Industrial Demister / Mist Eliminator
Wire mesh demisters / mist eliminators are used in vertical column vessels to strip liquid particles from process flows, flue gases, exhaust air and steam.
Wire mesh demisters / mist eliminators are commonly incorporated into:
- Seawater desalination plants
- Sulphuric acid plants
- Vacuum columns
- Sound absorbers and vibration dampers
- Distillation and rectification plants
- Oil separators
Construction is in a variety of metal and plastic materials, as well as metal and plastic combinations, to cope with the demands of temperature and/or corrosive environmental conditions as well as different density fluids in the gas stream.
In the separation process, the droplets flow through the wire mesh and collide with the surface of the wire due to their inertia. The collected droplets coalesce at the cross points of the mesh and fall back as larger droplets into the vessel. The separation efficiency, which is influenced by the voids and the specific wire mesh surface area, improves with increasing flow velocity. A maximum flow velocity must not be exceeded since flooding will cause re-entrainment to occur.
The maximum droplet diameter for 99.9% fraction separation efficiency is within a range of 5µm to 12µm for standard mesh types. Specialised designs enable droplet size in this kind of separation process to be reduced to 3µm.
The wire mesh demisters / mist eliminators are made of fine knitted wires with different mesh widths (mesh densities) and the wire diameters generally used are from 0.10mm to 0.50mm.
The specific surface areas depending on the type, are between around 150m2/m3 to around 1100m2/m3.
Specially designed supports and/or cover grids are generally supplied to support the mesh pads which are arranged so that the free inflow area is approximately 90%. When installing the wire mesh the mesh pad must fit tightly to the wall of the column to prevent any bypass flow.
The pad of the wire mesh demister / mist eliminator is between 100mm and 150mm deep in most applications. If the gas or steam flow contains very fine droplets, such as are created during condensation, considerably deeper pads or multiple layers are required.