1000+ Steam Boilers, Engines, Nozzles & Turbines MCQ for LIC AAO [Solved]

1. On Millier chart, the constant pressure lines
A. Diverge from left to right
B. Diverge from right to left
C. Are equally spaced throughout
D. First rise up and then fall
Answer : A

2. The balanced draft furnace is one using
A. Induced draft fan and chimney
B. Induced draft fan and forced draft fan
C. Forced draft fan and chimney
D. Any one of the above
Answer : B

3. Which of the following compound steam engine requires a smaller flywheel?
A. Receiver type
B. Tandem type
C. Woolf type
D. All of these
Answer : A

4. When the cross-section of a nozzle increases continuously from entrance to exit, it is called a
A. Divergent nozzle
B. Convergent nozzle
C. Convergent-divergent nozzle
D. None of these
Answer : A

5. Pulverised fuel is used for
A. Better burning
B. More calorific value
C. Less radiation loss
D. Medium sized units
Answer : A

6. The shell diameter of a Locomotive boiler is
A. 1 m
B. 1.5 m
C. 2 m
D. 2.5 m
Answer : B

7. An economiser is installed in a boiler primarily to
A. Superheat the steam
B. Reduce fuel consumption
C. Increase steam pressure
D. All of these
Answer : B

8. With increase in load, convection superheater has
A. Drooping characteristic
B. Linear characteristic
C. Rising characteristic
D. Flat characteristic
Answer : C

9. For a Parson's reaction turbine, if ?? and ?? are fixed blade angles at inlet and exit respectively and ?? and ?? are the moving blade angles at entrance and exit respectively, then
A. ?? = ?? and ?? = ??
B. ?? = ?? and ??= ??
C. ?? < ?? and ?? > ??
D. ?? = ?? and ?? = ??
Answer : B

10. The stage efficiency (?_S) is given by (where ?_B = Blading efficiency, and ?_N = Nozzle efficiency)
A. ?_S = ?_B × ?_N
B. ?_S = ?_B / ?_N
C. ?_S = ?_N / ?_B
D. None of these
Answer : A

11. In a velocity compounded impulse turbine, when steam flows through the second row of moving blades,
A. Velocity increases
B. Velocity decreases
C. Velocity remains constant
D. Pressure remains constant
Answer : B

12. The diameter of superheated tubes in a locomotive boiler is
A. 13 mm
B. 31 mm
C. 130 mm
D. 230 mm
Answer : C

13. The relative efficiency is defined as the
A. Ratio of thermal efficiency to Rankine efficiency
B. Ratio of brake power to the indicated power
C. Ratio of heat equivalent to indicated power to the energy supplied in steam
D. Product of thermal efficiency and Rankine efficiency
Answer : A

14. A packaged boiler is one in which various parts like firing equipment, fans, feed pumps and automatic controls are
A. Supplied by same manufacturer loose and assembled at site
B. Supplied mounted on a single base
C. Purchased from several parties and packed together at site
D. Packaged boiler does not exist
Answer : B

15. The supersaturated flow of steam through a nozzle as compared to a stable flow, the available heat drop
A. Remains the same
B. Increases
C. Decreases
D. Is unpredictable
Answer : C

16. In order to compare the capacity of boilers, the feed water temperature and working pressure are taken as
A. 50°C and normal atmospheric pressure
B. 50°C and 1.1 bar pressure
C. 100°C and normal atmospheric pressure
D. 100°C and 1.1 bar pressure
Answer : C

17. The latent heat of steam at pressures greater than atmospheric in comparison to latent heat at atmospheric pressure is
A. Less
B. More
C. Equal
D. May be less or more depending on temperature
Answer : A

18. The change in internal energy in steam engines equals to
A. Work done during the Rankine cycle
B. Work done during compression
C. Work done during adiabatic expansion
D. Change in enthalpy
Answer : A

19. During storage, the heating value of coal
A. Increases
B. Decreases
C. Remain constant
D. May increase or decrease depending upon the method of storage
Answer : B

20. Which of the following statement is wrong?
A. Locomotive boiler is a water tube boiler
B. Water tube boilers are internally fired
C. Lamont boiler is a low pressure water tube boiler
D. All of the above
Answer : D

21. A stage, in reaction turbine, is represented by
A. Number of casing
B. Number of entries of steam
C. Number of exits of steam
D. Each row of blades
Answer : D

22. The length of Cornish boiler is of the order of
A. 24 m
B. 35 m
C. 57.5 m
D. 79 m
Answer : C

23. The basic purpose of drum in boiler is to
A. Serve as storage of steam
B. Serve as storage of feed water for water wall
C. Remove salts from water
D. Separate steam from water
Answer : D

24. The shell of the Cochran boiler is made hemispherical
A. To give maximum space and strength
B. To withstand the pressure of steam inside the boiler
C. Both (A) and (B)
D. None of the above
Answer : C

