Experimental study on the inertization of wood-based biomass with solid inerts

Wood pellets are one of the primary solid substitutes for fossil fuels worldwide. They present both advantages and disadvantages that have been widely studied, where one of the main disadvantages is the risk of self-heating, which may lead to smouldering combustion or explosion. The risk of smouldering increases with decreasing particle size, while the difference in fire behaviour due to particle sizes needs to be studied in more detail. One of the techniques used to avoid, or decrease, the risk of smouldering is inertization. Inertization with gases is ineffective due to the difficulty gas has in accessing all voids in solid materials. An alternative solution is to use inert solids instead of gas.

This research empirically studies the fire behaviour of wood pellets and wood dust with particle size of less than 1 mm, and the influence of solid inertization in both materials in two different configurations: mixed and layered. The ignition initiation of both particle sizes is similar, while the cool-down phase is quicker in the case of dust. However, inertization of dust needs a significantly higher amount of inert solids than in the case of pellets, being easier to avoid smouldering when the inerts are disposed in layers rather than mixed with the materials.