Compressed air dryers extract the water vapor found in the compressed air. There are mainly two types of dryers.
-Refrigerated Dryers:
They are dryers that dry the condensed air of water vapor, for that it is necessary to cool the air, to achieve that the water vapor condenses into drops of water and separates from the air. It has a limitation to dry the air and we cannot cool the water vapor to less than 0ºC because it turns into ice, and obstructs the passage of air and can break the evaporator due to expansion. So we can only dry the up to 3ºC pressure dew point. That is to say that above the dew point, drops of water will not be produced, worse if below this temperature.
– Fixed cycle dryers, these types of dryers are constantly adjusting the condensation temperature of the air, achieving a constant dew point. In some models, if there is no air consumption, they also stop to save energy.
– Thermal Mass Dryers. In these dryers there is an evaporator that has a thermal mass, which can be sand, water + glycol, etc., which cools down and when it reaches the temperature it stops, and until the evaporator temperature rises again, it does not return to turn on In low load conditions, they save a little more energy than fixed cycle dryers, but also the dew point is more variable, with oscillations of 5 to 7 ºC in dew point.
-Adsorption dryers:
These dryers do not cool the air to dry it, but use the absorption capacity of the alumina or molecular sieve. For that, two towers are used, through one the air passes and dries, and through the other, which is saturated with humidity, it regenerates. Regeneration can be done with the same compressed air, and between 10% to 15% of the compressor air is used. So these dryers use compressed air. But they achieve dew points of -40ºC to -70ºC.
– Regenerated by air, the regeneration of the towers uses compressed air, and spends compressed air, between 10% and 15%. They can incorporate a dew point meter, which controls the regenerations depending on the dew point, and saves regeneration air.
– Hot air regenerator, the regeneration of the towers, does not use compressed air, but a turbine that regenerates the towers, and to be more effective it can also be heated, this type of dryers use large flow rates, providing significant savings compared to those regenerated by air.
