By Christine LaFave Grace, Plant Services managing editor
Internet-connected (and interconnected) technologies on the plant floor offer unprecedented opportunities to generate, track and analyze asset performance data. But just as important, they can be a vital tool for bolstering back-to-the-basics best practices for optimizing asset use, Joe Ghislain, recently retired senior manager at Ford Motor Co., said at Smart Industry 2017.
In a session on how compressed air systems fit into and advance Ford's digital manufacturing strategy,
Ghislain noted that compressed air remains vital in helping drive even new, highly sophisticated technologies. When Ford made the move to an aluminum body for its F150 truck, it completely overhauled its Dearborn, Mich., manufacturing plant, installing 500 new robots and implementing a new chemical coating system and hydroforming system during a four-week transformation. Those robots, whether they're spot welding or applying paint, depend on compressed air.
"All of those things are driven by compressed air," Ghislain noted. And because compressed air is such a critically important—and energy-intensive—tool, it demands a smart, holistic management strategy, he said.
For Ford, compressed air system costs can run into the millions of dollars per year, said Ghislain—not a big surprise, given that across the country, according to the U.S. Dept. of Energy, compressed air systems account for $5 billion per year in energy costs. Unfortunately, even well-managed compressed air systems aren't extremely efficient: For every 7.5 hp input, 1 hp is returned as useful work, thanks to power losses on the supply and demand sides, Ghislain noted. (One of the ways Ghislain recommends saving on compressed air is by using electric power as an alternative for a given application whenever possible.) But when poor compressor control, inappropriate use and air leaks factor in, waste—and costs—can skyrocket.
Systems approach needed
"It's a dynamic system; you have to go through and control it," by continuously monitoring the ever-changing supply-and-demand dynamics for compressed air and optimizing your combination of compressors in use, he said. That's where smart compressor controller technologies come in.
Modern energy management systems that incorporate permanent metering can aid in not only helping a facility accurately calculate its baseline compressed air use but also monitor the performance of compressors and end-use applications. "The key is to use a systems approach," Ghislain said. "It's no different from when you go to the doctor and get your temperature checked, your blood pressure checked and get everything else checked."
Getting baseline compressed air readings (key measurements: air flow and electric use) will provide a starting point for compressed air waste-reduction efforts. Pressure readings, which will constitute a system's pressure profile, should be taken over a period of time and under different conditions at the following points, according to Ghislain: before and after the main supply components, at the beginning and end of the main piping distribution system and at several critical points of use. The pressure variation that's observed will show how the system responds to demand fluctuations and what control actions need to be taken.
In addition, as an organization trends its compressed air use and costs over time and correlates them with production data, these baseline measurements will help tell a story to justify further or continued investment in compressed air management. "If you don't show that you've made improvements, you don't win investment," said Ghislain. "It's about dollars."
Declining costs of sensors and permanent metering systems are making these technologies more accessible, he added. By flagging suboptimal compressor performance and potential equipment issues early, they can support a more-proactive—and thus likely more-efficient and lower-cost—compressed air maintenance strategy. For example, when a problem with a bearing is detected early and historical data together with OEM recommendations gives an indication of when the bearing is likely to fail, it might be possible to replace the bearing during scheduled facility downtime rather than either 1) taking a compressor out of commission and halting a production line, or 2) watching the compressor fail, with potentially catastrophic consequences.
Data from smart handheld tools such as ultrasonic leak detectors—or, in a new twist, leak-detection apps available for download on a tablet—further can support smarter compressed air management. ("You don't always have to go elaborate and expensive" when it comes to leak detection, Ghislain commented.) And the opportunity for savings by reducing system pressure is dramatic: Every decrease in system pressure of 2 psi equals a 1% efficiency gain, he stated—so at 10 cents per kWh, running a 1,000 hp compressor running at 80 psi rather than 100 psi would save $60,000 per year.
At Ford's Woodhaven, Mich., stamping plant, an air leak detection and correction team was formed as part of a larger effort to get a better grip on the facility's compressed air use. Armed with data on leaking seals and pressure-drop points, the plant moved to fix its leaks, remove satellite compressors and dryers, and shut down one 800 hp compressor and adjust controls on the remaining compressors so that they would consume less energy.
The results: Compressed air use was reduced by 18%; system pressure was reduced by 5 psi; and the facility realized savings of 7.9 million kWh—$400,000 per year.
"It's trying to get the right pressure at the right quality for the least amount of cost," Ghislain said. And for facilities running a mix of rotary, reciprocating and/or centrifugal compressors, sophisticated sequencing controllers and connected, whole-facility energy management systems can be invaluable in giving visibility into and thus allowing for smarter control of compressors.
"The whole point of doing a digital transformation is to make things more efficient," Ghislain said, "and this is an area where you can do that."
