liquidfluidized

Liquidfluidized is a term used to describe a bed of solid particles suspended and well mixed by an upward flow of liquid, creating a dynamic, fluid-like state known as a liquid-fluidized bed. In such a system, the superficial liquid velocity exceeds the minimum fluidization velocity, causing particles to lift, separate, and interact, which produces high interparticle mixing and an expanded bed with a relatively uniform void fraction.

The underlying mechanism involves a balance of forces on the particles: buoyancy reduces the effective weight, while drag from the flowing liquid provides the lifting force. As liquid velocity increases beyond Umf (the minimum fluidization velocity), the bed expands and the apparent viscosity decreases, enhancing mass and heat transfer between the liquid and solids. The regime remains stable when flow and particle properties are matched to prevent excessive entrainment or channeling.

Characteristics of liquidfluidized beds include good solid-liquid contact, high surface area for reactions or transfer processes, and efficient heat transfer due to vigorous mixing. They can handle a range of particle sizes and are advantageous for processes requiring uniform temperature and rapid mixing, such as certain catalytic, crystallization, and wastewater treatment applications.

Common design and operational considerations focus on particle size distribution, density difference between solids and liquid, liquid viscosity, and flow rate to avoid solids carryover, channeling, or bed collapsing. Practical challenges include entrainment of fines, solids deposition, and the need for appropriate solids separation or overflow schemes.

See also: fluidized bed, liquid-solid fluidization, granular flow.