超临界蒸汽参数对燃气蒸汽联合循环性能影响研究

Study of the Influence of the Supercritical Steam Parameters on the Performance of a Gas-steam Combined Cycle

为进一步提高联合循环效率,参考现有燃气蒸汽联合循环12.5 MPa/568℃亚临界蒸汽参数,提出27 MPa/585℃超临界蒸汽参数,根据燃气蒸汽联合循环计算模型,以397 MW燃气轮机联合循环机组为例,计算了超临界蒸汽参数与两种亚临界蒸汽参数的底循环效率和联合循环效率,并分析对比了3种蒸汽参数的底循环效率对联合循环效率的贡献。研究表明：对于同一燃气轮机,超临界和亚临界中低压蒸汽参数不同时,超临界蒸汽参数的底循环效率比亚临界提高了4.3%,蒸汽底循环输出功率占联合循环机组输出功率的百分比由30.21%增加到32.62%,联合循环净效率增加了2.21%,联合循环机组的输出功率增加了20.38 MW;中低压蒸汽参数相同时,超临界蒸汽参数的底循环效率比亚临界提高了2.87%,蒸汽底循环输出功率占联合循环机组输出功率的百分比由31.16%增加到32.62%,联合循环净效率增加了1.44%,联合循环机组的输出功率增加12.5 MW。

To further improve the efficiency of a combined cycle under the condition of an increasing temperature of the exhaust gas from gas turbines ,with the subcritical steam parameters 12.5 MPa/568℃ of a gas-steam combined cycle serving as the reference, supercritical steam parameters 27 MPa/585℃ were proposed. According to a gas-steam combined cycle calculation model, with a 397 MW gas turbine combined cycle unit serving as an example, the efficiencies of the bottom cycle and combined cycle at su- percritical steam parameters and two kinds of subcritical steam parameters were calculated and the contri- butions to the efficiency of the combined cycle made by the efficiency of the bottom cycle with steam pa- rameters in three kinds were analyzed and compared. It has been found that for a same gas turbine, when the supercritical and subcritical intermediate and low pressure steam parameters are different, the efficien- cy of the bottom cycle with the supercritical steam parameters will increase by 4.3 percentage points com- pared with that with the subcritical steam parameters, the output power of the bottom steam cycle will oc- cupy a percentage of that of the combined cycle unit from 30.21% to 32.62% ,the net efficiency of the combined cycle will increase by 2.21 percentage points and the output power of the combined cycle unit will increase 20.38 MW. When the intermediate and low steam parameters are identical, the efficiency of the bottom cycle with supercritical steam parameters will increase by 2.87 percentage points compared with that with the subcritical steam parameters, the output power of the bottom steam cycle will occupy a percentage of that of the combined cycle unit from 31.16% to 32.62%, the net efficiency of the com- bined cycle will increase by 1.44 percentage points and the output power of the combined cycle unit will increase 12.5 MW.