Mass metering for the food industry

KROHNE OPTIMASS ? crevice-free straight-tube design livens up the sector
By Bernd Schumacher, Industry Manager, Food and Beverage,
KROHNE, Duisburg

Mass metering is increasingly replacing conventional volume measurement in the food industry. Coriolis flowmeters are not only replacing electromagnetic flowmeters, for example, but also scales and pistons used in batch processes. KROHNE's OPTIMASS 7000 is the ideal Coriolis mass flowmeter for food and beverage applications. The straight-tube design, KROHNE's patented "Adaptive Sensor Technology" (AST), compliant hygienic connectors and approvals have enabled OPTIMASS to overcome the usual food industry limitations and have opened up entirely new fields of application for Coriolis meters. Practice has shown that OPTIMASS has no problems delivering reliable and precise flow measurements, even in the most difficult applications such as measuring highly viscous products.

Furthermore, OPTIMASS is approved for custody transfer to OIML R 117 accuracy class 0.3. This makes OPTIMASS the only Coriolis meter family approved for the highest achievable accuracy class for custody transfer.

OPTIMASS ? designed for the food industry
KROHNE manufactures the OPTIMASS 7000 to meet food and beverage industry specifications. Wetted surfaces have a roughness of 0.8 μm (even 0.5 μm as an option); all materials are FDA-approved and manufactured in accordance with Cenelec, ATEX, and FM. KROHNE Coriolis flowmeters can be CIP and SIP-cleaned up to 150°C (302°F). OPTIMASS 7000 has no flow splitter, is self-draining and suitable for sterilization. A welded-on aseptic flange with no internal gaskets is available in addition to welded-on Tri-Clamp / Tri-Clover connections.

A key advantage of this connector is the elaborate patented gasket system for aseptic connectors to DIN 11864-2. It meets even the strictest hygiene requirements. The OPTIMASS design complies with a range of standards, including ASME Bioprocessing Equipment, EHEDG and 3A. OPTIMASS is the first straight-tube mass flowmeter to feature components in titanium, stainless steel, or Hastelloy, thus ensuring optimum corrosion resistance. OPTIMASS can measure flow rates of 10 ? 430,000 kg/h.

Precision Tequila dosing
Drinking tequila is not only de rigueur for European tourists visiting Latin America ? in Mexico, it is also one of the most popular drinks consumed by the locals. This makes the alcoholic beverage an economic factor for both the Mexican and international markets. Jalisco is the only Mexican state that is permitted to use agave commercially. The juice from the plant is used to make tequila. There are therefore a number of tequila producers in Jalisco, one of the largest of which, Jose Cuervo, exports the alcoholic beverage in 20-tonne truckloads. Jose Cuervo operates a filling station used to load the tequila onto trucks. For tax reasons, it is important to precisely measure the loading of the trucks.

The ownership transfer that occurs when the alcohol is loaded is subject to duty. By using OPTIMASS, Jose Cuervo not only ensures that the amount of tequila that is charged to the purchaser is actually delivered, but also that the state is paid the applicable liquor tax. OPTIMASS has an accuracy of +/-0.1% of the measured flow rate. The KROHNE Coriolis flowmeters installed at Jose Cuervo feature Tri-Clamp connectors and a pulse output that controls a batch controller.

The most important aspects of this application for the user are the flowmeter's accuracy and reliability. The following examples discuss applications in which the innovative features of KROHNE's OPTIMASS have earned high marks, thanks to its ability to also measure the difficult products that are often encountered in the food industry. The reliability of the process and cost savings are also closely examined in these examples.

Precise measurement of highly viscous products
OPTIMASS regularly achieves impressive results when measuring highly viscous products with low flow rates. These results have convinced one of the most important suppliers to the European brewing industry, Decker Maschinenbau, to integrate KROHNE's OPTIMASS into its fully automated hops dosing systems.

During the extraction process, the hops (density about 1.04kg/l, viscosity up to 10,000 mPas) are heated to 45°C in a heating chamber so that the extract becomes fluid enough to be pumped. Very precise dosing of the hops extract in the wort kettle minimizes the amount of hops extract required and thereby lowers the cost. Through the Profibus PA interface, other parameters such as the current product temperature can also be measured.

Decker Maschinenbau tested KROHNE's OPTIMASS 7000 straight-tube meter by comparing the flowmeter's readings to those on calibrated scales. The results of the trials were impressive, as the deviations using the two different methods were minimal. On average, the OPTIMASS deviated from the scales? readings by less than +/-0.1% for a total dosed mass of 8 kg. A decisive factor in favor of OPTIMASS was its ability to measure the highly viscous hops even at low flow rates.

This is where the advantages of Adaptive Sensor Technology come into play, as they enable the meter to deliver outstanding accuracy, even at flow rates that may be much lower than 10% of rated flow. The tests conducted by Decker Maschinenbau confirm the outstanding meter characteristics of OPTIMASS in terms of accuracy and zero-point stability. The superior technology of OPTIMASS is further characterized by such features as minimum pressure-loss compared to competing systems, accompanied by an excellent price-to-performance ratio.

