Guided Wave Radar in Narrow Storage Silo for Overfill Protection and Empty Message

Guided Wave Radar in Narrow Storage Silo for Overfill Protection and Empty Message
In aggregate, quarry and mining applications level measurement devices need to be robust with total reliability as standard to ensure a continuous stress-free production process.

For a concrete and cement manufacturer in Germany who has implemented guided wave radar sensors this level measurement technology offered multiple support for his storage process optimization. The TDRs with their high compatibility is used for consistently accurate continuous level detection under difficult varying process conditions, such as high pull-off forces, caking, or condensate formation.

For a concrete and cement manufacturer in Germany who has implemented guided wave radar sensors this level measurement technology offered multiple support for his storage process optimization. The TDRs with their high compatibility is used for consistently accurate continuous level detection under difficult varying process conditions, such as high pull-off forces, caking, or condensate formation.

Modern level measurement technology for precise results unaffected by dust and buildup

The stored raw products and additives undergo different processing stages on the way to the final mortar and different kinds of concrete, ready-mixed concrete, and special concretes. The solids in particular have different densities, particle sizes with different dust development, and differing moisture content. Cement and other different raw material solids such as sand and chalk need to be stored properly and transparently. The storage devices of the plant have a measuring range of up to 14 meters. Within the single-chamber silos, there are temperatures around 80°C (176°F) and a process pressure of up to 0,8bar (11,6psi). We have no vibration and no electrostatic charge but a dusty atmosphere with some low moisture. Furthermore, there was a heavy buildup of the materials to be detected.   NivoGuide® radar sensors are used for continuous level measurement in liquid and bulk solids applications.

The measuring range of up to 75m (246ft) and its high sensitivity from a DK value of 1.5 make them versatile usable in silos, tanks, and pipes. The guided wave radar does not contain any moving parts inside the process vessel. The microwaves are emitted at low frequencies so that even with high dust intensity, no spurious reflection is generated. As a result, the energy content of the microwave can be used exclusively for determining the specific filling level within the storage processes. It is protected against thawing explosions and precisely measures ±2mm even under difficult process conditions. Two series have been implemented, the NivoGuide® NG 3000, which is specifically tailored to the needs of solids, and the NivoGuide® NG 8000 for applications in liquids. The device versions are each equipped with probes that can be individually adapted to the application.

For the storage applications of the cement plant, the guided wave radar of the NG 3100 series as rope version was the perfect solution. These TDRs are specially designed for solids measurement detection with an amplified coupling for high pull-off forces and a reliable design that is not affected by strong dust. Moreover, the sensor is really flexible and needs no recalibration when the material changes. The measuring signal is guided on the rope and is reflected by the medium, received again at the sensor, and converted into a level signal. This makes it possible to measure reliably even in narrow and tall containers, regardless of the formation of condensation or buildup.

During the storage processes, there occurred some attachments to the boom, which can lead to faulty circuits. Thus the rope of the NG 3100 radar has been equipped with a special PA coating to prevent adhesion and also to improve the abrasion resistance of the ropes. Fine-grained bulk materials cannot settle in the mesh of the rope. Further, an optimized coupling to the bulk goods area was installed, which is characterized by axial support of the probe inside the process connection and which differs constructively from conventional guided wave radar sensors. As a result, the tensile forces acting on the probe were optimally distributed, which allowed a load of up to 30kN. Different rope diameters of 4 and 6 millimeters are optimally designed for the prevailing tensile forces. The rope therefore does not travel under high load and supports the endurance of the sensor.

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UWT GmbH is one of the world's leading manufacturers of measurement technology for the detection and monitoring of levels, limit levels in any kind of bulk materials, solids as well as in liquids, pastes and foam. We have successfully demonstrated that over the decades a family-owned business can, with clear principles, dedicated employees and innovative ...

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