March 29, 2011
Adsorption
Delair use following methods for drying compressed air:
- Refrigeration
- Sorption
Refrigeration removes moisture by cooling the air below its dew point and condensing the moisture.
Sorption removes moisture by passing air over material capable of extracting moisture. Sorption can be further classified into :
- Adsorption : It Adsorbs water on the surface of sorbent without undergoing change.
- Absorption : It removes moisture by chemically combining with water.
Delair Adsorption dryer works on the principal of heatless compressed air dryer (regeneration by purge) is based on the physical property of desiccants to adsorb and desorb water vapour. A desiccant is a substance that promotes drying by absorbing moisture or water vapor from the air.
THERE ARE DIFFERENT TYPES OF DESICCANTS FOR ADSORPTION :
SILICA GEL
Silica occurs in nature as Silica dioxide, SiO. It is processed into gel-like beads for use as a desiccant dryer.
Silica gel was first used in World War I to absorb vapor in gas mask canisters. Pure silica gel is one of the few desiccants that is safe for use around food.
INDICATING SILICA GEL
Indicating silica gel is silica gel that is processed with cobalt chloride. The cobalt chloride will change color from blue to pink as the silica gel absorbs moisture. This ‘indicates’ when the silica gel is becoming saturated. Because cobalt chloride is a heavy metal salt, it cannot be safely used around food.
CLAY
Clay that is high in magnesium aluminum silicate, a naturally occurring mineral, is processed into Montmorillonite clay for use in drying. It works best at room temperature or below. Clay is one of the most inexpensive desiccants, which makes it popular for industrial use
QUICKLIME AND GYPSUM
Quicklime is a common term for Calcium Oxide. It is alkaline and highly caustic, so special care in handling is necessary. Its chief benefit is that it can be used to gradually drop the humidity to a very low state. Gypsum is Calcium Sulfate. Its color-indicating form is Drierite™.
MOLECULAR SIEVE
Molecular Sieve is a synthetic desiccant manufactured from aluminosilicates. Like the name sounds, it has many tiny holes or pores the absorb liquid and gas. It is a highly effective desiccant that can absorb water up to 22% of its own weight.
DELSORB 10
Delsorb 10 is one of the major adsorbent/ desiccant used world wide for moisture removal, purification and other treatments. A highly porous form of aluminum oxide, it works both under static and dynamic conditions.
Delair desiccant air dryers use delsorb 10 and delsorb 21 desiccant for adsorption.
