Steam Boilers, Engines, Nozzles & Turbines MCQ Solved Paper for RRB Group D

1. The ratio of the workdone on the blades to the energy supplied to the blades, is called
A. Blading efficiency
B. Nozzle efficiency
C. Gross or stage efficiency
D. Mechanical efficiency
Answer : A

2. The pressure of steam __________ while flowing through a nozzle.
A. Increases
B. Decreases
C. Remains constant
D. None of these
Answer : B

3. 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

4. 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

5. In a boiler, the heat is lost
A. To dry flue gases
B. In moisture present in the fuel
C. To steam formed by combustion of hydrogen per kg of fuel
D. All of the above
Answer : D

6. 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

7. A compound steam engine in which piston rods of high pressure and low pressure cylinders ' are attached to two different cranks set at 180° to each other, is called
A. Receiver type compound engine
B. Tandem type compound engine
C. Woolf type compound engine
D. Both (A) and (B)
Answer : C

8. 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

9. Expansion ratio is the ratio of
A. Swept volume to the volume at cut-off
B. Clearance volume to the swept volume
C. Volume at cut-off to the swept volume
D. Swept volume to the clearance volume
Answer : A

10. 100% efficiency of a thermal cycle cannot be achieved because of
A. Frictional losses
B. It is not possible to achieve 0°K temperature
C. Leakage
D. Non availability of ideal substance
Answer : B

11. In water tube boilers
A. Water passes through the tubes which are surrounded by flames and hot gases
B. The flames and hot gases pass through the tubes which are surrounded by water
C. Forced circulation takes place
D. None of these
Answer : A

12. 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

13. The condition of steam in boiler drum is always
A. Dry
B. Wet
C. Saturated
D. Supersaturated
Answer : B

14. Pick up the wrong statement about water tube boiler in comparison to fire tube boilers
A. Former occupies less space for same power
B. Rate of steam flow is more in former case
C. Former is used for high installed capacity
D. Chances of explosion are less in former case.
Answer : D

15. The efficiency of reaction turbine is maximum when (where ? = Angle made by the absolute velocity V at inlet)
A. V_b = 0.5 V cos?
B. V_b = V cos ?
C. V_b = 0.5 V² cos?
D. V_b = V² cos?
Answer : B

16. Rateau turbine is
A. Simple reaction turbine
B. Velocity compounded turbine
C. Pressure compounded turbine
D. Pressure-velocity compounded turbine
Answer : C

17. Cut-off governing as compared to throttle governing is
A. Less efficient and less economical
B. Less efficient and more economical
C. More efficient and less economical
D. More efficient and more economical
Answer : D

18. In an ideal impulse turbine, the
A. Absolute velocity at the inlet of moving blade is equal to that at the outlet
B. Relative velocity at the inlet of the moving blade is equal to that at the outlet
C. Axial velocity at inlet is equal to that at the outlet
D. Whirl velocity at inlet is equal to that at the outlet
Answer : B

19. The function of a crosshead is to guide motion of the _________ and to prevent it from bending.
A. Piston rod
B. Connecting rod
C. Eccentric rod
D. Valve rod
Answer : A

20. The temperature of flue gases at air heater outlet should be
A. 100°C
B. Above dew point temperature of flue gases
C. Below dew point temperature of flue gases
D. Less tha wet bulb temperature of flue gases
Answer : B

21. 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

22. The basic job of feed water treatment in boilers is to overcome the problem of
A. Corrosion
B. Scale
C. Carryover
D. All of the above
Answer : D

23. Stoichiometric quantity of air is the
A. Air present in atmosphere at NTP conditions
B. Air required for complete combustion of fuel with no excess air
C. Air required for optimum combustion so as to have reasonable excess air
D. Air required to convert CO into CO?
Answer : B

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

25. In forced circulation steam boilers, the force is applied
A. To draw water
B. To circulate water
C. To drain off the water
D. All of these
Answer : B

26. 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

27. 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

28. By compounding the expansion of steam in two or more cylinders, the length of stroke
A. Does not change
B. Increases
C. Decreases
D. None of these
Answer : C

