The ultimate analysis of a coal sample is given below :

Carbon $61\mathrm{.}5\%,$ Hydrogen $3\mathrm{.}5\%,$ sulphur $0\mathrm{.}4\%,$ Ash $14\mathrm{.}2$ nitrogen $1\mathrm{.}8\%,$ and rest oxygen. Calculate :

$($a$)$ The theoretical oxygen requirement per unit weight of coal,

$($b$)$ The theoretical dry air requirement per unit weight of fuel, and

$($c$)$ The Orsat analysis of flue gases when the coal is burned with $90\%$ excess dry air.

Sol. Basis : $100kg$ coal

It contains $61\mathrm{.}5kg$ carbon, $3\mathrm{.}5kg$ hydrogen, $0\mathrm{.}4kg$ sulphur, $14\mathrm{.}2kg$ ash, $1\mathrm{.}8kg$ nitrogen and $18\mathrm{.}6kg$ oxygen.