1. The fluidizing speed of materials layer is quite high, and the turbulent fluidizing state of material layer has been realized, so that the bubbles inside the materials layer disappear and become fine pulverized airflow and enter the enter the suspending section. 

2. Quite a number of fine particles in turbulent fluidization has the conditions to escape from the interface of the bed of material, forming the particles group of suspending section with higher concentration, so that the interface between the dense phase zone and dilute phase zone is very fuzzy, the particle dispersion in the whole hearth, the concentration field is rare at upper part and thick at lower part, the particle size decreases gradually from bottom to top. 

3. Owing to the strong mixing and impacting of particles, as well as the heat transfer and mass transfer of higher concentration, the temperature field  inside the hearth is very uniform and higher heat transfer coefficient is formed. 

4. The combustion share is divided into three big parts of dense-phase zone material layer, dilute phase zone suspension section and cycle returns system , so that the combustion share inside the material layer can be reduced greatly. 

5. The cycle returns system structured by the external separator is the necessary condition to maintain the materials balance.