In order to ensure the accuracy of the air volume of the boiler dial of coal-fired units,it is necessary to calibrate the cold air volume.Taking the calibration of secondary air-cooled air volume of a unit as an example,the calibration parameters of cold state were calculated according to the equal differential pressure(equal momentum),equal wind speed and equal mass flow.It can be seen from the calculation results that the air flow of different cold and hot air volumes is similar,and the air volume correction coefficient is consistent.It is only necessary to calibrate the cold air volume in one working condition.However,in order to verify the linear correlation of the measuring device,cold air volume calibration under several working conditions should be carried out,and it is appropriate to select cold air volume calibration conditions with the difference pressure of cold and hot air flow equal,that is,cold air volume mass flow is about 1.4 times of hot air volume mass flow.The main reason for the inconsistency of air volume correction coefficient in different cold and hot conditions in the actual test is the different opening of the damper.
cold air volume calibrationworking condition selectionprinciple of similaritymomentum equality
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