Fuels and Combustion
High amount of sulphur and phosphorous in coke causes

Decrease in its calorific value
Brittleness of steel made by using it
None of these
Increase in its strength

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Fuels and Combustion
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

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Fuels and Combustion
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 : 6.39, CO : 1.60, O₂ : 3.99, H₂O:25.96, N₂:72.06
CO₂ : 7.60, CO : 1.90, O₂ : 4.75, N₂ : 85.74
CO₂ : 7.42, CO : 1.86, O₂ : 4.64, N₂:86.02
CO₂ : 6.26, CO : 1.56, O₂ : 3.91, H₂O :15.66, N₂ : 72.60

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