Fuels and Combustion
Presence of free moisture in coal is most disadvantageous during

Combustion of fire slacks on the grates
Its pulverisation (as it requires more power)
None of these
Handling (e.g. when emptying wagons)

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Fuels and Combustion
Ratio of primary air to secondary air increases with increase in the rank of coal, because the

Oxygen content progressively decreases
Ratio of fixed carbon to volatile matter increases
High rank coals have higher amount of volatile matter
Calorific value of the coal increases

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