SSC CPO - Steam Boilers, Engines, Nozzles & Turbines 1000+ MCQ [Solved] PDF Download

1. A safety valve usually employed with stationary boilers is
A. Lever safety valve
B. Dead weight safety valve
C. High steam and low water safety valve
D. All of these
Answer : D

2. The economiser is used in boilers to
A. Increase thermal efficiency of boiler
B. Economise on fuel
C. Extract heat from the exhaust flue gases
D. Increase flue gas temperature
Answer : A

3. The air pressure at the fuel bed is reduced below that of atmosphere by means of a fan placed at or near the bottom of the chimney to produce a draught. Such a draught is called
A. Natural draught
B. Induced draught
C. Forced draught
D. Balanced draught
Answer : B

4. The impulse reaction turbine has its driving force
A. As an impulsive force
B. As a reaction force
C. Partly as an impulsive force and partly as a reaction force
D. None of the above
Answer : C

5. For combustion of a fuel, following is essential
A. Correct fuel air ratio
B. Proper ignition temperature
C. O? to support combustion
D. All the three above
Answer : D

6. Cochran boiler is a
A. Horizontal fire tube boiler
B. Horizontal water tube boiler
C. Vertical water tube boiler
D. Vertical fire tube boiler
Answer : D

7. Boiler stays are used to
A. Prevent flat surfaces under pressure from tearing apart
B. Take care of failure in shear
C. Take care of failure in compression
D. Provide support for boiler
Answer : A

8. The main object of a boiler trial is
A. To determine the generating capacity of the boiler
B. To determine the thermal efficiency of the boiler when working at a definite pressure
C. To prepare heat balance sheet for the boiler
D. All of the above
Answer : D

9. Thermal efficiency of well maintained boiler will be of the order
A. 40 %
B. 50 %
C. 75 %
D. 90 %
Answer : D

10. In locomotives, the draught is produced by
A. Chimney
B. Induced draft fan
C. Both combined (A) and (B)
D. Steam jet draught
Answer : D

11. The function of an eccentric rod is
A. To provide reciprocating motion to the slide valve
B. To convert reciprocating motion of the piston into rotary motion of the crank
C. To convert rotary motion of the crankshaft into to and fro motion of the valve rod
D. To provide simple harmonic motion to the D-slide valve
Answer : C

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

13. The high pressure and low pressure cylinders in a Tandem type compound engine are regarded as having cranks
A. 180° to each other
B. 90° to each other
C. 0° to each other
D. None of these
Answer : C

14. Fire tube boilers are those in which
A. Flue gases pass through tubes and water around it
B. Water passes through the tubes and flue gases around it
C. Forced circulation takes place
D. Tubes are laid vertically
Answer : A

15. Which of the following is correct? (Where p_a = Actual mean effective pressure, p_m = Theoretical mean effective pressure, and K = Diagram factor)
A. p_a = p_m/K
B. p_a = p_m × K
C. p_a = K/p_m
D. p_a = p_m + K
Answer : B

16. Which of the following are boiler accessories?
A. Economiser
B. Superheater
C. Both (A) and (B)
D. None of these
Answer : C

17. The turbine blades are
A. Straight
B. Circular
C. Curved
D. None of these
Answer : C

18. 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

19. The number of flue tubes in Lancashire boiler is
A. Zero
B. One
C. Two
D. Four
Answer : C

20. The saturation temperature of steam with increase in pressure increases
A. Linearly
B. Rapidly first and then slowly
C. Slowly first and then rapidly
D. Inversely
Answer : B

21. 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. 0.4
B. 0.56
C. 0.67
D. 1.67
Answer : A

22. Mechanical equivalent of heat for 1 kcal or Joule's equivalent is equal to
A. 421 kg.m
B. 421 kg.m
C. 539 kg.m
D. 102 kg.m
Answer : A

23. The function of a safety valve is
A. To blow off steam when the pressure of steam inside the boiler exceeds the working pressure
B. To indicate the water level inside the boiler to an observer
C. To measure pressure of steam inside the steam boiler
D. None of the above
Answer : A

24. The fire tubes in, a Coarran and Scottish marine boiler are
A. Horizontal
B. Vertical
C. Inclined
D. Both horizontal and vertical
Answer : A

25. An air preheater is installed
A. Before the economiser
B. Before the superheater
C. Between the economiser and chimney
D. None of these
Answer : C

