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

1. Blading efficiency is also known as
A. Stage efficiency
B. Diagram efficiency
C. Nozzle efficiency
D. None of these
Answer : B

2. The nozzle efficiency is the ratio of
A. Workdone on the blades to the energy supplied to the blades
B. Workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam
C. Energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam
D. None of the above
Answer : C

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

4. Lancashire boiler is a
A. Stationary fire tube boiler
B. Stationary water tube boiler
C. Water tube boiler with natural/forced circulation
D. Mobile fire tube boiler
Answer : A

5. In regenerative air preheaters, the heat is transferred
A. From a metal wall from one medium to another
B. From heating an intermediate material and then heating the air from this material
C. By direct mixing
D. Heat is transferred by bleeding some gas from furnace
Answer : B

6. 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

7. 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

8. The ratio of the energy required to produce the artificial draught (expressed in metres head or J/kg of flue gas) to the mechanical equivalent of extra heat carried away per kg of flue gases due to natural draught, is known as
A. Efficiency of the boiler
B. Efficiency of the chimney
C. Efficiency of the fan
D. Power of the boiler
Answer : B

9. 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

10. The specific volume of steam with increase in pressure decreases
A. Linearly
B. Slowly first and then rapidly
C. Rapidly first and then slowly
D. Inversely
Answer : C

11. 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

12. Parson's reaction turbine is a __________ reaction turbine.
A. 40 percent
B. 50 percent
C. 60 percent
D. 70 percent
Answer : B

13. The basic purpose of drum in boiler is to
A. Serve as storage of steam
B. Serve as storage of feed water for water wall
C. Remove salts from water
D. Separate steam from water
Answer : D

14. The impulse turbine rotor efficiency will have a maximum value of 0.5 cos 2?, where ? is the nozzle exit flow angle, if the
A. Blades are equiangular
B. Blade velocity coefficient is unity
C. Blades are equiangular and frictionless
D. Blade solidity is 0.65
Answer : C

15. 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

16. 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

17. Which of the following boiler works on a forced circulation of water?
A. Lamont boiler
B. Benson boiler
C. Loeffler boiler
D. All of these
Answer : D

18. The number of flue tubes in Lancashire boiler is
A. Zero
B. One
C. Two
D. Four
Answer : C

19. The function of a piston in a steam engine is
A. To guide motion of the piston rod and to prevent it from bending
B. To transfer motion from the piston to the crosshead
C. To convert heat energy of the steam into mechanical work id) to exhaust steam from the cylinder at proper moment
D. None of these
Answer : C

20. 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

21. Which of the following statement is correct?
A. The efficiency of steam turbines is greater than steam engines
B. A flywheel is a must for steam turbine
C. The turbine blades do not change the direction of steam issuing from the nozzle
D. The pressure of steam, in reaction turbines, is increased in fixed blades as well as in moving blades
Answer : A

22. The draught produced by a steam jet issuing from a nozzle placed in the ash-pit under the fire grate of the furnace is called
A. Induced steam jet draught
B. Chimney draught
C. Forced steam jet draught
D. None of these
Answer : C

23. During polytropic process
A. Heat transfer takes place across cylinder walls
B. Work is done
C. Steam may be wet, dry or superheated after expansion
D. All of the above
Answer : D

24. 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

25. 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

26. Sublimation region is the region where
A. Solid and vapour phases are in equilibrium
B. Solid and liquid phases are in equilibrium
C. Liquid and vapour phases are in equilibrium
D. Solid, liquid and vapour phases are in equilibrium
Answer : A

27. 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

28. If partial pressure of air and steam be p_a and p_s respectively in a condenser, then according to Dalton's law, the pressure in condenser is equal to
A. p_s - p_a
B. p_a - p_s
C. p_a + p_s
D. None of these
Answer : C

29. 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

30. The latent heat of steam at pressures greater than atmospheric in comparison to latent heat at atmospheric pressure is
A. Less
B. More
C. Equal
D. May be less or more depending on temperature
Answer : A

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. 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

33. One kg of steam sample contains 0.8 kg dry steam; Its dryness fraction is
A. 0.2
B. 0.8
C. 1.0
D. 0.6
Answer : B

34. 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

35. The saturation temperature of steam with increase in pressure increases
A. Linearly
B. Rapidly first and then slowly
C. Slowly first and then rapidly
D. Inversely
Answer : B

36. Reheating of steam under ideal conditions takes place at constant
A. Entropy
B. Enthalpy
C. Pressure
D. Temperature
Answer : D

37. 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

38. Thermal efficiency of a thermal power plant is of the order of
A. 15 %
B. 20 %
C. 30 %
D. 45 %
Answer : C

39. 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

40. 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

41. If the critical pressure ratio for steam is 0.546, then the steam is initially
A. Wet steam
B. Dry saturated steam
C. Superheated steam
D. None of these
Answer : C

42. Water tube boilers are those in which
A. Flue gases pass through tubes and water around it
B. Water passes through the tubes and flue gases around it
C. Work is done during adiabatic expansion
D. Change in enthalpy
Answer : C

43. A nozzle is said o 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

44. The safety valve on boiler drum compared to safety valve on superheater is set at
A. Same value
B. Higher value
C. Lower value
D. Lower/higher depending on steam flow
Answer : B

45. The heat balance sheet for the boiler shows the
A. Complete account of heat supplied by 1 kg of dry fuel and the heat consumed
B. Moisture present in the fuel
C. Steam formed by combustion of hydrogen per kg of fuel
D. All of the above
Answer : A

46. An air preheater is installed
A. Before the economiser
B. Before the superheater
C. Between the economiser and chimney
D. None of these
Answer : C

47. 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

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

49. 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

50. The isentropic enthalpy drop in moving blade is two-third of the isentropic enthalpy drop in fixed blades of a turbine. The degree of reaction will be
A. 0.4
B. 0.56
C. 0.67
D. 1.67
Answer : A