多变量因素下的锅炉低压省煤器节能效果测试与分析

在多变量因素条件下测试了某220MW机组低压省煤器的节能效果，用等效焓降法计算了低压省煤器不同运行方式、不同运行参数下的节能效果。针对200 MW容量等级的机组，当低压省煤器进水流量较大和进水温度稍高时，应优先采用6号低加出水，220 MW工况下，进低压省煤器最佳流量为250 t/h左右，机组热效率提高0.645%；若低压省煤器进水来自于7号、8号低加出口，进水温度较低，则低压省煤器出水应引至6号低加出口，并应使低压省煤器出水温度略高于6号低加出口水温，否则，节能效果相比最佳工况降低，220 MW试验工况下，从8号低加和7号低加出口抽取凝结水370 t/h，经低压省煤器加热后回水至6号低加出口，机组热效率提高2.003%。对不同的低压省煤器运行方式，都存在一个最佳回水位置和最佳进水流量。

Analysis on Energy Saving Effect of Low-Pressure Economizer in Boiler Under Multi-variable Factors

The energy saving effect of low-pressure(LP) economizer of a 220 MW unit was tested under multivariate factors. Using equivalent enthalpy method, the energy saving effect of LP economizer at different operation modes and different operating parameters has been calculated. For 200MW grade units, when it is necessary to have higher water flow rate and inlet temperature of LP economizer, the condensate water from NO.6 LP heater outlet should be used priority. Under the condition of 220 MW, the optimal flow rate into LP economizer is about 250 t/h, increasing thermal efficiency of the unit by 0.645%. If the inlet water is from the outlet of NO.7 and NO.8 LP heater, the LP economizer inlet temperature is lower, the outlet of the LP economizer should return to the outlet of NO.6 LP heater. And water temperature at LP economizer outlet should be slightly higher than that of NO.6 LP heater outlet. Otherwise, the energy efficiency will decrease compared with the best condition. Under the condition of 220MW, 370 t/h condensate water is extracted from outlet of NO.8 and NO.7 LP heater, entering main condensate water pipe at outlet of NO.6 LP heater after heated. The heating efficiency of the unit increases 2.003%. For different LP economizer operation mode, there are an optimal water returning location and optimal inlet flow.