5.4.6.3. External hot regeneration


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Fig. 5.15: Adsorption material after 6- 8 hrs drying time
With hot regeneration the drying and regeneration times are around 6- 8 hrs. During the long drying time the moisture deposits on the inner and outer surfaces of the adsorption material. To reverse this process heat must be brought from outside. If the regeneration temperature of the drying material
is exceeded by heat from outside, the surface energies that occur outweigh the adhesive forces in the drying material and the water evaporates. A small flow of regeneration air drains off the moisture.

The regeneration temperature depends on the pressure dew point of the regeneration air. The lower it is, the lower the regeneration temperature of the dryer.

With external regeneration air is drawn in from the atmosphere by a fan and heated in a heating register. This happens in three phases:
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Fig. 5.16:
Op. diagram of an adsorption dryer,
external hot regeneration
1st Phase

The drying tank B is slowly heated to the necessary regeneration temperature by the flow of hot air. Once the regeneration temperature is reached, the water releases itself from the Adsorption material. The fan continues to supply hot regeneration air through drying tank B. This flow of regeneration air takes on the moisture and transports it into the open through an outlet valve.

2nd Phase

In a cooling phase the operating temperature drops back to the temperature of drying tank B. For this purpose the heating register of the fan is switched off and cold air from the atmosphere is directed through the drying tank.

3rd Phase

At the end of cooling, dry, relaxed compressed air flows from the compressor and through the drying tank, in order that the atmospheric does not bring moisture back into the dryer.


Features
    • Economical with high volume flows
    • Higher regeneration temperatures allow a lower pressure dew point.
    • Low additional consumption of compressed air. Only a small part of the regeneration air is taken from the pneumatic system.
    • Prefiltration of inlet air.
      A pre-filter removes most of the oil, water droplets and dirt particles from the compressed air.
    • Postfiltration of dried compressed air.
      Drying materials taken with the compressed air from the drying tank must be filtered out of the compressed air.