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Question 1.1.2: Calculate the mass of air needed for the complete combustion......

Calculate the mass of air needed for the complete combustion of 5 kg of coal containing C = 80%; H = 15%, O = rest

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\begin{aligned} \text{Oxygen required from air} & =  \text{Total}  O_2  \text{required}  –  O_2  \text{in fuel}\\&  =  3.333  –  0.05 = 3.283 ~kg\end{aligned}

Weight of air required for combustion of 1 kg of fuel = 3.283 × \frac{100} {23} = 14.27 ~kg

\begin{aligned}\text{Therefore, weight of air required for combustion of 5 kg of fuel} = 14.27 × 5 =  &71.369 ~kg\\ \\ & [Ans = 71.369 ~kg] \end{aligned}
Constituent Amount per kg of the coal sample Combustion reaction
Weight of \bf O_2 required
C 0.80 kg C +O_2 \rightarrow CO_2
0.80 × \frac{32}{12} = 2.133 ~kg
H 0.15 kg H_2 +\frac{1}{2}  O_2 \rightarrow H_2O
0.15 × \frac{16}{2} = 1.20 ~kg
O
1.00−(0.80 + 0.15) = 0.05 kg
\text{Total}  O_2  \text{required} \\ = 2.133 + 1.20=3.333 ~kg

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