Performance and Operation Strategy Analysis of BEST Cycle 1000MW Double Reheat unit under Different Operating Conditions

Abstract

Improving steam parameters in a coal-fired power unit boosts cycle efficiency, lowers coal consumption, and reduces emissions. The backpressure extraction steam turbine (BEST) cycle addresses the problem of excessive superheating of extraction steam. This study analyzed a 1000 MW double reheating unit, finding that heat rate in the conventional and BEST cycle systems is heavily influenced by load under THA conditions. At 100% and 75% loads, the BEST cycle’s heat rate decreases but increases at 50% load. For safe operation during flow interruption and high load rates, a pairwise grouping method is recommended for high-pressure heater interruption. When multiple low-pressure heaters are simultaneously cut off, the unit load needs to be limited based on the number of heaters being removed. when multiple low-pressure heaters are simultaneously cut off, the unit load needs to be limited based on the number of heaters being removed. Removing two low-pressure heaters lowers the load to 90%, and three lowers it to 80%. These findings optimize the thermal system’s parameters and enhance overall efficiency.