26. Willian's law states that the steam consumption per hour provided with a throttled governor is proportional to (where I.P. = Indicated power)
A. 1/(I.P)
B. 1/(I.P)²
C. I.P.
D. (I.P.)²
Answer : C

27. 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

28. The device attached to the steam chest for preventing explosions due to excessive internal pressure of steam is called
A. Safety valve
B. Water level indicator
C. Pressure gauge
D. Fusible plug
Answer : A

29. The average value of diagram factor lies between
A. 0.2 to 0.5
B. 0.5 to 0.65
C. 0.65 to 0.9
D. 0.8 to 1.2
Answer : C

30. Which of the following statement indicates the difference between Cornish boiler and Lancashire boiler?
A. Cornish boiler is a water tube boiler whereas Lancashire boiler is a fire tube boiler
B. Cornish boiler is a fire tube boiler whereas Lancashire boiler is a water tube boiler
C. Cornish boiler has one flue tube whereas Lancashire boiler has two flue tubes
D. Cornish boiler has two flue tubes whereas Lancashire boiler has one flue tube
Answer : C

31. The difference between Cornish boiler and Lancashire boiler is that
A. Former is fire tube type and latter is water tube type boiler
B. Former is water tube type and latter is fire tube type
C. Former contains one fire tube and latter contains two fire tubes
D. None/of the above
Answer : C

32. The function of a piston in a steam engine is
A. To guide motion of the piston rod and to prevent it from bending
B. To transfer motion from the piston to the crosshead
C. To convert heat energy of the steam into mechanical work id) to exhaust steam from the cylinder at proper moment
D. None of these
Answer : C

33. 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

34. The expansion of steam, as it flows over the blades in reaction turbine, represents
A. Isothermal process
B. Isentropic process
C. Throttling process
D. Free expansion process
Answer : B

35. When the speed of the engine is controlled by means of a valve in a steam pipe, which regulates the pressure of steam entering the engine, then the governing is known as
A. Throttle governing
B. Cut-off governing
C. By-pass governing
D. None of these
Answer : A

36. De-Laval turbine is a
A. Simple impulse turbine
B. Simple reaction turbine
C. Impulse-reaction turbine
D. None of these
Answer : A

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

38. 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 above
Answer : D

39. The fire tubes in a Cochran boiler usually have _________ diameter.
A. 6.25 mm
B. 62.5 mm
C. 72.5 mm
D. 92.5 mm
Answer : B

40. The ratio of the energy required to produce the artificial draught (expressed in metres head or J/kg of flue gas) to the mechanical equivalent of extra heat carried away per kg of flue gases due to natural draught, is known as
A. Efficiency of the boiler
B. Efficiency of the chimney
C. Efficiency of the fan
D. Power of the boiler
Answer : B

41. A condenser in a steam power plant
A. Increases expansion ratio of steam
B. Reduces back pressure of steam
C. Reduces temperature of exhaust steam
D. All of these
Answer : D

42. 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 these
Answer : C

43. At critical point, i.e. p = 225.65 kg/cm², the latent enthalpy of vaporisation is
A. Maximum
B. Minimum
C. Zero
D. Depends on temperature also
Answer : C

44. A _________ in a boiler is used to put off fire in the furnace of the boiler when the level of water in the boiler falls to an unsafe limit.
A. Blow off cock
B. Fusible plug
C. Stop valve
D. Safety valve
Answer : B

45. The value of the reheat factor varies from
A. 1.02 to 1.06
B. 1.08 to 1.10
C. 1.2 to 1.6
D. 1.6 to 2
Answer : A

46. Sulphur content of fuels is very important to the plant operators because it
A. Has high heating value
B. Retards electric precipitation
C. Promotes complete combustion
D. Has highly corrosive effect
Answer : D

47. In a 50% reaction turbine stage, tangential component of absolute velocity at rotor inlet is 537 m/s and the blade velocity is 454 m/s. The power output in kW of steam will be
A. 260 kW
B. 282 kW
C. 296 kW
D. 302 kW
Answer : B

48. Latent heat of dry steam at atmospheric pressure is equal to
A. 539 kcal/ kg
B. 539 BTU/ lb
C. 427 kcal/ kg
D. 100 kcal/ kg
Answer : A

49. A wet vapour can be completely specified by
A. Pressure only
B. Temperature only
C. Dryness fraction only
D. Pressure and dryness fraction
Answer : D

50. Caking coals are those which
A. Form lumps or masses of coke
B. Burn freely
C. Show little or no fusing action
D. Burn completely
Answer : A