This document discusses how coal properties influence boiler design and operation. Key coal properties like moisture content, ash content, volatile matter, and sulfur content affect combustion performance, mill performance, boiler efficiency, slagging, fouling, ESP performance, and the life of boiler components. The furnace design must consider factors like fuel ratio, ash loading, heat release rates, and slagging/fouling characteristics. Indian coals generally have higher ash and moisture contents compared to international coals, which impacts the design of systems like mills and ESPs. The boiler engineer must carefully evaluate these coal properties to optimize boiler performance.