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

1. The coal requirement per kW hour generation in the thermal power plant is of the order of
A. 0.1 to 0.2 kg
B. 0.2 to 0.4 kg
C. 0.6 to 0.8 kg
D. 1.0 to 1.5 kg
Answer : C

2. 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

3. The device attached to the steam chest for preventing explosions due to excessive internal pressure of steam is called
A. Safety valve
B. Water level indicator
C. Pressure gauge
D. Fusible plug
Answer : A

4. 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

5. The increase in pressure
A. Lowers the boiling point of a liquid
B. Raises the boiling point of a liquid
C. Does not affects the boiling point of a liquid
D. Reduces its volume
Answer : B

6. Besides mean effective pressure, the data required to determine the indicated power of an engine include
A. Piston diameter, length of stroke and calorific value of fuel
B. Piston diameter, specific fuel consumption and Calorific value of fuel
C. Piston diameter, length of stroke and speed of rotation
D. Specific fuel consumption, speed of rotation and torque
Answer : C

7. 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

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

9. The high pressure and low pressure cylinders in a Tandem type compound engine are regarded as having cranks
A. 180° to each other
B. 90° to each other
C. 0° to each other
D. None of these
Answer : C

10. An economiser is installed in a boiler primarily to
A. Superheat the steam
B. Reduce fuel consumption
C. Increase steam pressure
D. All of these
Answer : B

11. The friction present between the steam and the nozzle surfaces reduces the heat drop by
A. 10 to 15 %
B. 15 to 25 %
C. 25 to 40 %
D. 40 to 60 %
Answer : A

12. 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

13. The theoretical indicator diagram of a simple steam engine is based upon the assumption that
A. There is no pressure drop due to condensation
B. Steam is admitted at boiler pressure and exhausted at condenser pressure
C. The expansion (or compression) of the steam is hyperbolic
D. All of the above
Answer : D

14. The artificial draught is produced by
A. Steam jet
B. Centrifugal fan
C. Chimney
D. Both (A) and (B)
Answer : D

15. 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

16. When the nozzle operates with the maximum mass flow, the nozzle is said to be
A. Choked
B. Under-damping
C. Over-damping
D. None of these
Answer : A

17. 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

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

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

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

21. 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 the nozzle
Answer : D

22. 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

23. Which of the following is steam dial?
A. Non-coking bituminous coal
B. Brown coal
C. Pulverised coal
D. Coking bituminous coal
Answer : A

24. 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

25. 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

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

27. 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

28. 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

29. A throttle governed steam engine develops 15 kW with 280 kg per hour of steam and 35 kW with 520 kg per hour of steam. The steam consumption in kg per hour when developing 20 kW will be nearly
A. 150 kg/h
B. 210 kg/h
C. 280 kg/h
D. 340 kg/h
Answer : D

30. The function of a valve rod is
A. To provide reciprocating motion to the slide valve
B. To convert reciprocating motion of the piston into rotary motion of the crank
C. To convert rotary motion of the crankshaft into to and fro motion of the valve rod
D. To provide simple harmonic motion to the D-slide valve
Answer : D

31. The pressure of feed water has to be raised before its entry into the boiler. The pressure is raised by a device known as
A. Feed pump
B. Injector
C. Feed check valve
D. Pressure gauge
Answer : A

32. 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

33. The actual vacuum in a condenser is equal to
A. Barometric pressure + actual pressure
B. Barometric pressure - actual pressure
C. Gauge pressure + atmospheric pressure
D. Gauge pressure - atmospheric pressure
Answer : B

34. Ultimate analysis of fuel is determination of percentage of
A. Carbon, hydrogen, nitrogen, sulphur, moisture
B. Fixed carbon, ash, volatile matter, moisture
C. Higher calorific value
D. Lower calorific value
Answer : A

35. The shell of the Cochran boiler is made hemispherical
A. To give maximum space and strength
B. To withstand the pressure of steam inside the boiler
C. Both (A) and (B)
D. None of the above
Answer : C

36. The ultimate 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 : B

37. 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

38. While steam expands in turbines, theoretically the entropy
A. Remains constant
B. Increases
C. Decreases
D. Behaves unpredictably
Answer : A

39. The evaporation of 15.653 kg of water per hour from and at 100°C is called
A. Evaporative capacity
B. Factor of evaporation
C. Equivalent evaporation
D. One boiler h.p.
Answer : D

40. On Mollier chart, free expansion, or throttling process from high pressure to atmosphere is represented by
A. Horizontal straight line
B. Vertical straight line
C. Straight inclined line
D. Curved line
Answer : A

41. The discharge is __________ at critical pressure.
A. Zero
B. Minimum
C. Maximum
D. None of these
Answer : C

42. Caking coals are those which
A. Form lumps or masses of coke
B. Burn freely
C. Show little or no fusing action
D. Burn completely
Answer : A

43. 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

44. 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

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. 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

47. 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

48. 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

49. The actual power generated in the engine cylinder is called
A. Indicated power
B. Brake power
C. Frictional power
D. None of these
Answer : A

50. A _________ in a boiler is used to put off fire in the furnace of the boiler when the level of water in the boiler falls to an unsafe limit.
A. Blow off cock
B. Fusible plug
C. Stop valve
D. Safety valve
Answer : B