超临界二氧化碳发电系统紧急停车过程动态特性研究

Study on the Dynamic Characteristics of a Supercritical CO Power System During Emergency Shutdown

针对某300 kW功率等级的超临界二氧化碳简单回热发电系统建立了全系统动态仿真模型,研究了系统发生紧急停车时的动态响应过程及阀门流量特性对过程控制品质的影响。结果表明:涡轮旁通策略可以有效控制系统紧急停车过程的转速上升幅度,保障系统安全;整个紧急停车过程持续约50 s,其中第一阶段持续数秒,其特性主要受旁通阀特性主导,动作时间2 s内的快开型旁通阀可满足系统的安全控制要求;第二阶段呈单调衰减趋势,持续时间40~50 s,主要受系统自身特性影响;在紧急停车的第一阶段,压缩机出口和涡轮出口压力分别上升1.5%和7.3%,回热器冷侧和热侧入口质量流量分别上升35%和80%,回热器热侧入口温度上升约30 K;冲击效应对设备安全造成的影响应在超临界二氧化碳发电系统设计时予以特别考虑。

A dynamic model of a 300 kW supercritical CO2 simple cycle power system was established, the dynamic responses of the system during emergency shutdown and the influence of valve characteristics on process control quality were studied. Results show that the turbine bypass strategy can effectively control the speed rise of the system during emergency shutdown and ensure the safety of the system. The emergency shutdown process which can be divided into two stages lasts about 50 s. The first stage which lasts for several seconds is mainly dominated by the characteristics of bypass valve. The quick opening valve with a full action time smaller than 2 s can meet the safety control requirements of the system. The second stage which lasts for 40-50 s is monotonic decay and mainly affected by the characteristics of the system itself. In the first stage, the pressure of compressor outlet and turbine outlet increase by 1.5% and 7.3%, the inlet mass flow rate of cold side and hot side of recuperater increase by 35% and 80%, and the inlet temperature of hot side of recuperater increases about 30 K. The impact of shock effect on equipment safety should be considered in the design of supercritical CO2 power system.