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


Every year, over 40 million cubic meters of ready-mixed concrete is processed in Germany. Already 85% of all concrete and fresh mortar required on construction sites are mixed in ready-mixed concrete plants. In aggregate, quarry and mining applications, the conditions are often harsh, noisy and dusty. The TDR level measurement devices with their high compatibility are 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
Within the steel storage silos of the production facilities of a cement plant in Germany the guided wave radar sensor from UWT was implemented to replace defective level measurement sensors. 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 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. The guided wave radar of the NivoGuide® 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. 

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.The rope of the radar has been equipped with a special PA coating to prevent adhesion and also to improve the abrasion resistance of the ropes.