采用凝汽系数法分析喷水减温方式对机组热经济性的影响

Exhaust coefficient method based analysis on influence of different spray desuperheating modes on unit thermal economy

采用凝汽系数法建立了不同喷水减温方式对机组热经济性影响的计算模型,结合某台超超临界1 000MW机组,以相同的主、再热蒸汽减温喷水量为假设前提,计算了过热器和再热器在不同喷水减温方式下对机组热经济性的影响。结果表明,无论过热器还是再热器喷水减温,从最高级加热器出口分流的喷水减温系统较从给水泵出口分流的喷水减温系统对机组热经济性的影响小;与过热器喷水减温相比,再热器喷水减温使机组热经济性降低较大;对于相同喷水份额,再热器喷水减温使机组热经济性的下降值约为过热器喷水减温的10倍;对于相同的喷水减温方式,机组热经济性的降低与喷水份额成正比。

Calculation model for evaluating the influence of different spray desuperheating modes on the unit thermal economy was established by exhaust coefficient method.Taking an ultra supercritical 1 000 MW unit as the object,the unit thermal economy under different spray desuperheating modes was evaluated,with assumption that the spray desuperheating flow rate of main steam equaled to that of the reheat steam.The results showed that,for both superheater and reheater spray desuperheating system,the one shunted from the final heater outlet had smaller effect on the unit thermal economy than that from the water feed pump outlet;the spray desuperheating for reheater caused more unit thermal efficiency drop than that for superheater;for the same spray quantity,the unit thermal efficiency drop resulted from the reheater spray desuperheating system was about 10 times larger than that from the superheater spary desuperheating system;for the same spray desuperheating mode,the unit thermal efficiency drop was proportional to the spray quantity.