Engineered plastic cooling towers are transforming the industry, eliminating the problems that plague galvanized metal cooling towers - corrosion, leakage, maintenance costs and process disruptions caused by internal and environmental pH factors.
The "traditional" metal-clad cooling tower is under attack from all sides, particularly in the process industries where they are critical to maintaining temperature ranges for every process that creates heat. Not only are exorbitant maintenance costs and disruptions making those classic zinc-plated models outmoded, but the very laws of nature seem to working against metal cooling towers for a wide variety of industrial applications.
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"Metal-clad cooling towers are being eaten alive by harsh environments," says "Jim Ruddy, President of Proprietary Systems, Inc., Westlake Village, California. "They rust and corrode all the time. They are attacked internally by process chemicals and externally by environmental elements. Metal tower technology is antiquated and very expensive to maintain. Metal towers can also corrupt processes, causing headaches that can cost thousands of dollars many times over."
|Metal-clad cooling towers are literally being eaten alive by harsh environments. They are being attacked internally by process chemicals and externally by environmental elements.|
|Two engineered plastic cooling towers installed at an industrial facility. The tower on the left was installed 25 years before the tower on the right and shows no damage from corrosion.|
Having come from the metals processing industry, Ruddy received a first-hand education on the disruptions and expenses that can result from problematic metal cooling towers.
"In our business we used big power supplies for heating and melting through induction," Ruddy explains. "Metal cooling towers were plagued by rust and corrosion. Rust would get into the water system and lodge in an SCR (silicon-controlled rectifier) and short it out. Poof - there goes another $2,000 SCR. The maintenance guys sometimes changed SCRs like light bulbs."
The natural and mortal enemy of metal-clad cooling towers is pH, usually on the low side. A high pH leads to excessive calcium and other ceramic-like deposits. When the pH of a liquid coolant becomes acidic (low), either because of external (e.g. atmospheric) elements or infiltration of process elements (e.g. material fines), the veneer of zinc galvanizing used on most metal towers immediately begins to deteriorate. Because the zinc plating is thin (normally a scant 2.5 oz. per sq. ft), a pH lower than 4 will destroy this protective lining in a matter of months. At that point contractors are required to replace the zinc galvanizing by expensive coatings and repair any cavities and other damage that may have occurred. If the repair process is extensive, costly process interruptions may be required.
Ruddy, whose earlier experience led him to the cooling tower business via Proprietary Systems, says pH problems can come from a number sources.
"We have customers who use solvents or de-scalers to prevent scale from occurring in their process fluids," Ruddy says. "These chemicals sometimes leak into the cooling system and they corrode the cooling towers. Sometimes the solvents attack the metal at the seams, other times they just wear down the galvanizing. But either way, once the zinc plating of a metal tower is undermined, you're looking at escalating trouble, possibly including expensive repairs or even replacement"
Reinventing the cooling tower
The inherent susceptibility of metal cooling to high and low pH has led to the development of a new technology that is rapidly replacing the older one, particularly in the process industries: the engineered plastic cooling tower.
Composed of material that is literally impervious to the harsh pH environments that devastate metal cooling towers, engineered plastic cooling towers are energy efficient, available in a wide array of capacities and air flows, and will operate with both process and energy efficiency for many years.
Ruddy's distribution organization, Proprietary Systems, provides engineering consultation as well as the latest designs in corrosion-proof polyethylene-plastic cooling tower technology from Delta Cooling Towers (www.deltacooling.com) of Rockaway NJ.