Several different types of mist eliminator are designed for the separation
of liquid entrainment. To choose the appropriate equipment, the four basic
mechanisms
used to capture droplets on a wire or filament must be considered.
- Diffusional Deposition is only effective in the separation
of very finely dispersed aerosols with droplets typically smaller than
1µm – that is small enough to be affected by Brownian
Motion.
- Direct Interception assumes the droplet
of a given diameter and negligible mass follows the stream line around
the ‘target’ wire or fibre and is separated as it touches
the target or collection fibre.
- Inertial Interception considers the droplet
mass and predicts how momentum will make it deviate from the gas stream.
- Gravitational Deposition works on the principle
that large, slow moving droplets may separate from a gas stream under
gravity. This is restricted to large droplet sizes and low superficial
gas velocities - making separator dimensions both prohibitively large
and uneconomical. Therefore, it can be disregarded as an effective
option.
Within the three effective mechanisms, KnitMesh
mist elimination equipment falls into two groups:
Each mechanism is critically dependent on the
droplet size distribution for a given application. A summary of the typical
characteristics of liquid entrainment and corresponding equipment groups
is shown in Figure 1.
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Figure 1.
Typical entrainment characteristics and corresponding separation equipment
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Figure 2. Droplet Collection Mechanisims
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