Manufacturer's new cooling tower stands up to salt and yields unusual benefits
Cooling towers used to cool industrial processes and HVAC systems have undergone substantial design changes over the years. This is particularly noticeable with the introduction of HDPE (high-density polyethylene) cooling towers, which aim to provide longer service life and reduced maintenance requirements.
While these attributes are compelling, the idea of incorporating this technology to increase production capacity is, for many, an unexpected benefit of the HDPE cooling tower technology.
An example of this benefit occurred when Tencarva Machinery was asked by Strand-Tech Martin, a manufacturer of prestressed concrete strand and high carbon wire, to evaluate a galvanized cooling tower that had required extensive service over its lifespan, and was beyond repair.
Tencarva Machinery is a distributor of liquid process equipment and custom engineered systems, most of which incorporate pumping packages and electrical controls. The company serves industrial and municipal markets in the Southeast.
“Our inspection made it clear that the existing cooling tower was beyond practical repair,” says Chad Plott of Tencarva.
Plott explains that the main problem was a destructive, corrosive effect on the metal-clad shell produced by salt air that permeates coastal areas such as Charleston, SC, where Strand-Tech Martin’s manufacturing plant is located.
The process used by Strand-Tech to produce its PC strand wire and high-carbon wire products requires a cooling tower for the wire-drawing machines, which run at very high temperatures.
The Strand-Tech application is an open cooling system, Plott explains. It includes pumps that feed water to the wire drawing machines from the cooling tower. The cooling water goes through some heat exchangers on the wire drawing machines, provides some spray cooling on the machine, and also travels through coolant passages in the wire drawing dies. Eventually, the water gravity-feeds from that production equipment back to the cooling tower.
Plott explains that one of the primary reasons for the customer’s inquiry into a new type of cooling tower was that because, in addition to structural damage, the old tower’s efficiency had fallen off. As a result, cooling capacity was only marginally sufficient for production, and the company was looking to increase production capacity significantly.
When Plott was asked to make a recommendation for a replacement cooling tower, he suggested an HDPE type of tower manufactured by Delta Cooling Towers. According to the company, HDPE engineered plastic cooling towers are designed to solve corrosion problems that can otherwise stem from circumstances including soft water, aggressive water treatment, and ambient factors such as salt air or caustic industrial gasses.
The design that Tencarva selected for the wire production facility was the TM Series, a modular cooling tower system that allows isolation of up to eight cooling cells for maximum operational flexibility. Plott recommended a four-cell configuration, which can produce up to 1,580 cooling tons.
Plott says that since the new HDPE tower system was installed, in late 2014, it has provided an additional 30% cooling capacity, more than enough for the added production output his customer has required, and will likely meet additional production increases in the foreseeable future.
If yet more cooling capability had been needed, the modular design of the TM Series could have allowed doubling the capacity of the four-cell cooling tower that was recently commissioned via the installation of an eight-cell version.
Among other benefits is the 20-year standard warranty on the double-walled HDPE shell, which is a standard warranty on all Delta products. Also, the tower fans now come with direct-drive motors that relieve the maintenance and downtime issues commonly associated with belt-driven or gear reducer systems.
Another advantage according to Plott is the cooling tower’s higher efficiency, including the fan drive system. It is composed of direct drive fans staged with two fans per cell. “This staged design means it’s not always necessary to run all of the fans continuously,” Plott says. “The payoff is a substantial savings on electric power consumption.
“As far as installation was concerned, nothing unexpected occurred,” Plott continued. “Tencarva supplied the pumps and cooling tower, and the customer provided a contractor who performed the installation. Even with the modular design, installation was fairly easy to complete. The installers were able to use the existing footprint as well as use the same water storage area underneath the cooling tower mounting pad.”
Maintenance is another positive. Not only will the corrosion problem of the salt air become obviated, but also the simplicity of the direct-drive fan system will require minimal service.
In the end, the new solution is expected to provide the best of both worlds: added production capacity with no maintenance headaches or downtime surprises.