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 dimension-less 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.Accord-ing 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 trans-formation 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 ex-change 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 transforma-tion,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 trans-formation 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 trans-formation.The performance of the air preheater is at a good level.The calculation method can more accu-rately evaluate the actual performance of the air preheater and the transformation effect.
rotary air preheaterheat exchange efficiencyXR correctioncalculation method
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