Going to Extremes
An engineered plastic cooling tower stands up to New Hampshire winters before it is relocated to Maui, where it assists a condenser process despite harsh wind, warm temperatures, salt air and UV rays.
When Kolani Distillers, on the island of Maui, decided to convert an old sugar mill into a distillery and produce a line of rum at the site of the island’s only remaining sugar plantation, they realized they had their work cut out for them - but mostly, they hoped, labors of love.
The father and son team, Paul and Brian Case, had to make a substantial investment to meet the federal code governing building facilities. The regulations were stringent and applied to the stainless steel tanks, boilers and other distillation equipment. Also, the regulations required an elaborate fire containment system - one that could make 3,500 gal/min of water available and could be sustained for three hours. And, finally, they needed a reliable cooling tower that could remove the heat from the alcohol condenser system regardless of the tropical weather conditions. The cooling tower was integral to the operation of the distillery’s alcohol condensation process, Paul Case explains.
“After vaporous alcohol leaves our stills, it runs through a condenser, which condenses the alcohol back to a liquid form so we can process it,” he says. “The condensers are cooled by water. So, we have to take that water, which becomes heated while cooling the alcohol, and send it to the cooling tower to reduce the water temperature, and then send it back through the continuous condenser loop.”
|The effects of wind, salt air and UV rays on the north shore of Maui have taken their toll on the distillery building but not on the engineered plastic cooling tower.|
Selecting an appropriate cooling tower was a special consideration due to Hawaii’s year-round high ambient temperatures. Any tower selected also would have to stand up long-term against the stiff gusts of corrosive salt air that blow in off the surf just half a mile from the distillery’s location in Paia. The winds on the north shore of Maui - which are strong and constant enough to make it a premier windsurfing spot in the world - also presented unique site-specific challenges for any cooling tower selected.
Wind-blown salt and other corrosives are the archenemy of metal-clad cooling towers, often necessitating frequent maintenance such as re-sheeting, welding and rebuilding within just a few years. An engineered plastic tower would be nearly impervious to corrosives. Yet the relentless Hawaiian sun would bombard the tower with UV radiation that could damage anything but the toughest plastic material.
In the process of exploring alternatives, Case found a used cooling tower constructed of heavy-duty, engineered HDPE available from a computer chip manufacturer that had closed a plant in New Hampshire. The cooling tower was a Paragon Series built by Delta Cooling Towers, Rockaway, N.J., and had been in service at the chip manufacturing plant since 1999.
“I did some research and found that the cooling tower manufacturer produced a quality product, and decided that for the price, we could afford to buy the secondhand tower and controls, have it disassembled, shipped to Maui and reassembled at our distillery site,” Case explains.
Like other Delta designs, the Paragon model is relatively light in weight, impervious to UV rays and corrosion-proof. Case adds that he was impressed with the weather tolerance of the cooling tower, which had operated for about six years in the brutal winters of the Northeast, and now has operated in the tropical sun at the distillery since 2006.
|The cooling tower is integral to the alcohol condensation process. After vaporous alcohol leaves the stills, it runs through a condenser. The water, which is heated while cooling the alcohol, is sent to the cooling tower to reduce its temperature and then back through the continuous condenser loop.|
Surprising Service Call
After the cooling tower had operated without fault for years in Maui, vandals climbed to the top of the unit and smashed the tower’s fan blades. Although the damage could have been worse, it was bad enough to stop production. The cooling tower could not operate in Hawaii’s consistently warm temperatures without the fan, so Case called the manufacturer’s headquarters in New Jersey.
“I explained to them what had happened, and that it was a second-hand tower,” he says. “Amazingly, they jumped right on it. They looked up the history of the tower and identified the fan assembly we needed to replace, and [then they] shipped it out to us with service instructions.”
Case’s maintenance people were able to quickly replace the entire fan assembly, which was a proprietary, noncorroding, fiber-reinforced polypropylene unit. Immediately afterward, the plant was up and running again.
“When you consider that the cooling tower had changed hands about five years before and was about 15 years old, Delta Cooling really took fabulous care of us,” Case says.
Today, Kolani Distillers’ Old Lahaina Premium Rum is sold throughout the Hawaiian islands. The father-son team hopes to distribute the line nationally in the near future.
Sidebar: Effective Water Temperature Control
Even in the idyllic conditions of island life, effective temperature control is essential to process operations. Paul Case notes that the design of the cooling tower fan system provides important energy savings for the distillery. The tower controls regulate the fan speed according to the ambient air temperature.
“In the cooler morning hours, the fan doesn’t even come on,” Case says. “Then, later in the day as the ambient air warms up, the fan rotates automatically at the appropriate speed to cool the condenser water from up to about 180°F [82°C] back to about 80°F [26°C].”
Case says the resulting energy savings are important to companies like his because the energy costs in Hawaii are among the highest in the country.