Preventing air pollution connected to the explosion of different types of flours in dedicated storage and transportation systems

Abstract

Air pollution, caused by explosion and/or fire of flammable substances, is typical for the majority of technological processes, e.g., flour storage and transportation systems in the food industry. If explosion venting systems are not properly designed, an explosion might lead to many causalities, substantial losses, and significant release of combustion products into the ambient atmosphere. This article presents a study on four selected types of flours: rice flour, oat flour, cornmeal, and chickpea flour. The chosen ignition and explosion indices were determined (heat of combustion, pmax, (dp/dt)max) and TGAs were conducted. The results were used to calculate the explosion venting area according to EN 14491. Despite similar origins, samples were characterized by slightly different courses of explosion, leading to significant differences in required venting areas. Chickpea dust was found to be the most distinguishing sample with the highest values of pmax, (dp/dt)max, and KSt recorded (7.7 bar, 313.08 bar/s, and 85 mbar/s, respectively). To avoid structure failure resulting in the emission of pollutants into the atmosphere, a change in the stored flour type should be preceded by a revision of safety measures taken, as the required vent area might differ significantly depending on the KSt, L/D ratio, and desired maximum static pressure.