Measuring the Flow of Viscous Syrup
By Kaitlyn Siner
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| The versatile Krohne flowmeter allows for a single pump to be used for both high- and low-flow conditions. |
The high viscosity of syrup presents a special challenge for the mass flowmeters used in fruit canning operations. Many flowmeters cause a significant pressure drop as the syrup passes through the meter, decreasing accuracy of the concentration measurement and increasing demand on pumps.
During a recent upgrade of its production facilities, Signature Fruit (SFC) of Modesto, CA, recognized the importance of installing mass flowmeters that accurately measure flow and concentration and yet cause minimal pressure drop. “In general, we were looking for a more efficient and more accurate syrup blending system that is automated and requires less labor to operate, and improves our sugar usage efficiencies,” says Don Jepson, director of engineering at SFC, and a 30-year industry veteran. “We sought a mass flowmeter that would allow us to deliver uniform pressure to all our filling lines, to maintain product consistency and quality.”
SFC is California’s oldest and largest processed-foods company, annually processing 160,000 tons of peaches, 50,000 tons of pears, 15,000 tons of apricots, and about 10,000 tons of grapes into shelf-stable food products. Now a subsidiary of John Hancock Life Insurance Co., SFC sells its products under the Libby’s and Nature’s Orchard brands, as well as customer-owned labels for the retail, food service, international, and industrial markets.
Upgrading the Production Process
In light of increasing global competition, especially from South America and South Africa, the production facility upgrade is part of a major initiative to prepare the company for the future.
“Our energies have been directed toward selecting the finest growers, implementing strict quality-management systems, and strengthening our manufacturing core competency,” says SFC President and Chief Executive Officer David Long.
SFC is replacing antiquated batch systems for syrup blending that involved labor-intensive dilutions and manual testing of sugar concentration with sucrose Brix refractometers. The company was using mechanical meters and pumps to measure flow to a mixing operation for bulk syrup, which consisted of canners corn syrup, high fructose, and sucrose.
“Initially, we designed the new automated blending system based on a particular manufacturer’s Coriolis mass flowmeter that has a straight-through design involving dual quarter-inch tubes,” explains Jepson. “However, this restriction caused significant pressure drops. Moreover, this flowmeter had a limited range, and therefore two meters would be required, one for high-flow and another for low-flow conditions. We therefore searched for a better solution.”
Economic Benefit of Lowered Pressure Drop
After a thorough investigation of the available mass flowmeters, SFC purchased Optimass 7000 Single Straight Tube Coriolis Mass Flowmeters from Krohne Inc., of Peabody, MA.
“We choose the single-tube design because it creates a lower pressure drop and is resistant to blocking or fouling,” reports Jepson.
“The Krohne flowmeters were the most economical choice for a number of reasons. Because of the low[ered] pressure drop, we were able to reduce the size of the meter by a full size, compared to the other manufacturer’s meter that we had originally specified. The low[ered] pressure drop of the Krohne meters also meant that we did not need to scale up our pumping capacity, and we were able to use more of our current pumps than if we had used an alternative flowmeter design.
“Moreover, the Krohne flowmeters are extremely versatile,” Jepson continues, “allowing us to use a single pump for both high-flow and low-flow conditions, unlike alternative solutions that require multiple meters, with additional piping, fittings, controls, and maintenance.”
Utilizing Krohne’s adaptive Sensor Technology design, the Optimass 7000 flowmeter is extremely stable and adaptively tuned, independent of external forces and fluid density. The Optimass 7000 also has advanced electronics, which incorporate front-end signal processing to provide excellent turndown capabilities for measuring low flow.
The meters are manufactured from materials specially selected to conform to FDA guidelines, with titanium, stainless steel, and Hastelloy on all wetted parts.
SFC has purchased 19 of the Optimass 7000 flowmeters for use during initial blending of concentrates to achieve bulk product at the desired degrees Brix, which is calculated by the control system’s programmable logic controller from the measured mass flow readings. The meters are also used during a second phase, as the blended syrup is diluted with water and placed into containers with the fruit, with a particular concentration of sugar depending on the attributes of the fruit, the desired taste of the product, and other factors.
Reliability and Accuracy
“Reliability and accuracy were extremely important to us when selecting the Krohne meters,” Jepson emphasizes. “We process the fruit at the moment of peak freshness, and we have a short and intensive processing season that operates only from June through September. Therefore, downtime on any of our lines would be extremely expensive. We have been very pleased with the high reliability of the Krohne meters.”
With the success of the blending automation program, SFC will be upgrading all of its 45 processing lines with Optimass 7000 meters during the next few years.
“The main goal of automating the blending process,” says Jepson, “was to operate more efficiently and with more precision, reducing variation of Brix in the end product from a half percent to one- or two-tenths of a percent. With the Krohne meters, we are achieving this goal, delivering a high-quality product and minimizing our syrup purchasing costs.”
Kaitlyn Siner is a communication specialist based in Boston, MA.
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- March/April 2007
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