동일한 출력을 생산하는 상황에서 급수가열기를 바이패스 시 해당 급수가열기 추기량이 줄어들고, 보일러로 공급되는 최종급수량, 주증기량, 급수온도도 낮아졌다. 또 재열증기 유량은 약간 증가하는데, 이들을 기반으로 계산된 터빈 열효율은 감소하는 것을 확인하였다. 고출력 운전 때에 비해 저출력에서는 감소량이 줄어들 뿐 저출력에서도 특별히 터빈효율에 반전을 주는 급수가열기 운전조합은 없었다. 터빈 부속 설비인 급수가열기 운전변화는 최종 급수온도와 급수유량에 변화를 가져와 보일러 운전에도 영향을 주었다. 배기가스 온도 감소로 보일러 손실이 줄고 효율이 높아지는 효과가 있었다. 터빈과 보일러 효율을 종합한 플랜트 효율은 급수가열기 바이패스 모든 케이스에서 나빠짐을 확인하였다. 급수가열기 바이패스로 인한 터빈 사이클 효율 저하량이 배기가스 감소로 인해 생기는 보일러 효율 상승보다 훨씬 커서 플랜트 효율 향상에 도움이 되지 못하였다. 따라서 급수가열기는 부분부하에서도 8대 모두 정상적으로 운영함이 플랜트 효율에 효과적이다. 다만 발전소에서 보일러 배기가스 는 특별한 경우에는 최종 급수가열기를 운전부하를 조정하면 배기온도 감소의 효과를 얻을 수 있다.
Changes in the environment of the power industry surrounding coal power plants are rapidly progressing. The government''s shift in energy policy and the people''s demand for fine dust reduction are becoming the spirit of the times. Standard coal-fired power, the only model in Korea with 20 units, cannot be an exception to this wave. It is expected that low-power operation time that has not been experienced so far will increase and voices for efficient operation will grow. The study was conducted to find ways to operate high efficiency in a new environment where such standard coal-fired power will be encountered. It is installed to increase cycle efficiency by extracting some of the steam working in turbines with standard coal-fired power, thereby reducing fuel consumption in boilers, and reducing heat thrown away into polymers. Standardization power is typically operated with eight water supply heaters installed and all eight in normal service. In this study, we studied whether the eight normal driving units under low loads, which will be the driving section in the future, are efficient in terms of plant operation or there is a more efficient driving combination. For the study, we created a model that implements turbine thermal performance changes and a boiler-cutter heat exchange model using a cycle of a power plant system simulation program, Gate Cycle. Two models are constructed into a single comprehensive model, allowing one-time verification of turbine and boiler operation values according to the research case. The research case adjusted the water supply heat load rate for water supply heaters No. 7 and No. 8 each or at the same time, receiving cold water from high-pressure turbines. Load rate adjustment means adjusting the flow rate through the heater using the water heater bypass system. When the water supply bypassed the heat in the same output, the water supply first decreased the amount of heat, and the final water supply, main steam, and water supply temperature supplied to the boiler also decreased. The re-heat vapor flow rate is also slightly increased, and based on these, the calculated turbine thermal efficiency is reduced. Compared to high-power operations, there was no combination of water heater operations that reduced the amount of reduction at low power, but also reversed turbine efficiency. Among the many driving combinations, the most efficient combination is when the water heater 8 is operated normally and the water heater 7 is driven at 50% load, with both of them 0.15%P lower at 375MW and 0.11%P lower at 250MW than normal driving conditions. For reference, the 500MW was 0.18% lower. Changes in operation of the water heater, an auxiliary facility for turbines, also affected boiler operation by changing the final water temperature and water flow rate. Reducing exhaust gas temperature reduced boiler loss and increased efficiency. Boiler efficiency increased by about 0.06%p for a 5℃ reduction in exhaust gas temperature at the exit of the cutting machine. Plant efficiency, which combines turbine and boiler efficiency, has been identified as deteriorating in all cases of water supply heat bypass. The reduction in turbine cycle efficiency due to water supply heat bypass was much larger than the increase in boiler efficiency caused by exhaust gas reduction, which did not help improve plant efficiency. Therefore, all eight units are operated normally even under partial load, which is effective in plant efficiency. However, in special cases, boiler exhaust gas in power plants can be reduced by adjusting the operation load of the final water supply heat.
