The search for alternative energy sources, especially renewable ones, to replace non-renewables such as oil has been a focus of discussion in both academia and industry. This is where biomass comes in, a renewable source with major energy, environmental and economic advantages, and with it the need to measure wood chip moisture.
Knowing the moisture content when buying biomass is extremely important because it directly affects consumption. Water, an inert, non-combustible material, hampers combustion and represents transported and purchased mass that will not be used. The higher the chip moisture, the more chips are needed to produce the same energy (in kcal), which raises the company’s final cost.
To address this, since 2011 a moisture meter for granular materials, the MUG-M75, made in Brazil by Marrari Automação, has been available on the market. It gives instant moisture readings for particulate organic materials.
Why the dielectric method
The meter is widely used by biomass buyers and suppliers to confirm that the material’s moisture matches what was agreed. Before it, the main check was the gravimetric (oven-dry) method described in the Brazilian standard ABNT NBR 14929, a slow and poorly representative process.
Calibration: how to create a recipe
For calibration, the MUG-M75 requires, for each material it will be used on, a data set relating the dielectric response (as a bit count) to moisture, forming a calibration curve (recipe). These data sets are usually separated by particle size and by material.
The sequence below summarises the steps needed to create a recipe:
Recommendations for best performance
Overall, the MUG-M75 meets the needs of the chip-buying market and efficiently relates moisture content to the dielectric property of wood. For best performance, always:
- classify the material to be analysed (by supplier, for example);
- create a recipe for each type of material;
- train the operator who will use the meter.
Author: André Simon, Eng., After-Sales Coordinator at Marrari Automação
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