Drying Desk: Ways to prevent dryer fires and explosions
Among bulk solids processing operations, drying is one of the most notorious for its potential to create fires and explosions. Despite the dangers, however, dryer manufacturers and users often overlook key fire and explosion safety factors during the dryer's design engineering phase.
First, some combustion basics: Combustion is an exothermic chemical reaction, meaning that it releases heat to its surroundings. The rate at which the combustion propagates through the fuel source (typically, the material being dried) determines whether an explosion will occur. The combustion rate is determined by several factors: the material's moisture content, the ratio of particle surface area to particle volume, the concentration of particles and the extent of their disbursement in the drying air, and the degree of air turbulence. When these factors combine to allow the combustion to propagate extremely quickly, the quick rise in air temperature will cause a large pressure wave to form, thus producing an explosion.