Rick Brown is the Senior Sales Engineer with IMEC, a longstanding Atlas Copco business partner located in nearby Ayer MA. IMEC is a custom mechanical design/build firm with unique compressed air experience and also a certified Project Expediter (PEX) of the local electric utility, National Grid. Brown recalls that Garelick Farms had been using three (3) 25-horse-power positive displacement lobe-type blowers, each with 250 CFM flow capacity for a total of 750 CFM. “With two new membranes going in, Rink Wheeler was looking to double CFM capacity to 1500,” Brown says. “The simple option was to get an additional positive displacement blower. Another approach would be a single, larger positive displacement blower to satisfy the entire demand. A 125-horsepower unit that could satisfy the demand was quoted, but the noise level was already scary with the existing blowers creating around 100 dB(A) each. If Garelick Farms stayed with positive displacement technology, they’d be making the work environment even louder and operating inefficiently. I thought we could do better.”
At this point, Rick Brown consulted with Ron Whelan, the local Atlas Copco Oil-free Air and Key Account Sales Manager, and the two combined efforts to select a rotary screw blower solution for the project. “The variation in effluent output from the Garelick Farms wastewater treatment plant and resultant compressed air requirement at different load points made Variable Speed Drive a natural fit for the application,” Whelan explained. An Atlas Copco model ZS 75+VSD was selected to meet both the flow and pressure requirements.
Brown reached out to National Grid, which offers financial incentives to companies that install energy conserving equipment, to learn whether Garelick Farms could benefit. “I prepared a comparison of product data to determine if the project qualified under the National Grid New Construction Custom program,” Brown explains. “To qualify, you specify a base case solution, with equipment that is less expensive to purchase but also less efficient to operate, and a proposed case solution with equipment that requires a larger initial investment but operates with higher energy efficiency. Our base case was a new positive displacement rotary lobe blower sized for the application. Our proposed case included an Atlas Copco ZS 75+VSD oil-free rotary screw blower with Variable Speed Drive, which provided energy savings to establish the incentive. We used the positive displacement blower curve and Atlas Copco’s engineering data for our screw blower to calculate those savings based on the varying load requirement at Garelick.”
The energy calculations determined that operation of the ZS 75+VSD would result in annual energy savings of 83,647 kWh compared to the equivalently sized rotary lobe unit. National Grid offered Garelick Farms an incentive of $17,271 to invest in the more energy efficient Atlas Copco equipment, resulting in simple payback period of just 18 months.
“There was no question this was the way to go,” says Wheeler, “but a key issue was that our management decided they wanted the new blower right away. We had already scheduled the membrane replacement, which involves pumping down the 600,000 gallon water treatment system, and they didn’t want to do it twice. It takes several weeks to build and deliver a brand new ZS 75+VSD blower, but Ron Whelan and the Atlas Copco team were able to source a similarly sized new machine for us to use on loan until our blower was built. Actually they went through hoops to secure that blower for us. As it turned out, the loaner had virtually the same specifications as what we ordered and it was meeting our demand just fine in operation. Given that the time and effort involved in replacing the loaner with another machine that was practically identical, we arranged it with Atlas Copco so we could maintain possession of the loaner.”
Whelan says, “I was ecstatic that our team was able to react quickly and pull something out of stock to help the customer. Garelick Farms was able to not only satisfy their tight project timeline, but also could start realizing the energy saving benefits sooner.”