Compressed air, frequently referred to as the ‘fourth utility’ in…
How to remove moisture from the compressed air system?
It is known to all that moisture is always present in atmospheric air even if we cannot see. When a compressed air system compresses air, it basically cools the air beyond its dew point. Further, it condenses that into liquid water. This process creates a conundrum, as the compressed air system completely depends on dry air and cannot function properly if moisture is present in the air. To be specific, air must not contain any type of liquid moisture. It should be at a relative humidity of less than 50% to prevent corrosion within the system.
How is moisture harmful to the system?
There are multiple damaging effects of moisture or liquid water if it is present inside a compressed air system.
- • It can create a blockage in control airlines, prevent instruments from reading or actuating properly which results in great malfunction of the entire system.
- • Due to the presence of moisture, water hammer events (an event where hydraulic shockwave forcefully prevents a flow or change its direction) may occur that damage equipment and piping.
- • Air tools get damaged due to a lack of proper lubrication.
- • It hampers product integrity and spoils different parts of it.
- • When water vapour enters the air system the entire process can be directly impacted in a negative way.
Techniques of removing moisture from the air
There are several scientific techniques available for eliminating moisture from compressed air.
Cooling plus Separation:
The name of the technique itself suggests the steps that are needed to follow for separating moisture from air. When the hot and compressed air cools off, it allows a large amount of water to condense. Without condensation, this separation is difficult. To separate vapour from a large amount of air, an aftercooler is the ideal solution. Even a heat exchanger works if it requires cooling of hot compressed air. It results in precipitation of the water instead of condensation. Refrigerate type of dryers does this with perfection.
Over-compression:
In this process, the air is compressed to a higher pressure than it is actually necessary. It is much higher than the intended working pressure. After separation, air goes back to the pressure required for the work. As the work procedure involves high energy, over-compression suits it. With airflow rates being smaller, this process works perfectly.
Membrane drying:
With selective permeation, gas components in the air separates the water vapour out. While entering into the cylinder, wet and filtered compressed air turns into water vapour and collects on the fibres. Simultaneously, the dry hair continuously flows through those fibres.
Absorption drying:
This procedure involves chemicals like Sodium chloride or Sulfuric acid. Whenever water vapour comes in close contact with these chemicals, they become bound to this procedure. Absorption material can either be solid or liquid. Moreover, these are easily available and are very common.
Adsorption drying:
In this process, a hygroscopic or desiccant material is used to dry the flow of moist air. Silica gel, molecular sieves, and activated alumina are some of the most commonly used materials. Dryers that function following this way are purge regenerated adsorption dryers, heated purge regenerated dryers, blower regenerated dryers, and heat of compression dryers.
Significance of removing moisture from the air
It is very evident that removing moisture is necessary for protecting corrosion especially for the equipment using the air and the air system itself. Particles created from the rust and scale might generate foul lines and damage system components highly. In the worst-case scenario, corrosion ends up damaging pipework generating leaks and preventing air from reaching the designated area of operations.
Moisture-free air is ideal for system operations
To protect the system from damage, using dryers is one of the most popular methods among manufacturers to eliminate moisture from the air. When air emits from the compressor, it remains heated and saturated with water vapour which can hamper product integrity and spoil different parts of the system. So, the solution is to remove moisture to run seamless operations. As the heated air cools down after emission, the condensation begins. Generally, it happens because the air has a tendency to get into the system whenever it cools down. Moreover, the air system also passes through cold outdoor areas before entering into the processing area. That is why the manufacturers prefer to dry the air before putting it into the air net. It makes the system work flawlessly. There are filters and separators available in the market to remove liquid moisture droplets from an air compressor system. However, no option is better than a dryer if the concern is to remove moisture completely from the air. With so many options available in the market, separating moisture from the air becomes easier and helps run the system operations smoothly.
