How are particles kept in suspension in a bubbling fluidized bed (BFB)?

In a bubbling fluidized bed (BFB), particles are kept in suspension primarily by the upward flow of combustion air and gases. This phenomenon occurs due to the dynamics of the gas-solid interaction within the bed. When gas is injected from below through a distribution plate, it flows upwards through the particles, creating drag forces that counteract the weight of the particles. As the velocity of the gas increases, it becomes sufficient to lift and support the particles, allowing them to become suspended and behave like a fluid.

This fluidization results in a more uniform temperature distribution and efficient mixing of the particles, which is essential for processes such as combustion, drying, and chemical reactions. The ability of BFB to maintain particles in a suspended state due to this upward flow is what makes it a particularly effective technology in various industrial applications.