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

1. Boiler parameters are expressed by
A. Tonnes/hr. of steam
B. Pressure of steam in kg/cm²
C. Temperature of steam in °C
D. All of the above
Answer : D

2. 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

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

4. When the cross-section of a nozzle __________ continuously from entrance to exit, it is called a convergent nozzle.
A. Increases
B. Decreases
C. Remain same
D. None of these
Answer : B

5. In order to reduce the rotor speed of an impulse turbine, the method employed is
A. Velocity compounding
B. Pressure compounding
C. Pressure-velocity compounding
D. All of these
Answer : D

6. Gradually increasing temperature of flue gases at inlet to chimney for given steam outputs is an indication of
A. Higher effectiveness of boiler
B. High calorific value coal being burnt
C. Fouling of heat transfer surfaces
D. Raising of steam temperature
Answer : C

7. Bomb calorimeter is used to determine
A. Higher calorific value at constant volume
B. Lower calorific value at constant volume
C. Higher calorific value at constant pressure
D. Lower calorific value at constant pressure
Answer : A

8. The balanced draft furnace is one using
A. Induced draft fan and chimney
B. Induced draft fan and forced draft fan
C. Forced draft fan and chimney
D. Any one of the above
Answer : B

9. Which device is used in thermal power plants to reduce level of pollution?
A. Induced draft fan
B. Smoke meter
C. Chimney
D. Precipitator
Answer : D

10. The diameter of Cornish boiler varies from
A. 0.5 to 1 m
B. 1 to 2 m
C. 1.25 to 2.5 m
D. 2 to 3 m
Answer : B

11. Curtis turbine is a
A. Simple reaction turbine
B. Velocity compounded turbine
C. Pressure compounded turbine
D. Pressure-velocity compounded turbine
Answer : D

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

13. Green coal, in order to be burnt, must be
A. Heated sufficiently
B. Burnt in excess air
C. Heated to its ignition point
D. Burnt as powder
Answer : C

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

15. When the circulation of water, in a boiler, is by convection currents which are set up during the heating of water, then the boiler is known as
A. Internally fired boiler
B. Externally fired boiler
C. Natural circulation boiler
D. Forced circulation boiler
Answer : C

16. Water tube boilers are
A. Internally fired
B. Externally fired
C. Internally as well as externally fired
D. None of these
Answer : B

17. In an impulse turbine, steam expands
A. Wholly in blades
B. Wholly in nozzle
C. Partly in the nozzle and partly in blades
D. None of these
Answer : B

18. The size of a boiler drum in pulverised fuel fired boiler, as its size and capacity, (steam pressure and flow ratings) increase
A. Increases
B. Decreases
C. Remains unchanged
D. Increases/decreases depending on steam temperature requirements
Answer : B

19. Which of the following boilers is best suited to meet fluctuating demands?
A. Babcock and Wilcox
B. Locomotive
C. Lancashire
D. Cochran
Answer : B

20. 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

21. 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

22. The difference of supersaturated temperature and saturation temperature at that pressure is called
A. Degree of super-saturation
B. Degree of superheat
C. Degree of under-cooling
D. None of these
Answer : C

23. 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

24. 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

25. The velocity of steam leaving the nozzle (V) is given by (where K = Nozzle coefficient or nozzle efficiency, and h_d = Enthalpy or heat drop during expansion of steam in a nozzle)
A. V = 44.72 h_d K
B. V = 44.72 K h_d
C. V = 44.72 K h_d
D. V = 44.72 K h_d
Answer : C

26. 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

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

28. 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

29. The length of Cornish boiler varies from
A. 2 to 4.5 m
B. 3 to 5 m
C. 5 to 7.5 m
D. 7 to 9 m
Answer : C

30. Pick up wrong statement about desired properties of a good fuel
A. High calorific value
B. Produce minimum smoke and gases
C. Ease in storing
D. High ignition point
Answer : D

31. 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

32. Which of the following substance will have same percentage in both proximate and ultimate analysis?
A. Ash
B. Volatile matter
C. Moisture
D. Hydrogen
Answer : A

33. On Mollier chart, flow through turbine is represented by
A. Horizontal straight line
B. Vertical straight line
C. Straight inclined line
D. Curved line
Answer : B

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

35. 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

36. 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

37. The amount of water evaporated in kg per kg of fuel burnt is called
A. Evaporative capacity of a boiler
B. Equivalent evaporation from and at 100° C
C. Boiler efficiency
D. None of these
Answer : A

38. In a Parson's turbine stage, blade velocity is 320 m/s at the mean radius and rotor blade exit angle is 30°. For minimum kinetic energy of the steam leaving the stage, the steam velocity at the exit of the rotor will be
A. 160/3 m/s
B. 320/3 m/s
C. 640/3 m/s
D. 640 m/s
Answer : C

39. In forced recirculation 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 : C

40. The heat loss in a boiler takes place in the form of
A. Heat carried away by flue gases
B. Heat carried away by ash
C. Moisture present in fuel and steam formed by combustion of hydrogen in fuel
D. All of the above
Answer : D

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

42. Which of the following statement is wrong?
A. The mechanical draught reduces the height of chimney.
B. The natural draught reduces the fuel consumption.
C. A balanced draught is a combination of induced and forced draught.
D. All of the above
Answer : B

43. The velocity of steam at throat of the nozzle is __________ the velocity of sound.
A. Equal to
B. Less than
C. More than
D. None of these
Answer : A

44. The steam temperature with increase in load in case of a boiler fitted with radiation superheater
A. Increases
B. Decreases
C. Remain unaffected
D. First increases and then decreases
Answer : B

45. A fusible plug is fitted in small boilers in order to
A. Avoid excessive build up of pressure
B. Avoid explosion
C. Extinguish fire if water level in the boiler falls below alarming limit
D. Control steam dome
Answer : C

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

47. The draught produced by a steam jet issuing from a nozzle placed in the chimney is called
A. Induced steam jet draught
B. Chimney draught
C. Forced steam jet draught
D. None of these
Answer : A

48. The performance of a boiler is measured by the
A. Amount of water evaporated per hour
B. Steam produced in kg/h
C. Steam produced in kg/kg of fuel burnt
D. All of these
Answer : D

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

50. When steam after doing work in the cylinder passes into a condenser, the engine is said to be a
A. Slow speed engine
B. Vertical steam engine
C. Condensing steam engine
D. Non-condensing steam engine
Answer : C