1000+ Steam Boilers, Engines, Nozzles & Turbines Multiple Choice Question Answer [Solved]

1. The efficiency of an impulse turbine is maximum when (where V_b = Blade speed, V = Absolute velocity of steam entering the blade, and ? = Nozzle angle)
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 : A

2. There is always some steam left in the clearance space from the previous stroke. This steam left in the clearance space is called
A. Wet steam
B. Saturated steam
C. Superheated steam
D. Cushion steam
Answer : D

3. Efficiency of Rankine cycle can be increased by
A. Decreasing initial steam pressure and temperature
B. Increasing exhaust pressure
C. Decreasing exhausts pressure
D. Increasing the expansion ratio
Answer : A

4. 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 above
Answer : A

5. 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

6. The diameter of internal flue tubes in a Lancashire boiler compared to its shell is
A. One-half
B. One-third
C. Two-fourth
D. Two-fifth
Answer : D

7. In turbines, the fluid undergoes a continuous steady flow process and the speed of flow is
A. Low
B. Very low
C. High
D. Very high
Answer : D

8. A supercritical boiler is one that operates above the pressure and temperature of following values
A. 100 kg/cm² and 540°C
B. 1 kg/cm² and 100°C
C. 218 kg/cm² abs and 373°C
D. 218 kg/cm² abs and 540°C
Answer : C

9. The flow through a nozzle is regarded as
A. Constant volume flow
B. Constant pressure flow
C. Isothermal flow
D. Isentropic flow
Answer : D

10. 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

11. The number of drums in Benson steam generator is
A. One
B. Two
C. One steam drum and one water drum
D. No drum
Answer : D

12. The indicated thermal efficiency is defined as the
A. Ratio of thermal efficiency to the 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 : C

13. A nozzle is said to be a convergent 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 above
Answer : B

14. 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

15. Efficiency of a thermal cycle increases by
A. Regeneration
B. Reheating of steam
C. Both (A) and (B)
D. Cooling of steam
Answer : C

16. 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

17. The missing quantity per stroke is equal to
A. Cylinder feed indicated mass of steam
B. Cylinder feed + indicated mass of steam
C. Mass of cushion steam + indicated mass of steam
D. Mass of cushion steam + cylinder feed
Answer : A

18. The cylinder dimensions of a compound engine may be designed on the basis of
A. Equal power developed in each cylinder for uniform turning moment
B. Equal initial piston loads on all pistons for obtaining same size of piston rod, connecting rod etc. for all cylinders
C. Equal temperature drop in each cylinder for economy of steam
D. All of the above
Answer : D

19. The critical pressure ratio for initially dry saturated steam is
A. 0.546
B. 0.577
C. 0.582
D. 0.601
Answer : B

20. Carbonisation of coal is the process of
A. Pulverising coal in inert atmosphere
B. Heating wood in a limited supply of air at temperatures below 300°C
C. Strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
D. Binding the pulverised coal into briquettes
Answer : C

21. The mechanical draught _________ with the amount of smoke.
A. Increases
B. Decreases
C. Does not effect
D. None of these
Answer : B

22. Water at pressure of 4 kg/cm² and 160°C temperature when exposed to atmosphere will
A. Boil
B. Flash i.e. get converted into steam
C. Remain as it was
D. Cool down
Answer : B

23. In natural circulation type boiler,
A. Heating takes place at bottom and the water supplied at bottom gets converted into the mixture of steam bubbles and hot water which rise to drum
B. Water is supplied in drum and through down comers located in atmospheric condition it passes to the water wall and rises to drum in the form of mixture of water and steam
C. Feed pump is employed to supplement natural circulation in water wall type furnace
D. Water is converted into steam in one. Pass without any recirculation
Answer : A

24. In a nozzle, the effect of super-saturation is to
A. Decrease dryness fraction of steam
B. Decrease specific volume of steam
C. Increase the entropy
D. Increase the heat drop
Answer : C

25. In water wall furnace, the heat is transferred to the water walls by
A. Convection
B. Radiation
C. Conduction
D. Radiation and conduction
Answer : B

