Electricity + Control September 2017

High-Tech Processing lead E&I engineer, Reinhardt Grobler.

SENSORS. SWITCHES + TRANSDUCERS

Take Note!

In building a beverage process plant, one of the primary objectives is to gain increased pro- duction and consistent product quality. To achieve the objec- tives, effective process automation is employed. Effective process au- tomation requires suit- able instrumentation, capable of producing accurate and repeatable indication of the process status.

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Well known as the leaders in instrumentation in the Food and Beverage Industry, Endress+Haus- er was able to provide expert advice on reliable, quality measurements that would supply the nec- essary data for the ideal process. The application involved the measurement of volume in 15 m high tanks containing 2 200 hl of cider. The tanks were equipped with an agitator and the product would often form thick layers of foam. The Deltapilot (FMB70) was selected for level measurement in the tanks. It is not affected by foam and is per- fectly adapted to fast changing process conditions. The patented hermetically sealed CONTITE meas- uring cell is condensate and climate resistant. The sensor shows best performance and long-term stability and accuracy even following CIP/SIP cy- cles. Hydrostatic level transmitters are probably the simplest to use and apply. A sensor converts the pressure of liquid head acting on a process dia- phragm into an electrical signal. When the density of the liquid is known, this signal is a direct indica- tion of the level. Hydrostatic level transmitters are the most commonly used level measurement in the Food and Beverage Industry. However, when the customer decided to use the tanks for a variety of different products: With a change in product characteristics, the calculated volume was affected by the changes in density. To overcome the challenge of the changing den- sities, and to gain more accuracy of the volume measurements, a density computer was used. In conjunction with the tuning fork, Liquiphant M, the density computer FML621 returns a continuous measured density value. The volume of the tank can now easily be calculated since the density and hydrostatic pressure is known. The new volume calculation, with the corrected density, now resulted in a +-1,5% inaccuracy of the total volume of 2 200 hl. There was a decrease in lost production time since production was also able to optimise their packaging process to plan better due the more accurate volume measure- ment. With the changes in density previously af- fecting the calculated volumes, packaging could not plan efficiently. The number of bottles to be packaged did not correspond to the volumes in the tank. As a result the line would have to stop and wait for more bottles so that the tanks could be emptied out or on counter side, bottles remaining empty on the line with the tank running empty ear- lier than expected. With the now density compensated volumes, the plant was able to decrease the amount of product sent to drain, and as a result decreased production costs and wasted product. The taxes

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on alcohol drove plant management to focus on more accurate stock take measurements to elim- inate taxes on false volumes. The density com- pensated volume measurements made this task much easier, resulting in fewer internal loses. Profibus DP was selected as the communi- cation protocol. Reinhardt preferred the use of digital communication which simplified com- missioning and helped ensure efficient op- eration. “Profibus allowed more information to be available to optimise the process, for example; the density sensor was also used to detect the low level in the tank as well as measure the changing density. It also en- sured that possible losses over an analogue line are eliminated and thus resulted in a more accurate data value transfer between the Density Computer and the PLC. With in- telligent communication, information can be used to monitor instrument diagnostics and therefore ensure optimum performance”. Conclusion With a satisfied end customer and a project well done, the only thing left to do was to repeat the solution. High-Tech Processing already has plans to use the system on a new project involving the volume measurement in 20 new tanks.

With intelligent communication, information can be used to monitor instrument diagnostics and therefore ensure optimum performance.

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Natlee Chetty is the Industry Manager, Food & Bev, at Endress+Hauser.

Tel. +27 (0) 11 262 8065 Natlee.Chetty@za.endress.com www.za.endress.com

Electricity + Control

SEPTEMBER 2017

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