

b) The friction in the nozzle increases the dryness fraction of steam

c) The pressure of steam at throat is called critical pressure

d) All of the mentioned

Answer: All of the mentioned

Turbine and Nozzles Types Multiple Choice Questions And Answers

1. What is the critical pressure ratio for initially dry saturated steam?

a) 0.546

b) 0.577

c) 0.586

d) 0.578

Answer: 0.577

2. A nozzle is said to be a divergent nozzle ____________

a) when the cross-section of the nozzle increases continuously from entrance to exit

b) when the cross-section of the nozzle decreases continuously from entrance to exit

c) when the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit

d) none of the mentioned

Answer: when the cross-section of the nozzle increases continuously from entrance to exit

3. The ratio of the isentropic heat drop to the heat supplied is called ____________

a) stage efficiency

b) reheat factor

c) internal efficiency

d) rankine efficiency

Answer: rankine efficiency

4. The reheat factor depends upon ____________

a) exit pressure

b) turbine stage efficiency

c) initial pressure and superheat

d) all of the mentioned

Answer: all of the mentioned

5. In order to reduce the rotor speed of an impulse turbine, the method employed is ____________

a) pressure compounding

b) velocity compounding

c) pressure-velocity compounding

d) all of the mentioned

Answer: all of the mentioned

6. In an impulse turbine, steam expands ____________

a) wholly in nozzle

b) partly in the nozzle and partly in blades

c) wholly in blades

d) none of the mentioned

Answer: wholly in nozzle

7. A steam nozzle converts ____________

a) heat energy of steam into potential energy

b) potential energy into heat energy of steam

c) heat energy of steam into kinetic energy

d) kinetic energy into heat energy of steam

Answer: heat energy of steam into kinetic energy

8. If the critical pressure ratio for steam is 0.546, then the steam is initially ____________

a) wet

b) dry saturated

c) superheated

d) none of the mentioned

Answer: superheated

9. A stage, in reaction turbine, is represented by ____________

a) each row of blades

b) number of entries of steam

c) number of exits of steam

d) none of the mentioned

Answer: each row of blades

10. Which of the following statement is correct?

a) The pressure of steam, in reaction turbines, is increased in fixed blades as well as in moving blades

b) The efficiency of steam turbine is greater than the steam engines

c) A flywheel is a must for steam turbine

d) The turbine blades do not change the direction of steam issuing from the nozzle

Answer: The efficiency of steam turbine is greater than the steam engines

11. The ratio of the work done on the blades per kg of steam to the total energy supplied per stage per kg of steam is called?

a) nozzle efficiency

b) stage efficiency

c) mechanical efficiency

d) blading efficiency

Answer: stage efficiency

12. What is the purpose of governing in steam turbines?

a) reheat the steam and improve its quality

b) maintain the speed of the turbine

c) reduce the effective heat drop

d) completely balance against end thrust

Answer: maintain the speed of the turbine

13. A steam turbine, in which a part of the steam after partial expansion, is used for process heating and the remaining steam is further expanded for power generation, is known as?

a) pass out turbine

b) impulse turbine

c) low pressure turbine

d) high pressure turbine

Answer: pass out turbine

14. The process of draining steam from the turbine, at certain points during its expansion and using this steam for heating the feed water in feed water heaters and then supplying it to the boiler is known as?

a) regenerative heating

b) reheating of steam

c) bleeding

d) none of the mentioned

Answer: bleeding

15. Which of the following statement is wrong?

a) The flowing the convergent portion of the nozzle is sub-sonic

b) The critical pressure gives the velocity of steam at the throat equal to the velocity of sound

c) The flow in the divergent portion of the nozzle is super-sonic

d) To increase the velocity of steam above sonic velocity (super-sonic) by expanding steam below the critical pressure, the divergent portion for the nozzle is not necessary

Answer: To increase the velocity of steam above sonic velocity (super-sonic) by expanding steam below the critical pressure, the divergent portion for the nozzle is not necessary

