Demister is also known as mist eliminator, wire mesh separator or wire mesh blanket. It separates mist or dust contained in a fluid. This is a kind of high efficiency separation devices, is essential in many process operations to remove liquid droplets from gas or vapor streams.
Wire mesh demister pads are used in chemical, petroleum, sulfate, medicine, metallurgy, marine and environment protection.
Demister pad is mainly used to eliminate streams with diameter of more than 3μm to 5μm. It can be fabricated in any desired size and shape. Along with wire diameter and mesh density, another important parameter in design and operation is the vapour velocity. This can be controlled by careful selection of the mesh area. Optimal area will depend on operating temperature, pressure and pressure drop. Under normal operating conditions, 99% removal efficiency can be achieved with a very low pressure drop.
The operating principle of the mist eliminator is simple.
As the wet vapour stream rises through layers of contracting surfaces within the knitted and crimped wire mesh demister pad, entrained as they continuously impact each surface.
The gas within the vapour stream continues to rise and passes easily as the heavier liquids separate, attach and coalesce into droplets within a mesh. As the droplets grow and become heavier until they fall to the bottom of the vessel due to gravity.
Liquid accumulations can then be drained out of the bottom as the overhead gas is free of entrained liquid and routed through the top of the Vessel.