Effect of Gas Switching on Powder Fluidization

In this paper, the effect of gas switching on powder fluidization were studied. Several powders, including Fluid Catalytic Cracking (FCC), glass bead and pulverized coal were used as experimental materials, and He、N₂、Ar and CO₂ were used as fluidized gases while they were changed from one to another during the fluidization at a constant gas velocity. Experimental results showed that a decrease of the bed pressure drop might occur after switching the fluidizing gases, where the emulsion phase was compressed, bubbles disappear and channels were formed. The maximum relative decrease of bed pressure drop, the time duration of defluidization and the defluidization intensity were used to quantitatively describe this process, and the effect of gas, powder properties and gas switching sequence were discussed.