Gear-Driven High-Efficiency Blowers From Inovair Deliver Substantial Savings

A blower upgrade helps a Kentucky clean-water plant optimize aeration basin airflow and significantly reduce energy consumption

Gear-Driven High-Efficiency Blowers From Inovair Deliver Substantial Savings

The stacked blowers (Inovair) in place and operational.

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For years the Paducah McCracken County Joint Sewer Agency dealt with too much or not enough air supply in its clean-water plant’s aeration basins.

However, the utility, in Paducah, Kentucky, recently found a solution that strikes the perfect balance. The treatment facility previously relied on three multistage blowers to feed oxygen to its six 250,000-gallon aeration basins.

“Our old blowers were installed in 1977, so it was time for an upgrade,” says Chris Hatton, maintenance supervisor for the plant. It wasn’t simply the age of the blowers, but the lack of control and energy inefficiency that spurred the plant to seek a more modern solution, in the form of gear-driven high-efficiency blowers on a feedback loop for dissolved oxygen control.

Seeking happy medium

Previously, on hot summer days, the plant needed to run all three multi-stage blowers; in winter months there were times when one would suffice. The problem was the in-between. “We’d get to a point where one wasn’t enough, but running two was too much,” Hatton says. “There was no middle ground.”

The old blowers in their original form ran either on or off, leaving operators with limited control. It also took a tremendous surge of energy to start the blowers, driving up peak power demand and therefore higher electric utility bills. In an effort to exert more control, the plant team ordered Allen-Bradley variable-frequency drives (Rockwell Automation).

“We put two of the blowers on VFDs to help reduce energy consumption and gain airflow control,” Hatton says. “They gave us a little adjustment, but not a whole lot.” Also limiting the VFDs’ effectiveness was the cooling design of the old blowers: “They needed to run fast enough to keep themselves cool. If we slowed them down too much, they would overheat.”

An airtight solution

Looking to optimize aeration, the team hired an engineering firm to research new options. Their search pointed the agency toward blower manufacturer Inovair. “They actually brought a small unit here to show us their product, and right away we liked what we saw,” Hatton says. “It was simple, and I like it to be simple and functional.”

Straightforward functionality is something Inovair emphasizes, notes Glen Roderique, sales engineer: “We try to design the packages to use as many industry standard components as possible to help keep costs down and help plants with quick repairs.” Along with an appealing design, the decision came down to efficiency and capital cost, both of which favored Inovair.

The treatment plant’s air flow is now supplied by a pair of 125 hp Inovair IM-30 high-efficiency blowers, arranged in a stacked configuration and plumbed to operate independently, or collectively if needed.

“We don’t have to have the same horsepower for each unit, so we can size them specific to the application,” Roderique says. “For example, a 50 hp on top and a 100 hp on the bottom would give the whole package a range of 500 to 3,000 cfm. Paducah chose two 125 hp units. They were looking for a maximum flow around 5,200 cfm and a minimum flow around 1,400 cfm. We were able to hit that flow range without a problem.”

To achieve those wide ranges, IM-30s use an integrally geared compressor to step up speeds from industry standard 1,800 rpm or 3,600 rpm motors, as opposed to using high-speed motors. Roderique says. That technology, along with modular design, enables the blowers to deliver a greater range of air supply in a much smaller footprint than the previous blowers.

Getting set up

Hatton praises his maintenance team. Their ability, along with the design and some instruction from Inovair, enabled them to install the blowers themselves.

“We are a hands-on facility,” says Hatton. “There are four maintenance guys under me, and between us we pretty much do all of our own maintenance and repairs. The hardest part was getting the units through our existing doorway. But once we got it through, everything went really well, and it was actually pretty easy.”

Another bonus was that the previously purchased VFDs were compatible with the new blowers. Once everything was installed, Inovair sent a technician to finish the setup, install a master panel and turn the blowers on.

Automatically better

The units have been running since January 2021 and, according to Hatton, they have been flawless. Most of the time the plant runs only one blower, using the other as a backup, or for support if the first unit isn’t providing enough airflow.

That automated adjustment is made possible by DO meters connected to the control panel. In the past, DO measurement was done by hand, followed by manual adjustments. Things are easier now.

“The IM-30s came with Hach DO meters,” says Hatton. “We have three of them installed in our aeration bay, and this system is driven by those meters. We have a desired 1.5 ppm DO concentration. The sensors take readings and transmit the information to the VFDs which control the rpm of the blowers.”

The control goes beyond keeping a desired DO range. Hatton and his team have the ability to set the percentage at which each blower is operating, allowing them to choose the share of work each blower is providing.

To keep both blowers operating for similar hours, Hatton alternates them: “Every 336 hours, or two weeks, they automatically rotate. No. 1 will be the main blower for two weeks, while No. 2 serves as backup. After two weeks, they switch roles.”

Running smoothly

The results of the blower upgrade speak for themselves. “It has always been about gaining control of our air supply, and that is by far the biggest thing they provide,” Hatton says. “Now that we have it, we are definitely seeing energy savings,” already estimated at roughly 20% and possibly heading higher.

“We are still learning the best route with these blowers,” Hatton says. “But we have learned some good tricks. For instance, we now have general winter and summer settings. During the winter, we can back off the air supply, and in summer, we are cranking it up.” Operators could not easily do that before.

Says Hatton, “I’ve been with the plant for 22 years and this whole thing has been one of the better upgrades I have been involved with.”


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