When the air distribution plate is measured, the air distribution plate shall have no bed materials. At the beginning of measurement, close all the manhole doors. Start the induced draft fan and primary air fan, gradually open  the adjusting damper baffle, and slowly and smoothly increase the air flow. Generally increase  4000-4000 m3 / h air volume every time, record the opening of the primary air damper and the corresponding data of air velocity, air pressure, air temperature ad the  air chamber air pressure, until increase to maximum air volume. And then gradually reduce the air volume from the maximum air volume , and record the corresponding baffle opening, air volume, air temperature and air pressure. Use the average value of upstream and downstream data as the last data. Use the smooth curve at the plane rectangular coordinates; Connect these points, then get the relation of air distribution resistance with the change of air volume ;After mathematical processing to the curve, the resistance calculation formula of air distribution plate can be obtained. During test, the negative pressure of hearth is kept at about ± 100 pa.