基于XR修正的回转式空气预热器换热效率计算方法

依据逆流换热器换热理论模型，基于换热器无因次变量效能、传热单元数和热容量比之间的关系，对回转式空气预热器换热过程进行分析，提出基于XR修正的回转式空气预热器换热效率计算方法。根据某600 MW机组的空气预热器的设计参数及运行数据，利用该计算方法求解得到实际运行工况换热效率。并对该空气预热器进行了蓄热元件更换、密封间隙调整等改造，对改造前后实际运行工况换热效率进行计算。结果表明：未修正的换热效率与XR有较强的相关性，修正后的换热效率离散程度降低，更能反映空气预热器本身的换热能力。不进行修正情况下，改造前、后的平均换热效率分别为67.6%和67.4%，与设计值69.7%有较大的差距，不能体现出空气预热器改造的效果。通过XR修正，改造后的平均换热效率69.3%与设计值69.7%基本相当，高于改造前的平均换热效率，基本达到改造预期效果。该计算方法可更准确的评价空气预热器的实际性能及改造效果。

Calculation Method of Heat Exchange Efficiency of Rotary Air Preheater based on XR Correction

Based on the theory of counterflow heat exchanger heat transfer model, using three dimensionless variables including heat exchanger effectiveness of heat exchanger, number of heat transfer unit and heat capacity ratio, through the analysis of the rotary air preheater heat transfer process, a calculation method of heat exchange efficiency of rotary air preheater based on XR correction was proposed. According to the design parameters and operation data of the air preheater of a 600 MW unit, the calculation method was used to obtain the heat exchange efficiency under the actual operating condition. The transformation for this air preheater was carried out, such as heat storage element replacement and sealing clearance adjustment, and the heat exchange efficiency under the actual operating condition before and after the transformation was calculated. The results show that the unmodified heat exchange efficiency is strongly correlated with the XR, and the modified heat exchange efficiency is less discrete, which can better reflect the heat exchange capacity of the air preheater itself. If not correced, the average heat exchange efficiency before the transformation is 67.6%, and the average heat exchange efficiency after the transformation is 67.4%, which is slightly lower than the heat exchange efficiency before the transformation, and there is a large gap with the design value of 69.7%, which cannot reflect the effect of the air preheater transformation. After correction, the average heat transfer efficiency of 69.3% after the transformation is basically equivalent to the design value of 69.7%, and higher than the average heat transfer efficiency of 67.3% before the transformation, which basically achieves the expected effect of the transformation. The performance of the air preheater is at a good level. The calculation method can more accurately evaluate the actual performance of the air preheater and the transformation effect.