Drying Desk: Spontaneous combustion in drying
Can materials wetted with water (not solvent) spontaneously combust? Here's what to know about your vulnerable materials, including charcoal, hay, grains, manure, sawdust, coal fines, and finely divided metals (such as iron, cobalt, nickel, and uranium).
Combustion requires three elements: fuel, oxygen, and an ignition source. When evaporating water from organic solids in an open-cycle drying circuit, the fuel is the organic material and the drying air supplies the oxygen. Combustion may occur if the airstream's oxygen content is above the limiting oxygen concentration (LOC). For most organic solids, the drying air’s LOC is approximately 12 per cent by volume but may be as low as 10 per cent by volume.