New Places to Look for Energy Savings

Lowering pressures, plugging air leaks and updating your motors can have a huge impact on your plant’s energy efficiency.

By Mike Pehanich, Plant Operations Editor

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Soaring energy costs - and the chronic risk that they will only climb higher - have altered the economics of the food processor's supply chain. One way processors can get a grip on energy is to maximize the efficiency of equipment on processing and packaging lines.

Kettle Foods has one of the largest commercial solar arrays in the Pacific Northwest on top of its plant. It generates approximately 120,000 kWh per year.

"The market is being challenged by high energy prices," says Ted Worlick, engineering director for Schneider Electric (www.us.schneider-electric.com), Palatine, Ill. "A lot of companies saw their natural gas bills double. Now we're at a new high plateau for natural gas. Electricity costs continue to head upward."

The challenge is doubled in that processors, who are finally running plants at higher capacity utilization rates, cannot - and should not - sacrifice manufacturing output with equipment replacement or plant modifications. But processors do need to make energy investments that create savings over the long term.

Despite the enormous burden to operations costs that soaring fuel bills have added in recent years, many food companies have yet to take important energy-savings steps: from developing comprehensive energy programs to replacing or modifying equipment to making the necessary plant upgrades to save big energy bucks.

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Incredibly, some companies have barely scratched the surface when it comes to processes and procedures to identify waste and save significantly on fuel costs. Heat recovery, capital projects for energy conservation and investment in energy control optimization continue to come on strong and have become more sophisticated - especially for companies that already have plucked the low-hanging fruit with the simplest changes in plant practices.

Lower pressures, higher savings

Manufacturers have put energy efficiency high on their priority lists. "We've addressed energy efficiency in heating and cooling, pumping, homogenizing, and fluid and product movement," says Jim LeClair, technical director for APV Invensys (www.apv.invensys.com), WHERE. "Mixing, too. The more efficiently your equipment uses energy, the lower your cost of ownership (the sum of energy and maintenance costs). Your payback comes back quickly."

Today's high efficiency centrifugal pumps, for example, have added 20-30 percent energy efficiency on top of the overall performance efficiency of the pumps, compared to pumps of the 1970s and '80s. "We have gone from 45 percent pump efficiency to 75-85 percent efficiency. That means for every horsepower you put into a pump, you are getting an average 70 percent return. That's a significant difference," says LeClair.

Those are the kinds of savings plant personnel frequently overlook. But the addition of small improvements - even on systems as seemingly inconsequential as clean-in-place systems - can add up to big savings.

Heat exchangers have been other key targets for energy savings. New designs operate more efficiently at lower pressure. Heat exchangers operating at 75 psi today may work as effectively as those that operated at 100 psi in the past.

Manufacturers have focused on pressure and efficiency of heat exchangers to lower energy requirements.

"The lower the pressure drop required to maintain adequate pressure, the less pumping your equipment will need to do," explains LeClair. "As for the efficiency of heat exchange or the heat exchange pump, it is determined by the thickness of the plate and how (flows - port to port and cross flow - across the plate."

Energy-efficient designs can have significant long-term impact on plant energy costs. For example, LeClair touts APV's corrugated tubular heat exchanger for its energy efficiency. "The corrugated tube creates more turbulence and produces a better mixing of heat."

Homogenizers and mixers that require lower pressure to operate also are proving their worth in energy savings.

"The more efficiently you can make a homogenizing valve, the less pressure you'll need and the less energy you will use," says LeClair. In dairy operations, for example, taking a homogenizer's 1,800 to 2,600 psi requirement down to 1,100 psi will result in a huge energy savings.

"We have valve systems that will take pressure requirements down to 100 psi. That's $10,000 to $20,000 savings just due to the pressure difference in one year," says LeClair.

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