Thermodynamic Performance and CO2 Cost Implications of Regenerative Feedwater Heating in a 217 MW Coal-Fired Power Plant

This paper presents a thermodynamic modelling and performance analysis of a 217 MW coal-fired steam power plant, based on operating data from the only currently active coal-fired unit in Croatia. The study provides a concise technical description of the plant and a detailed thermodynamic analysis of energy flows across all major components of the steam cycle. The analysis was carried out using two complementary approaches: analytical calculations based on standard thermodynamic balance equations and numerical simulations performed with the commercial software Ebsilon Professional Version 17.00. The results obtained by both methods were validated against data reported in the literature and showed deviations within acceptable limits. Using the validated model, the influence of the number of regenerative feedwater heaters on overall plant efficiency was analysed. Additionally, sensitivity analyses were conducted to evaluate the influence of selected parameters, including the fuel net calorific value (NCV), the terminal temperature difference (TTD) of feedwater heaters, and pressure drops within the regenerative system. The results show that increasing the TTD from 2 K to 8 K reduces the net thermal efficiency from approximately 37.01% to 36.79%, while variations in pressure drop have a negligible effect on plant performance. Finally, a CO2 emission cost analysis was conducted for each configuration, and conclusions regarding efficiency improvement and emission reduction were drawn. It was found that removing any regenerative feedwater heat exchanger decreases the observed overall plant efficiency by approximately 0.55% on average and increases plant CO2 emissions by approximately 0.025 Mt per year on average.