A stable fluidized bed requires the air distribution plate to have a certain amount of pressure drop, on one hand, the speed of the airflow under the air  distribution plate  shall be  uniform, on the other hand, due to the reasons of fluctuation of air bubbles and bed layer, the distribution of particles and the speed of airflow are not even. The pressure drop of air distribution plate is proportional to the square of the aperture ratio of air nozzles on the air distribution plate. The pressure drop of air distribution plate will cause the head loss and the power consumption of the fan, therefore in the design of the air distribution plate, the resistance of air distribution plate shall be the minimum pressure drop of air distribution plate required in order to maintain smooth and stable bed. Generally speaking when the resistance of the air distributor plate is 20% to 30% of the resistance of the whole bed layer( the resistance of the air distribution plate plus the resistance of the materials layer), the stable running of the bed.