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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.

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 lot system

The NivoBob® electromechanical lot sensor was successfully used for permanent level measurement within the silo. The UWT lot system was the first choice for this, 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.
As an alternative to the tape version, UWT also offers the lot system in a cable version. In addition to applications with solid material surfaces, this is also suitable for measurements with soft or muddy measuring substances.

Robust double-chamber housing

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.
Depending on the version of the NivoBob®, the lot sensor also offers an optimum solution for interface measurement in sediment tanks or basins. This enables precise detection of the solids level in liquids. Typical fields of application are the detection of sediments in water and the measurement of sludge levels. This ability to identify different layer densities makes the NivoBob® an indispensable tool in process control and monitoring of complex industrial processes.
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 precision of the lot sensor

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.

Precise measurements in a wide range

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. These are specially designed to handle all grain sizes in the bulk solids range and can be configured according to requirements and sensitivity. In order to also fulfil the measuring principle of interface measurement, UWT also offers special sensor weights that can be adapted to specific viscosities.
If large angles of repose are to be expected due to the material, customised sensor weights facilitate accurate measurement. These specially developed sensor elements prevent the weight from slipping or tilting on steep cones, for example, which further increases the reliability and accuracy of the measuring process.
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

The NivoBob® has proven itself not only in Central Asia, but also in other demanding markets such as China and South America, where it is used in various building material applications in coal, limestone and iron ore in addition to cement.
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.

Optimisation of bulk solids measurement

By implementing the NivoBob® NB 3200, the cement manufacturer was able to effectively automate its level monitoring for raw cement. Simple commissioning was important to the operator and that the devices could cope with the extremely dusty conditions. UWT’s success at the cement plant epitomises the company’s core principles - Technology, Performance and Partnership. This solution demonstrates UWT’s ability to innovate and adapt its technologies to customer-specific requirements. The case study here illustrates a conclusive solution provided by UWT to the challenges posed by difficult conditions.

The right measurement technology

UWT solutions for level and point level measurement of bulk solids and liquids are already being used successfully worldwide in silos and process vessels in the cement and building materials industries. Innovative technologies combined with comprehensive industry knowledge enable the German manufacturer to provide a comprehensive range of customised measurement technology to meet the variable and complex challenges of this industry with absolute flexibility.
As one of the world’s leading suppliers of level sensors, UWT has almost 50 years of extensive expertise and experience in level measurement and control. The company always endeavours to provide modern, established, and compatible devices. This includes all types of rotary paddle level switches, vibrating forks and rods, capacitive sensors, electromechanical lot sensors, radar sensors and guided wave radars.