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

1. Film boiling occurs at
A. Very low pressure
B. Atmospheric pressures
C. Medium pressures
D. Very high pressures
Answer : D

2. 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

3. Orsat meter is used for
A. Gravimetric analysis of the flue gases
B. Volumetric analysis of the flue gases
C. Mass flow of the flue gases
D. Measuring smoke density of flue gases
Answer : B

4. The critical pressure ratio (p?/p?) is given by
A. (p?/p?) = [2/(n - 1)] ^{n/(n + 1)}
B. (p?/p?) = [2/(n + 1)] ^n/(n-1)
C. (p?/p?) = [(n - 1)/2] ^{n + (1/n)}
D. (p?/p?) = [(n + 1)/2] ^{n - (1/n)}
Answer : B

5. 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

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

7. 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

8. 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

9. The effect of friction in the nozzle __________ dryness fraction of steam.
A. Has no effect on
B. Decreases
C. Increases
D. None of these
Answer : C

10. In a reaction turbine, when steam flows through the fixed blades,
A. Pressure increases while velocity decreases
B. Pressure decreases while velocity increases
C. Pressure and velocity both decreases
D. Pressure and velocity both increases
Answer : B

11. At very low temperature, the melting and boiling temperatures become equal. This temperature is
A. 373°K
B. 273.16°K
C. 303°K
D. 0°K
Answer : B

12. Coke is produced by
A. Pulverising coal in inert atmosphere
B. Heating wood in a limited supply of air at temperatures below 300°C
C. Strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
D. Enriching carbon in the coal
Answer : C

13. Water and sediment in fuel oil can be removed by
A. Heating the oil in the settling tanks
B. Cooling the oil in the settling tanks
C. Burning the oil
D. Suspension
Answer : A

14. In cross compounding, the cylinders are arranged
A. Side by side and each cylinder has common piston, connecting rod and crank
B. Side by side and each cylinder has separate piston, connecting rod and crank
C. At 90° and each cylinder has common piston, connecting rod and crank
D. At 90° and each cylinder has separate piston, connecting rod and crank
Answer : B

15. 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

16. 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

17. 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

18. 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

19. 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

20. Hard coke is produced by carburisation of coal at
A. Atmospheric temperature
B. 500-600°C
C. 700-850°C
D. 950-1100°C
Answer : D

21. Vacuum for reciprocating steam engines compared to steam turbines is
A. More
B. Equal
C. Less
D. Could be more or less depending on the size of plant
Answer : C

22. For combustion of a fuel, following is essential
A. Correct fuel air ratio
B. Proper ignition temperature
C. O? to support combustion
D. All the three above
Answer : D

23. 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

24. 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

25. 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

26. The basic job of feed water treatment in boilers is to overcome the problem of
A. Corrosion
B. Scale
C. Carryover
D. All of the above
Answer : D

27. The length of Lancashire boiler varies from
A. 5 to 6 m
B. 6 to 7 m
C. 7.25 to 9 m
D. 9 to 10 m
Answer : C

28. 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

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. The cylinder dimensions of a compound engine may be designed on the basis of
A. Equal power developed in each cylinder for uniform turning moment
B. Equal initial piston loads on all pistons for obtaining same size of piston rod, connecting rod etc. for all cylinders
C. Equal temperature drop in each cylinder for economy of steam
D. All of the above
Answer : D

31. 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

32. In locomotive boiler, maximum steam pressure is limited to
A. 1 kg/cm²
B. 5 kg/cm²
C. 10 kg/cm²
D. 18 kg/cm²
Answer : D

33. The ratio of brake power to the indicated power is known as
A. Mechanical efficiency
B. Overall efficiency
C. Indicated thermal efficiency
D. Brake thermal efficiency
Answer : A

34. Rateau turbine is
A. Simple reaction turbine
B. Velocity compounded turbine
C. Pressure compounded turbine
D. Pressure-velocity compounded turbine
Answer : C

35. Blow off cock in a boiler is used to
A. Control the flow of steam from the boiler to the main pipe and to shut off the steam completely when required
B. Empty the boiler when required and to discharge the mud, scale or sediments which are accumulated at the bottom of the boiler
C. Put off fire in the furnace of the boiler when the level of water in the boiler falls to an unsafe limit
D. Increase the temperature of saturated steam without raising its pressure
Answer : B

36. The maximum steam pressure in a Locomotive boiler is limited to
A. 0.18 MN/m²
B. 1.8 MN/m²
C. 18 MN/m²
D. 180 MN/m²
Answer : B

37. 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

38. Size of boiler tubes is specified by
A. Mean diameter and thickness
B. Inside diameter and thickness
C. Outside diameter and thickness
D. Outside diameter and inside diameter
Answer : C

39. 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

40. The ratio of the useful heat drop to the isentropic heat drop is called
A. Condenser efficiency
B. Nozzle efficiency
C. Boiler efficiency
D. Vacuum efficiency
Answer : B

41. Which of the following is correct? (Where p_a = Actual mean effective pressure, p_m = Theoretical mean effective pressure, and K = Diagram factor)
A. p_a = p_m/K
B. p_a = p_m × K
C. p_a = K/p_m
D. p_a = p_m + K
Answer : B

42. 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

43. 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

44. For burning 1 kg of carbon to CO as per chemically correct combustion, amount of air required is
A. 1 kg
B. 4/3 kg
C. 8/3 kg
D. 2 kg
Answer : B

45. Sulphur content of fuels is very important to the plant operators because it
A. Has high heating value
B. Retards electric precipitation
C. Promotes complete combustion
D. Has highly corrosive effect
Answer : D

46. Stoichiometric quantity of air is the
A. Air present in atmosphere at NTP conditions
B. Air required for complete combustion of fuel with no excess air
C. Air required for optimum combustion so as to have reasonable excess air
D. Air required to convert CO into CO?
Answer : B

47. 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

48. 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

49. 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

50. The fire tubes in a Cochran boiler usually have _________ diameter.
A. 6.25 mm
B. 62.5 mm
C. 72.5 mm
D. 92.5 mm
Answer : B