Biomass Fuel Characterization: Ultimate/Proximate Analysis, Dulong's Heating Value Formula & Stoichiometric Air

• Operational Characteristics of Screw Conveyors:
• screw conveyor consists of a helical auger revolving inside a stationary U-shaped or cylindrical trough.
• Due to continuous rubbing friction between the material, auger flights, and trough wall:
• Power consumption is relatively high compared to belt conveyors or bucket elevators ($2-3$ times higher power).
• Continuous abrasive contact makes screw flights and bearings more susceptible to wear.
• Conclusion: Require relatively high power and are more susceptible to wear (Option 2).

Correct option: (2) Require relatively high power and are more susceptible to wear

• Dulong's Formula for Fuel Calorific Value:
• Ultimate / Elemental Basis: Dulong's formula is a classic empirical thermochemical equation used to calculate the Higher Heating Value (HHV) of fuels based directly on their elemental composition (percentage of Carbon, Hydrogen, Oxygen, and Sulfur determined by ultimate analysis):

$$\text{HHV} = 338.2\,\text{C} + 1442.8\left(\text{H} - \frac{\text{O}}{8}\right) + 94.2\,\text{S}\quad [\text{kJ/kg}]$$

• Comparison: Proximate analysis provides moisture, volatile matter, fixed carbon, and ash content, but not elemental mass fractions.
• Conclusion: Elemental (Option 3).

Correct option: (3) Elemental

• Stoichiometric Oxygen Requirement for Methane Combustion:
• Stoichiometric Reaction Equation:

$$\text{CH}_4 + 2\text{O}_2 \longrightarrow \text{CO}_2 + 2\text{H}_2\text{O}$$

• Molecular Weights:
• $\text{CH}_4 = 12 + 4(1) = 16\text{ g/mol}$
• $2\text{O}_2 = 2 \times (2 \times 16) = 64\text{ g/mol}$
• Mass Ratio:

$$\text{Mass of Oxygen required per kg of Methane} = \frac{64\text{ kg }\text{O}_2}{16\text{ kg }\text{CH}_4} = 4\text{ kg }\text{O}_2$$

• Conclusion: Four kilograms of oxygen are required (Option 4).

Correct option: (4) Four