Steam Boilers, Engines, Nozzles & Turbines MCQ Solved Paper for GATE

1. The diagram 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 : A

2. 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

3. The critical pressure ratio for initially dry saturated steam is
A. 0.546
B. 0.577
C. 0.582
D. 0.601
Answer : B

4. The pressure of steam __________ while flowing through a nozzle.
A. Increases
B. Decreases
C. Remains constant
D. None of these
Answer : B

5. 1 kg.m is equal to
A. 9.81 Joules
B. 102 Joules
C. 427 Joules
D. None of these
Answer : A

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

7. The best suited coal for chain or travelling grate stoker boiler is
A. Coking coal
B. Non-coking or free burning coal
C. Pulverised coal
D. High sulphur coal
Answer : B

8. 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

9. The turbine blades are
A. Straight
B. Circular
C. Curved
D. None of these
Answer : C

10. 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

11. 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

12. The missing quantity per stroke is equal to
A. Cylinder feed indicated mass of steam
B. Cylinder feed + indicated mass of steam
C. Mass of cushion steam + indicated mass of steam
D. Mass of cushion steam + cylinder feed
Answer : A

13. Alkaline pyrogallate is used in Orsat's apparatus for absorption of
A. CO?
B. CO
C. O?
D. N?
Answer : C

14. The blade friction in the impulse turbine reduces the velocity of steam by __________ while it passes over the blades.
A. 10 to 15 %
B. 15 to 20 %
C. 20 to 30 %
D. 30 to 40 %
Answer : A

15. 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

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

17. 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

18. The function of a piston rod is
A. To guide motion of the piston rod and to prevent it from bending
B. To transfer motion from the piston to the cross head
C. To convert heat energy of the steam into mechanical work
D. To exhaust steam from the cylinder at proper moment
Answer : B

19. The effect of friction on the flow of steam through a nozzle is to
A. Decrease the mass flow rate and to increase the wetness of steam
B. Increase the mass flow rate and to increase the exit temperature
C. Decrease the mass flow rate and to decrease the wetness of steam
D. Increase the exit temperature without any effect on mass flow rate
Answer : C

20. In impulse turbines, when friction is neglected, the relative velocity of steam at outlet tip of the blade is __________ the relative velocity of steam at inlet tip of the blade.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : A

21. The value of diagram factor depends upon
A. Initial conditions of steam
B. Back pressure
C. Initial pressure of steam
D. All of these
Answer : D

22. Sulphur in coal results in
A. Corroding air heaters
B. Spontaneous combustion during coal storage
C. Facilitating ash precipitation
D. All of the above
Answer : D

23. The ratio of the volume at cut-off to the swept volume is called
A. Cut-off ratio
B. Expansion ratio
C. Clearance ratio
D. None of these
Answer : A

24. The working pressure range for a LaMont boiler is
A. 0.5 to 10 MN/m²
B. 1 to 15 MN/m²
C. 2.5 to 15 MN/m²
D. 3.5 to 20 MN/m²
Answer : D

25. Pour point of fuel oil is the
A. Lowest temperature at which oil will flow under set condition
B. Storage temperature
C. Temperature at which fuel is pumped through burners
D. Temperature at which oil is transported
Answer : A

26. The fire tubes in a Locomotive boiler has _________ diameter.
A. 4.75 mm
B. 5.47 mm
C. 7.45 mm
D. 47.5 mm
Answer : D

27. The pressure compounded impulse turbine as compared to velocity compounded turbine require __________ number of stages.
A. Same
B. Less
C. More
D. None of these
Answer : C

28. The actual power supplied by the engine crankshaft is called
A. Indicated power
B. Brake power
C. Frictional power
D. None of these
Answer : B

29. 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

30. Which of the following statement is correct?
A. A horizontal steam engine requires less floor area than a vertical steam engine
B. The steam pressure in the cylinder is not allowed to fall below the atmospheric pressure
C. The compound steam engines are generally non-condensing steam engines
D. All of the above
Answer : B

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

32. 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

33. There is always some steam left in the clearance space from the previous stroke. This steam left in the clearance space is called
A. Wet steam
B. Saturated steam
C. Superheated steam
D. Cushion steam
Answer : D

34. Thermal efficiency of well maintained boiler will be of the order
A. 40 %
B. 50 %
C. 75 %
D. 90 %
Answer : D

35. Boiler stays are used to
A. Prevent flat surfaces under pressure from tearing apart
B. Take care of failure in shear
C. Take care of failure in compression
D. Provide support for boiler
Answer : A

36. 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

37. In an impulse reaction turbine, the pressure drops gradually and continuously over
A. Fixed blades
B. Moving blades
C. Both fixed and moving blades
D. None of these
Answer : C

38. 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

39. 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

40. 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

41. 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

42. In case of condensing steam engines, the pressure of steam in the cylinder during exhaust stroke is _________ the atmospheric pressure.
A. Equal to
B. Lower than
C. Higher than
D. None of these
nswer : C

43. Which of the following boiler is best suited to meet the fluctuating demand of steam?
A. Locomotive boiler
B. Lancashire boiler
C. Cornish boiler
D. Babcock and Wilcox boiler
Answer : A

44. A closed vessel made of steel and used for the generation of steam is called a
A. Steam boiler
B. Steam turbine
C. Steam condenser
D. Steam injector
Answer : A

45. A regenerative steam cycle renders
A. Increased work output per unit mass of steam
B. Decreased work output per unit mass of steam
C. Increased thermal efficiency
D. Decreased work output per unit mass of steam as well as increased thermal efficiency
Answer : D

46. The steam enters the nozzle at a
A. High pressure and a low velocity
B. High pressure and a high velocity
C. Low pressure and a low velocity
D. Low pressure and a high velocity
Answer : A

47. 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

48. Calorific value of coal is of the order of
A. 200-400 kcal/ kg
B. 800-1200 kcal/ kg
C. 2000-4000 kcal/ kg
D. 5000-8000 kcal/ kg
Answer : C

49. 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

50. 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