Fuels and Combustion

461.White flue gas (resembling steam) coming out of the chimney of a thermal power plant indicates that the fuel used in the boiler furnace is

  1. Tar
  2. Coke oven gas
  3. Pitch
  4. Pulverised coke

Correct answer: (B)
Coke oven gas

462.Width of the coke oven towards coke side is slightly more than that on pusher side to

  1. Facilitate easy discharging of coke as it swells during carbonisation
  2. Facilitate uniform heating of the oven
  3. Increase the output of the coke
  4. None of these

Correct answer: (A)
Facilitate easy discharging of coke as it swells during carbonisation

463.With increase in C/H ratio of a fuel, the amount of CO2 formed on its complete combustion

  1. Increases
  2. Decreases
  3. Remain same
  4. Either (A) or (B), depends on other factors

Correct answer: (A)
Increases

464.With increase in C/H ratio of a fuel, the dew point of flue gases

  1. Increases
  2. Decreases
  3. Remain same
  4. May increase or decrease; depends on the type of fuel

Correct answer: (B)
Decreases

465.With increase in calorific value of fuels, their adiabatic flame temperatures

  1. Increase
  2. Decrease
  3. Remain unchanged
  4. May increase or decrease; depends on the quantity of products of combustion

Correct answer: (D)
May increase or decrease; depends on the quantity of products of combustion

466.With increase in moisture content of coal, its

  1. Calorific value increases
  2. Caking properties diminish
  3. Swelling during carbonisation becomes excessive
  4. None of these

Correct answer: (B)
Caking properties diminish

467.With increase in the oxygen content of the coal, its _________ decreases.

  1. Calorific value
  2. Caking power
  3. Both (A) & (B)
  4. Neither (A) nor (B)

Correct answer: (C)
Both (A) & (B)

468.With increase in the temperature of carbonisation of coal

  1. Hydrogen content of coke oven gas increases due to cracking of hydrocarbons
  2. Methane content in the coke oven gas decreases and carbon monoxide content increases
  3. Calorific value of the coke oven gas decreases due to cracking of hydrocarbons which is not compensated by increase in CO & H2 content
  4. All (A), (B) and (C)

Correct answer: (D)
All (A), (B) and (C)

469.With increase in the time of carbonisation at a particular temperature (say 1000°C), the _________ percentage in coke oven gas increases.

  1. Hydrogen
  2. Methane
  3. Unsaturated hydrocarbons
  4. All (A), (B) and (C)

Correct answer: (A)
Hydrogen

470.With increases in carbonisation temperature

  1. Coke even gas yield increases
  2. Tar yield increases
  3. Hydrogen percentage in the coke oven gas decreases
  4. Methane percentage in the coke oven gas increases

Correct answer: (A)
Coke even gas yield increases

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