Metal towers lined with galvanizing or other coatings have been around for a long time -- sometimes too long. Decades-old metal cooling towers frequently become high-maintenance with a drop in performance. Over time, they may become thin-skinned, inefficient, leaky or corroded, and may disrupt the manufacturing process. Unplanned repairs may mean days or weeks offline, shutting down a process.
“We were spending between $5,000 and $10,000 a year on cooling tower repairs -- patching metal, putting in rubber seals and gasketing,” says Marvin Richer, president of Brock Equipment Co., Crystal Lake, Ill., a manufacturer of hydraulic pumps and related tools. Richer called the repairs “band-aid” fixes just to keep the tower from leaking, noting that his other option was to replace his aging metal-lined towers, a time-consuming endeavor that also is expensive, as is the installation of additional towers to increase cooling capacity.
“Given our choices, we were most likely going to install a new tower similar to the old one,” Richer says, but first he looked into a new type of plastic cooling tower he heard was reliable and required less maintenance.
What Richer checked into is engineered molded-plastic cooling towers. Just as advanced plastics have replaced metal in many high-tech and industrial applications, plastics may be a solution to metal-skinned towers with chronic deficiencies.
When selecting cooling towers, the focus of any plant engineer beyond efficiently meeting duty requirements is on reliability, reduced maintenance and installation ease. Given these considerations and a choice between metal and plastic towers, many engineers are opting for plastic, which are now high capacity and lightweight, and may be more energy efficient.
At Brock Equipment, the company was throwing good money after bad by continually spending time and money on its old, deteriorating galvanized metal-lined tower installed in 1950.
“As the tower got older, not only did we have ongoing leak problems, we started to have a structural problem,” Richer says. “Water is pretty heavy, and the tanks that hold the water on the bottom were getting heavier and heavier as we added more and more materials to fix the leaks. All that weight was beginning to bend the structural members that held the cooling tank together.”
Metal cooling towers like Brock's also are subjected to constant changes in pH, requiring chemical treatments that attack the galvanized metal lining, often wearing it out in just a year or so. Environmental conditions such as sunlight, pollution, salt air and harsh process chemicals also may contribute to galvanized steel's early demise.
Engineered molded-plastic cooling towers are one-piece units so there are no problems with seams, welds and patches wearing prematurely. Competitive in price, plastic towers are rust and corrosion proof, according to Delta Cooling Towers Inc., Rockaway, N.J.
Brock's cooling tower does not interface with manufacturing processes but supports an absorption-chiller that conditions plant air.
Richer says the plastic cooling tower has been trouble-free for more than three years, noting that “there has been no repair work on the tower, no leaks at all.”
For more information, contact Delta Cooling Towers at (800) 289-3358 or www.deltacooling.com.