Sand Filters Offer Cleaner Cooling Water
September 1, 2006
A cooling tower does more than just cool. It also acts as an air-scrubber for removing dust, pollen and pollution circulating through the system. Three types of chemicals can be used to control such contaminants, says Alain Blais, president of Sonitec Inc., a Holyoke, Mass., and Montreal-based manufacturer of technologies for water used in heating and cooling. One prevents scale buildup, another reduces the potential for corrosion, and a third eliminates bacterial algae, microorganisms and mold.
“Chemical treatment will dispense with a lot of this stuff,” he explains. “Ultimately, however, you get too many particles, so it's best to use a system employing both chemicals and filtration.”
One type of filter, the Vortisand from Sonitec, combines centrifugal force with sand filtration. The system forces suspended solids to accumulate near the inside walls of the tank and removes them via an automatic backwash cycle. This design makes it possible to use a much finer grain of sand to remove very small particles (down to 0.45 micron) without clogging the filter. Via the turbulence strategy, the work of chemical-dispersing agents is enhanced, inhibiting the elements that contribute to corrosion and bacteria growth.
Temperature is a critical factor in robotic auto-welding, for example. Cooling water loops are used to provide cooling to the welding tips. A variation of just a few degrees can be enough to increase the need for welding tip replacement and experience possible downtime. Using a Vortisand filter allowed one company to reduce total suspended solids in the cooling water.
“We use a Vortisand filter as part of our equipment cooling apparatus,” says Patrick Browder, onsite technician, The BOC Group Inc., an industrial gas manufacturer in Cayce, S.C. “The system is closed loop. It sends water to the cooling compressors we use in the plant via very small tubes. This is where the system earns its stripes. It removes small particles from the system that might otherwise clog the pipes and make heat transfer more difficult.”
Before using the Sonitec filter, BOC had to remove the coolers and send them off for cleaning and reinstallation, Browder continues. It took 10 days on average to get them back, an inconvenience exacting a penalty in money and downtime.