Page 161 - Advanced Mine Ventilation

Respirable Dust Control 141

10.2 Collection of Dust Particles by Filters

Most scrubbers use some kind of filter for the collection of dust particles after spraying
the dust cloud with water. We can, therefore, discard any electrostatic forces acting on
dust particles. This leaves the following four mechanisms for dust collection:
1. Inertia,
2. Interception,
3. Sedimentation, and
4. Diffusion.
Fig. 10.3 shows an approximate model of a fibrous filter.
The spacing between fibers is 2h, and the diameter of the fiber strand is 2R. The
inlet velocity is U 0 . Fuchs [4] gives the efficiency of inertial deposit as E : ¼ 1 e l i
where:
τ UH
λ = o
i 2 (10.4)
23 h

where H is the total thickness of the filter bed, and s is the relaxation time defined
earlier (Chapter 8).
Similarly, efficiency of deposit by interception is given by Eq. (10.5).
E= 1 − e -λ
h
2
3r H (10.5)
Where λ h =
23 2 ( h )R+h

Figure 10.3 Model of a fibrous filter.