Sterling SDAA 25-100 Standard Features, What is desiccant?, Process/Regeneration Cycle

A small amount of ambient air is introduced into the process air stream to make up for the air lost during the bed regeneration. Because the process air is typically much drier than the ambient air, the air mixture maintains drying efficiency at a consistently high level. This air is heated to 500° F (260° C) before entering the bed that is on regeneration forcing moisture from the desiccant before exhausting. To compensate for the humidity content in the air, this dryer is supplied with the proper amount of desiccant.

What is desiccant?

Desiccant is a material that attracts and holds (absorbs) water from the air. The desiccant our dryers use is a synthetic crystalline metal aluminosilicate blended with a clay binder and formed into beads.

The Process/Regeneration Cycle

Our dryers have two desiccant beds. While one bed is on-line in the process air loop, the other is off-line, being regenerated.

When a desiccant bed is on-line, it absorbs moisture from the process air. In time, the bed becomes saturated with moisture and needs to be regenerated. The dryer automatically redirects the process airflow to the second bed, and starts the regeneration cycle on the first bed.

During regeneration, the dryer system heats air and forces it through the desiccant bed. The moisture driven off the bed bleeds to the atmosphere.

2-3 Standard Features

Mechanical Features

•Dual desiccant beds

•Electrically-actuated air valve

•13X Molecular Sieve

•Single regenerative process blower

•Drying temperature range of 180ºF to 250ºF (71° C to 121° C).

•2.5” hose connections

Electrical Features

•Process thermocouple to be connected to drying hopper air inlet.

•Nema 12 control enclosure

Dehumidifying Dryers Chapter 2: Functional Description 12 of 59