When it comes to heavy industrial cooling applications like oil refineries, chemical plants and paper mills cooling towers have been employed for decades. Yet, according to industry research, the utilization of the technology in these sectors is on the rise. There are several notable reasons including a longer average lifespan, consistent reliable cooling and significant energy savings over alternative cooling options.
Traditionally, however, these heavy industrial manufacturers required cooling towers that were the size of buildings and constructed on-site. This is no longer the case, as advanced cooling tower technologies are not only offering a smaller footprint but also delivering greater efficiencies with significantly less maintenance.
So was the case for a chemical processor in North Carolina where after years of incurring considerable expenses refurbishing and maintaining its aging cooling towers, the plant finally reached a critical point. The facility was looking to replace its existing wooden crossflow units with a more modern cooling tower solution. By switching to towers constructed of high-density polyethylene (HDPE) engineered plastic, the facility has been able to not only dramatically reduce its maintenance costs, but also boost efficiency.
“The company was spending tens of thousands of dollars each year on maintenance trying to keep the old towers operational and it just became cost prohibitive,” explained Varun Ganesh, sales engineer with Tencarva Machinery, a Greensboro, N.C.-based integrator of industrial process equipment.
Enduring the elements
In addition to the costs associated with maintenance, the efficiency of the old towers was also beginning to decline. Recognizing the need to reduce maintenance expenses and enhance efficiency, the company decided something had to be done. Given the nature of their chemical process, they needed a cooling tower solution that could withstand the demands of their environment.
“In this operation, there was a high likelihood that chemicals from the processing plant would enter the cooling system and deteriorate a metal tower,” said Ganesh. “So, they looked at two replacement options which included cooling towers made of stainless steel and engineered plastic.”
In this application, the industrial cooling towers are used to reduce the heat from the equipment required to produce the chemical reaction. In the closed-loop system, water circulates from the source, also called “the pond,” around several reactor tank vessels that require external jacketed cooling. The water then runs through the cooling towers where the temperature must be reduced by as much as 10–15-degrees Fahrenheit. Then the cooled water is recycled back into the pond.
While stainless steel was considered early in the process, the company ultimately decided on engineered plastic. HDPE cooling towers are impervious to the natural and chemical causes of rust and corrosion. They also require lower amounts of expensive water treatment chemicals and less downtime for repair or maintenance requirements.
“When spending such a large capital investment on a major utility they were not going to compromise on quality,” added Ganesh. “They were also hoping to find the lowest total cost of ownership and the engineered plastic tower’s corrosion-proof shell gave the facility the opportunity to greatly minimize repair and maintenance costs over time.”
Bonding with Plastics
Ultimately, the chemical processor selected four TM series towers from Delta Cooling. Together the engineered plastic towers offer a cooling capacity of 1,580 tons and can cool about 6,000 gallons of water per minute. Delta Cooling developed the first HDPE cooling towers in the 1970’s with many of the original towers still in operation today.
While HDPE cooling towers typically cost less than comparable stainless-steel models, there was another big reason that the chemical manufacturer felt confident in transitioning to engineered plastic.
“I think the 20-year warranty offered by Delta Cooling goes a long way to relieve any concerns,” said Ganesh. “That’s significantly longer than any stainless-steel or even galvanized-metal models that I am aware of.”
In addition to virtually eliminating maintenance – aside from standard preventive activities – the engineered plastic towers are proving to be significantly more energy efficient than the previously installed crossflow towers, further decreasing the overall cost of ownership.
“The older crossflow towers used large, 30-horsepower fans on each unit, which demanded a lot of electric power,” explained Ganesh. “The new Delta HDPE units are equipped with smaller, 60-inch fans that operate at a lower horsepower, so the energy consumption is far less.”
Delta Cooling also offers fans that are directly driven by a variable frequency drive (VFD). This lets them vary the fan speed and avoid running them at max RPM except when necessary. The ability to tailor fan usage to cooling demand encourages greater energy efficiency – and substantial savings.
High yield, low corrosion
The towers have also proven to be more efficient. The original installation at the plant consisted of four cooling towers constructed of a corrugated metal outer shell with internal parts fabricated out of wood. During the warm summer months, the facility required all four to properly cool the water. However, with the new, engineered plastic towers only three of the four are needed during peak times, a significant gain in efficiency.
“The final cell of the new towers is now available for increasing capacity at the facility if the chemical processor needs to scale up production in the future,” added Ganesh. “Plus, not having to use the additional motors on the fourth tower further increases their energy savings.”
Furthermore, the ease of installation is facilitated by the fact that the cooling towers are pre-assembled in the factory and arrive at the site in just two pieces. The modular design of the towers required a smaller footprint allowing for two towers to fit in the same footprint as one of the old wooden cooling towers.
According to the plant maintenance supervisor, the towers are already offering a return on investment for the project.
“Plant management says they are getting better cooling now than they ever experienced at this location before,” concluded Ganesh.