Dusty and particularly harsh conditions prevail in the building materials industry, in quarries or in mining. High demands are placed on level measuring devices - solid sensor technology with uncompromising robustness and unrestricted reliability are therefore of the utmost importance.
Flexibility and precision for continuous level measurement - plumb bob sensor defies cement dust and high temperatures
We successfully completed a challenging project at one of the largest cement plants in Kazakhstan. The plant operator required a solution for a reliable continuous measurement process in the cement silo. The significant challenges in this project lay in the extreme environment - characterised by high dust formation, lump formation, and high process temperatures. In addition, the installation of the sensor required it to be mounted on an existing, high set nozzle.
Electromechanical pilot system fulfils all local requirements
The was the first choice for the cement plant, as it can be adapted to specific installation requirements thanks to its modular design and its wide range of configuration options.
At the Kazakh plant, the tape version of the NivoBob® - NB 3200 was used as the resilient solution, as it can withstand the demanding conditions of these industrial environments.
A key feature of the NivoBob® with the tape design is the integrated cleaner, which effectively prevents the accumulation of adhering bulk materials such as cement dust in the housing and thus enables permanently precise measurement. This is particularly important during filling processes, where the device must cope with an exceptionally dusty environment. As the belt is continuously unwound and rewound, it is continually cleaned, thus preventing contamination from entering the mechanical chamber.
Robust double-chamber housing guarantees
precision and durability
In the two-chamber housing of this sensor system, the areas for the mechanics and electronics are meticulously separated from each other so that the electronic components are hermetically isolated from the mechanical elements. This design prevents the ingress of dust and moisture, increases the reliability and durability of the system, and also makes the sensor unaffected by changes in moisture in the bulk material.
In this cement plant, the model contributes to further optimizing operational safety by featuring a suspended load weight that effectively prevents the tape from twisting. Additionally, the tape cleaning system is equipped with a guide rail that not only prevents potential damage but also ensures the longevity and functionality of the measurement system. Moreover, the tape version of the NB 3200 is certified according to explosion protection standards, qualifying it for use in particularly hazardous industrial areas.
Adaptability and accuracy: lot sensor in a demanding measuring environment
Further challenges at the plant in Kazakhstan were posed by an existing base, which required a high nozzle feed-through for the process connection. In addition, the measuring instrument used must be able to bridge long distances of up to 22 metres. Due to the height of the silo, the material may pile up to form a cone with a steep gradient. Precise measurements must also be guaranteed under these conditions.
In order to meet the diverse conditions on site, simple device installation is possible via a flange or threaded connection. The connection pipe of the NivoBob® can also be configured in different lengths. In this case, the extended version enabled installation with a high pipe feed-through connection. The basic device was installed in the flange version on the plinth.
The required measuring distance is no challenge for the NB 3200, as the lot sensor offers very high measuring accuracy even at distances of up to 50 metres. This ensures precise detection even in narrow silos. As an additional safety feature, a maximum run-off length for the sensor weight has been defined. The NivoBob® is also characterised by its simple commissioning: The electromechanical lot system is immediately ready for use after entering just four silo-specific parameters.
Customised sensor technology:
precise measurements in a wide range of materials and conditions
A wide range of sensing weights and accessories are available for further adaptation for different industrial process conditions, such as varying temperatures, angles of repose and separation layers.
If large angles of repose are to be expected due to the material, customised sensor weights facilitate accurate measurement. In the application at the plant in Kazakhstan, the use of a stainless-steel sensor weight with a spike was recommended for the powdery materials of the cement dust with a steep angle of repose. The tip of the weight first penetrates the fine-grained material until the actual weight is applied in order to be able to take an accurate measurement.
What also characterises the NivoBob® is its low demand on the environment. The measuring principle of the lot sensor is independent of the material of the silo, so that weld seams and material deposits on the walls do not affect the measuring accuracy.
Robust durability and user-friendly functionality of the lot sensor
The system's user-friendly software makes it much easier to set up and adjust the measurement parameters and helps to ensure that the lot can be put into operation quickly and efficiently. Entering just a few function parameters and the choice of software language considerably simplifies device parameterisation. The lot sensor also has an LCD display with pushbuttons for various setting options as well as LEDs and a display to indicate the switching status.
The device's brushless motor guarantees a long service life of up to 500,000 measurement cycles and 60,000 operating hours, which corresponds to a motor service life of around 28.5 years with a continuous 30-minute measurement interval around the clock. This has been tested and proven in the case of a device that has been continuously providing reliable measurements for a customer for over 30 years. Surely a wise investment!
