Steam Boilers Engines Nozzles and Turbines

21. Boiler stays are used to

  1. prevent flat surfaces under pressure from tearing apart
  2. take care of failure in shear
  3. take care of failure in compression
  4. provide support for boiler
  5. provide foundation of boiler.

Correct answer: (A)
prevent flat surfaces under pressure from tearing apart

22. Bomb calorimeter is used to determine

  1. Higher calorific value at constant volume
  2. Lower calorific value at constant volume ,
  3. Higher calorific value at constant pressure
  4. Lower calorific value at constant pressure
  5. None of the above.

Correct answer: (A)
Higher calorific value at constant volume

23. Caking coals are those which

  1. form lumps or masses of coke
  2. burn freely
  3. show little or no fusing action
  4. burn completely
  5. do not form ash.

Correct answer: (A)
form lumps or masses of coke

24. Calorific value of coal is of the order of

  1. 200-400 kcal/kg
  2. 800-1200 kcal/kg
  3. 2000-4000 kcal/kg
  4. 5000-8000 kcal/kg
  5. 8000-10,000 kcal/kg.

Correct answer: (C)
2000-4000 kcal/kg

25. Carbonisation of coal is the process of

  1. pulverising coal in inert atmosphere
  2. heating wood in a limited supply of air at temperatures below 300°C
  3. strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
  4. binding the pulverised coal into brick-ettes
  5. enriching carbon in the coal.

Correct answer: (C)
strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel

26. Cochran boiler is a

  1. horizontal fire-tube boiler
  2. horizontal water-tube boiler
  3. veritcal water-tube boiler
  4. vertical fire tube boiler
  5. forced circulating boiler.

Correct answer: (D)
vertical fire tube boiler

27. Coke is produced by

  1. pulverising coal in inert atmosphere
  2. heating wood in a limited supply of air at temperatures below 300GC
  3. strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
  4. binding the pulverised coal into brick-etts
  5. enriching carbon in the coal.

Correct answer: (C)
strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel

28. Deaeration of feed water is carried out because it reduces

  1. cavitation of .boiler feed pumps
  2. corrosion caused by oxygen
  3. heat transfer coefficient
  4. pH value of water
  5. weight of water to be handled.

Correct answer: (B)
corrosion caused by oxygen

29. Duplex feed pumps are used in small steam boilers. These operate on the principle of

  1. centrifugal pump
  2. axial flow pump
  3. gear pump
  4. ejector pump
  5. reciprocating pump.

Correct answer: (E)
reciprocating pump.

30. During polytropic process

  1. heat transfer takes place across cylinder walls
  2. work is done
  3. steam may be wet, dry or superheated after expansion
  4. all of the above
  5. none of the above.

Correct answer: (D)
all of the above

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