Steam Boilers, Engines, Nozzles & Turbines 1000+ MCQ with answer for CAT

1. The rate of discharge through the nozzle __________ when the exit pressure is gradually reduced.
A. Remains same
B. Decreases
C. Increases
D. None of these
Answer : C

2. Feed water conditioning in thermal power plants in done to
A. Reduce hardness and for removal of solids
B. Increase efficiency of thermal power plant
C. Increase heat transfer rate
D. Increase steam parameters
Answer : A

3. When the inlet pressure of steam is equal to the exit pressure, then
A. There is a pressure drop in the nozzle
B. Fluid flows through the nozzle
C. Pressure drops and fluid flows through the nozzle
D. There is no pressure drop and fluid does not flow through the nozzle
Answer : D

4. Blow off cock in a boiler is used 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 : B

5. The diameter of tubes for natural circulation boiler as compared to controlled circulation boilers is
A. More
B. Less
C. Same
D. Could be more or less depending on other factors
Answer : A

6. The maximum efficiency of a reaction turbine is
A. 2 sin²?/(1 + sin²?)
B. 2 cos²?/(1 + cos²?)
C. (1 + sin²?)/2 sin²?
D. (1 + cos²?)/2 cos²?
Answer : B

7. 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

8. 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

9. In a boiler, feed water supplied per hour is 205 kg while coal fired per hour is 23 kg. The net enthalpy rise per kg of water is 145 kJ. If the calorific valve of the coal is 2050 kJ/kg, then the boiler efficiency will be
A. 56 %
B. 63 %
C. 74 %
D. 78 %
Answer : B

10. 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

11. The number of water level indicators in a boiler are generally _________ in number.
A. One
B. Two
C. Three
D. Four
Answer : B

12. 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

13. Which of the following gases has the highest calorific value?
A. Producer gas
B. Coal gas
C. Water gas
D. Blast furnace gas
Answer : B

14. Which of the following statement is correct?
A. A fire tube boiler occupies less space than a water tube boiler, for a given power.
B. Steam at a high pressure and in large quantities can be produced with a simple vertical boiler.
C. A simple vertical boiler has one fire tube.
D. All of the above
Answer : C

15. 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

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

18. A single stage impulse turbine with a diameter of 1.2 m runs at 3000 r.p.m. If the blade speed ratio is 0.42, then the inlet velocity of steam will be
A. 79 m/s
B. 188 m/s
C. 450 m/s
D. 900 m/s
Answer : C

19. Which of the following statement is correct for a compound steam engine?
A. The cost of the engine, for the same power and economy, is more than that of a simple steam engine.
B. The forces in the working parts are increased as the forces are distributed over more parts.
C. The ratio of expansion is reduced, thus reducing the length of stroke.
D. The temperature range per cylinder is increased, with corresponding increase in condensation.
Answer : C

20. An economiser _________ the steam raising capacity of a boiler.
A. Increases
B. Decreases
C. Has no effect on
D. None of these
Answer : A

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. Boiler H.P. is defined as the
A. Steam evaporation rate per kg of fuel fired
B. Work done in evaporating 1 kg of steam per hour from and at 100°C into dry saturated steam
C. The evaporation of 15.65 kg of water per hour from and at 100°C into dry saturated steam
D. Work done by 1 kg of steam at saturation condition
Answer : C

23. 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 than wet bulb temperature of flue gases
Answer : B

24. In a compound steam engine, the first stage of expansion is carried out in a high pressure cylinder whereas the last expansion is completed in low pressure cylinder. The diameter of high pressure cylinder is _________ the low pressure cylinder.
A. Equal to
B. Less than
C. More than
D. None of these
Answer : B

25. The proximate analysis of fuel lists
A. Various chemical constituents, carbon, hydrogen, oxygen etc, plus ash as percents by volume
B. Various chemical constituents, carbon, hydrogen, oxygen, etc, plus ash as percents by weight
C. Fuel constituents as percents by volume of moisture, volatile, fixed carbon and ash
D. Fuel constituents as percents by weight of moisture, volatile, fixed carbon and ash
Answer : D

26. One kilowatt-hour energy is equivalent to
A. 1000 J
B. 360 kJ
C. 3600 kJ
D. 3600 kW/sec
Answer : C

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

28. Pick up the wrong statement about critical condition of steam
A. Latent heat is zero
B. Liquid directly becomes steam
C. Specific volume of steam and liquid is same
D. This is the maximum pressure limit
Answer : D

29. 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

30. A turbine is said to have an axial discharge when the steam leaves the blade tip at _________ to the direction of the blade motion.
A. 60°
B. 90°
C. 180°
D. 270°
Answer : B

31. Locomotive boiler is a
A. Single tube, horizontal, internally fired and stationary boiler
B. Single tube, vertical, externally fired and stationary boiler
C. Multi-tubular, horizontal, internally fired and mobile boiler
D. Multi-tubular, horizontal, externally fired and stationary boiler
Answer : C

32. 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

33. 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

34. 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

35. The velocity of whirl at outlet for an axial discharge turbine is
A. Minimum
B. Maximum
C. Zero
D. None of these
Answer : C

36. A boiler in India should conform to safety regulations of
A. DIN
B. BS
C. ASTM
D. IBR
Answer : D

37. For the same diameter and thickness of tube, a water tube boiler has ________ heating surface as compared to fire tube boiler.
A. More
B. Less
C. Equal
D. None of these
Answer : A

38. The high steam and low water safety valve is used to blow off steam when the
A. Steam pressure exceeds the working pressure
B. Water level in the boiler becomes too low
C. Both (A) and (B)
D. None of the above
Answer : C

39. Which of the following is not a boiler mounting?
A. Blow off cock
B. Feed check valve
C. Economiser
D. Fusible plug
Answer : C

40. A steam nozzle converts
A. Heat energy of steam into kinetic energy
B. Kinetic energy into heat energy of steam
C. Heat energy of steam into potential energy
D. Potential energy into heat energy of steam
Answer : A

41. The fittings mounted on the boiler for its proper and safe functioning is a
A. Water level indicator
B. Pressure gauge
C. Safety valve
D. All of these
Answer : D

42. Throttle 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 : B

43. Benson boiler requires
A. No drum
B. One drum
C. Two drums
D. Three drums
Answer : A

44. 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

45. Which of the following is a fire tube boiler?
A. Lancashire boiler
B. Babcock and Wilcox boiler
C. Yarrow boiler
D. None of these
Answer : A

46. 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

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

48. Steam turbines may be classified according to
A. Direction of steam flow
B. Number of stages
C. Mode of steam action
D. All of these
Answer : D

49. A safety valve mainly used with locomotive and marine boilers is
A. Lever safety valve
B. Dead weight safety valve
C. High steam and low water safety valve
D. Spring loaded safety valve
Answer : D

50. 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