集成电制热熔盐储热的燃煤发电系统热力性能研究

Thermodynamic Analysis on the Coal-Fired Power Plant Integrated WithPower-to-Heat Molten Salt Thermal Energy Storage System

随着我国能源发展方向的转变,可再生能源的开发利用变得越来越重要,以新能源为主体的新型电力系统对燃煤电厂的灵活性提出了更高的要求。本文构建了三种集成电制热熔盐储热的燃煤发电系统,结合600 MW亚临界机组案例开展了不同熔盐储热系统的热力性能分析。研究结果表明,储热过程中电加热器的[火用]损失达44.30%,在耦合系统储放热循环中[火用]损失占比最大;在不同的分流比下,储热系统的最大释热功率为329.18 MW,此时熔盐储罐释热时长为1.9 h;利用熔盐-水换热器承担部分锅炉热负荷或加热给水可提高系统热力性能,系统的等效往返效率(电-热-电)最高为49.36%。

With the change of energy development direction in China,the development and utilization of renewable energy become more and more important.The new power system with renewable energy as the main body puts forward higher requirements for the operational flexibility of coalfired power plants.In this study,three systems of the coal-fired power plant(CFPP)integrated with molten salt thermal storage with power-to-heat heaters are proposed.To evaluate the thermodynamic performance of the integrated thermal energy storage system,simulation and thermodynamic models for a reference 600 MW CFPP were developed.The molten salt thermal storage systems(MSTES)were designed,and maximum discharging power and the discharge duration of MSTES are 329.18 MW and 1.9 h at different split ratios,respectively.Exergy analysis results show that the exergy loss of electrical heaters in the charging process takes up to 44.30%of power-to-heat-to-power cycle,which is the largest exergy loss of the integrated system.Compared with the standalone coal-fired power plant,using MSTES to replace part of the boiler heat load or extracting steam from turbines can enhance the system’s thermodynamic performance.The largest equivalent round-trip efficiency(electricity-to-electricity)of the system is 49.36%.