Abstract: Boiler is an important practical application in heat transfer devices. Its function is to transfer the heat produced by the combustion of fuel to water, and ultimately to generate steam. This paper was carried out by taking data of Pulverized fuel boiler which is a water tube boiler having pressure 138 bar and temperature 540⁰C.The fuel used in this boiler is low grade bituminous coal having a calorific value of 4204kcal/kg. The performance of this boiler was conducted by calculating thermal efficiency and heat losses of pulverized fuel boiler by indirect method. Gross calorific value of fuel, wind velocity, surface temperature of boiler shell, and ambient temperature, humidity of air, fuel firing rate, specific heat of flue gas and steam are taken as input parameters. Thermal efficiency, heat losses such as heat losses due to dry flue gas, evaporation of water formed due to H₂ in fuel, moisture present in fuel, moisture present in air, incomplete combustion, radiation and convection and unburntfuel in fly ash and bottom are calculated.

Keywords: boiler, pulverized fuel boiler, heat losses, Thermal efficiency, GCV of coal.