Performance assessment of the novel coal-fired combined heat and power plant integrating with flexibility renovations

Abstract

The operational flexibility of coal-fired combined heat and power (CHP) plants is critical for the power grid to accommodate high-penetration renewable energy. Flexibility renovations, including the high back-pressure (HBP) renovation and the low-pressure turbine zero power output (LZPO) renovation, are integrated within CHP plants and can enhance the heat-power supply flexibility. In this study, the existing two renovations are compared in consideration of flexibility, energy and exergy performance. The performance assessment of the novel CHP plant integrating with flexibility renovations are conducted. Quantitative analyses are then conducted on a characteristics day. Results show that compared with the HBP renovation, the LZPO renovation presents greater potential to improve the accommodation of renewable energy and energy efficiency, whereas is not satisfactory in larger exergy loss. Besides, compared with the conventional plant, the feasible peak-shaving capacity and heating capacity of the novel renovated plant are improved by 43 MW and 320 MW, respectively. The maximal energy utilization efficiency increases from 71.70% to 80.91%, and the exergy loss decreases from 216.9 MW to 151.2 MW. Moreover, the accommodation of renewable energy increases by 5.1 million kWh while the standard coal consumption rate for power generation decreases from 248.3 g/kWh to 222.3 g/kWh.