Technical article

Application of Molecular Sieve 4A and Activated Alumina in Air Dryers


The adsorption dryer uses the characteristics of adsorbents (activated alumina, silica gel, molecular sieve) to adsorb water to reduce the moisture content in compressed air. Generally speaking, it can achieve a dew point of -40 degrees or above in the outlet air. Today, we will focus on the core components of the dryer: adsorbent molecular sieve 4A and activated alumina.
Molecular Sieve 4A and Activated Alumina are commonly used desiccants in air dryers. They play a crucial role in removing moisture and humidity from compressed air systems. Let's dive into the application of these adsorbents in more detail! 
Molecular Sieve 4A is a synthetic zeolite with a precise pore structure and high adsorption capacity for water molecules. It is widely used in air dryers due to its ability to selectively adsorb water while allowing other gases to pass through. Here's how it works:
* Adsorption: Once the compressed air enters the air dryer, it passes through a bed of Molecular Sieve 4A. The zeolite adsorbs moisture from the air by trapping water molecules in its porous structure.
* Regeneration: Over time, the Molecular Sieve 4A becomes saturated with water. To maintain its effectiveness, the desiccant needs to be regenerated. This is done by reducing the pressure and purging the zeolite bed with dry air or heating it to remove the accumulated moisture. Once regenerated, it is ready to adsorb moisture again.
Activated Alumina is a highly porous material made from aluminum oxide. It is commonly used alongside Molecular Sieve 4A in air dryers to achieve even better drying results. Here's how it contributes to the air drying process:
* Adsorption: Activated Alumina has a large surface area, allowing it to adsorb moisture effectively. It works by attracting and trapping water vapor present in the compressed air stream, preventing it from reaching downstream equipment.
* Regeneration: Similar to Molecular Sieve 4A, Activated Alumina requires regeneration once it becomes saturated with moisture.

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Tracy Chen
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