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Filtration |
- Removal of solids from fluid (gas or liquid) by a filtering medium on which solid particles are deposited.
- For filtration, external force is applied to a
 (gas or liquid + solid) mixture to make it flow through the medium.
- Filtration, when applied to gas cleaning, usually refers to the removal of fine particles
 like dust from air or flue gas. In such case, a polymeric fiber or cloth is wrapped over a pretreated metallic cylinder, capable of capturing micron size particles, including soot and fly-ash.
- Very large size ceramic based filters for high temperature applications are also commercially available.
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In this and the next lectures we will confine our discussion to liquid – solid filtration . |
- The liquid–solid filtration is often called “cake–filtration”, because the separation of solids from the slurry by the filtering medium is effective during the initial stages of filtration. Later, the ‘cakes' or deposits collected over the medium act as the filter. Therefore, cake thickness increases during filtration and the resistance (hydraulic) offered by the cake–material is larger than that by the filtering medium.
- There are two types of operation:
- Constant-pressure
- Constant filtering rate
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