Fuels and Combustion

31.A fuel with high heat release rate will

  1. Require smaller combustion chamber
  2. Have high calorific value
  3. Have high adiabatic flame temperature
  4. None of these

Correct answer: (A)
Require smaller combustion chamber

32.A gaseous fuel in order to develop luminosity on burning, must contain

  1. Carbon monoxide
  2. Hydrocarbons
  3. Hydrogen
  4. Oxygen

Correct answer: (B)
Hydrocarbons

33.A good coking coal should have high _________ content.

  1. Ash
  2. Sulphur & phosphorus
  3. Moisture
  4. None of these

Correct answer: (D)
None of these

34.A good metallurgical coke

  1. Should have high porosity
  2. Should be brittle
  3. Must contain moderate quantities of ash, moisture, sulphur and volatile matters
  4. Should have low fusion point of its ash

Correct answer: (A)
Should have high porosity

35.A good metallurgical coke should have very low

  1. Sulphur & phosphorous content
  2. Porosity
  3. Fusion point of its ash
  4. Hardness & strength

Correct answer: (A)
Sulphur & phosphorous content

36.A good quality coal should have

  1. Low fusion point of ash
  2. High ash content
  3. High sulphur
  4. None of these

Correct answer: (D)
None of these

37.A liquid/gaseous fuel containing hydrocarbons and high amount of sulphur is burnt with 40% excess air. The flue gas still contains large amount of carbon monoxide. This may be due to the

  1. Presence of large quantity of hydrogen in the fuel
  2. Low calorific value of the fuel
  3. High sulphur content in the fuel
  4. Lack of thorough mixing of fuel with air

Correct answer: (D)
Lack of thorough mixing of fuel with air

38.A particular coal is said to be free burning when it

  1. Burns completely
  2. Gives smokeless burning
  3. Shows little or no fusing action
  4. None of these

Correct answer: (C)
Shows little or no fusing action

39.A sample of natural gas containing 80% methane (CH4) and rest nitrogen (N2) is burnt with 20% excess air. With 80% of the combustibles producing CO2 and the remainder going to CO, the Orsat analysis in volume percent is

  1. CO2 : 6.26, CO : 1.56, O2 : 3.91, H2O :15.66, N2 : 72.60
  2. CO2 : 7.42, CO : 1.86, O2 : 4.64, N2:86.02
  3. CO2 : 6.39, CO : 1.60, O2 : 3.99, H2O:25.96, N2:72.06
  4. CO2 : 7.60, CO : 1.90, O2 : 4.75, N2 : 85.74

Correct answer: (B)
CO2 : 7.42, CO : 1.86, O2 : 4.64, N2:86.02

40.A travelling grate stoker is meant for the efficient burning of _________ coal.

  1. Caking
  2. Pulverised
  3. Non-caking
  4. High ash

Correct answer: (C)
Non-caking

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