Summary of common compressed air drying and water removal methods

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All atmospheres contain water vapor, but when the air is compressed, the relative humidity of water increases to 100%. To avoid problems caused by water deposits in pipelines and connected downstream equipment, compressed air dryers must be equipped. Among the post-treatment equipment of an air compressor, there are mainly storage tanks, dryers and filters. Dry compressed air ensures unhindered operation of the air compressor air system and production process. The role of the dryer is to eliminate condensate in the compressed air and ensure the discharge of dry and clean compressed air.

The air is compressed to a higher pressure than the expected operating pressure, which means that more water is condensed out of the system during the compression process. The additional water is separated out as the air is cooled in the compressor aftercooler. The air is then allowed to expand to operating pressure and a lower pressure dew point is obtained. This method is only suitable for very small air flow rates due to its high energy consumption.

The principle of operation of an adsorption dryer is simple - moist air flows through the desiccant to dry it. Once the desiccant material is absorbed by water, it is regenerated to restore its drying capacity. Adsorption dryers are usually constructed with two drying vessels, the first vessel drying the incoming compressed air and the second vessel taking care of the regeneration.

The refrigerant drying process involves cooling the compressed air to allow large amounts of water to condense and separate. After cooling and condensing, the compressed air is reheated to room temperature so that condensation does not form on the outside of the ductwork.

The temperature at which unsaturated air is reduced to saturation while keeping the water vapor partial pressure constant (i.e., keeping the absolute water content constant) is called the dew point. When the temperature drops to the dew point, there will be condensation in the wet air droplets precipitation. The dew point of wet air is not only related to the temperature, but also with the amount of moisture content in the wet air, the dew point of water content is high, the dew point of water content is low. Wet air is compressed, the water vapor density increases, the temperature also rises. Compressed air cooling, relative humidity increases, when the temperature continues to fall to the relative humidity of 100%, there will be water droplets from the compressed air precipitation, the temperature at this time is the compressed air pressure dew point.

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