Author: Richard Juskowiak, Donaldson process filtration division
Food and beverage producers widely use compressed air at various stages of the technological process. However, through compressed-air systems, oil, other contaminants and microorganisms can enter the products being manufactured.
Preventing moisture and oil from entering the air is of primary importance for maintaining its sterility. The most common contaminants in compressed-air systems are liquids, predominantly water and oil.
Bacteria that feed on water and oil can multiply in cracks and other defects of compressed-air lines. In addition, a biofilm of oil and water can move further downstream and clog or completely block the process pipelines.
Industry: Spring water Problem: A producer may claim that its water has «natural purity» only if it meets certain requirements and…
To minimize the risk of water, oil and bacteria entering the product, a set of filters is installed at the outlet of the air-compression and cooling equipment.
Below are the main measures to prevent the risks associated with moisture entering the air.
The sequence of filtration and drying
The moisture-related problems of all compressed-air systems arise already in the compressor room. Depending on the ambient-air conditions and the seasonal changes of weather or climate, only the volume moisture.
Refrigeration dryers cool the air and remove the free moisture formed during condensation. In the process, a significant amount of liquid may remain in the air. To remove liquid particles, it is recommended to use staged treatment with a reduction in the size of retained particles at each treatment stage. The following filters are used: 1) a cyclone separator that removes most of the large water particles; 2) a coalescing filter that extracts aerosols of liquid particles from the compressed air; 3) an air dryer that removes the remaining water vapors in the air. The type and size of each component should be chosen carefully, taking into account the initial air humidity and the treatment requirements.
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At the first treatment stage, most of the water remaining in the air is removed by a cyclone separator. The coalescing filter installed after it retains and drains off the tiniest water droplets. At the final stage, an air dryer removes the water vapors. Drying the air is just as important as cleaning it of contaminants, since it prevents the growth of bacteria in the air downstream. For this, a high-quality adsorption dryer is used (for example, the Donaldson Ultrapac™ Smart dryer).
The adsorption dryer is also an indicator of the efficiency of the previous cleaning stages. For example, an increased pressure dew point may indicate insufficient water-removal efficiency of the cyclone separator or coalescing filter.
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Designing the filtration system
It is recommended to install all the components of the designed filtration system during the construction or re-equipment of the plant. The installation of components in existing process lines is also permissible.
When designing the system, place the coalescing filter and the dryer as close as possible to the production line. At each point where the process air comes into contact with the product, install a fine filter. Fine-fiber filters retain the microorganisms and contaminants remaining in the system, for example particles of metals or corrosion.
It is also necessary to take into account the layout of the equipment at the production. For example, if cooled air from the compressor room passes through a pipeline outside the premises and is subject to fluctuations in ambient temperature, moisture may condense in the air, which will need to be removed again.
It is also important to take into account changes in weather conditions. In regions with high humidity or significant fluctuations in temperature and humidity, the most unfavorable scenario with a peak load must be taken into account when sizing the equipment.
Cooperation with such an experienced supplier of compressed-air filtration solutions as Donaldson will make it possible to create the most suitable moisture-control system for the existing technological process.
