Layout of purge air regulation for reducing air consumption
Application Note
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Energy management function at adsorption dryer PDAD
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1.10
Page 8 of 17
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Layout of purge air regulation for reducing air consumption
3.1
Nature of the task
Regenerative dryers have to eject a portion of the process air in order to remove the moisture which accumulates
inside them. During times when only small amounts of air are required, this loss is unnecessary and thus
undesirable. In many cases the compressor runs nearly uninterruptedly in order to compensate for the dryer’s
purge air loss.
Example:
The compressor for central compressed air preparation is started up again and again due to the purge
air function and the associated pressure drop, although no air consumption is required for the application.
Compressor start-up results in noise
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in some cases disagreeably at night. The temperature in the room might
also rise, so that applications with low pressure dew points may be influenced.
The adsorption dryer PDAD is equipped with an energy management function by means of which the purge
function can be shut down during times when little or no air is required. The dryer’s regulator is equipped with a
set of easily accessible contacts with which the solenoid valves (which regulate the dryer’s purge function) can be
shut down, thus resulting in zero air loss at via dryer.
In order to makes use of this function, the operator must provide a switching system with acceptable logic which
informs the dryer when little or no air is required. Several examples of frequently used switching systems are
provided in the following pages (with varying complexity).
