Reliable leveling technology for the perfect coffee blend

In the northern Italian town of Vicenza, two perfectionists found each other. One was looking for the perfect aroma, the other for the perfect position for a sensor in the silo. 

Multinational company Julius Meinl is considered a global ambassador of Viennese coffee house culture with more than 150 years of experience. For a perfect bean requires not only sophisticated processes, but above all the skill and ability of the coffee roaster, who oversees every step of the production process. This involves the entire processing cycle, from the arrival and storage of the green coffee through cleaning and roasting to packaging the product for the consumer. However, the team at Julius Meinl in Vicenza, where a state-of-the-art roastery was built in 2005, was not satisfied with the level measurement. The amount of coffee beans in the silos was estimated based on the weight of the incoming product, so the actual stock of the raw material in the silo was not known. The result: significant inaccuracies and an expensive production process. 

No shortage of challenges

When it comes to measuring the level of coffee beans, the storage silos in Vicenza immediately presented several challenges. For starters, the hoppers, each between 3 and 4 m high, have different internal structures. Also, the shape of the silos is not really easy for level measurement: they are square and have a conical bottom. Moreover, the storage silos for roasted coffee naturally contain a lot of suspended dust and fouling. So the radar lens gets dirty every time. Finally, an environment like this is classified as ATEX zone 20, so different installation points for the level sensor were first tried out to find the optimal location.

VEGAPULS tracks silo content closely

Julius Meinl chose the non-contact measuring radar level sensors VEGAPULS, which are distinguished by extremely strong focusing and a large dynamic range. A total of 23 measuring instruments were installed here. The transmission frequency of 80 GHz enables a very precise measuring signal: with an antenna of 80 mm, an opening angle of only 3° is created. Moreover, the sensors can reliably measure even in silos with internal structures, as the narrow signal simply passes through them. This makes the measurement more accurate and reliable than was previously possible. Especially during silo filling, the 80GHz radar sensor convinced with its extreme accuracy. Thanks to an adjustable flange seal, the sensor antenna can be directed optimally to the bulk material surface. This further optimizes the measurement. 

Improved operational processes

Thanks to the application of the level measuring instrument of the VEGAPULS type, it is now possible to see the level in the system in real time, thus knowing the actual stock of the silos. This not only results in improved operational processes, but above all facilitates the planning of blend changes. Furthermore, because exactly how much coffee is known, a timely indication is given when the silo is completely empty (stock below the specified minimum level).

Reliable complete emptying

In addition, nine sensors of type VEGAPOINT 31 were installed that detect the empty level in the charge throughput bunkers. After the blends have been prepared, it is necessary to check whether there is any product residue in the bunkers. Any deviation could lead to measurement errors with major consequences. Previously used capacitive sensors also had to be calibrated very regularly due to temperature fluctuations. But with the level switch VEGAPOINT 31, convenience comes first. Prior to commissioning, it does not have to be calibrated. Therefore, VEGAPOINT sensors are installed on the flow funnels. They report whether raw materials are present there or not. Based on these measured values, production batches are tracked. That it is robust has long been demonstrated by the sensor in practice. Since its installation, VEGAPOINT 31 has been working correctly and detects an empty silo with high reliability.

Reliable guidance during the commissioning process

Julius Meinl was not only delighted with the sensors, but also with the service provided by VEGA. The coffee specialist especially praised the patience in finding the best installation point for the radar level sensor, with the goal of avoiding problems later on. VEGA's technicians supervised the commissioning process, especially to eliminate malfunctions due to the internal structures in the silo. Within this framework, a careful linearization was carried out based on the volumetric data of the tanks. As a result, highly accurate measurement is now possible, which can also be used to monitor the phases of filling and emptying the silos with great accuracy. The installation and commissioning of the VEGAPOINT sensors was done wirelessly using the VEGA Tools app and via a Bluetooth connection by the employees themselves. After a few calibration steps with the smartphone, the VEGAPOINT sensor was able to detect when the flow funnel was completely empty - even with fouling on the sensor. By the way, all switching states are visible from a glance thanks to the LED round status display. This additional process display makes the VEGAPOINT sensor a valuable instrument even in hard-to-reach places.