Independent of installation
There are no installation restrictions for OPTIMASS. The flowmeter can be installed almost anywhere in the piping. This is because KROHNE has integrated "Adaptive Sensor Technology" (AST) into the straight-tube flowmeter, which guarantees that OPTIMASS will deliver the same excellent results under any operating conditions. AST compensates outside influences related to the installation itself, as well as the effects of density fluctuations in the product. This was one of the main reasons one of the world's largest food producers decided to purchase OPTIMASS.

The Swiss subsidiary of a Dutch food company ? a long-term KROHNE customer ? was looking for a flowmeter that could deliver accurate and repeatable results when filling gourmet salad dressing pouches used in restaurants. The viscosity of salad dressing is similar to that of hops extract, and it must also be measured at low flow rates. However, an additional challenge in this application was entrained air. KROHNE's OPTIMASS straight-tube meter was applied in an automated filling line in which the flowmeter's reliability was also essential to guaranteeing smooth and uninterrupted operation.

The line is used to fill ten-liter pouches with salad dressing. Each station consists of two flowmeters that dispense two different products into the same pouch; either simultaneously or sequentially, depending on the dressing. Each pouch is filled in seven seconds or less. OPTIMASS gives the dressing producer a meter that is able to dose high-quality product and meet challenging process specifications, even under unusual installation conditions and for a high viscosity product at low flow rates.

Loading vegetable oils
One of the leading refiners of vegetable oils in Great Britain relies on the easy installation and start up of KROHNE's OPTIMASS to monitor the mass flow of its products when loading tanker trucks. Karlshamns Ltd. in Hull has consistently achieved excellent results using the OPTIMASS 7000 straight-tube flowmeter. KROHNE's meters are used in the loading stations for the tanker trucks, where various compositions of oils for the food and pharmaceutical industries are loaded.

Once again, OPTIMASS shone by delivering outstanding accuracy and excellent repeatability and, in the process, reaffirmed and strengthened the long-established business partnership between Karlshamns and KROHNE. Karlshamns loads the various vegetable oils at different temperatures, which means the viscosity of the product being measured also changes. KROHNE's OPTIMASS had to handle viscosities that ranged from 8cP to 100cP when moving products from the storage tanks to the trucks. The average flow rate was 60 tonnes per hour. The vegetable oil flows through two separate piping systems, each with its own measuring point to determine the flow before the product reaches the loading station. KROHNE's Coriolis flowmeters send signals to a batch controller that shuts off the pumps and the flow as soon as a specific amount of vegetable oil has been transferred.

In the past, this application has not been without its problems, as explained by the employee in charge of the system at Karlshamns: "Many Coriolis meters may be suitable for continuous flow, but in batch processes they were not able long-term to meet our dosing requirements with regard to stability and repeatability, and they were also hard to clean."

It was also important to Karlshamns that there were no installation restrictions for the meter: "In the past, Coriolis flowmeters have always been extremely difficult to install and there were countless rules regarding positioning, inlet and outlet runs, etc. The space required was enormous."

And in the food industry, where pipelines are far from straight, this space is usually not available. This is also the situation at Karlshamns, where the OPTIMASS is installed in a two meter-high loop to ensure that no steam is trapped. Conventional mass flowmeters would not have been robust enough to handle this configuration, particularly with viscous, non-Newtonian, shear-sensitive or solids-bearing fluids ? OPTIMASS excelled. Because this meter does not split the flow into two smaller parallel tubes, the flow velocity is comparable to that in the product piping.  The meter's innovative design provides installation flexibility without compromising its ability to measure with great precision and repeatability.

Saving the best for last: tea biscuits
A well-known cookie producer installed two OPTIMASS flowmeters to precisely dose syrup and vegetable fat after conventional meters had problems dealing with the temperature-dependent viscosity changes in an inhomogeneous syrup mixture. The problems went as far as product quality variations that depended on the time of year; i.e., whether it happened to be summer or winter. The problem could not be solved even by installing pipe insulation and heating - the accuracy of the measurements simply did not meet expectations.

The meters were measuring the volume flow rate instead of the mass flow rate of the individual ingredients. As soon as viscosity changed significantly, either too little or too much of the ingredient was dosed, causing the fill weight to deviate from the target value by up to 20%. These batches could not be released for sale. Now that the bakery has installed OPTIMASS, the cakes are manufactured so precisely that they?ll always taste the same, whatever time of year you enjoy them.

Summary
OPTIMASS 7000 is the ideal Coriolis meter for the food industry. Its main advantages are:

	easily drained and easy to clean
	low flow velocity and therefore low pressure loss
	low shear forces avoids damaging sensitive products
	precise mass and density measurement
	FDA approved, 3A, EHEDG and ASME Bioprocessing certified
	approved for custody transfer for the highest accuracy class

Index

	OPTIMASS ? designed for the food industry
	Precision Tequila dosing
	Precise measurement of highly viscous products
	Independent of installation
	Loading vegetable oils
	Saving the best for last: tea biscuits
	Summary

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