Extinguishing Smoldering Fires in Wood Pellets with Water Cooling: An Experimental Study

Smoldering fires in stored or transported solid biofuels are very difficult to extinguish. The current study has explored heat extraction from the combustion zone as a method for extinguishing such flameless fires. Heat extraction from the sample was made feasible using water flowing through a metal pipe located inside the sample. The fuel container was a steel cylinder with insulated side walls, open at the top and heated from below. Wood pellets (1.25 kg, 1.8 l) was used as fuel. Results from small-scale experiments provide proof-of-concept of cooling as a new extinguishing method for smoldering fires. During self-sustained smoldering with heat production in the range 0 W to 60 W, the heat loss to the cooling unit was in the range 5 W to 20 W. There were only marginal differences between non-extinguished and extinguished cases. Up-scaling is discussed, cooling could be feasible for preventing smoldering fires in silos.