1000+ Steam Boilers, Engines, Nozzles & Turbines Multiple Choice Question Answer [Solved]

1. When the back pressure of a nozzle is below the designed value of pressure at exit of nozzle, the nozzle is said to be
A. Choked
B. Under-damping
C. Over-damping
D. None of these
Answer : B

2. Primary air is the air used to
A. Provide air around burners for obtaining optimum combustion
B. Transport and dry the coal
C. Convert CO (formed in lower zone of furnace) into CO? at higher zone
D. Air delivered by forced draft fan
Answer : B

3. 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

4. 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

5. The discharge of steam in a convergent-divergent nozzle __________ after the throat (i.e. in the divergent portion of the nozzle)
A. Remains constant
B. Decreases
C. Increases
D. None of these
Answer : A

6. Which of the following statement is wrong?
A. The critical pressure gives the velocity of steam at the throat equal to the velocity of sound.
B. The flow in the convergent portion of the nozzle is subsonic.
C. The flow in the divergent portion of the nozzle is supersonic.
D. To increase the velocity of steam above sonic velocity (supersonic) by expanding steam below the critical pressure, the divergent portion for the nozzle is not necessary.
Answer : D

7. 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

8. The value of the reheat factor varies from
A. 1.02 to 1.06
B. 1.08 to 1.10
C. 1.2 to 1.6
D. 1.6 to 2
Answer : A

9. 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

10. In fire 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 : B

11. The diameters of fire tubes and superheater tubes in locomotive boiler are
A. 47.5 mm, 130 mm
B. 32.5 mm, 180 mm
C. 65.5 mm, 210 mm
D. 24.5 mm, 65 mm
Answer : A

12. 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

13. In a reaction turbine
A. The steam is allowed to expand in the nozzle, where it gives a high velocity before it enters the moving blades
B. The expansion of steam takes place partly in the fixed blades and partly in the moving blades
C. The steam is expanded from a high pressure to a condenser pressure in one or more nozzles
D. The pressure and temperature of steam remains constant
Answer : B

14. Steam turbines are used for
A. Large marine propulsion
B. Electric power generation
C. Direct drive of fans, compressors, pumps
D. All of these
Answer : D

15. 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

16. Which is not correct statement about pulverised fuel firing?
A. High burning rate is possible
B. Heat release can be easily controlled
C. Fuel burns economically
D. It is the best technique for burning high ash content fuel having low fusion ash
Answer : D

17. 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

18. The draught (in mm of water), for maximum discharge of flue gases through the chimney, is given by (where H = Height of the chimney in metres, and T₁ = Absolute temperature of air outside the chimney in K)
A. T₁ /88.25H
B. 88.25H/T₁
C. T₁ /176.5H
D. 176.5H/T₁
Answer : D

19. 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

20. The ratio of the temperature rise of cooling water to the vacuum temperature minus inlet cooling water temperature is called
A. Condenser efficiency
B. Vacuum efficiency
C. Nozzle efficiency
D. Boiler efficiency
Answer : A

21. 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

22. The selection of type and size of a steam boiler depends upon
A. The power required and working pressure
B. The geographical position of the power house
C. The fuel and water available
D. All of the above
Answer : D

23. In a reaction turbine when the degree of reaction is zero, then there is
A. No heat drop in moving blades
B. No heat drop in fixed blades
C. Maximum heat drop in moving blades
D. Maximum heat drop in fixed blades
Answer : A

24. 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

25. Equivalent evaporation is the amount of water evaporated in a boiler from and at
A. 0°C
B. 100°C
C. Saturation temperature at given pressure
D. Room temperature
Answer : B

26. 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

27. 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

28. Heating of dry steam above saturation temperature is known as
A. Enthalpy
B. Superheating
C. Super saturation
D. Latent heat
Answer : B

29. The change in internal energy in steam engines equals to
A. Work done during the Rankine cycle
B. Work done during compression
C. Work done during adiabatic expansion
D. Change in enthalpy
Answer : A

30. 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

31. 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

32. 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

33. Pulverised fuel is used for
A. Better burning
B. More calorific value
C. Less radiation loss
D. Medium sized units
Answer : A

34. 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

35. 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

36. The aim of a compound steam engine is
A. To reduce the ratio of expansion in each cylinder
B. To reduce the length of stroke
C. To reduce the temperature range in each cylinder
D. All of the above
Answer : D

37. 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

38. 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

39. 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

40. 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

41. Spontaneous combustion is a phenomenon in which
A. All the fuel burns instantaneously producing high energy release
B. Fuel burns with less air
C. Coal bursts into flame without any external ignition source but by itself due to gradual increase in temperature as a result of heat released by combination of oxygen with coal
D. Explosion in furnace
Answer : C

42. The expansion of steam in a nozzle follows
A. Carnot cycle
B. Rankine cycle
C. Joule cycle
D. Stirling cycle
Answer : B

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

44. Desecration of feed water is carried out because it reduces
A. Cavitation of boiler feed pumps
B. Corrosion caused by oxygen
C. Heat transfer coefficient
D. pH value of water
Answer : B

45. Which of the following is a water tube boiler?
A. Locomotive boiler
B. Cochran boiler
C. Cornish boiler
D. Babcock and Wilcox boiler
Answer : D

46. The draught in locomotive boilers is produced by a
A. Chimney
B. Centrifugal fan
C. Steam jet
D. None of these
Answer : C

47. 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

48. In a Tandem type compound engine, the high pressure and low pressure cylinders
A. Have common piston rod
B. Are set at 90°
C. Have separate piston rods
D. Are set in V-arrangement
Answer : A

49. 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

50. The power of a boiler may be defined as
A. The ratio of heat actually used in producing the steam to the heat liberated in the furnace
B. The amount of water evaporated or steam produced in kg per kg of fuel burnt
C. The amount of water evaporated from and at 100° C into dry and saturated steam
D. The evaporation of 15.653 kg of water per hour from and at 100° C
Answer : B