Thermal performance study of tower solar aided double reheat coal-fired power generation system

In this paper, a novel tower solar aided coal-fired power generation (TSACPG) system with double reheat ultra-supercritical boiler is proposed. Part of the steam at the primary reheater inlet of the boiler is heated by tower solar collector and returned to the primary reheater according to the principle of energy grade matching. The thermal performances of the TSACPG system under different operation loads are studied. The maximum steam extraction mass flow of the boiler first reheater and the utilization rate of solar energy are obtained. The results show that the maximum steam extraction mass flow rates of the boiler are 70 kg/s in 100% THA, 75 kg/s in 80% THA and 87 kg/s in 60% THA load, respectively. And the standard coal consumption rates are decreased by 4.85 g/kWh, 8.79 g/kWh and 18.55 g/kWh, respectively. The boiler exergy efficiency ascends significantly and the thermal efficiency of the TSACPG system is obviously improved. With the increase of the replaced steam, both the power output and the proportion of solar power generation are gradually increased, and the solar-to-electricity efficiency is also improved. Compared with other integration schemes in references, the boiler exergy efficiency and solar-to-electricity efficiency of the TSACPG system could be increased by 9.64% and 7.07%, respectively. •A novel tower solar aided coal-fired power generation (TSACPG) is proposed.•The maximum steam extraction mass flows of TSACPG at different loads are obtained.•Thermal performances of the TSACPG system under different loads are studied.•Solar-to-electricity efficiencies at different loads and DNI values are analyzed.