Maintaining the proper air quality level is essential for keeping compressed air energy costs down and to ensure reliable production. Poor air quality can have a negative effect on production equipment and can increase energy consumption and maintenance needs. The quality of air produced should be guided by the quality required by the end-use equipment
AIR CLEANING DEVICES.
- Dust collectors
- Electrostatic precipitator
- Fabric collectors
- Wet collectors
- Dry centrifugal collectors
2. Air filters
SELECTION OF AIR FILTRATION EQUIPMENT
The selection of air filtration equipment is based on;
- Dust holding capacity
- Pressure drop
METHODS OF AIR FILTRATION
Straining: straining occurs when a particle is larger than the opening between fibers and cannot pass through. It is a very ineffective method of filtration because the vast majority of particles are far smaller than the spaces between fibers.
Impingement: when air flows through a filter, it changes direction as it passes around each fiber. Larger dust particles, however, cannot follow the abrupt changes in direction because of their inertia. As a result, they do not follow the air stream and collide with a fiber. Filters using this method are often coated with an adhesive to help fibers retain the dust particles that impinge on them.
Interception: interception is a special case of impingement where a particle is small enough to move with the air stream but, because its size is very small in relation to the fiber, makes contact with a fiber while following the tortuous air flow path of the fiber.
Diffusion: diffusion takes place on particles so small that their direction and velocity are influenced by molecular collisions. These particles do not follow the air stream, but behave more like gases than particulate. Diffusion is the primary mechanism used by most extremely efficient filters.
Electrostatic: A charged dust particle will be attracted to a surface of opposite electrical polarity. Most dust particles are not electrically neutral, therefore, electrostatic attraction between dust particle and filter fiber aids the collection of efficiency of all barrier type air filters.