Perseverance with Process Cooling
When compared to space cooling, process cooling — or the removal of heat from the fluid that serves water-cooled equipment used in a manufacturing process — is a bird of a different feather.
Interesting though, and the source of some fascination among those in the HVAC trades, is that much of the equipment, tools, and techniques remain the same.
Water temperatures can be very different between the two water-based cooling applications. In a process cooling loop, it’s not uncommon to blend cool and hot water before passing water through a cooling tower. The controls used are often very different, and there’s little tolerance for water pressure fluctuation in most process cooling applications.
“Designers of process cooling loops must have an intimate understanding of every component in the system,” said Larry Moore, mechanical engineer at Envelop Group.
The manufacturer’s representative firm, headquartered in Indianapolis, is the parent company of Validated Custom Solutions and Open Control Systems, which focus on equipment and controls specification, respectively.
“But for those who know the industry, process cooling work can be a mainstay in times of uncertainty,” he continued. “During the recession, process cooling kept us afloat. Today, it accounts for roughly 35% of my sales.”
Moore installed process loops as a contractor for many years before becoming a manufacturer’s rep. The Midwest is ripe with manufacturing facilities of all kinds, and he has worked with them all.
The process cooling guy
Moore designed his first process loop in 1990, and when he became a rep, he made it a goal to become the go-to “Process Cooling Guy” in his territory. Today, a long list of companies, like Ingersoll Rand, Essex Wire, and Nidec Sankyo, know him as such and are quick to call if a question arises.
“The biggest single loop I’ve designed is 9,100 gpm,” explained Moore. “The facility produces aluminum billets from scrap metal. Because the temperatures in the machines are so high, fail-proof cooling was needed, even in the event of power loss or catastrophic pump failure.”
The system features two National 150-HP vertical turbine pumps, a 330,000-gallon remote concrete sump, and two massive Evapco cooling towers. It even includes a water tower — larger than many city water towers — capable of gravity-feeding the cooling loop in an emergency.
“We don’t just chase a spec,” he explained. “We provide a design, and we’re involved with the project for years to come through maintenance, training, and consultation. We also stock the replacement parts for equipment we specify, like pumps, transducers, and controls. In this way, we’re able to forge a relationship with manufacturers that leads to continuing business.”
Envelop has engineers on staff, but for most process cooling applications, the design is submitted to a third-party structural or mechanical P.E. for review and approval.
A shining example of how Envelop Group has been a continuing resource for manufacturers can be seen at TOA USA, in Mooresville, Indiana. The manufacturer produces the chassis and suspension components for Subaru.
A first need
What began as an inquiry about a single cooling tower replacement at the auto parts manufacturer has evolved into a multi-building, A-Z design/build project for TOA-USA, and a true professional partnership that’s since allowed the business to evolve into a more efficient, sustainable facility with a healthier indoor environment.
When Moore first visited the site, he assessed the need for a large cooling tower replacement on the existing plant process cooling loop that serves a variety of stamping presses. Albert Decker, facility engineer, TOA-USA, showed him the aging galvanized cooling tower in place, noting the deterioration on both tower cells.
“I’d gotten Larry’s information from a friend of mine who’s a building maintenance specialist,” said Decker. “The existing cooling towers were failing prematurely, and Larry offered a lot of insight in a short amount of time. It wasn’t long before new equipment was arriving on-site.”
Moore worked with Evapco to specify a two-cell, stainless steel counter-flow cooling tower as a replacement. The stainless construction eliminated any future concerns about the possibility of corrosion.
“I selected a counter-flow AT Series tower to replace the existing cross-flow tower because they can cut water consumption by as much as 75%,” said Moore. “This design is also less vulnerable to freezing, and algae growth is dramatically reduced because sunlight doesn’t shine directly on the water.”
Sized for 775 gpm with 120°F inlet water and 85° leaving water, the new tower would be installed on the existing elevated dunnage. Only minor changes were required, and the new towers provide more capacity from the same footprint. The Evapco tower supplied for TOA USA is Cooling Tower Institute (CTI)-certified, meaning the performance of the towers has been tested and verified.
Harrell-Fish Inc., a union mechanical contractor in Bloomington, Indiana, was hired to install the new cooling tower in addition to the components that serve it. Moore specified a pump skid built by ACS Group and custom Carel PLC control panels.
“While the new units were being built, Albert wanted to learn more about the Evapco AT Series cooling tower,” said Moore. “So we drove to Greenup, Illinois, so he could see his new tower under construction at Evapco’s manufacturing plant.”
On the drive, Decker mentioned two major upcoming needs at TOA-USA beyond that of the first cooling tower replacement. His hope was that Envelop Group could design and supply process cooling equipment for a massive plant addition and offer makeup air solutions for the entire property. When the additions were complete, the plant would have nearly a half-million square feet under roof.
“Based on the success we had with Envelop Group on the cooling tower replacement, we brought Larry in early on the design process for the plant expansion,” said Decker.
After several meetings with management at TOA-USA regarding the layout and size of the new process loops being designed for the expansion, the specification would come to include towers for three new process loops along with another tower replacement in an existing space. Attention was simultaneously turned to indoor air.
“The negative pressure atmosphere inside the existing plant was obvious,” said Moore. “Welding equipment and machine hoods had been added steadily over the years as the company grew without an increase in makeup air supply.”
Moore and others at Envelop Group formulated a plan to bring the existing plant up to AHSRAE 62.1 standards with numerous Innovent dedicated outdoor air systems (DOAS) installed on-grade. The same units were specified for the various plant expansions soon to come.
This included an engineering analysis to determine the extent of ventilation needed. Meetings were also conducted with TOA’s selected construction firm, Force Construction Company Inc., and Harrell-Fish Inc., who installed all mechanical components airing the different phases. Both became valuable allies throughout the entire construction process.
Ultimately, Envelop Group was able to secure the equipment order and control integration to accommodate each new addition: the new East Plant, North Stamping Plant and the new E-Coat Plant.
The complete process loop bill of materials included seven Evapco AT series cooling towers ranging from 400-800 gpm, two ACS custom pump skids with process pumps, recirculation pumps, dual duty backup/standby pumps, and Carel PLC custom controls with BACnet integration.
Also, there were numerous dual-well stainless storage tanks and all required filtration equipment, including Shelco stainless filter housings connected in parallel, which allowed the filters to be replaced while the cooling loops are still in operation.
The comprehensive ventilation design included 1,700 tons of ventilation and HVAC systems via 14 custom Innovent DX cooling and natural gas makeup air units, which were painted to match the plant’s façade.
“Where the cooling towers that served the existing plant were a constant concern, the new ones are merely an afterthought,” said Decker. “We have routine maintenance performed, and that’s the end of the story. It’s fair to say that TOA-USA now has the Cadillac of process cooling systems.”
Within two years of starting the engineering process, TOA was in production on its new manufacturing lines.
Today, Moore points to the work and technology at TOA as a showcase for Envelop Group’s capabilities and products, allowing others to see how a partnership creates innovative, energy efficient, custom-tailored solutions in all markets of the HVAC and industrial process cooling industries.