Many of the first cooling towers featuring seamless HDPE plastic shells are still going strong in commercial and industrial installations around the world. When you consider the products introduced to the marketplace in the early 1980s, most of them are no longer with us. During that time, for example, the first personal computers were running the DOS operating system, the DeLorean “Back to the Future” sports car hit the street, and Sony was offering the world its Betamax video cassette player and the Walkman personal music player.
The year 1981 also saw the introduction of the world’s first 150-ton molded seamless plastic cooling tower. Featuring a seamless high-density polyethylene (HDPE) shell, this breakthrough design was essentially impervious to the corrosion problems that plagued conventional, metal-clad cooling towers.
Today, after 35 years of virtually continuous operation, some early HDPE cooling towers are still running strong, including the one installed by chemical manufacturer Ardmore Inc. in Newark, NJ. Ardmore’s cooling tower is the second Paragon® unit manufactured by Delta Cooling Towers, Inc. In the early 1970s, Delta developed the first HDPE towers with forced draft models ranging from 10-100 cooling tons. The Paragon model that Ardmore installed was introduced in 1981 as a line of induced-draft, counter flow design that offered 55-250 cooling ton capacities. Ardmore’s unit is a 150-ton model.
When he first looked at the HDPE cooling tower, Ardmore president, Albert Sharphouse, thought that the unitary plastic shell would last far longer and operate more economically than metal-clad cooling tower designs.
“We chose the Delta tower because plastic is non-corrosive, so it would last far longer,” Sharphouse explains. “Secondly, we use city water for makeup in the cooling tower, and the HDPE shell design would not require expensive water treatment chemicals (only dichloride tablets are used), so that would provide ongoing economies.”
Ardmore, which manufactures a variety of chemicals, uses the cooling tower to extract heat from the water flowing through the heat exchangers and jacketed production vessels as well as a process flaker. Sharphouse notes that while some of the chemicals and allied products that his company produces have changed over the years, the application and cooling system equipment has remained unchanged.
Located on top of the roof of the building, the cooling tower design gives it a distinctive, somewhat futuristic look, less industrial-looking than many traditional towers, says Ardmore’s mechanical engineer, Walter Sommer.
“Although we’ve now had the tower a long time, it still looks great, especially when you compare it with some of the conventional cooling tower structures,” Sommer says. “Also, with those galvanized metal-clad models you have a lot of maintenance. After a few years they can start to disintegrate and have to be replaced.”
Sommer asserts that some people don’t to realize that cooling towers are exposed to continuous evaporation, salts, and other aggressive elements that contribute to corrosion. In some cases these towers are affected by other destructive factors such as acids, aerosols, salt air, or other contaminants that are rough on metal-clad towers.
Sommer adds that the HDPE tower still provides a “green” benefit after 35 years of operation, not only because of its longevity but also because it doesn’t require harsh water treatment chemicals. He also says maintenance and downtime have been minimal. While he has replaced the motor and bearings over the years, in the overall, service has been nominal.
A two-speed motor powers Ardmore’s cooling tower fan and water circulator with a belt-driven fan. While many cooling tower users specify a direct drive motor (Delta’s standard offering now) for energy savings, Sommer is happy with the belt-driven design.
“The motor with the belt drive has been very reliable over the years,” he explains. “In the summertime we run it on high, and in the wintertime, we just switch it over to low speed. That is part of the beauty of the cooling tower’s design simplicity, and why it has been so good for our application.”
Although Delta’s cooling tower design have evolved since the 1980s, the company still offers Paragon series models. The company also offers engineering and installation assistance to aid companies such as Ardmore in making the best selection for their applications.