Fluidized beds

A Fluidized bed is formed when a quantity of a solid particulate substance (usually present in a holding vessel) is placed under appropriate conditions to cause the solid/fluid mixture to behave as a fluid. This is usually achieved by the introduction of pressurized fluid through the particulate medium. This results in the medium then having many properties and characteristics of normal fluids; such as the ability to free-flow under gravity, or to be pumped using fluid type technologies.

The resulting phenomenon is called fluidization. Fluidized beds are used for several purposes, such as fluidized bed reactors (types of chemical reactors), fluid catalytic cracking, fluidized bed combustion, heat or mass transfer or interface modification, such as applying a coating onto solid items.

Properties of Fluidized beds

A fluidized bed consists of fluid-solid mixture that exhibits fluid-like properties. As such, the upper surface of the bed is relatively horizontal, which is analogous to hydrostatic behavior. The bed can be considered to be an inhomogeneous mixture of fluid and solid that can be represented by a single bulk density.

Furthermore, an object with a higher density than the bed will sink, whereas an object with a lower density than the bed will float, thus the bed can be considered to exhibit the fluid behavior expected of Archimedes' principle. As the "density", (actually the solid volume fraction of the suspension), of the bed can be altered by changing the fluid fraction, objects with different densities comparative to the bed can, by altering either the fluid or solid fraction, be caused to sink or float.

In fluidized beds, the contact of the solid particles with the fluidization medium (a gas or a liquid) is greatly enhanced when compared to packed beds. This behavior in fluidized combustion beds enables good thermal transport inside the system and good heat transfer between the bed and its container Similarly to the good heat transfer, which enables thermal uniformity analogous to that of a well mixed gas, the bed can have a significant heat-capacity whilst maintaining a homogeneous temperature field.

Application

Fluidized beds are used as a technical process which has the ability to promote high levels of contact between gases and solids. In a fluidized bed a characteristic set of basic properties can be utilized, indispensable to modern process and chemical engineering, these properties include:

• Extremely high surface area contact between fluid and solid per unit bed volume
• High relative velocities between the fluid and the dispersed solid phase.
• High levels of intermixing of the particulate phase.
• Agglomerating
• Baking
• Balancing
• Conditioning
• Cooling Evaporator
• De-dusting
• drying
• Fermenting
• Freeze dryer
• Inert gas dryer
• pasteurizing
• Puffing
• Reacting
• Roasting
• Sterilizing
• steam stripping

Advantage:

• low energy
• Easy operation
• High capacity
• No need washing
• Working Continuous
• Customer design for your product
• Heavy duty designed for the toughest application
• Well mixed fluidization . we cover the entire spectrum and accurately control the spread residence time
• very gentle on your product
• All stainless steel product contact areas , other alloys are available . we work with all materials of construction