When looking at all the challenges that pellet plant operators are tasked with, moisture control is one of the biggest. In fact, sensing moisture in wood pellets is one of the most important steps, especially after manufacture when pellets are stored.

Those who are proactive in taking steps to monitor moisture in wood pellets understand that they can save money and avoid packaging product that is low in quality or wet. Measuring moisture in wood pellets can also help save energy wasted in over-drying. By measuring moisture continually through the production of wood pellets, proactive avoidance of moisture issues is accomplished. Our goal at MoistTech is to help those who manufacture wood pellets to deliver only the highest quality product through our moisture sensor technology.

Importance of Moisture Content

Making pellets is a fairly straightforward process from a 30,000-foot view, feeding biomass into a pellet mill die chamber and the rolls work to press out a beautiful pellet with a high quality sheen right?  Not so fast, there are several metrics that must be considered when it comes to making a quality pellet day in and day out. 

Something to know about pellet mills is that they are only as efficient as the consistency of the material that is being inputted.  There are several factors that must be considered such as: the wood species, the die specifications, the grind size, the geometry of the grind, the conveyance, binder requirements and so on.  However, one metric that is often overlooked or rather undervalued, is the moisture rate of the biomass.  This area is neglected in biomass pelletizing systems due to a lack of knowledge about its importance – changing the moisture percentage even by as little as 1% makes a noticeable difference in the pellet quality both in the durability and in the sheen.  If the moisture rate varies by 3-5% it is almost impossible to consistently make a durable pellet at all.  The other factor that moisture directly affects is the amperage of the main drive on the pellet mill.  In wood pelleting specifically, if the moisture rate trends upwards the amperage of the motor swings upwards as well.  When the moisture rate drops the amperage falls significantly. 

This bouncing of the amperage rate can have a detrimental effect on the production capacity of the pellet mill. Plants can experience over a 20% decrease in production rates simply because the inbound biomass wasn’t a consistent moisture, not to mention there is the possibility of plugging the mill.  How is this overcome? Proper moisture measurement and control throughout the production process. Programming of the dryer system to provide a more consistent biomass moisture rate in real time that directly correlates to a higher production capacity and a better-quality pellet