Schneider Weisse advances CIP at Bavarian brewery

Munich, Germany - Schneider Weisse, which is best known for its wheat beers, has achieved some major efficiencies following the installation of high accuracy conductivity sensors to optimise the clean-in-place (CIP) process at its Bavarian brewery.

By replacing aging existing sensors with four-electrode conductivity devices - Rosemount Analytical 410VP sensors from Emerson Process Management - the brewer has reduced the total caustic detergent, water and energy being used and save valuable end product. It can also now bring production back online quicker and so increase total production.

“We continually strive to improve our production processes in order to maximise output and efficiency,” said Norbert Appoltshauser, automation manager, Schneider Weisse. “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.”

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, whilst 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 the 410VP sensors. The existing sensors were aging 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 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 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 of production.

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, the brewer has been able 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 and reduced the overall water consumption by 10m3 per day - saving Schneider Weisse around Euro8000 a year (based on around 160 production days). About 3000kW/h of electrical energy is also saved, reducing costs by a further Euro500 a year.

The 410VP sensor’s four-electrode design provides exceptional linearity between 1 uS/cm and 1,400,000 mS/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. Because 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 230 VAC and 24VDC supply, which resulted in Schneider Weisse having to use two different sensors in the past. By offering the capability to work using either 230VAC or 24VDC, the Rosemount 410VP could be applied in both areas of the plant, reducing inventory and training requirements.

“We are extremely confident of the new measurement system,” explained Appoltshauser. “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 simple to use menu navigation screen ensured that the sensors were extremely easy to set up.

“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. This was very different to what we were used to,” said Appoltshauser.