控制方式对燃煤sCO2发电系统部分负荷运行特性的影响

Effect of control method on partial load operating characteristics of coal-fired sCO2 power generation system

  • 摘要: 为研究不同控制方式对燃煤超临界二氧化碳循环(sCO2)发电系统部分负荷运行特性的影响,建立了300 MW 燃煤sCO2再压缩循环(RC)发电系统,并分别采用存储控制、旁路控制以及温度控制3种控制运行方式使系统运行在30%~100%负荷范围内,对系统关键参数的变化规律进行了分析。结果表明:采用存储控制时热效率先增后减,最大值为49.82%,并且随负荷率降低锅炉进口CO2温度升高、加热温区减小,这会给锅炉的壁温安全和烟气余热回收带来挑战。在旁路控制运行方式下,随负荷率降低旁路阀门节流㶲损快速增大,使系统热效率减小较快。负荷率为30%时,系统热效率从设计值49.53%降至26.30%。采用温度控制时,随负荷率降低压缩机功耗几乎不变使热效率减小,并且部分负荷运行时较大的主气温度变化使系统的最大负荷变化速率在1.3%/min左右,无法满足快速调峰需求,更适合启停过程。研究结果可为sCO2发电系统的部分负荷运行及动态调控提供参考。

     

    Abstract: In order to study the influence of different control methods on the partial load operation characteristics of coal-fired supercritical carbon dioxide (sCO2) power generation system, a 300 MW coal-fired SCO2 recompression cycle (RC) power generation system was established. Then, the inventory control, bypass control, and temperature control methods are adopted to make the system run in the range of 30%−100% load, and analyze the changes in key parameters of the system. The results indicate that when using inventory control, the system’s thermal efficiency (ηth) changes parabolically with load ratios, reaching a maximum value of 49.82%. Additionally, as the load ratio decreases, the CO2 temperature entering the boiler increases, which poses challenges to the safety of wall temperature and the recovery of flue gas waste heat in boiler. Under bypass control, as the load decreases, the throttling loss of the bypass valve increases rapidly, causing the thermal efficiency to decrease quickly. At 30% load, ηth decreased from the design value of 49.53% to 26.30%.When temperature control is used, the compressor power consumption remains almost unchanged as the load rate decreases, resulting in reduced thermal efficiency. The significant temperature variation of the main gas during partial load operation causes the system’s maximum load variation rate to be around 1.3%/min, which cannot meet the demand for rapid peak shaving. Thus, temperature control is more suitable for start-stop processes. The research results of this paper can provide references for the partial load operation and dynamic regulation of sCO2 power generation systems.

     

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