Researchers have devised an easy and practical way of measuring moisture content.
The moisture content of biomass destined for bioenergy is very important, as it influences the net calorific value of the biomass and therefore the price of fuel chips. In the past, accurate calculations of moisture content took place by drying samples in specialised ovens. This method was very slow and the results were often not known until after the biomass was combusted. The Metso MR Moisture Analyser (Metso) was developed to try and create a tool that could quickly and accurately determine biomass moisture content. The Metso measures moisture content within two minutes by magnetic resonance, and this new method was compared with the oven drying method at sites in Sweden and Canada.
The Swedish research was carried out on stemwood and residue chips (mostly spruce). The Canadian research was carried out on softwood bark (mostly spruce) from local sawmills, stemwood chips produced in the forest from mixed species, bark free pulp chips (mostly spruce) from local sawmills, and mixed fuel from all three of the above. The moisture content of these materials ranged from 17 to 65 % on a total weight basis. In Sweden, the Metso made a negligible overestimation of 0.23 % compared to the oven dry method, and in Canada the overestimation was slightly higher at 1.84 % overestimation of moisture content. This showed that the Metso method could be used to quickly, easily and accurately estimate moisture content in two minutes, even if multiple samples are needed.
The research was titled “An accurate and fast method for moisture content determination”, and was published in the International Journal of Forest Engineering, Vol. 25(3), 2014. The researchers were L Fridh, S Volpe and L Eliasson. The article can be downloaded free-of-charge from http://www.tandfonline.com/doi/full/10.1080/14942119.2014.974882