Compressed air dryers are immensely important In maintaining air quality and keeping the industrial environment moisture-free. They keep the machines rust-free and the environment free from bacterial growth. However just fitting an air dryer to maintain environment is not enough; you have to maintain the dryer itself for it to keep performing its function. In this blog, we will give you detailed tips on maintaining the various types of compressed air dryers.
No matter what type of climate you are located in, every type of atmosphere contains dirt and moisture. In an air-compressed dryer, the contaminants and moisture are compressed, and this heats up the air. The heated air has more capacity to hold water vapor. Once the air cools down, the water vapor condenses. This results in water leakage in seals, rusty pipelines, and more erosion on moving components. If you want to minimize the maintenance issues, it is best to decide on the right type of dryer that requires less maintenance.
Refrigerated dryers have a mechanism which removes moisture by reducing air temperature. The air temperature falls till moisture condenses. Once the water has fully condensed it is drained off and the dry air passes on downstream.
There are two kinds of refrigerated dryers, cycling and non-cycling. Dryers that operate continuously are non-cycling but cycling dryers do not and are also much more energy efficient as they utilize a glycol mixture or special fluid to conserve energy. In times when the workload is low the cycling compressor shuts off until temperature of the fluid exceeds a specific point.
Cycling dryers consist of a heat exchanger which must also be maintained. The heat exchanger should remain filled with water at all times. The water should not exceed a specific contaminant level. The water purity must be maintained by regular inspection, and chemical treatment should be done if the water becomes too contaminated.
A less popular dryer is a deliquescent dryer. Their drying mechanism consists of a solid desiccant like salt, urea, or calcium chloride to absorb moisture. The drying process in these drying model types uses a pressure vessel filled with desiccant tablets. The wet air enters the pressure vessel. The airflow slows down after entering the vessel, and large water droplets are filtered out while the desiccant bed sucks the moisture.
A regenerative dryer is the third kind of dryer that is widely used in industrial facilities. A regenerative or desiccant drier employs a desiccant (either silica gel or activated alumina beads) to absorb moisture and big particles, which are then ejected during regeneration. The setup consists of two towers, each with a desiccant bed, switching valves, and pipes to control airflow. Air flows alternately between the two towers in 5-minute periods. One bed dries the air while the other regenerates. This sort of dryer comes in both heated and unheated versions.
Regenerative dryers consist of two filters instead of one. These are known as prefilter and after filter, and both need to be replaced periodically. The first filter safeguards the desiccant, while the second one restricts the flow of the desiccant to other components of the dryer. A desiccant drier needs both a prefilter and an afterfilter. The first safeguard is the delicate desiccant, which would otherwise be rapidly damaged by pollutants. The second prevents desiccant from being carried over to downstream components.
Membrane or mechanical dryers are the most basic and cost-effective. It employs a textile filter composed of hundreds of individual fibers to trap big particles and force moisture to form huge droplets (coalesce). These particles and droplets accumulate at the filter's base and are washed away. The filter transports water vapor to a sweep chamber, where it is discharged.
The maintenance requirements vary depending on the type of dryer. Refrigerated air dryers are widely used and have low maintenance requirements. Dust should be cleaned from the condenser fins and the drain valve maintained on a regular basis. The prefilter should also be inspected and replaced as necessary.
Chemical dryers require extra care despite the fact that they contain no moving parts. This is due in part to the corrosive nature of the desiccant. Although this salty solution is unlikely to spill over, if it escapes downstream, it could cause equipment maintenance issues. Wastewater from any compressed air system should be disposed of properly. This is especially true when using a chemical drier. In rare circumstances, drain off may require special treatment before disposal. Additionally, the desiccant must be replaced on a regular basis.
Desiccant dryers have special maintenance requirements. Even long-lasting components require occasional inspection. Controls also require regular adjustments. The desiccant in unheated units should be replenished every 3–5 years. Desiccant in heated units should be updated more frequently, usually every year or two. Furthermore, pre- and afterfilters should be tested and replaced on a regular basis.
Membrane dryers contain no moving parts and require minimal maintenance or adjustment. An industrial-grade membrane can persist for years. When using a combination filter/separator, keep the weep or float drain clear and inspect the filters on a regular basis, replacing them as needed.
There are two types of filters that are used in compressed air dryer models of various designs. They are
Particulate filters are often composed of tiny mesh glass fiber, plastic fiber, or woven wire cloth. They use centrifugal force to remove big particles and strain out smaller particles. The filter is rated based on the largest particle it will let to pass.
Particulate filters act in tandem with coalescing filters. Coalescing filters are high-efficiency filters that remove water and lubricants from compressed air using a fine stainless steel mesh or woven fiber fabric (e.g., cotton co-knit).
Adsorption filters employ activated carbon to remove gaseous pollutants from compressed air. They absorb oil vapor in the pores of the carbon granules and must be changed once saturated with collected oil. They are point-of-use filters that require an upstream coalescing filter to function properly. Adsorption filters are suitable for areas that need germ-free environments, such as clean rooms, medicines, and food and beverage processing. Filters significantly increase the performance and usage life of compressed air dryers.
Let us look at the filter care instructions to ensure that they remain functional for a long time
1. Make sure that the filter size matches the dryer design.
2. Coalescing filters should complement the lubricant's chemical composition.
3. The maximum pressure drop limit, as specified by the maker, should never be exceeded.
4. Periodic replacement of filters should not be overlooked.
Conclusion
Proper maintenance of your compressed air dryer is vital to ensure its efficiency, longevity, and optimal performance. Regularly checking and replacing filters, monitoring the system for moisture and contaminants, and performing routine inspections are essential steps in maintaining your dryer. Keeping a consistent maintenance schedule not only helps prevent costly repairs and downtime but also ensures the reliability of your compressed air system.
