The Influence of Throughput on Thermodynamic Efficiencies of a Thermal Power Plant

This study carried out energy and exergy analyses of a thermal power plant in order to evaluate the energetic and exergetic efficiencies and irreversibilities of units, sections and the overall system. It was also, to determine the optimum fuel-air ratio and optimum combustion temperature at different throughputs. The thermal plant consisting of 23 units and 4 sections was simulated using HYSYS simulation software and EXCEL spreadsheet. The EXCEL spreadsheet was used for the energy and exergy analyses. It was found that throughput did not influence the energy efficiencies of the units but the exergy efficiencies. Throughput did not influence the energy and exergy efficiencies of the sections. The overall energetic efficiencies of the plant were 18.17, 19.79, 21.42, and 21.45% and the overall exergetic efficiencies were 10.26, 11.22, 11.58, and 11.61% for throughputs of 50, 75, 100 and 110%, respectively. The overall irreversibilities of the plant increased as the throughput increased. The optimum fuel-to-air ratio which gave the optimum combustion temperature in the furnace was found to be 1:12.6 for all the throughputs which was an improvement over the current practice of 1:19.8. Throughput did not influence the maximum combustion temperature in the furnace.