FILTERATION

Filtration may be de defined as the
separation of solids from liquids by passing
a suspension through a permeable medium,
which retains the particles. Filtration is
considers one of the most common
applications of the flow of fluids through
packed bed. As carried out in industrially, it
is exactly analogues to the filtration carried
out in the chemical laboratory using filter
paper in a funnel. In every case, the
separation is accomplished by forcing the
fluid through porous media (membrane). The
solid particles are trapped within the pores
of the membrane and build up as a layer on
the surface of this membrane. The fluid,
which may be either gas or liquid, passes
through the bed of solid and through the
retaining membrane.
Industrial filtration differs from laboratory
filtration only in the bulk of material
handled and in the necessity that it be
handled at low cost. Thus, to attain a
reasonable throughput with a moderatesized
filter, the pressure drop for flow may
be increased, or the resistance to flow may
be decreased. Most industrial equipment
decreases the flow resistance by making the
filtering area as large as possible without
increasing the overall size of the filter
apparatus.
The choice of filter equipment depends
largely upon economics, but the economic
advantages will very depending upon the
following:
1. Fluid viscosity, density, and chemical
reactivity2.
Solid particle size, size distribution,
shape of particles’ flocculation
tendencies and deformability.
3. Feed slurry concentration.
4. Amount of material to be handled.
5. Absolute and relative value of liquid
and solid particles.
6. Completeness of separation required.
7. Relative costs of labor, capital, and
power