不同宽负荷脱硝系统变工况及瞬态性能的对比研究

Comparative Study on Load Cycling and Transient Performance of Different Wide-load Denitration Systems

对比了0号高压加热器、省煤器给水旁路和省煤器烟气旁路等宽负荷脱硝系统的宽负荷性能及瞬态特性。结果表明:在30%THA~100%THA负荷、旁路流量均为50%时,采用低过侧省煤器烟气旁路的SCR入口温度升高幅度最大,达31.2 K;采用各省煤器旁路方案均使机组标准煤耗率增大,采用低过侧省煤器烟气旁路和低再侧省煤器烟气旁路时,标准煤耗率每增大1 g/(kW·h),可分别提高SCR入口温度42.16 K和27.56 K;采用低过侧省煤器烟气旁路时,SCR入口温度变化滞后时间短且变化率高(达到34.65 K/min);投运0号高加后SCR入口温度变化滞后约1 min,功率平均变化率为10.22 MW/min。

The load cycling and transient performance were obtained when different wide-load denitration schemes were adopted,i.e.,No.0 high pressure heater,feed water bypass of economizer and flue gas bypass of economizer.Results show that:at 30%THA-100%THA load,the enhancement of SCR system inlet temperature is the largest using economizer flue-gas bypass on the low-temperature superheater side,reaching 31.2 K on average when the bypass flow is 50%.The standard coal consumption rates increase when economizer bypass schemes are adopted.By adopting economizer flue-gas bypass on the low-temperature superheater and low-temperature reheater sides,the improvement of SCR system inlet temperature can reach 42.16 K and 27.56 K,respectively,when the average standard coal consumption rate is increased by 1 g/(kW·h).The lag time of SCR system inlet temperature is very short and the change rate is high,reaching 34.65 K/min when economizer flue-gas bypass on low-temperature superheater side is adopted.Moreover,the temperature change at the inlet of the SCR system has a lag about 1 min when the No.0 high pressure heater is put into operation,and the average power change rate reaches 10.22 MW/min.