Flexible Operation Mode of Coal-fired Power Unit Coupling with Heat Storage of Extracted Reheat Steam

In order to provide more grid space for the renewable energy power, the traditional coal-fired power unit should be operated flexibility, especially achieved the deep peak shaving capacity. In this paper, a new scheme using the reheat steam extraction is proposed to further reduce the load far below 50% rated power. Two flexible operation modes of increasing power output mode and reducing fuel mode are proposed in heat discharging process. A 600 MW coal-fired power unit with 50% rated power is chosen as the research model. The results show that the power output is decreased from 300.03 MW to 210.07 MW when the extracted reheat steam flow rate is 270.70 t center dot h(-1), which increases the deep peak shaving capacity by 15% rated power. The deep peak shaving time and the thermal efficiency are 7.63 h center dot d(-1) and 36.91% respectively for the increasing power output mode, and they are 7.24 h center dot d(-1) and 36.58% respectively for the reducing fuel mode. The increasing power output mode has the advantages of higher deep peak shaving time and the thermal efficiency, which is recommended as the preferred scheme for the flexible operation of the coal-fired power unit.