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Sunday, 14 September 2014

Filtration

1. Filtration
Definition: is a process of separating a solid from a fluid by mean of porous medium that retains the solid but allows the fluid to pass.
Factors affecting on filtration rate(F.R):
1. Filter area: ↑area↑filtration rate (F.R)
2. Pressure (P): ↑pressure cause ↑filtration rate (F.R)
    If Pressure is constant cause↓ F.R
3. Viscosity: viscosity   mean F.R is inversely proportional to viscosity of the fluid. 
   4. Permeability coefficient: is a function of porosity
Factors affecting on filtration operation:
1. Properties of liquid
a. Viscosity
b. Density
c. Corrosiveness
2. Properties of solid
a. Particle shape
b. Particle size
c. Particle distribution
Types of filter medium
1. Metallic filter                       2. Nylon
3. Bounded fibrous                 4. Filter paper
Filter aid: are materials added to filter medium to make    cake more rigid, high porous & high permeability
Properties of Filter aid: should be light, porous, inert & irregular in shape e.g. Silicon oxide.
Filter cake: a accumulation of solid on filter.

Filtering Equipment
1. Filter press













 Advantage: 1. Simple
2. Occupies small floor space
3. Leakage can be detected
4. High pressure can be employed
Disadvantage: 1. Time is consumed
                       2. Filter cloth tend to wear off more rapidly
2. Centrifugal: this type of filtration is used to separate crystal and granules product from other liquid.
3. Sedimentation: The separations depend on the difference in the densities.
Uses: 1. for liquid-liquid separation
2. for solid-solid separation
3. Separation plasma from whole blood
4. Manufacture of insulin

Equipment
1. Perforated basket centrifuge:












Consist of Perforated metal basket mounted on vertical axis for separation coarse solid.
Advantage:     1. Final product is low moisture
                         2. The process is rapid
Disadvantage: 1. Expensive
                       2. Complex

2. Tubular centrifuge:













•Used to separation two immiscible liquid & solid liquid separations.
• Suspension feed from at the rotating base and clear liquid inlet from a weir at the top



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