中小型燃气–蒸汽联合循环系统的部分回热调控方法

Partially Recuperative Control Method of Medium/Small-sized Gas-steam Combined Cycle Power System

现代中小型燃气轮机相对具有较高的透平排气温度,而与之相匹配的底循环通常为单压或双压蒸汽动力系统,难以实现透平排气的高效、灵活热功转换。为提升该类燃气-蒸汽联合循环供能系统高效灵活性,提出回热可调控的燃气轮机联合循环系统(recuperative control,GTCC-RC),在全工况范围调节顶、底循环功比。以50MW级燃气轮机为例,以常规燃气-蒸汽联合循环系统为基准,设计GTCC-RC系统,并从㶲损失和热效率的角度进行全工况性能分析,提出系统的全工况最佳调控策略。案例研究表明:GTCC-RC提升了燃气轮机㶲效率。随着回热比例增加,燃料输入量减少。回热调控提升了案例联合循环系统的热效率和灵活性。与没有回热的基准系统相比,GTCC-RC系统调峰深度增加6.51%,联合循环热效率相对提升达6.47%。

Advanced medium/small-sized gas turbines have relatively higher turbine exhaust temperature, while the matched bottom power cycles generally in the form of single pressure or dual pressure are often incompetent for efficient and flexible power conversion from turbine exhaust heat. In order to improve the efficiency and flexibility of the gas-steam combined cycle(GTCC) power system based on the above-mentioned gas turbines, recuperative control(GTCC-RC) was proposed for adjusting the power ratio of the topping cycle to the bottom cycle at overall partial loads. Taking a 50MW gas turbine as an example, based on the conventional reference gas-steam combined cycle system, a GTCC-RC system was designed and the part-load performance was analyzed from the viewpoints of exergy loss and thermal efficiency;and the load-control strategies were proposed. The case study shows that the GTCC-RC improves the exergy efficiency of gas turbines.GTCC fuel input decreases with the increase of recuperative ratio. Recuperative control enhances the efficiency and flexibility of the GTCC case system. In comparison with the reference system without recuperator, the depth of peak shaving relatively increases by 6.51% and the GTCC thermal efficiency relatively improves by up to 6.47% in the proposed GTCC-RC system.