Using the microwave systems from Berthold, the water content or dry content of bulk materials can be measured in a non-contacting manner.
The measurement is carried out online, providing real-time information about the process. The instruments can be installed on
- Conveyor belts
- Chutes
- Pipelines
Due to the wide range of sensor types, the optimal system configuration is evaluated for every individual application.
A measuring system consists of:
[1] Evaluation unit including a microwave module
[2] High frequency cables
[3] Microwave sensor or antennae.
Measuring Principle
The microwave irradiates the product with very little power (< 0.1 mW). The material components are polarised at different strengths and as a result of this, the microwaves lose speed and energy. Water molecules have a 40 times larger effect on the microwaves than other material components. Due to this high sensitivity of water molecules, the water content can be determined very accurately.
As an option, radiometric area weight compensation can complement the measurement if strong fluctuations of the bulk density and bulk height occur, see arrangement 1.
Advantages:
- High accuracy by selective sensitivity to water.
- Non-contacting
- Representative measurement by penetrating the complete material interface.
- Simple installation by computerised sample taking and automatic calibration.
- Robust sensors, use of wear resistant materials.
- Very low amount of maintenance.
Examples of successful applications
- Coking Coal
- Lignite and Hard coal
- Sand
- Wood Chips
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