烟气再循环联合循环中燃气轮机温度控制方案

Temperature Control Scheme for Gas Turbine of Combined Cycles with Exhaust Gas Recirculation

在部分负荷工况下,采用余热锅炉排气再循环与压气机进口导叶调节联合应用(EGR-IGVC)策略,可有效改善燃气轮机联合循环性能.但此策略若配合联合循环电站部分负荷工况中燃气轮机常采用的等T3(透平入口温度)-T4_(m)(透平排气温度最大允许值)温控方案,在较低负荷下会造成较大的底循环[火用]损失,底循环做功能力下降明显.提出了一种更适用于EGR-IGVC策略的等T3-T4_(m)-T4_(d)(透平排气温度设计值)温控方案,以PG9351FA型燃气轮机联合循环为研究对象,采用能量与[火用]分析方法,对比研究了EGR-IGVC策略配合两种温控方案时的联合循环部分负荷性能.研究结果表明,当环境温度为15℃,部分负荷率在80%负荷以上时,EGR-IGVC策略配合等T3-T4_(m)方案效果仍为最佳;在30%~80%负荷时,与配合等T3-T4_(m)方案相比,EGR-IGVC策略配合等T3-T4_(m)-T4_(d)方案可使燃气轮机效率提高0.15~0.47个百分点,余热锅炉[火用]损失减少0.51%(2.15 MW)以上.研究亦表明,当环境温度在0~40℃间变化时,采用等T3-T4_(m)-T4_(d)方案总能获得更高的联合循环效率,且随环境温度上升,部分负荷效率增幅更为明显.

Under partial-load conditions,the combined application of exhaust gas recirculation of heat recovery steam generator and compressor inlet guide vane adjustment(EGR-IGVC)can effectively improve the performance of gas turbine combined cycle.However,if this strategy is combined with the temperature control scheme of constant T3(turbine inlet temperature)-T4_(m)(maximum allowable turbine exhaust temperature),which is often adopted in gas turbine combined cycles under part-load conditions,it would cause a large bottoming cycle exergy destruction and a significant decrease in bottoming cycle power output at relatively lower loads.In this paper,a constant T3-T4_(m)-T4_(d)(the design value of turbine exhaust temperature)scheme suitable for the EGR-IGVC strategy is proposed,the PG9351FA gas turbine combined cycle unit is taken as the research object,and the partial-load performance of combined cycle under the two temperature control schemes is compared and investigated based on energy and exergy analysis.The results show that the combination of the EGR-IGVC strategy with the constant T3-T4_(m) scheme is still the best at the ambient temperature of 15℃ and the partial-load rate of above 80%.At a load of 30%—80%,compared with the constant T3-T4_(m) scheme,the EGR-IGVC strategy combined with the constant T3-T4_(m)-T4_(d) scheme can increase the gas turbine efficiency by 0.15%—0.47%,and decrease the exergy destruction of the heat recovery steam generator by more than 0.51%(2.15 MW).The results also show that adopting the constant T3-T4_(m)-T4_(d) scheme can always obtain higher combined cycle efficiency when the ambient temperature varies between 0 and 40℃.In addition,the increase in partial-load efficiency becomes more evident with the rise of ambient temperature.