25. The pressure of feed water has to be raised before its entry into the boiler. The pressure is raised by a device known as
A. Feed pump
B. Injector
C. Feed check valve
D. Pressure gauge
Answer : A

26. In a nozzle, whole frictional loss is assumed to occur between
A. Inlet and throat
B. Inlet and outlet
C. Throat and exit
D. All of these
Answer : C

27. The compounding of turbines is done in order to
A. Reduce speed of rotor
B. Improve efficiency
C. Reduce exit losses
D. All of these
Answer : D

28. At which pressure the properties of water and steam become identical
A. 0.1 kg/cm²
B. 1 kg/cm²
C. 100 kg/cm²
D. 225.6 kg/cm²
Answer : D

29. Film boiling occurs at
A. Very low pressure
B. Atmospheric pressures
C. Medium pressures
D. Very high pressures
Answer : D

30. Primary air is the air used to
A. Provide air around burners for obtaining optimum combustion
B. Transport and dry the coal
C. Convert CO (formed in lower zone of furnace) into CO? at higher zone
D. Air delivered by forced draft fan
Answer : B

31. The radius of a dished head is taken approximately as
A. One fourth
B. Half
C. One
D. Two
Answer : C

32. Hard coke is produced by carburisation of coal at
A. Atmospheric temperature
B. 500-600°C
C. 700-850°C
D. 950-1100°C
Answer : D

33. The water tubes in a Babcock and Wilcox boiler are
A. Horizontal
B. Vertical
C. Inclined
D. Horizontal and inclined
Answer : C

34. All steam engines work on
A. Zeroth law of thermodynamics
B. First law of thermodynamics
C. Second law of thermodynamics
D. None of these
Answer : C

35. Water and sediment in fuel oil can be removed by
A. Heating the oil in the settling tanks
B. Cooling the oil in the settling tanks
C. Burning the oil
D. Suspension
Answer : A

36. For the same diameter and thickness of tube, a water tube boiler compared to a fire tube boiler has
A. More heating surface
B. Less heating surface
C. Equal heating surface
D. Heating surface depends on other parameters
Answer : A

37. In order to reduce the rotor speed of an impulse turbine, the method employed is
A. Velocity compounding
B. Pressure compounding
C. Pressure-velocity compounding
D. All of these
Answer : D

38. The diameter of fire tubes in Cochran boiler is of the order of
A. 2 cm
B. 6 cm
C. 8 cm
D. 12 cm
Answer : B

39. The natural draught is produced by
A. Steam jet
B. Centrifugal fan
C. Chimney
D. Both (A) and (B)
Answer : C

40. The height of chimney in a power plant is governed by
A. The draft to be created
B. Limitation of construction facilities
C. Control of pollution
D. Quantity of flue gases to be handled
Answer : C

41. In a De-Laval nozzle expanding superheated steam from 10 bar to 0.1 bar, the pressure at the minimum cross-section (i. e. pressure at throat, p?) will be
A. 3.3 bar
B. 5.46 bar
C. 8.2 bar
D. 9.9 bar
Answer : B

42. The purpose of governing in steam turbines is to
A. Maintain the speed of the turbine
B. Reduce the effective heat drop
C. Reheat the steam and improve its quality
D. Completely balance against end thrust
Answer : A

43. The dry saturated steam at very high pressure (150200 kg/cm²) when throttled to atmosphere will become
A. Wet
B. Superheated
C. Remain dry saturated
D. Dry
Answer : A

44. The critical pressure ratio for initially superheated steam is __________ as compared to initially dry saturated steam.
A. More
B. Less
C. Same
D. None of these
Answer : B

45. When the speed of the crankshaft is between 100 r.p.m. and 250 r.p.m., the engine said to be a
A. Slow speed engine
B. Medium speed steam engine
C. High speed steam engine
D. None of these
Answer : B

46. Curtis turbine is a
A. Simple reaction turbine
B. Velocity compounded turbine
C. Pressure compounded turbine
D. Pressure-velocity compounded turbine
Answer : D

47. De-Laval turbine is a
A. Single rotor impulse turbine
B. Multi-rotor impulse turbine
C. Impulse reaction turbine
D. None of these
Answer : A

48. If partial pressure of air and steam be p_a and p_s respectively in a condenser, then according to Dalton's law, the pressure in condenser is equal to
A. p_s - p_a
B. p_a - p_s
C. p_a + p_s
D. None of these
Answer : C

49. Reheating of steam under ideal conditions takes place at constant
A. Entropy
B. Enthalpy
C. Pressure
D. Temperature
Answer : D

50. Equivalent evaporation is the amount of water evaporated in a boiler from and at
A. 0°C
B. 100°C
C. Saturation temperature at given pressure
D. Room temperature
Answer : B