The processes in the biggest grain mill in Switzerland are extremely complicated—every intermediate storage, every processing step, and every quantity of product delivered—has been thoroughly recorded at Swissmill. This is made feasible by level sensors from VEGA, whose quantified values offer the basis for trustworthy tracking of various product streams.
The granary on the Limmat river in Zurich is known to be the biggest grain warehouse in the world. Around 1,000 tons of grain has been processed daily, most of which has been directly delivered to the plant by rail via the city. Most of the semolina, flour, and flakes are processed in huge bakeries, starch factories, or pasta processing plants.
The primary goals of production are energy savings and smooth-running processes. Both go side by side sometimes. The processes in the factory have been altered so that one less processing step compared to the majority of the other grain mills employ is needed. All product streams are tracked. This involves working with the customer closely.
Modern Radar Level Sensors for Simple Measurements in the Flour Silo
Where the level measurement is concerned, flours are difficult to quantify. For one thing, vast amounts of dust are produced when filling and the dust cloud settles slowly inside the silo.
The roughly 120 different flours vary somewhat in their dielectric constant. Karl Dahlke, manager of the flour silos and batch logistics at Swissmill, and his deputy Simon Rochat accept that bran is known to be the most complex product to quantify: “It has an Epsilon value of only 1.4 in the summer.”
This material has been stored in a very slender, 10 m-high reinforced concrete silo, making accurate level measurement even harder.
In recent years, new-level sensors from VEGA were frequently tested here. One hardship was that the cable of guided microwave sensors would sometimes unravel, enabling separate product grains to become stuck.
This produced incorrect measurement signals. Meanwhile, this instrument type has been substituted by VEGAPULS 69 with an 80 GHz operating frequency. It helps quantify without contact and could surely detect the medium even via thick dust clouds.
Reliable Level Measurement in a Wide Variety of Applications
In the plant, levels are measured everywhere. Several different kinds of quantifying instruments are applied for this. For instance, the wheat receiving station has around 137 VEGACAP 63 capacitive probes.
But level sensors are also utilized in animal feed production for process control. When the product is being pelletized, the pre-depot always has to be filled to guarantee that the density of the pellets is right.
As a result, a particularly trustworthy measuring signal is needed in the overflow cell in the pelletizing process, as additional cells might or may not be opened depending on the filling level. If the cell overflows, the dosing units turn off.
If the situation cannot be fixed, the mills are switched off, implying that the process planners require a 100% accurate signal; if not, the complete production plan could run off course.
The piping network conveys the intermediate products to the roller mills. Every process step is comprehensively monitored during operation. Image Credit: VEGA Grieshaber KG.
Live inventory data from end customers enables a more efficient replenishment process. Image Credit: VEGA Grieshaber KG.
The level measuring instruments tackle a unique and extra task in inventory measurement. Not only do they quantify the levels in Swissmill’s 200-grain silo cells, but they also track another 150 silos that belong to their customers.
Thanks to VEGA technology, we can look directly into the customer's silos and, if necessary, place an order for them. The companies are basically handing over responsibility for their raw materials management to us.
Karl Dahlke, Manager of the Flour Silos and Batch Logistics, Swissmill
VEGA Inventory System is a web-based software available for data acquisition and visualization of level data in silos and storage tanks. It allows ideal raw materials logistics from the supplier up to the production facility.
We greatly appreciate the collaboration with VEGA Switzerland. In the future, we’re going to rely exclusively on radar measurement technology, and wherever possible, with the high frequency of 80 GHz. The sensors are easy to replace, even in sensitive food environments, and they measure with great reliability.
Karl Dahlke, Manager of the Flour Silos and Batch Logistics, Swissmill
This information has been sourced, reviewed and adapted from materials provided by VEGA Grieshaber KG.
For more information on this source, please visit VEGA Grieshaber KG.