1. The primary air volume is used to maintain the fluidized state of combustion and to adjust the certain bed temperature; the secondary air volume is to used to control total air volume. When the full-capacity is reached,  the ratio of primary air and secondary air is 60% : 40%, The induced air amount is adjusted to keep the negative pressure around 100 pa. 

2. During operation, the negative pressure shall be kept in the specified range. The boiler is not allowed to operate under the positive pressure. When the boiler load is increased or decreased or the  operation that have effect on combustion is conducted,  it is required to pay special attention to keeping  the normal negative pressure and bed temperature of  boiler hearth, to keep negative pressure of hearth, primary air volume and secondary air volume stable and to keep balance change in order to avoid that the adjusting amplitude is too large. 

3. During operation, if the main steam temperature is too low, the negative pressure of hearth of 200Pa -200 Pa can be  kept. 4. When the negative pressure of boiler hearth is automatically controlled and air supply volume is adjusted, the adjusting shall be slowly conducted in order to prevent the positive pressure occurring in the hearth. 

5. The differential pressure  is the differential pressure of top pressure of dense-phase area and the pressure of output of the chamber, during normal operating, the differential pressure of hearth shall be kept between 800-1400Pa. 

6. If the differential pressure of the hearth is too high, the working condition of returns feeder is not stable, less  amount of circulating ash can be discharged to  control the differential pressure of hearth.