26. Reheating of steam in a turbine
A. Increases the workdone through the turbine
B. Increases the efficiency of the turbine
C. Reduces wear on the blades
D. All of these
Answer : D

27. The capacity of induced draft fan compared to forced draft fan in a boiler is
A. Same
B. More
C. Less
D. Less or more depending on size of boiler
Answer : B

28. In a throttling process
A. Heat transfer takes place
B. Work is done by the expanding steam
C. Internal energy of steam changes
D. None of the above
Answer : D

29. The efficiency of a boiler is defined as
A. Ratio of heat actually used in producing steam to the heat liberated in the furnace
B. Ratio of the mass of steam produced to the mass of total water supplied in a given time
C. Ratio of the heat liberated in the furnace to the heat actually used in producing steam
D. None of the above
Answer : A

30. The diameter of fire tube of Cornish boiler compared to its shell is
A. One half
B. One third
C. One fourth
D. One fifth
Answer : A

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

32. Locomotive boiler is of the following type
A. Multi tubular
B. Horizontal
C. Internally fired
D. All of the above
Answer : D

33. 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

34. In order to obtain superheated steam, a superheater is added in an existing boiler. As as result, furnace vacuum will
A. Remain unaffected
B. Improve
C. Worsen
D. May improve/worsen depending on size
Answer : C

35. The factor of evaporation for all boilers is always
A. Equal to unity
B. Less than unity
C. Greater than unity
D. None of these
Answer : C

36. The working pressure range for a LaMont boiler is
A. 0.5 to 10 MN/m²
B. 1 to 15 MN/m²
C. 2.5 to 15 MN/m²
D. 3.5 to 20 MN/m²
Answer : D

37. Over fire burning is the phenomenon of
A. Supply of excess, air
B. Supply of excess coal
C. Burning CO and unburnts in upper zone of furnace by supplying more air
D. Fuel bed firing
Answer : C

38. 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. Choked
B. Under-damping
C. Over-damping
D. None of these
Answer : B

39. If a steam sample is nearly in dry condition, then its dryness fraction can be most accurately determined by
A. Throttling calorimeter
B. Separating calorimeter
C. Combined separating and throttling calorimeter
D. Bucket calorimeter
Answer : A

40. 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

41. The equivalent evaporation of a boiler is a measure to compare
A. The given boiler with the model
B. The two different boilers of the same make
C. Two different makes of boilers operating under the same operating conditions
D. Any type of boilers operating under any conditions
Answer : D

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

43. The diagram factor is the ratio of the
A. Area of the actual indicator diagram to the area of theoretical indicator diagram
B. Actual workdone per stroke to the theoretical workdone per stroke
C. Actual mean effective pressure to the theoretical mean effective pressure
D. Any one of the above
Answer : D

44. In a steam condenser, the partial pressure of steam and air are 0.06 bar and 0.007 bar respectively. The condenser pressure is
A. 0.007 bar
B. 0.053 bar
C. 0.06 bar
D. 0.067 bar
Answer : D

45. Parson's turbine is a
A. Simple impulse turbine
B. Simple reaction turbine
C. Impulse-reaction turbine
D. None of these
Answer : B

46. Thermal equilibrium means that the flow of steam is
A. Isothermal
B. Isentropic
C. Hyperbolic
D. Polytropic
Answer : B

47. The value of diagram factor depends upon
A. Initial conditions of steam
B. Back pressure
C. Initial pressure of steam
D. All of these
Answer : D

48. Lancashire boiler is
A. Stationary fire tube boiler
B. Internally fired boiler
C. Horizontal boiler
D. All of these
Answer : D

49. The pressure of steam in the engine cylinder at the beginning of the stroke is ________ the boiler pressure.
A. Equal to
B. Less than
C. Higher than
D. None of these
Answer : B

50. An economiser is generally placed between
A. Last superheater or reheater and air preheater
B. Induced draft fan and forced draft fan
C. Air preheater and chimney
D. None of the above
Answer : A