fluidizable

Fluidizable refers to the property of a particulate solid material that allows it to behave like a fluid when a suitable gas or liquid is passed upwards through it at a certain velocity. This phenomenon is known as fluidization. For a material to be fluidizable, it must consist of discrete solid particles. The key factor is the upward flow of the fluidizing medium. As the fluid velocity increases, it exerts a drag force on the particles, counteracting gravity.

At low fluid velocities, the particles remain stationary, and the fluid percolates through the bed. As the velocity is increased to a point called the minimum fluidization velocity, the drag force equals the weight of the particles, and the bed begins to expand and behave like a fluid. The particles are suspended and move freely within the upward-flowing fluid. Beyond the minimum fluidization velocity, further increases in velocity lead to different fluidization regimes, such as bubbling, turbulent, or fast fluidization, depending on the particle and fluid properties.

Materials that are easily fluidizable typically have particles that are not too large or too small, and their density is not excessively different from the fluidizing medium. The shape of the particles also plays a role, with more spherical particles generally being easier to fluidize. Fluidizable materials are crucial in various industrial processes, including catalytic cracking, drying, combustion, and gasification, where the fluid-like behavior enhances heat and mass transfer.