How to purify compressed air?

Purifying compressed air is essential for many industrial applications, as it helps remove contaminants such as water vapor, oil, dust, and other particles that can affect the performance and longevity of equipment. Here's a step-by-step guide on how to purify compressed air:

Sources of compressed air pollutants:

1. Atmosphere

Air compressors suck in and compress a large amount of atmosphere. They continue to fill the system while bringing in extremely small pollutants. These pollutants include: water vapor, atmospheric dirt, dust and pollen particles, oil vapor, and microorganisms.

2. Air compressor

In addition to the pollutants inhaled from the atmosphere, the air compressor will also mix a small amount of oil into the compressed air flow during the air compression process. This oil may exist in the form of liquid oil, aerosols and oil vapor. It is also worth noting that although so-called oil-free compressors do not directly inject oil into the airflow, they still compress the same contaminated air like an air compressor, so any oil vapor in the surrounding environment will still be affected. It is compressed and enters the downstream system. After the compression stage, the aftercooler cools the air, which can condense any water vapor and mix it into the compressed air stream in the form of liquid water or aerosol.

Primary Filtration

Coalescing Filters: These filters remove oil and water droplets by forcing the air through a fine mesh. They are typically installed after the air compressor.

Particulate Filters: These remove solid particles from the air, often used before the coalescing filter.

Air Dryers

Refrigerated Air Dryers:These reduce the temperature of the compressed air, causing water vapor to condense and be removed.

Desiccant Air Dryers: Use a desiccant material (like silica gel) to absorb moisture. They are more effective but also more expensive.

Secondary Filtration

Sub-micron Filters: These remove even smaller particles and droplets that might have passed through the primary filters. They are often used near the point of use to ensure extremely clean air.

Drainage

- Install automatic drain valves at low points in the system to remove accumulated water and contaminants.

Regular Maintenance

- Clean or replace filters regularly to maintain efficiency.

- Check and service air dryers as recommended by the manufacturer.

- Regularly inspect the entire system for leaks and other issues.

Point-of-Use Filtration

- Install additional filters close to where the air will be used if higher purity levels are required.

Tips:

Pressure Dew Point: Ensure that the dew point of the air is appropriate for your application. This is the temperature at which water starts to condense out of the air.

Flow Rate:Make sure your filters and dryers are rated for the flow rate of your system.

Contamination Levels: Know the contamination levels required for your specific application and select filters and dryers accordingly.

By following these steps, you can effectively purify compressed air for various industrial uses, ensuring optimal performance and longevity of your equipment.