29. In a steam engine, superheated steam from the boiler is fed into the steam chest at a pressure of
A. 10 atmospheres
B. 20 atmospheres
C. 30 atmospheres
D. 40 atmospheres
Answer : B

30. The maximum steam pressure in a Locomotive boiler is limited to
A. 0.18 MN/m²
B. 1.8 MN/m²
C. 18 MN/m²
D. 180 MN/m²
Answer : B

31. 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

32. Which of the following statement is correct?
A. A horizontal steam engine requires less floor area than a vertical steam engine
B. The steam pressure in the cylinder is not allowed to fall below the atmospheric pressure
C. The compound steam engines are generally non-condensing steam engines
D. All of the above
Answer : B

33. The average operating pressure of Benson boiler is
A. 100 bar
B. 150 bar
C. 200 bar
D. 250 bar
Answer : D

34. Degree of reaction is defined as the ratio of
A. Heat drop in fixed blades to the heat drop in moving blades
B. Heat drop in moving blades to the heat drop in fixed blades
C. Heat drop in moving blades to the heat drop in fixed blades plus heat drop in moving blades
D. Heat drop in fixed blades plus heat drop in moving blades to the heat drop in moving blades
Answer : C

35. The function of injector used in small capacity boilers is to
A. Create vacuum
B. Inject chemical solution in feed pump
C. Pump water, similar to boiler feed pump
D. Add make up water in the system
Answer : C

36. In case of non-condensing steam engines, the pressure of steam in the cylinder during exhaust stroke is _________ the condenser pressure.
A. Equal to
B. Lower than
C. Higher than
D. None of these
Answer : C

37. Which of the following statement is wrong?
A. The factor of evaporation for all boilers is always greater than unity.
B. The amount of water evaporated in kg per kg of fuel burnt is called equivalent evaporation from and at 100° C.
C. The ratio of heat actually used in producing the steam to the heat liberated in the furnace is called boiler efficiency.
D. None of the above
Answer : D

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

39. Willians line follows the law (where b = A constant representing the shape of the Willians line, a = Another constant i.e. no load consumption per hour, I.P. = Indicated power, and m = Steam consumption per hour)
A. I.P. = a × m + b
B. m = a + b × I.P.
C. I.P. = b × m + a
D. m = (b/I.P.) - a
Answer : B

40. The best suited coal for chain or travelling grate stoker boiler is
A. Coking coal
B. Non-coking or free burning coal
C. Pulverised coal
D. High sulphur coal
Answer : B

41. The flow of steam is supersonic
A. At the entrance to the nozzle
B. At the throat of the nozzle
C. In the convergent portion of the nozzle
D. In the divergent portion of he nozzle
Answer : D

42. The equivalent evaporation is defined as
A. The ratio of heat actually used in producing the steam to the heat liberated in the furnace
B. The amount of water evaporated or steam produced in kg per kg of fuel burnt
C. The amount of water evaporated from and at 100°C into dry and saturated steam
D. The evaporation of 15.653 kg of water per hour from and at 100°C
Answer : C

43. Which of the following is a fire tube boiler?
A. Locomotive boiler
B. Babcock and Wilcox boiler
C. Stirling boiler
D. All of the above
Answer : A

44. In an experiment to determine dryness fraction of steam, the mass of water separated was 1.2 kg in 15 mts. and the mass of steam passed out in same time was 4.8 kg. Dryness fraction is
A. 40 %
B. 25 %
C. 50 %
D. 80 %
Answer : D

45. The fire tubes in a Scotch marine boiler are
A. Horizontal
B. Vertical
C. Inclined
D. None of these
Answer : A

46. 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

47. Which of the following statement is correct for steam turbines as compared to reciprocating steam engines?
A. A steam turbine develops higher speeds
B. The efficiency of steam turbine is higher
C. The steam consumption is less
D. All of these
Answer : D

48. Which of the following statement is correct?
A. Lancashire boiler is a fire tube boiler.
B. Fire tube boilers are internally fired.
C. Babcock and Wilcox boiler is a water tube boiler.
D. All of the above
Answer : D

49. 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

50. The action of steam in a steam turbine is
A. Static
B. Dynamic
C. Static and dynamic
D. Neither static nor dynamic
Answer : B