A boiler produces \(15000 \mathrm{~kg} / \mathrm{h}\) of steam at 7 bar, \(300^{\circ} \mathrm{C}\). The feed water temperature is \(70^{\circ} \mathrm{C}\). The calorific value of fuel \(=30,000 \mathrm{~kJ} / \mathrm{kg}\). The grate is to be designed to burn \(450 \mathrm{~kg}\) of coal/ \(m^{2} . h\). Find the grate area required assuming combustion efficiency \(=90 \%\) and combined boiler and superheater efficiency \(=75 \%\). Take \(C_{p s}=2.19 \mathrm{~kJ} / \mathrm{kg} . \mathrm{K}\).