(Basic knowledge) What is compact fluidization?

Aggregated fluidized state: The particles are unevenly distributed within the bed, resulting in a two-phase structure. One phase is a continuous phase in which the particle concentration and porosity are relatively uniform, and it resembles the initial fluidized state; this phase is known as the emulsified phase； The other phase is a discontinuous bubble phase in which a small amount of particles are entrained in the form of bubbles as they move upward through the bed, and it is therefore also known as bubbling fluidization. Aggregated fluidized state occurs in systems with a large density difference between the fluid and the solid, such as gas-solid fluidized beds. In clustered fluidization, a large amount of gas beyond what is required for initial fluidization aggregates into bubbles that rise, burst at the bed surface, and propel the particles into the space above the bed. This not only causes large fluctuations at the bed interface and pressure drop variations ； An even greater disadvantage is that the gas passing rapidly through the bed in the form of bubbles has very little contact with the particles, whereas the gas in the emulsified phase, due to its low flow rate, remains in contact with the particles for an extended period of time, resulting in uneven gas-solid contact.