This is
the simplest type of Air Dryer with Activated Alumina / Molecular
sieves Drying agent. Investment wise also this is the cheapest.
This design is virtually maintenance free, fully automatic,
and requires no attention for years.Heatless
type dryers do not require any heating for re-generation and
therefore are very simple in design and smooth in operation.
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In Heatless Dryers, two vessels filled with desiccant are
provided, which cycle automatically, producing Dry air continuously.
In these units, wet air enters the bottom of one vessel and
passes upwards through the desiccant bed where the moisture
is adsorbed. The dry air comes out from the top. A small portion
of Dry air is passed downward through the desiccant bed in
the second vessel, which is under re-generation. Moisture
laden purge air is then vented out to atmosphere. The purge
loss is around 7.5% of the total air flow. At preset interval,
the vessels changeover automatically, and Dry air is available
continuously, without any surges, The purge air requirement
is around 20% if (-)800C dew point is needed.
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