A new type of filter system for chilled water circuits combines the benefits of primary circuit filtration and side-stream (or by-pass) filtration. The filter does not create any pressure fluctuations and can be cleaned without shutting interrupting operation.
The chilled water system in a plastics processing operation often requires a great deal of maintenance. Contaminants such as lime, microorganisms, corrosion residues and metal particles must be thoroughly removed from the chilled water circuit. If cleaning is neglected, connections and water lines can become clogged. This reduces the cooling capacity and leads to problems in production.
To date, two concepts for removing solid materials and other contaminants have been available on the market. In primary circuit filtration, the water in the cooling circuit passes through a centrally located filtration system; in side-stream (or by-pass) filtration, the water filter is located in a by-pass circuit that is part of the cooling system.
Both systems have drawbacks. With primary circuit filtration, the filter must be cleaned at regular intervals. To permit uninterrupted operation during cleaning, the cooling system requires an additional by-pass around the filter. The pressure fluctuations that occur in the system are a serious problem when the filter becomes clogged slowly. The disadvantage of side-stream filtration is that not all of the water passes through the filter. Some contaminants that can disturb production always remain in the system.
The process cooling equipment manufacturer Reisner Gmbh has now developed an alternative to the conventional cooling systems. The BO-X return-line filter is installed in the primary circuit and is equipped with an overflow to maintain constant system pressure. Since all of the water in the primary circuit must pass through it, the return-line filter can removed all solids directly. If the ability of the filter to allow water through is reduced because of the contaminants that have been collected, the excess water flows directly to tank – pressure fluctuations are avoided; production remains unaffected.
When the filtering action in no longer adequate, an alarm signal indicates the need for maintenance. Production continues without interruption during cleaning. The number of filter elements can be selected on the basis of the volume of water to be filtered. Retrofitting of already existing cooling water systems with this new filter concept, however, is possible in only certain situations. Accordingly, cooling water treatment should be taken into consideration as soon as possible when planning a production operation.