Fuels and Combustion
The weathering index of a coal

Is a measure of its size stability, when stored & exposed to weather
Gives an idea of the fusion temperature of ash
Is a measure of its caking tendency
Is related to its calorific value

ANSWER DOWNLOAD EXAMIANS APP

Fuels and Combustion
Sometimes water is sprayed during coal charging in the coke oven, which helps in

All of these
Reducing the cracking of hydrocarbons in the gas and increasing the percentage of CO & H₂ in the gas (due to the endothermic reaction represented by C + H₂O = CO + H₂)
Controlling the dust nuisance while charging the coal
Prevention of clinker formation in the oven

ANSWER DOWNLOAD EXAMIANS APP

Fuels and Combustion
Producer gas containing least amount of tar is produced by the

High pressure gasification of coal (e.g. in Lurgi gasifier)
Atmospheric pressure gasification of coal (e.g., in Kopper-Totzek gasifier)
Partial combustion of large size (< 50 mm) coke
Partial combustion of coal

ANSWER DOWNLOAD EXAMIANS APP

Fuels and Combustion
A carbonaceous fuel (containing no H₂ or hydrocarbons) is burnt and the resulting flue gas contains 21% CO₂. It means that

No excess air has been used for combustion
21% excess oxygen has been used for combustion
Complete combustion of fuel has taken place
21% excess air has been used for combustion

ANSWER DOWNLOAD EXAMIANS APP

Fuels and Combustion
Lignite is

Can be used for gasification and steam generation
A coking coal
A black banded coal which burns with a non-smoky yellowish flame
A high rank coal

ANSWER DOWNLOAD EXAMIANS APP