Thermal Engineering 39

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Objective Questions and Answer: Thermal Engineering 39

Subject: Thermal Engineering 39

Part 39: Objective questions and answers of Thermal Engineering


Q1. Heating value of fuel used is as on fired basis. If it is reported for dry or moisture free fuel, then latter should be multiplied by the following factor to correct for as fired value

a) (1- moisture content)

b) (1 + moisture content)

c) 1 + moisture content

d) 1 – moisture content


Q2. Gradually increasing temperature of flue gases at inlet to chimney for given steam outputs is an indication of

a) Higher effectiveness of boiler

b) High calorific value coal being burnt

c) Fouling of heat transfer surfaces

d) Raising of steam temperature


Q3. Incomplete combustion can be best judged by

a) Smoky chimney exit

b) Excess air in flue gases

c) Measuring carbon mono-oxide in flue gases

d) Measuring temperature of flue gases at exit of furnace


Q4. The capacity of induced draft fan compared to forced draft fan in a boiler is

a) Same

b) More

c) Less

d) Less or more depending on size of boiler


Q5. Pulverized fuel is used for

a) Better burning

b) More calorific value

c) Less radiation loss

d) Medium sized units


Q6. 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


Q7. Evaporative capacity of boiler is expressed as

a) Kg of steam produced

b) Steam pressure produced

c) Kg of fuel fired

d) Kg of steam produced per kg of fuel fifed


Q8. Boiler parameters are expressed by

a) Tonnes/hr. Of steam

b) Pressure of steam in kg/cm2

c) Temperature of steam in °C

d) All of the above


Q9. The condition of steam in boiler drum is always

a) Dry

b) Wet

c) Saturated

d) Supersaturated


Q10. The balanced draft furnace is one using

a) Induced draft fan and chimney

b) Induced draft fan and forced draft fan

c) Forced draft fan and chimney

d) Any one of the above


Q11. In order to obtain superheated steam, a superheater is added in an existing boiler. As result, furnace vacuum will

a) Remain unaffected

b) Improve

c) Worsen

d) May improve/worsen depending on size


Q12. Maximum energy loss in a boiler occurs due to

a) Unburnt carbon in ash

b) Incomplete combustion

c) Ash content

d) Flue gases


Q13. Over fire burning is the phenomenon of

a) Supply of excess, air

b) Supply of excess coal

c) Burning CO and unburnts in upper zone of furnace by supplying more air

d) Fuel bed firing


Q14. Which is not the correct statement about moisture in coal?

a) Inherent moisture and surface moisture are different things

b) In some coals moisture may be present upto 40%

c) Some moisture in coal helps in better burning which is not possible with completely dry coal

d) It increases thermal efficiency


Q15. De-aeration 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


Q16. A supercritical boiler is one that operates above the pressure and temperature of following values

a) 100 kg/cm^2 and 540°C

b) 1 kg/cm^2 and 100°C

c) 218 kg/cm^2 abs and 373°C

d) 218 kg/cm^2 abs and 540°C


Q17. Natural water circulation, by convection in water tube boilers, with increase in pressure of boiler

a) Increases

b) Decreases

c) Remains unaffected

d) First increases and then decreases


Q18. The steam temperature with increase in load in case of a boiler fitted with radiation super heater

a) Increases

b) Decreases

c) Remains unaffected

d) First increases and then decreases


Q19. During storage, the heating value of coal

a) Increases

b) Decreases

c) Remains constant

d) May increase or decrease depending upon the method of storage


Q20. The relative heat absorption for successively added equal areas of boiler convection heating surfaces

a) Increases

b) Decreases

c) Remains unaffected

d) First increases and then decreases


Part 39: Objective questions and answers of Thermal Engineering


Q1. Answer: a

Q2. Answer: c

Q3. Answer: c

Q4. Answer: b

Q5. Answer: a

Q6. Answer: c

Q7. Answer: d

Q8. Answer: d

Q9. Answer: b

Q10. Answer: b

Q11. Answer: c

Q12. Answer: d

Q13. Answer: c

Q14. Answer: d

Q15. Answer: b

Q16. Answer: c

Q17. Answer: b

Q18. Answer: b

Q19. Answer: b

Q20. Answer: b

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