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

1. 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

2. 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

3. The three Ts for good combustion are
A. Temperature, time, and turbulence
B. Total air, true fuel, and turbulence
C. Thorough mixing, total air and temperature
D. Total air, time, and temperature
Answer : A

4. A compound steam engine in which piston rods of high pressure and low pressure cylinders are attached to two different cranks set at 90° 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 : A

5. 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

6. The ratio of total useful heat drop to the total isentropic heat drop, is called
A. Stage efficiency
B. Internal efficiency
C. Rankine efficiency
D. None of these
Answer : B

7. 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

8. When the circulation of water, in a boiler, is by a centrifugal pump, then the boiler is known as
A. Internally fired boiler
B. Externally fired boiler
C. Natural circulation boiler
D. Forced circulation boiler
Answer : D

9. Vacuum for reciprocating steam engines compared to steam turbines is
A. More
B. Equal
C. Less
D. Could be more or less depending on the size of plant
Answer : C

10. Cut-off governing of steam engines is a method of controlling the engine output by varying
A. Volume of intake steam
B. Pressure of intake steam
C. Temperature of intake steam
D. All of these
Answer : A

11. The chimney draught varies with
A. Climatic conditions
B. Temperature of furnace gases
C. Height of chimney
D. All of these
Answer : D

12. A safety valve in a locomotive starts leaking. The leaking medium will be
A. Water
B. Dry steam
C. Wet steam
D. Super heated steam
Answer : D

13. 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

14. De-Laval turbines are mostly used
A. Where low speeds are required
B. For small power purposes and low speeds
C. For large power purposes
D. For small power purposes and high speeds
Answer : D

15. The effect of friction on the flow of steam through a nozzle is to
A. Decrease the mass flow rate and to increase the wetness of steam
B. Increase the mass flow rate and to increase the exit temperature
C. Decrease the mass flow rate and to decrease the wetness of steam
D. Increase the exit temperature without any effect on mass flow rate
Answer : C

16. The rate of steam produced in Benson boiler is
A. 100 tonnes/h
B. 135 tonnes/h
C. 175 tonnes/h
D. 250 tonnes/h
Answer : B

17. The bituminous coal is no caking if its carbon content is
A. 78-81 %
B. 81-85 %
C. 85-90 %
D. 90-95 %
Answer : A

18. Locomotive type' boiler is
A. Horizontal multi-tubular water tube boiler
B. Water wall enclosed furnace type
C. Vertical tubular fire tube type
D. Horizontal multi-tubular fire tube type
Answer : D

19. 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

20. Sulphur in coal results in
A. Corroding air heaters
B. Spontaneous combustion during coal storage
C. Facilitating ash precipitation
D. All of the above
Answer : D

21. Steam engine operates on
A. Carnot cycle
B. Joule cycle
C. Stirling cycle
D. Brayton cycle
Answer : D

23. The ratio of heat utilised to produce steam and the heat liberated in furnace is known as
A. Boiler effectiveness
B. Boiler evaporative capacity
C. Factor of evaporation
D. Boiler efficiency
Answer : D

24. 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

25. 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

26. The ratio of the workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam is called
A. Blading efficiency
B. Nozzle efficiency
C. Stage efficiency
D. Mechanical efficiency
Answer : C

27. 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

28. Maximum energy loss in a boiler occurs due to
A. Unburnt carbon in ash
B. Incomplete combustion
C. Ash content
D. Flue gases
Answer : D

29. The feed check valve is used in order to
A. Regulate flow of boiler water
B. Check level of water in boiler drum
C. Recirculate unwanted feed water
D. Allow high pressure feed water to flow to drum and not allow reverse flow to take place
Answer : D

30. The numbers of fire tubes in a Cochran boiler are
A. 75
B. 115
C. 165
D. 225
Answer : C

31. Which type of boiler can meet rapid changes of load?
A. Vertical fire tube type
B. Horizontal fire tube type
C. Horizontal water tube type
D. Forced circulation type
Answer : D

32. 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

33. 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. Back pressure turbine
B. Pass out turbine
C. Low pressure turbine
D. Impulse turbine
Answer : B

34. 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

35. The principal function of a stop valve is to
A. Control the flow of steam from the boiler to the main pipe and to shut off the steam completely when required
B. Empty the boiler when required and to discharge the mud, scale or sediments which are accumulated at the bottom of the boiler
C. Put off fire in the furnace of the boiler when the level of water in the boiler falls to an unsafe limit
D. Increase the temperature of saturated steam without raising its pressure
Answer : A

36. 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

37. 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

38. A device used to heat feed water by utilising the heat in me exhaust flue gases before leaving through the chimney, is known as
A. Economiser
B. Fusible plug
C. Superheater
D. Stop valve
Answer : A

39. 1 kg.m is equal to
A. 9.81 Joules
B. 102 Joules
C. 427 Joules
D. None of these
Answer : A

40. 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

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

42. The amount of water evaporated from feed water at _________ into dry and saturated steam at 100° C at normal atmospheric pressure is called equivalent evaporation from and at 100° C.
A. 0°C
B. 40°C
C. 60°C
D. 100°C
Answer : D

43. The fusible plug in small boilers is located
A. In the drum
B. In the fire tubes
C. Above steam dome
D. Over the combustion chamber
Answer : D

44. The velocity of flue gases (V) through the chimney under a static draught of (H') metres is given by
A. V = 2g H'
B. V = 2g/H'
C. V = H'/2g
D. V = 2gH'
Answer : A

45. 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

46. 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

47. The critical pressure ratio for gases is
A. 0.528
B. 0.546
C. 0.577
D. 0.582
Answer : A

48. 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

49. A device used to increase the temperature of saturated steam without raising its pressure, is called
A. Blow off cock
B. Fusible plug
C. Superheater
D. Stop valve
Answer : C

50. 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