Quantification of interparticle forces in gas-agglomerated particles fluidized beds

Interparticle forces (IPFs) dominate the fluidization of fine and ultrafine particles and are responsible for the formation of agglomerates. Two equivalent equations are proposed in this study for the quantification of IPFs in a gas–solid fluidized bed. The first is the generalized Umf deviation equation correlating the magnitude of IPFs to the ratio of experimental and theoretical minimum fluidization velocities. The second is the generalized form of the Dynamic Hausner Ratio (DHR) equation, which was developed based on the appearance of an overshoot in the bed pressure drop profile at Umf. The generalized DHR equation relates the magnitude of IPFs to the agglomerate size in addition to the DHR, i.e., the ratio of minimum fluidization and loose bulk voidages. The proposed equations can be employed under various conditions, including ambient and elevated operating conditions, as well as individual and agglomerated particles fluidization. They help quantify the resultant IPFs acting on particles irrespective of the types of these forces. The quantified IPFs by the proposed equations were verified and qualitatively validated with different principles. The results indicated that different fluidization behaviors correspond to varying magnitudes of IPFs. The opportunities and limitations of the proposed equations are further discussed.