The determination of moisture in dry fibrous material is important to keep the boiler efficiency constant. Especially in summer, when the wood chip stockpiles are moistened, the water concentration can vary drastically.
The Berthold LB 568 analyser provides an online and real-time moisture measurement of digester-fed wood chips. The LB 568 generates multiple microwaves in a wide frequency range, emitted by an antenna below the conveyor. The microwaves penetrate the wood chips and are received by a second antenna above the belt. When penetrating the wood chips, the microwave signal‘s characteristics change in terms of attenuation and phase shift. These changes directly correlate to the wood chip moisture. Variations in layer thickness and bulk density are compensated with the use of a radiometric bulk density compensation system component. The complete system thus provides a stable and reliable moisture reading. The microwave moisture analysers are installed at the feeding line to the digester and the transmitter is mounted close to the LB 568s. Depending on the sampling representativity and measurement conditions a typical accuracy of better than ±1.0 % (1 sigma) can be achieved.
These advantages are used to make critical applications more reliable:
- Accurate moisture leads to accurate „bone dry“ solids addition leads to accurate digester chemical charge
- Measurement independent of wood species
- Operates reliably at moisture levels up to and above 50%
- Transmission measurement provides representative sample as opposed to traditional „surface only“ measurements