Thermal Performance Analysis of 1000MW Secondary Reheating EC-BEST Unit Under Variable Operating Conditions

The study was conducted on the operational characteristics and thermal economy of the EC-BEST system for conventional 1000MW ultra supercritical secondary reheating units, addressing issues such as high extraction superheat and significant irreversible heat transfer losses in the reheating system. Under the same boundary conditions, EBSILON software is used to model and simulate the thermal performance changes of the 1000MW secondary reheating unit after adopting the EC-BEST system, including extraction superheat, feedwater temperature, power output and efficiency of each cylinder block, and heat consumption rate. The reasons for the thermal performance changes are briefly analyzed. The results show that the 1000MW secondary reheating unit using EC-BEST system can effectively solve the problems of high steam extraction superheat in existing conventional secondary reheating units, improve the heat exchange efficiency of the entire feedwater system and deaerator, and enhance the unit's cycle efficiency. Under THA working conditions, the degree of superheat of the No.2 to No.6 stage extraction steam is reduced from above 250°C to below 100°C, and the inlet steam of the deaerator is reduced from superheated steam to wet steam, the temperature of the feedwater increases by 3.1°C; The cycle efficiency of the unit increases, and the heat consumption rate of the unit decreases by about 23kJ/kg, equivalent to a coal consumption of about <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{0.83g}/(\mathbf{kW}\cdot \mathbf{h})$</tex> for the unit.