Study on The Analysis of Coal Calorific Value Changes on Boiler Efficiency at PLTU Nii Tanasa

Abstract

This study aims to analyze the effect of variations in coal calorific value on boiler efficiency at the Nii Tanasa Steam Power Plant (PLTU Nii Tanasa) in Southeast Sulawesi. The research is motivated by the fluctuation in coal quality used during plant operations, which can influence thermal performance and fuel consumption. The main objective is to determine how changes in coal calorific value affect boiler efficiency and to identify the major sources of energy loss in the combustion system. The research employed an energy balance method, using both primary and secondary data obtained from boiler operations. Primary data included the coal’s calorific value, proximate and ultimate analysis, and operational parameters for three different calorific values: 4003 kcal/kg, 4159 kcal/kg, and 4185 kcal/kg. Secondary data were collected from the boiler’s technical specifications and operational records at PLTU Nii Tanasa. The analysis was conducted using the indirect/heat loss method to calculate the heat input, useful heat output, flue gas losses, and overall thermal efficiency. The results show that higher coal calorific values lead to increased boiler efficiency. Efficiency rose from 88.02% at 4003 kcal/kg to 89.1% at 4185 kcal/kg. The largest energy losses were observed in flue gas and radiation heat, accounting for more than 20% of the total energy. Therefore, maintaining coal quality and controlling combustion air are key factors in improving the thermal efficiency of boilers at PLTU Nii Tanasa.