381. Incomplete combustion of fuel in the furnace is judged by high __________ of the flue gases.
CO content
Dew point
CO₂ content
O₂ content
✅ The correct answer is option A.
Fuel and Combustion MCQs
382. 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
Presence of large quantity of hydrogen in the fuel
Low calorific value of the fuel
High sulphur content in the fuel
Lack of thorough mixing of fuel with air
✅ The correct answer is option D.
383. Which of the following would require least amount of secondary air for combustion?
Coke breeze containing 25% ash and 2% volatile matter
Anthracite containing 10% volatile matter and 8% ash
Bituminous coal containing 20% ash and 25% volatile matter
Semi-bituminous coal containing 25% ash and 20% volatile matter
✅ The correct answer is option A.
384. Presence of __________ in a dry gaseous fuel does not contribute to its calorific value.
Sulphur
Oxygen
Hydrogen
Carbon
✅ The correct answer is option B.
385. Blast furnace gas is a very poisonous gas because of its predominantly high __________ content.
H₂O
CO₂
CO
CH₄
✅ The correct answer is option C.
386. 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 reminder going to CO, the Orsat analysis in volume percent is
CO₂ : 6.26, CO : 1.56, O₂ : 3.91, H₂O :15.66, N₂ : 72.60
CO₂ : 7.42, CO : 1.86, O₂ : 4.64, N₂:86.02
CO₂ : 6.39, CO : 1.60, O₂ : 3.99, H₂O:25.96, N₂:72.06
CO₂ : 7.60, CO : 1.90, O₂ : 4.75, N₂ : 85.74
✅ The correct answer is option B.
387. Which of the following is not a product of tar distillation?
Phenol & naphthalene
Benzol & pitch
Anthracene & creosote
None of these
✅ The correct answer is option D.
388. Washing of coal is done to reduce the
Inherent impurities
Adhering impurities
Mineral matter
Both B and C
✅ The correct answer is option D.
389. Coal tar fuel – 200 (CTF 200) is a mixture of
Pitch and creosote oil
Light oil and pitch
Anthracene and crecosote oil
Solar oil and pitch
✅ The correct answer is option A.
390. Anthracite can be used for
Recarbonising steel
Making carbon electrodes
Blending with highly coking coal to check its swelling which helps in saving coke even walls from damage and to produce high strength coke
All of the above
✅ The correct answer is option D.