Experimental study the effect of excess air to unburn carbon and boiler efficiency using coal with heating value 4200 kcal/kg at a 500 MW steam power plant

Boiler is one of power plant equipment that has function to produce steam. Thermal boiler efficiency is defined as the ratio of energy output to energy input to produce steam. There are two methods for evaluating boiler efficiency, namely direct method (input output method) and indirect method (heat loss). The experimental method carried out in this study was to conduct experiments and retrieve data on a 500 MW steam power plant boilers with variations in the ultimate low range coal (LRC) having calorific value of 4200 kcal/kg of coal. By using the experiment data, this paper is to analysis the effect of variations in the percentage of excess air to unburn carbon and the efficiency of the boilers. The results of the data were then analyzed. And giving that the most optimum value of excess air to produce the lowest unburn carbon value in the 500 MW power plant with 4200 calorific value coal is 10%.