Atmospheric air is naturally moist. It contains a higher water content at elevated temperatures compared to low temperatures. This fact will have a significant impact on your air compression because when the air is compressed, the moisture content in it rises with a temperature rise.
While this might sound inconsequential, moisture inside your air compressors will cause significant damage through the rust of its internal components. Moreover, it will affect the accuracy of some of your industrial operations.
To this end, it is essential to have your air compressor dryer and your filter in top shape to get rid of moisture and debris, respectively. Several techniques exist for the removal of moisture from compressed air to avert the issues associated with moisture presence.
The following are the alternatives you have for your operation.
Cooling and Separation
With this technique, the compressed air will first be cooled to allow the water to condense. When condensed, the water can then be removed from your air. The cooling and separation method takes place in an after-cooler and at times, a refrigerant dryer.
This air-drying technique is primarily used in stationary compressors. While older machines use separate aftercoolers, most modern stationary air compressors have theirs built into the equipment.
This resembles the cooling and separation technique since the air will be cooled then the water separated. In overcompression, however, the air will be compressed at a higher pressure than its intended working pressure.
Once the moisture is separated, the air will be allowed to expand and reach its intended working pressure. While overcompression is one of the easiest techniques of drying compressed air, it only suffices for minimal flow rates since it consumes a high energy amount.
With this alternative, you rely on the selective permeation of the gases in your compressed air to remove the moisture present in it. Tiny hollow polymer fibres that have an inner coating will be lined in your air dryer’s cylinder and create a membrane.
The moisture in your air is trapped between these fibres while the dried air flows through the membrane to continue working in your machine as intended.
This technique employs chemicals that will bind the water vapour molecules. The standard chemicals used in this case are sulfuric acid and sodium chloride. Adsorption drying is, however, not as commonly used owing to the risk of corrosion of your machine’s parts and the high amount of absorption material used.
Here, moist air will flow over a desiccant or hygroscopic material that will dry it. The common materials used for adsorption drying include activated alumina, molecular sieves, and silica gel. The desiccant will be regenerated when it becomes saturated to preserve its adsorption capability.
Adsorption drying is generally used in critical operation since it can achieve pressure dew points of -400 C.
Buying the right air compression dryer for your operation is not a decision you should take lightly. Other than the above air-drying alternatives, you will choose several crucial elements that affect the operation and longevity of your machine.
To guarantee the choice you make will suffice, get a supplier who gives you unbiased advice on what best suits your needs.