DROPLET SEPARATORS (Demister)
Materials: metals, plastics
Wire mesh droplet separators (Demister)
are used for the removal of liquid particles from exhaust gases, ex-haust air and steam. A
wide range of practical experience in design forms up to 18 m in diameter lies in our
portfolio e. g. for the following applications and devices:
During separation, the
droplets enter the knitted wire mesh, and due to their moment of gravity, collide with the
wire surface. The collected droplets coalescence at the cross points in the mesh and fall
back as larger droplets into the vessel. The separation efficiency, which is influenced e.
g. by the voids and the specific wire mesh surface area, improves with increasing flow
velocity. Because of flooding the maximum flow velocity must not be exceeded, otherwise
re-entrainment will occur.
The achievable limiting
droplet size for 99,9% fractionational separation efficiency is within a range of 5 µm to
12 µm for standard mesh types. Special execution and layout of mesh types allow to reduce
the limiting droplet size down to 3 µm.
As an integral part of our
service, we offer our customers competent practical support regarding the material
selection for the particular application, as well as configuration calculations for the
optimum operation and the best separation efficiency, with consideration taken for the
essential influencing factors.
The wire mesh droplet
separators (Demister) are produced from thin wires in various mesh sizes. Normally a wire
diameter of 0.5 mm down to 0.1 mm is used. The specific surface area of the mesh pad
covers a range from approx. 150 m2/m3 up to 1100 m2/m3.
Usually, especially
constructed supports and/or cover grids are delivered as support for the mesh pads, which
are arranged so that the free inflow area is minimum 90 %. When installing the wire mesh,
it has to be ensured that the mesh pad is fitted tightly along the wall of the column, so
that no gas bypassing will occur.
VFF offers a wide range of
metallic materials and plastics as well as metal-plastic-combinations, in order to be able
to handle e. g. the temperature and/or corrosive conditions of the particular application.
The pad height of the wire
mesh droplet separators (Demister) in most applications lies between 100 and 150 mm. If
the gas- or steamflow contains very fine mist as created during condensation considerably
higher pad height or multiple layer design is required.
