Answer: The compressed air from the air source contains a large amount of liquid water, solid dust of varying particle sizes, oil, oil vapor, etc. If these impurities are allowed to enter the cold dryer directly, the working condition of the cold dryer will deteriorate. For example, oil will pollute the heat exchange copper tubes in the precooler and evaporator, affecting heat exchange; liquid water increases the workload of the cold dryer, and solid impurities are easy to block the drainage holes. Therefore, it is generally required to install a pre-filter upstream of the cold dryer air inlet for impurity filtration and oil-water separation to avoid the above situation. The pre-filter does not need to have a very high filtration accuracy for solid impurities, but it is better to have a higher separation efficiency for liquid water and oil.
Whether the post-filter of the cold dryer is installed should be determined by the user's quality requirements for compressed air. For general power gas, a high-precision main line filter can be equipped. When the gas requirements are higher, a corresponding de-oiling mist filter or activated carbon filter should be configured.
