U.S. Federal Energy Management Program Recommends Side-Stream Filtration for Cooling Towers
Side-stream filtration has been recognized by the Department of Energy, Federal Energy Management Program, and an increasing number of facilities engineers as the best means for increasing
the energy efficiency of cooling tower systems, while reducing water costs, maintenance costs and downtime.
Listed among the best management practices for cooling tower systems, "side-stream filtration is particularly helpful if your system is subject to dusty atmospheric conditions,” said Christopher Kim, sales engineer for Filter Sciences, Inc. “Side-stream filtration can turn a troublesome system into a more trouble-free system."
Water in a cooling tower loop always contains impurities because it is
open to the atmosphere. Air contains dust, dirt, soot, pollution, pollen, microbiological organisms such as, airborne bacteria, spores and fungi, as well as vegetation and insects, which are all being scrubbed into the water by the cooling tower.
"A typical 200-ton cooling tower in a season may assimilate upwards of 600 lbs of particulate matter from airborne dust and make up water supply," according to the American Society of Heating, Refrigeration and Air-conditioning Engineers’ 1996 handbook.
These contaminants interfere with the efficient operation of cooling equipment, raising energy costs for facilities and lowering profitability for chemical water professionals. According to the U.S. Department of Energy, "The thermal efficiency, proper operation and longevity of the water cooling system all depend on the quality of water and its reuse potential."
Side-stream filters are not substitutes for chemical water treatment
programs, but are being recognized by every authoritative source in the industry and scientific community as the best complementary technology for chemical water treatment. While chemical programs address dissolved solids such as iron salts, hardness and scale, filters remove suspended solids such as dust, dirt and debris, which are less predictable through the course of the cooling year.
"Install a side-stream filtration system that is composed of a rapid sand filter or high-efficiency cartridge filter to cleanse the water,” Kim said. “These systems draw water from the sump, filter out sediment and return the filtered water to the tower, enabling the system to operate more efficiently with less water and chemicals."
Among the well-established mechanical filtration technologies (centrifugal, bag, cartridge, etc.), granular or sand media filtration
currently has the best balance of performance and price for moderate-to-high volume institutional cooling towers. Filter Sciences has designed a class of sand media filters specifically for managers of cooling tower facilities.