Compressed Air Dryers
The principle of compressing air in factories for power tools and other high-pressure uses has a side benefit for the world of resin drying. Compressed air, once "de-compressed", re-enters atmospheric pressure with less moisture than it contained prior to compression. By ‘less moisture’, we mean that the moisture level (dew point) of the de-compressed air is reduced by about 40-50 degrees, usually to a level of between -10˚ to +10˚ F.
- This principle provides the ability to use compressed air for drying material in a hopper
- The compressed air is filtered, to remove course amounts of moisture and dirt
- It is then regulated down, heated and passed through a material hopper
- This heated, ‘dry air’ moves through the hopper, absorbs the moisture trapped in the resin and carries it out of the hopper
Compressed air dryers are simple and relatively maintenance free but they have some big drawbacks for several reasons:
- The process air NEVER attains a -40˚ dew point (-10˚ to +10˚ F. is typical)
- The dew point varies with the weather (rising in hot humid conditions)
- Lack of uniform drying results in rejected parts and taking the dryer offline
- Typical throughputs range up to only about 50 lb. /hr.
- The energy usage is very high compared to most other dryer types (see energy chart below)
Typical Energy Cost in Dollars per 100 lb. of Throughput (Based on $.10 /kwh)