Thermal Engineering 36

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Objective Questions and Answer: Thermal Engineering 36

Subject: Thermal Engineering 36

Part 36: Objective questions and answers of Thermal Engineering

 

Q1. Thermal efficiency of well-maintained boiler will be of the order

a) 20%

b) 40%

c) 50%

d) 90%.

 

Q2. Thermal efficiency of a thermal power plant is of the order of

a) 15%

b) 20%

c) 30%

d) 45%

 

Q3. It is required to produce large amount of steam at low pressure. Which boiler should be used?

a) Pulverized fuel fired boiler

b) Cochran boiler

c) Lancashire boiler

d) Babcock and wilcox boiler

 

Q4. The overall efficiency of thermal power plant is

a) Boiler efficiency, turbine efficiency, generator efficiency

b) All the three above plus gas cycle efficiency

c) Carnot cycle efficiency

d) Regenerative cycle efficiency

 

Q5. 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.

 

Q6. In forced circulation type boiler

a) Heating takes place at bottom and the water supplied at bottom gets converted into the mixture of steam bubbles and hot water which rise to drum

b) Water is supplied in drum and through down-comers located in atmospheric condition it passes to the water wall and rises to drum in the form of mixture of water and steam

c) Feed pump is employed to supplement natural circulation in water wall type furnace

d) Water is converted into steam in one pass without any recirculation

 

Q7. 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

 

Q8. The radius of a dished head is taken approximately as

a) One-fourth

b) Half

c) One

d) Two

 

Q9. 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

 

Q10. The heat loss in a boiler takes place in the form of

a) Heat carried away by flue gases

b) Heat carried away by ash

c) Moisture present in fuel and steam formed by combustion of hydrogen in fuel

d) All of the above.

 

Q11. The major axis of elliptical manholes on the shell should be provided

a) Longitudinally

b) Circumferentially

c) On dished end

d) Anywhere

 

Q12. In which of the following boilers, the draught in furnace is increased by utilizing exhaust steam from engine

a) Lancashire boiler

b) Locomotive boiler

c) Babcock and wilcox boiler

d) Cochran boiler

 

Q13. With increase in load, radiant superheater has

a) Drooping characteristic

b) Linear characteristic

c) Rising characteristic

d) Flat characteristic

 

Q14. With increase in load, convection superheater has

a) Drooping characteristic

b) Linear characteristic

c) Rising characteristic

d) Flat characteristic

 

Q15. The diameter of fire tubes in Cochran boiler is of the order of

a) 2 cm

b) 6 cm

c) 8 cm

d) 12 cm

 

Q16. In a recuperative air preheater, 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 gases from furnace

 

Q17. A safety valve in a locomotive starts leaking. The leaking medium will be

a) Water

b) Dry steam

c) Wet steam

d) Super-heated steam

 

Q18. The temperature of flue gases at air heater outlet should be

a) 100°C

b) Above dew-point temperature of flue gases

c) Below dew-point temperature of flue gases

d) Less than wet bulb temperature of flue gases

 

Q19. In regenerative air preheater, 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

 

Q20. In designing air preheater, the important design consideration is that

a) Approach temperature should be as low as possible

b) Handling and maintenance should be easier

c) Heat transfer area should be optimum

d) Stack gases should not be cooled to the dew point

 

Part 36: Objective questions and answers of Thermal Engineering

 

Q1. Answer: d

Q2. Answer: c

Q3. Answer: c

Q4. Answer: a

Q5. Answer: d

Q6. Answer: d

Q7. Answer: a

Q8. Answer: c

Q9. Answer: c

Q10. Answer: d

Q11. Answer: b

Q12. Answer: b

Q13. Answer: a

Q14. Answer: c

Q15. Answer: b

Q16. Answer: a

Q17. Answer: d

Q18. Answer: b

Q19. Answer: b

Q20. Answer: d

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