Fuel and Combustion MCQs

Lignite

Semi-anthracite

Sub-bituminous

Bituminous

Fire point

Smoke point

Burning temperature

Kindling temperature

Calorific value

Higher C/H ratio

Sulphur content

Difference in gross & net calorific value

Are soft & friable (poor strength and size stability)

Require longer time of carbonisation as ash offers resistance to heat transfer

Produce larger quantity of coke oven gas

None of these

Vitrain

Fussain

Both A & B

Neither A nor B

It can not burn low grade coal

It achieves higher fuel combustion efficiency

Less heat transfer surface area is required in boilers

None of these

Reduces its ash & sulphur content

Improves its coking properties

Increase the fusion point of its ash by removing chlorine compounds

All of the above

All tar is evolved at < 600°C

Evolution of H₂ and formation of methane and aromatics occur at > 700°C

Hard semi-coke starts shrinking at 600°C

All of the above

Semet-Solvay process

Segas process

Onia-Gegi process

Steam reforming of naphtha

Carbonisation

Oxidation

Coalification

Gasification