Fluïdisering

Fluïdisering is a process used in chemical engineering to suspend solid particles in a liquid or gas, causing the mixture to behave like a fluid. This is achieved by passing the fluid upwards through a bed of solid particles at a sufficient velocity. When the upward flow rate of the fluid equals the settling velocity of the particles, the particles become suspended and the bed expands. This state is known as fluidization.

Fluidized beds offer several advantages over static beds. They provide excellent heat and mass transfer due to the vigorous mixing of particles. This uniform mixing also leads to a consistent temperature throughout the bed, preventing hot spots or dead zones. The fluid-like behavior of the bed allows for easy handling and transport of solids, similar to pumping a liquid.

Common applications of fluidization include catalytic cracking in the petroleum industry, combustion of fuels in fluidized bed boilers, drying of solids, and chemical reactions where efficient contact between reactants is crucial. The choice of fluid (gas or liquid) and the operating conditions depend on the properties of the solid particles and the desired outcome of the process. Proper design of the distributor plate, which introduces the fluid into the bed, is essential for achieving uniform fluidization and preventing particle attrition or elutriation (loss of fine particles).