OMEGA AIR B-DRY Series, Installation And Operating Manual

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13.3 High Outlet Dew-point
In normal operating conditions the heatless adsorption dryer B-DRY maintains a pressure dew-
point between -25 and -70 °Ctd. The outlet dew-point is dependant on inlet volumetric flow,
inlet air temperature and adsorption time.
New adsorption dryer
could need a few hours of operation to reach a certain dew-point. This
is due to the fact that the adsorbent adsorbs a certain ammount of water vapour during
production and installation. Depending on the ammount of adsorbed water the dryer will
need a certain ammount of cycles to regenerate both tower enaugh to reach the desired dew-
point.
Lower inlet temperatures and volumetric flows result in more effective adsorption process
and thus lower pressure dew-pointslower. Higher inlet temperatures and volumetric flows
result in lower pressure dew-points. Once the dew-point rises above -25 °Ctd the molecular
sieve in the towers could be permanently damaged and needs to be replaced.
The following chapters describe the possible causes of high outlet dew-point.
13.3.1 Underdiemnsioned Adsorption Dryer
If the dryer is underdiemnsioned and the volumetric flow through the dryer is much higher
than the dryer rating the ammount of molecular sieve for adsorption and the quantitiy of the
air that passes through the molecular sieve during regeneration will be too small.
Consequently the pressure dew-point could continue to rise towards the point where
molecular sieve is saturated and the inlet and outlet dew-point are equal.
See chapter Technical data for more dimensioning information and correction factors.
13.3.2 Liquid Water in the Towers
If there is no cyclone separetar upstrem from the dryer or there is a malfunction of drain on
prefilter liquid water could start to gather in the towers. B-DRY has a bed of water resistant
silica gel for protection in such cases but if the ammount of liquid water is too great and it
passes this bed the molecular sieve will be destroyed and it will not adsorb the water vapour
anymore. The result is a higher pressure dew-point.
Replace the adsorbent and service and/or improve pre-filtration.
For more information on proper air preparation see the chapter Installation Layout .