Make cooling towers greener, cleaner, more efficient and safer - by Jim Peet

Jim Peet, Fairfield Investments

Cooling towers are an essential part of providing a comfortable living and working environment to millions of people.  But it is not easy to keep them running at peak efficiency.  There are a number of issues that reduce the ability of these systems to perform.

Scaling is a common one. Hard water scale will foul condenser tubes inhibiting heat transfer. This increases electricity use as the system has to work harder to compensate for the poor conductivity. Scale will also form on tower fill and will decrease the efficiency of the evaporation process. Mineral and organic contaminates can accumulate in the tower basin. These contaminates can easily accumulate several inches thick and create feed and breed grounds for many life forms creating a bio-mass. As these organisms progress through their life-death cycles, they create an acidic condition at the bottom of the tower surface and ultimately cause extensive metal degradation of the tower and all related plumbing components. If the contaminates from the basin are allowed to migrate to the condenser or the process equipment, they will decrease the efficiency of the heat transfer process and necessitate extensive and costly maintenance.  Biological contamination can form. Algae and numerous forms of bacteria can form a bio-mass in the tower water and on components of the tower system. The bio-mass inhibits heat transfer in the condenser and clogs process water equipment. Lastly, Legionella is also a frequent problem in open water systems.

The common approaches to solve these problems cause their own issues.  The use of toxic chemicals to treat the cooling tower water means not only the extra cost for the product and the need for workers to handle dangerous chemicals, it also means (since cooling tower water has always been discharged to sanitary sewers) that millions of gallons of toxic chemicals including biocides will be released and need to be removed by water treatment plants. The alternative of bleeding the system more frequently increases the water bill - cooling towers use huge quantities of water through heat rejection (evaporation) and bleed off. A relatively small tower, 500 tons, operating 12 hours a day at 3 cycles of concentration will consume approximately 3,000 gallons of water per day.  Doing nothing means higher energy costs and a shorter system life.  Most systems use a combination of these approaches and hope for the best.

While there are many technologies that claim to offer better solutions, some actually do work.  Through my activities as financial advisor I have become familiar with NART QMS (http://nartqms.com), whose Hydroplex solution offers the following:

• Reduction and reversal of scaling through processing the water flow with magnets. The magnetic treatment of the water and the solids in the water allow the system to operate with higher cycles of concentration while running clean.  No chemicals are needed, scaling is eliminated as an issue, and the systems runs cleaner and lasts longer.  This has been used in hundreds of locations, showing that a properly designed magnetic device can prevent the formation of hard water scale on heat exchange surfaces.

• Elimination of organic sediment with sweeper jets and filters. In addition to sediment that may get in the system in other ways, the elimination of old scaling will by itself generate precipitated solids.  Enhanced filtering keeps the efficiency high.

• Cleansing of bacteria and Legionella with silver copper ion technology.  This technology is widely used beyond cooling towers.  The release of copper/silver ions into water will control biological contamination while eliminating chemicals, bleed water pollution, and contaminated airborne drift.

The treated water is clean and free of chemical contaminates. This water can then be re-used for gray water applications such as irrigating landscaping.

If you are using chemicals to keep your cooling tower clean, it may be time to consider solutions that keep it both clean and green.

Jim Peet is a managing partner at Fairfield Investments, LLC, New York, N.Y.