What is absorption dryer?

One of the main components of the compressed air system is absorption dryer, which is placed after the air compressor and, like other dehumidifiers, it has the task of separating the water moisture in the air coming out of the compressor to prevent damage to industrial equipment and rust. Pipes prevented.

The air compressor absorption dryer, which is also known as absorption dryer or diskant, has two tower-shaped standing tanks in which there are moisture absorbing materials of the type (active alumina or silica gel or molecular resin). has it. These materials are generally spherical in shape and have surfaces with high porosity, where the water moisture in the air is trapped and absorbed in these micron holes, and it is removed by the drain valve placed in the device.


How does absorption dryer work?

In general, the operation of absorption dryers is simple: Moist air flows over the moisture absorbing material and dries as a result. The exchange of water vapor from the moist compressed air to the desiccant causes the desiccant to gradually become saturated with absorbed water. Therefore, the desiccant needs regular regeneration to regain its drying capacity, and absorption air dryers are usually built with two desiccant tanks for this purpose: The first vessel dries the incoming compressed air while the second one is being regenerated (similar to the operation of a nitrogen generator).

Each ship (“turret”) changes tasks when the other tower is completely rebuilt. A typical PDP that can be achieved is -40°C, making these dryers suitable for supplying very dry air for more critical applications.

What are the advantages of absorption dryer compared to refrigeration dryer?

As we know, absorption dryers and refrigeration dryers are used to produce dry and moisture-free compressed air.

If the ambient temperature is constantly above zero, you can use a refrigeration dryer, but if the desired environment has a temperature below zero, or if the dew point is below zero degrees, an absorption dryer must be used. When using a refrigeration dryer, the dew point is 3 degrees Celsius and at 7 bar pressure, the amount of moisture in the air is 0.7 grams per cubic meter. This is despite the fact that when using an absorption dryer, the temperature is about -40 degrees Celsius, and at 7 bar pressure, the amount of moisture in the air is 0.02 grams per cubic meter.

With these definitions, we can conclude that the rate of air drying is much higher in the absorption dryer (approximately 35 times than the refrigeration dryer).

Absorption dryer constituent parts

  • HOOK

Absorption dryer without heater or heatless

The simplest type of absorption dryer available in the industry is the absorption dryer without a heater, in this type, only dry compressed air flows through the layers of moisture absorbing materials. When the system starts working, tank 1 is placed in the circuit and performs moisture absorption operations, and when the absorbent materials in tank 1 reach the saturation limit, it is removed from the circuit and enters the recovery stage. Tank 2 enters the circuit. The amount of air purification in this dryer is 12 to 15% of the air entering the dryer, and this model is often used in capacities less than 30,000 liters per minute.

Absorption dryer with heater

An external heater and fan are used in this type of dryer to regenerate moisture absorbent materials as quickly as possible. Like the normal type, tower 1 performs the job of separating moisture and tower 2 increases the temperature by means of a fan and heater, and the moisture in this tower is separated from absorbent materials and by injecting part of the dry air produced in the purg line, the moisture is It is completely removed from the system and this process is done in the same way for Tower 1.

The amount of purg air in this model is 1 to 2% of the air entering the dryer and is generally used for capacities higher than 30,000 liters per minute. Since the heater and fan are used in this dryer, the initial cost and maintenance cost are higher than other models.

Advantages of absorption dryer

  • Dehumidification and creation of completely dry air (humidity less than 0.003 PPM)
  • Equipped with controller system, display and solenoid valve
  • Absorbent materials with quality and the best brands in the market and increasing their length by means of a suitable recovery system.
  • Tanks containing absorbent materials according to ASME and API standards
  • In models with heaters, the presence of heaters with high efficiency and very low energy consumption

How absorption dryer works