Why use pulverised coal firing in boilers? In steam-generating boiler furnaces, what is the principal advantage achieved by firing pulverised coal instead of lump coal?

Introduction / Context:
Pulverised coal (PC) firing grinds coal into fine particles and pneumatically conveys it to burners. This increases surface area for rapid devolatilization and char burnout, enabling high heat release rates in compact boilers.

Given Data / Assumptions:

• Comparing PC firing to lump/stocker firing.
• Single best advantage must be selected.

Concept / Approach:
Finely divided coal dramatically improves mixing with combustion air and shortens burnout time, producing high, controllable flame temperatures and complete combustion (lower CO and unburnt carbon losses). Calorific value is an inherent fuel property and does not increase by pulverizing. Smoke opacity can be reduced with proper burners and staging, but “smokeless” is not inherent. Wall erosion can worsen if ash-laden high-velocity jets impinge surfaces.

Step-by-Step Solution:

Verification / Alternative check:
Boiler performance tests show higher combustion efficiency and lower unburnt losses with well-designed PC burners compared to lump coal grates.

Why Other Options Are Wrong:

Common Pitfalls:
Assuming PC always reduces emissions; NOx and particulate controls still need optimized air staging and capture systems.

Final Answer:
better combustion