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Highly accurate Emerson Process Management four-electrode conductivity sensors are helping German brewer Schneider Weisse to optimise the clean-in-place (CIP) process at its Bavarian brewery.

Replacing ageing sensors with accurate Rosemount Analytical 410VP sensors has enabled the brewer to optimise the CIP process.

This has reduced the total caustic detergent, water and energy being used as well as saving valuable end product.

Schneider Weisse is now able to bring production back online quicker, enabling a potential increase in total production.

Norbert Appoltshauser, automation manager at Schneider Weisse, said: ‘We identified an opportunity to measure the interface between the CIP rinse water and end product more accurately and we have been delighted with the results.’ The company has been brewing since 1872 and is best known for its premium-quality Weiss, along with wheat beers that are drunk in Europe, the US, Canada, Hong Kong and the Dominican Republic.

CIP applications in the food and beverage industry present a number of challenges for conductivity sensors.

Devices must be easy to clean and able to withstand rapid changes in temperature.

Conductivity sensors used for this type of measurement are often encased in plastic and, in general, do not respond well to rapid temperature changes.

They also protrude into the pipe, creating an intrusion, which can disrupt flow in smaller lines.

These factors can reduce the dependability of the conductivity measurement.

As brewers have to ensure the effectiveness of the CIP process, while minimising product losses, the ability to optimise the process by introducing a more accurate instrument for the measurement of conductivity is attractive.

Working in co-operation with GEA Brewery Systems, three existing electrode conductivity sensors installed within pipes supplying the fermentation and storage tanks were replaced with Emerson’s Rosemount Analytical 410VP sensors.

The existing sensors were said to be ageing and unreliable, causing false switching during the different phases of the CIP process.

The customer was also unable to source replacement parts.

The sensors determine electrolytic conductivity, which allows the monitoring of the concentration of the CIP solution and the interface between rinse water and end product.

The CIP system is used to clean the process piping 12 times a day, with each process including three water flushes of three minutes in duration.

The CIP process uses a caustic solution to wash through and ensure product integrity.

The wash cycle includes a pre-flushing stage, followed by a caustic solution, an intermediate flushing, an acid solution and then a final flush prior to restarting production.

During an initial four-week trial period, Schneider Weisse identified that Emerson’s Rosemount Analytical 410VP sensor was operating accurately and effectively.

The accuracy of the conductivity and temperature measurements are critical to optimising the process.

Using the Rosemount 410VP to identify the exact point at which the different phases start and stop and when the interface between the CIP rinse water is replaced by in-specification beer, it has been possible to reduce the duration of each flush from three minutes to one minute.

This has reduced the total flush time by 72 minutes a day.

Minimising the flush periods has reduced the overall water consumption by 10m3 per day.

As well as delivering clear environmental benefits, using less wash water saves Schneider Weisse around EUR8,000 (GBP7,044) a year, based on approximately 160 production days.

About 3,000kW/h of electrical energy is also saved, reducing costs by a further EUR500 a year.

With the faster detection of the different phases, Schneider Weisse sees the potential for further optimisation and to eventually increase overall beer production.

Anton Ladenburger, sales manager for GEA Brewery Systems, said: ‘The strength of the Rosemount device is that it offers improved levels of accuracy and reliability over traditional technology.

‘Also, the Varivent connection allows the sensor to sit flat within the pipework, avoiding potential crevices, and it can be easily fitted to the bottom of the pipe, which ensures it is always wet,’ he added.

The 410VP sensor’s four-electrode design provides linearity between 1uS/cm and 1,400,000mS/cm and responds well to rapid temperature changes.

The sensor has a flat sensing face consisting of four circular electrodes arranged in a row.

The analyser injects an alternating current through the outer electrodes and measures the voltage across the inner electrodes.

The conductance of the electrolyte solution between the voltage electrodes is readily calculated from the measured current and voltage.

As the voltage measuring circuit draws almost no current, errors caused by series capacitance and cable resistance, which are significant in two-electrode measurements at high conductivity, are virtually eliminated.

The sensors are located in different areas of the plant, where there is a mixture of 230VAC and 24VDC supply, which, in the past, resulted in Schneider Weisse having to use two different sensors.

By offering the capability to work using either 230VAC or 24VDC, the Rosemount 410VP can be applied in both areas of the plant, reducing inventory and training requirements.

Appoltshauser continued: ‘The improved accuracy of the conductivity measurements has enabled us to pinpoint the exact point when the interface has passed through the process, allowing us to return to full production.

‘With the new Rosemount conductivity measurement, false switching is eliminated and the different CIP phases are detected within just two seconds, which is very fast.’ Existing connections within the pipes enabled the fast installation of the factory-calibrated 410VP sensors.

Rosemount Analytical Model 1056 intelligent analysers, incorporating a menu navigation screen, ensured that the sensors were simple to set up.

Appoltshauser added: ‘The 1056 analysers are very simple to work with and, because the sensors are pre-calibrated, the functional commissioning was straightforward, intuitive and self explanatory.’

Emerson Process Management

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