Turbine Blading Multiple Choice Questions And Answers

1. Turbo alternators run at speeds ____________

a) constant speed of 3000 rpm

b) constant speed of 1000 rpm

c) variable speed of 1000 rpm

d) none of the mentioned

Answer: variable speed of 1000 rpm

2. Water used in the steam plant is used for cooling in _______________

a) Condenser

b) Turbine only

c) Boiler tube

d) Boiler tubes and turbines

Answer: Condenser

3. In a reaction turbine when the degree of reaction is zero, then there is ____________

a) no heat drop in moving blades

b) maximum heat drop in fixed blades

c) no heat drop in fixed blades

d) maximum heat drop in moving blades

Answer: no heat drop in moving blades

4. Spray ponds are used to cool the warm water coming from the condenser in ________

a) Large power plants

b) Small power plants

c) Medium power plants

d) Both medium and large power plants

Answer: Small power plants

5. In turbines, the fluid undergoes a continuous steady flow process and the speed of flow is ____________

a) very high

b) high

c) low

d) very low

Answer: very high

6. Steam turbines may be classified according to ____________

a) number of stages

b) direction of steam flow

c) mode of steam action

d) all of the mentioned

Answer: all of the mentioned

7. In a velocity compounded impulse turbine, when steam flows through the second row of moving blades ____________

a) velocity decreases

b) velocity increases

c) pressure decreases

d) pressure increases

Answer: velocity decreases

8. In an impulse reaction turbine, the pressure drops gradually and continuously over ____________

a) moving blades

b) fixed blades

c) both moving & fixed blades

d) none of the mentioned

Answer: both moving & fixed blades

9. Air-Preheater in a steam power plant _____________

a) Recovers the heat from the flue gases leaving the economiser

b) Improves combustion rate

c) Raises the temperature of the furnace gases

d) All of the mentioned

Answer: All of the mentioned

10. Evaporative type of condenser has ________

a) Water in pipes surrounded by steam outside

b) Steam and cooling water mixed to give the condensate

c) Steam in pipes surrounded by water

d) None of the mentioned

Answer: Steam in pipes surrounded by water

11. A steam nozzle converts ____________

a) heat energy of steam into kinetic energy

b) kinetic energy of steam into heat energy

c) potential energy into heat energy

d) none of the mentioned

Answer: heat energy of steam into kinetic energy

12. Due to friction between the fluid & walls of the nozzle, the expansion process is?

a) reversible

b) irreversible

c) reversible adiabatic

d) irreversible adiabatic

Answer: irreversible adiabatic

13. The ratio of actual mass flow through the nozzle to the mass flow if the flow were isentropic is?

a) Coefficient of viscosity

b) Coefficient of velocity

c) Coefficient of discharge

d) None of the mentioned

Answer: Coefficient of discharge

14. What is the definition of the draught system?

a) A device used to pull in air

b) The difference between absolute gas pressure at any point in a gas flow and the ambient atmospheric pressure

c) The sum of the absolute gas pressure at any point in a gas flow and the ambient atmospheric pressure

d) A device used to pull out air

Answer: A device used to pull out air

15. A steam turbine with no nozzle is?

a) Reaction Turbine

b) Impulse Turbine

c) Reaction & Impulse Turbines

d) None of the mentioned

Answer: Reaction Turbine

16. The process of draining steam from the turbine, at certain points during its expansion and using this steam for heating the feed water in feed water heaters and then supplying it to the boiler is known as?

a) regenerative heating

b) reheating of steam

c) bleeding

d) none of the mentioned

Answer: bleeding

17. The pipes carrying steam are made up of?

a) Steel

b) Copper

c) Aluminium

d) Iron

Answer: Steel

18. Governing principle(s) of steam turbine is?

a) Nozzle control governing

b) Throttle governing

c) Bypass governing

d) All of the mentioned

Answer: All of the mentioned

19. What is use of the air pumps in the condenser?

a) Remove water

b) Air leaking in the condenser and to maintain the vacuum

c) Maintain atmospheric pressure and the condenser

d) Remove water & Air leaking in the condenser and to maintain the vacuum

Answer: Air leaking in the condenser and to maintain the vacuum

20. A condenser condenses the steam coming out from?

a) Boiler

b) Turbine

c) Economiser

d) Super heater

Answer: Turbine