Compressed air is used in a wide range of industrial applications. Proper compressed air treatment is necessary to protect equipment and avoid production downtime and maintenance. In almost all applications throughout a manufacturing plant, the use of clean, dry compressed air will result in lower operating costs.
If compressed air is left untreated, contaminants such as dirt, water, and oil will be deposited on the inner surfaces of pipes and fittings. The build-up will eventually cause an increase in pressure drop in the line. Lower air pressure will result in loss of the energy used to compress the air. Reduced pressure at the point of use will result in a loss of performance efficiency, amounting to thousands of dollars in lost production time and maintenance.
Liquid water present in the compressed air is particularly problematic as it will accelerate corrosion and shorten the useful life of equipment. Corrosion particles will plug valves, fittings, and instrument control lines, damaging sensitive equipment. Similar plugging will occur in cold environments if the water freezes.
For many years, problems from moisture in air were tolerated. To prevent freezing, alcohols were injected into the lines and electric heaters were used to separate moisture and other contaminants. These solutions did not completely solve the problem. Increased use of compressed air and the development of many new and more sophisticated devices and controls have accelerated the need for clean, dry air.
A membrane air dryer is a cost efficient and effective way to protect sensitive equipment from contaminants in plant compressed air.
How a membrane air dryer works
Parker membrane air dryers, for example, use specially formulated membrane microtubes that are selectively permeable to water vapor. The microtubes provide an excellent medium for producing dry air from standard compressed air. As the compressed air travels along the length of the membrane, water vapor diffuses through the membrane, producing clean, dry compressed air at the outlet. A small fraction of the dry air is then directed along the outside surface of the membrane to sweep the moisture-laden air away from the membrane. Figure 1 below shows how the technology works.
Figure 1 - How membrane technology works
Features and benefits
- Membrane dryers reduce the dew point of compressed air to as low as -40°F/°C.
- Designed with no moving parts and no requirement for electrical supply.
- Operate with very little noise output - just a small amount of purge air is emitted through small exhaust ports.
- Require minimal maintenance and are inherently explosion proof.
- Ideal for remote areas, explosive environments, sub-freezing environments, and applications requiring a consistent dew point.
This post was contributed by David Connaughton, product manager, Parker Industrial Gas Filtration & Separation Division.