Renovate for Sustainability

Environmental sustainability and its little brother, energy efficiency, drive many current plant renovations.

By Bob Sperber, Contributing Editor

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Finding technology to tie entire facilities into an integrated, ongoing energy program is harder still. But such a tool has surfaced that puts the maintenance department in a prime position to make a bottom-line difference.

"Studies suggest that by incorporating energy consumption into your asset management strategy, you can save 10 to 20 percent on energy costs," says John Murphy, director of global industry and product marketing for Infor (formerly Datastream), Alpharetta, Ga. The company upgraded its enterprise asset management system with "asset sustainability" features that offer new capabilities to track energy use as well as plant profitability.

Consider the tale of two chillers, identical except that one uses a filter costing $150 less. Both filters are changed every four months. After roughly 18 months, inspections show both chillers to be in top working condition when viewed from a traditional maintenance mode. Normally, the cheaper part would prevail in this context. Adding the tools to monitor energy usage, it turns out the more expensive filter is running at near-peak efficiency, while the cheaper one degrades to 60 percent by the end of its service life.

Instead of saving hundreds of dollars annually by using the cheaper filter on the equipment, the new features show that the cheaper filter has costing nearly $5,000 in higher energy costs.

Software systems are getting smarter, faster and cheaper every day throughout the plant, from heating, ventilation and air conditioning (HVAC) system controls to production and maintenance and up to top management.

Applications such as this may prod more software developers to add energy-related features to products — which is fortunate for meat and poultry specialists such as Gleeson Constructors LLC, Sioux City, Iowa. “We’re seeing more demand for metering of different water and energy uses,” says President Harlan Vandezandschulp, “and have been working to tie together different systems,” he says, citing HVAC, boilers, ovens and washdown water.

Turning up (and down) the heat

 

Food plants generally consume three kinds of energy. Direct-fired gas, such as that used for fryers, offers chances to capture waste heat through upgrades for flue gas recovery, which can assist with indirect heating. Indirect-fired gas energy heats boilers, which is commonly the focus of upgrades to again capture exhaust gas and raise boiler feed-water temperature. Then there’s the electricity used throughout the site.

Boilers present perhaps the biggest opportunity for indirect energy improvement, because “some of the old boilers aren’t efficient enough to improve,” says Praj Schneider’s Ware. Large systems are 75-85 percent efficient, while the newer are efficient into the 90s.

“You can add economizers, extend exchange surfaces in existing boilers and generally capture heat that otherwise would be wasted out the stack,” he says. Reclaiming and reusing heat to raise feedwater temperature reduces gas consumption, can prolong feedwater temperature retention, reduce repairs and increase boiler capacity more than 5 percent. Reducing steam pressure from 125 psi to 100 psi alone can save thousands of dollars per year. Add current-generation controls and “you can reduce energy usage by 20 percent,” Ware adds.

Compressors present a major electric-savings opportunity. Simply plugging air leaks can reduce consumption 10 percent — or any multiple of that. Likewise, proper staging, sizing and maintenance of compressor banks, filters and storage tanks can prevent pressure drops, reduce peak loading (avoid too-small tanks to minimize excessive cycling) and keep those packaging line actuators clicking. Integrating compressor controls into a single system also is important for reducing inefficient cycling of multiple units during an intermittent surge, such as a clean-in-place purge. 

New-age alternatives

 

 

This past Earth Day, Frito-Lay dedicated a system of 192 parabolic-mirrored solar collectors covering five acres at the SunChips plant in Modesto, Calif.

An interest in alternative energy sources drove Frito-Lay to tap AEA for a project at the snack giant's SunChips plant in Modesto, Calif. On this past Earth Day (April 22), Gov. Arnold Schwarzenegger flipped the switch on a new solar array that comprises a five-acre field of 192 parabolic-mirrored solar collectors. They rotate with the sun to focus heat on water running through glass tubes, ultimately feeding the plant's boiler system. When the second half of the field is completed this July, the solar field will generate more than 75 percent of the heat energy needed to produce SunChips.

That and other Frito-Lay energy innovation projects reportedly fueled parent PepsiCo's own industry-leading resource conservation programs, which require engineers to meet various Energy Star and LEED standards.

Trees, wood chips, tallow, oat hulls — anything that burns — is a hot topic for feeding indirect heat to all manner of equipment. Likewise, digesters can turn effluent into methane. But while biomass sounds like a great idea, “processes fluctuate, and you don’t always have a consistent, continuous supply," says Burns & McDonnell's Swanson. "Otherwise, the investment to accommodate it is wasted."

"For a long time, people didn't consider a project if it didn't pay back in 12 or 18 months," says Mark Frey, vice president and manager of automation and electrical engineering for Cincinnati-based AEC firm Hixson. But this may be changing as energy costs soar, because "everybody we meet is interested in saving on energy any way they can, [from] lighting to solar, geothermal, cogeneration and wind energy."

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