THERMOECONOMIC ANALYSIS OF DESULPHURISATION SYSTEM OF A POWER PLANT

Abstract

This study presents a comprehensive thermodynamic and economic assessment of a wet limestone flue gas desulfurization (FGD) system installed in a coal-fired power plant. Energy and exergy analyses were performed to evaluate the performance of the system and to identify the main sources of thermodynamic inefficiencies. The analysis was conducted based on real operating data of the desulfurization unit, including flue gas composition, mass flow rates, and system operating conditions. The results show that the largest exergy destruction occurs in the filter press unit due to the mechanical energy consumption required for solid–liquid separation, followed by the washing tower where chemical reactions and gas–liquid mass transfer processes take place. Pump units mainly contribute to the overall energy consumption through hydraulic work requirements. In addition to the thermodynamic evaluation, an economic feasibility analysis was carried out using the Net Present Value (NPV) method considering a 20-year operating lifetime. The results indicate that the investment cannot be economically justified when only avoided environmental penalties and heat recovery benefits are considered. However, when potential production losses caused by plant shutdown due to emission non-compliance are included, the system becomes economically feasible with a positive NPV and a payback period of approximately 0.157 years. The sensitivity analysis reveals that the avoided plant shutdown cost is the most influential parameter affecting the economic performance of the system. Overall, the results demonstrate that FGD systems play a crucial role not only in environmental protection but also in maintaining the operational continuity of large-scale power plants.