Ergun CFB Software

Particle Properties and Geldart's Diagram

Before beginning any design or modeling step, its always interesting to get an idea about the divers properties of solid phase particles.

The Geldart's classification diagram informs us about the aptitude of particles to be fluidized. Particles of class "C" (fine and light) are difficult to be fluidized. They always need "vibration", "mixing" or some "fluidization agent" to help the fluid bed to become "stable". The aptitude of the particles of class D to fluidization phenomenon is also ambiguous , depending on the size and the configuration of the fluidization bed (always slugging). Bubbles with this class of particles have a flat and irregular form.

In addition to the Geldart's classification, we also need to have an idea about the "minimum fluidization velocity" (Umf) and the "terminal velocity" (Ut) of particles. The operating velocity for a CFB is usually bigger than the terminal velocity of particles (note that the solid phase is made os particles of various size).

The "Particle" module of Ergun Software provides the Geldart's diagram, the "minimum fluidization velocity" and the "terminal velocity" of particles in a few clicks. An example of the results window is shown beside.

Ergun Design Technology

Example of results obtained from "Particle" module

Example of results obtained from "Particle" module

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