Introduction to Fluidization

Fluidized beds typically are more complex to design, build, and operate than other traditional reactors. Scale-up of fluidized beds continues to be challenge. Fluidized beds are prone to erosion and particle attrition. Solids (i.e., catalyst) losses can result in significant operating costs, especially when catalyst costs from $2 to $20 per pound. Bubbles also need to be managed, as large bubbles reduce the mass transfer between phases.

With all of these challenges, why did fluidized bed processes become so popular in the last century? Fluidized beds offer three distinct advantages compared to other process technologies: superior heat transfer characteristics, the ability to easily move solids like a fluid, and the ability to process materials that have a wide particle size distribution.

The benefits of using fluidized bed technology can easily outweigh the disadvantages, especially for processes requiring catalyst circulation or superior heat transfer. These benefits, however, only materialize with a good understanding of fluidization. Education and experience are the keys to reaping the benefits of fluidized beds.

This article will give insight into typical fluidized bed design and equipment, as well as describe the behavior of particles in fluidized beds based on their size and shape.