A Lancashire boiler is fired with coal of calorific value $30M\frac{J}{k}g$ and having an analysis of:

Carbon $=80\%,H_2=5\%,O_2=2\%,$Ash$=13\%{?}_{?}$

Take the flue gas temperature as $400C,$ the boiler$-$house temperature as $10C,$ and the

saturated and at a pressure of $1,2$MPa from feed water at $60C,$ when $470kg$ of coal is

burned per hour.

Determine:

$($a$)$ The mass of air supplied per $kg$ of coal if $30\%$ excess air is admitted.

$($b$)$ The heat lost to the dry flue gases per $kg$ of coal

$($c$)$ The thermal efficiency

$($d$)$ The equivalent evaporation