A sample of coal has the following composition C = 80 %, O = 8%, H = 6 %, S = 1.5%, N = 1 %, Calculate the higher and lower calorific values of coal.

Given: C = 80%, H = 6%, O = 8%, S = 1.5%, N = 1% (N does not contribute to the heat).

Dulong's formula (C, H, O, S in %):
\( \text{HCV} = \frac{1}{100}\left[8080\,C + 34500\left(H - \frac{O}{8}\right) + 2240\,S\right] \) kcal/kg
\( \text{LCV} = \text{HCV} - 0.09\,H \times 587 \) kcal/kg (latent heat of steam = 587 kcal/kg)

\( \text{HCV} = \frac{1}{100}\left[8080(80) + 34500\left(6 - \frac{8}{8}\right) + 2240(1.5)\right] \)

\( = \frac{1}{100}\left[646400 + 172500 + 3360\right] = \frac{822260}{100} \)

HCV = 8222.6 kcal/kg

\( \text{LCV} = 8222.6 - 0.09 \times 6 \times 587 = 8222.6 - 316.98 \)

LCV = 7905.62 kcal/kg