Technical Advances Can Turn Utility Costs Into Savings

From steam generation to compressors to motor drives, inefficiencies in plant utilities can drive up costs and sap profitability. Technology that flips the equation can introduce needed change.

By Kevin T. Higgins, Managing Editor

In the daily scramble to fill customer orders and make sure food defenses are functioning as intended, it’s easy for plant personnel to neglect facility upkeep and let infrastructure upgrades slide.

Chiller systems are among the biggest energy consumers for many companies, and inefficient performance and breakdowns can quickly magnify costs. Yet almost half (43 percent) of respondents to a survey conducted by Goodway Technologies say they do not use Eddy current testing to troubleshoot corrosion and scaling in tube walls, a maintenance shortcut that adds cost and can result in unscheduled downtime.

Assuming the fundamentals of preventive maintenance are being executed, plant managers and maintenance personnel can access a number of alternative technologies to address plant utility needs. For facilities with refrigeration systems, one option that can render a boiler redundant is a heat pump integrated in a single-screw compressor to recover latent heat.

The concept first was applied six years ago at a Nestle chocolate plant in the U.K. Kraft and other major food companies are among the early adopters. It was developed by the Vilter Manufacturing division of Emerson Climate Technologies (www.emersonclimate.com).

The waste heat from compressors typically is too low-grade to warrant recovery and reuse, but the heat pump is able to extract enough energy from return gases to raise the temperature of water to 140-150° F, according to Wayne Wehber, vice president-business development for Cudahy, Wis.-based Vilter. Two manufacturers that have integrated the compressors have since “shut off the boiler,” he reports.

High pressure is required to attain those temperatures. The single-screw compressors elevate the returning gas to about 360 psi, double the normal discharge pressure. The biggest impediment to applying the technology is determining how much demand a facility has for hot water, says Wehber. Between plant expansions and other variables, “it becomes a moving target” to calculate hot water demand, he says. Without that information, it’s impossible to calculate how many skid-mounted compressors will be required.

“The energy savings are amazing,” Wehber adds. “The key is being able to reliably compress the ammonia to a higher temperature and pressure.” Each unit measures about 12-by-6 ft. and is powered by about a 300 hp motor. Prevailing energy costs and the amount of piping and hot-water holding tanks necessary determine if ROI expectations can be met.

To weld or crimp?

A wide variety of utility pipes course through food & beverage facilities. The cost of piping — black pipe for gas, copper for glycol, stainless for process water — varies significantly, but one constant is the welds, sanitary and otherwise, needed to join them. Some manufacturers are concluding saving time is worth more than saving money by welding and are turning to pressed-in fittings.

Barrel O’ Fun’s Phoenix snack food plant makes extensive use of pressed-in fittings, with much of the work since 2008 done by local contractor Niemeyer Brothers. Supply lines for nitrogen, process water and compressed air are among the thousands of feet of piping installed, according to Rick Niemeyer, president, with more on the way. A new steam system is being installed at Barrel O’ Fun, which was acquired early this year by Shearer’s Foods.

“Pressed-in fittings were a huge labor savings, and it’s a lot more adaptable than welded pipe,” Niemeyer maintains. “People are always afraid to use a new product, but we’re seeing more and more demand. Hospitals and medical facilities love it because it eliminates solder.”

Many of Barrel O’ Fun’s pipes are copper and galvanized steel and are housed above a walkable ceiling. When the pipe drops below the ceiling to production areas, it transitions to 304 or 316 stainless. Niemeyer uses components from Viega ProPress for the fittings and to make the dielectric transition to different materials.

ProPress describes fittings for copper tubing and stainless steel, with MegaPress the brand name for carbon steel, explains Derek Bower, new products director for Viega LLC (www.viega.us), Wichita, Kan. Branding aside, the correct O ring to seal fittings and joints is important. Some O rings can withstand pressures up to 200 psi, others are appropriate for temperatures of 200°, but no single sealing element is appropriate for multiple applications.

Five-plus years of proven performance is demanded by most contractors before they will consider specifying a new product, Bower says. While Viega’s German technology has been available in North America longer than that, plant owners often are reluctant to shift from what’s working to what’s new. The exception is craft brewers. “They seem to be very open-minded and exploratory,” he says.

Rhett Keisler, co-owner of Revolver Brewing in Granbury, Texas, took a DIY approach when installing copper lines to carry glycol to cool beer fermenting in nine new 240-barrel vessels. Using a jaw-equipped power tool that resembles a drill, in-house maintenance workers were able to complete the installation in half the time soldering would have taken. “They gave us a solution that was quick, easy and affordable,” Keisler says, “and being able to do it right and by ourselves is great.”

When a valve began to leak, the brewery’s maintenance workers were able to swap it out under full pressure.

MRO experiences like that are a key to building trust for pressed-in fittings, Bower observes. “Once plant personnel start using it for repairs, they see how quick and easy it is.” The technology has limitations — it wouldn’t work for dairy sanitary valves that need to be cleaned and opened for visual inspection, for example — but he believes it has wide application with utility lines.

Regenerative drives

Electricity may be the most neglected utility, at least in terms of improving the efficiency of use. Low utility costs in North America discourage investment in energy efficiency. Another factor is gradual transition taking place from mechanical to electronics-based machinery that can leverage energy-efficient technology.

A case in point is AC regenerative drives. These servo-based drives transfer braking power when a machine stops or slows and feeds it back to where there is demand. “The target machinery for the technology continues to be machines with higher loads and longer stop cycles,” explains Dave Cameron, director-EDC sales at Bosch Rexroth’s electric drives and controls division in Hoffman Estates, Ill. (www.boschrexroth.com/indradrive-mi).

Robotic palletizers and case-packing machines are fertile ground for regenerative drives, but the technology also can be applied to primary packaging, provided the load is sufficient. An example is meat-wrapping machines fabricated by CP Packaging, an Appleton, Wis., OEM that debuted the technology eight years ago. The drives feed back electricity from deceleration, producing energy savings of 20-35 percent when energy is transferred on a common DC bus between driving and generating motors. Domestic manufacturers slowly are adopting the technology, says Cameron, but CP also exports machines to Europe, where energy efficiency is a priority.

Since introducing the integrated motor drive in 2007, Rexroth has made multiple upgrades. The most recent was last year’s “cabinet-free solution,” an IP65 power supply that mounts servos and power supplies on the machine frame, obsolescing electrical cabinets, says Cameron. Long gone are resistors to store energy, an approach tantamount to “throwing away power” because of the cooling they require. Cabinet-free design also reduces wiring to a fraction of what typically is required for power supply and communication.

Electric motors account for almost two-thirds of U.S. industrial power demand. Chillers and compressors can draw a big chunk of the remaining third. Collectively, they represent a golden opportunity to take command of plant utilities and drive down production costs.

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