燃气轮机/超临界二氧化碳联合循环余热利用及动态特性分析

Analysis of waste heat utilization and dynamic characteristics of gas turbine/supercritical carbon dioxide combined cycle

超临界二氧化碳(S-CO_(2))循环具有透平尺寸小、压缩机功耗小、循环效率高等诸多优势。为了探究S-CO_(2)循环耦合燃气轮机发电系统后发电效率最高的循环配置,提出了4种循环布局;并通过遗传算法以循环效率最高为优化目标,对循环系统的主要参数进行优化;对该方案进行动态系统分析,以底部循环输入热负荷为扰动变量,探究从满负荷分别阶跃降低到90%负荷、80%负荷和70%负荷后系统的动态响应情况。结果表明:4种方案中燃气轮机/两透平S-CO_(2)联合循环系统循环效率最高,为44.87%;烟气换热器附近参数响应时间比较快,而由于热惯性的影响在工质流程中离烟气换热器越远响应时间越长;且在同一位置,压力的响应时间略长于温度的响应时间,高温透平附近参数的下降幅度大于低温透平。

Supercritical carbon dioxide cycle has many advantages such as small turbine size,small compressor power consumption and high cycle efficiency.In order to explore the cycle configuration with the highest power generation efficiency after the power generation system of supercritical carbon dioxide cycle coupled gas turbine,four cycle layouts were proposed.The main parameters of the circulating system were optimized by genetic algorithm with the maximum circulating efficiency as the optimization objective.Among the four schemes,the gas turbine/two-turbine supercritical carbon dioxide combined cycle system has the highest cycle efficiency,which is 44.87%.And the dynamic system analysis of the scheme,with the bottom cycle input heat load as the disturbance variable,explore the dynamic response of the system after the step reduction from full load to 90%load,80%load and 70%load respectively.The results show that the response time of parameters near the flue gas heat exchanger is faster and the response time is longer when the shadow of thermal inertia is farther away from the flue gas heat exchanger in the working medium flow.At the same position,the response time of pressure is slightly longer than that of temperature,and the drop range of parameters near the high-temperature turbine is greater than that of the low-temperature turbine.