Preventing Air Pollution Connected to the Explosion of Different Types of Flours in Dedicated Storage and Transportation Systems

Marzena Półka,Szymon Ptak

doi:10.3390/su11247256

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.

Highlights

IntroductionThe susceptibility of a dust and air mixture to ignition and explosion is one of the most pronounced fire hazards in industry which concurrently causes changes in the environment and in air composition
According to the World Health Organization, dusts and combustion products form air pollution which have an adverse impact on health or is dangerous for other reasons such as a reduced visibility [3]
The results showed that increasing the venting area is not necessary for explosion doors when the silo volume is bigger or equal to 60 m3 but the mass of the venting element in relation to the vent area is lower than 20 kg/m2 considering that EN 14491 might be directly applied

Summary

Introduction

The susceptibility of a dust and air mixture to ignition and explosion is one of the most pronounced fire hazards in industry which concurrently causes changes in the environment and in air composition. Grain silos and other agricultural devices designated for reloading or processing of products are susceptible to explosions. Introduction of a volume or concentration of solid, liquid or gaseous substances to the atmosphere that are hazardous for the environment and, along with a release of thermal energy and pressure waves, is one of the main factors that cause the contamination of surrounding air. Dust or introduced energy are able to remain in the atmosphere for a certain period of time which, as a result, significantly changes the composition of air and may cause adverse consequences for the biosphere or other environmental elements. According to the World Health Organization, dusts and combustion products form air pollution which have an adverse impact on health or is dangerous for other reasons such as a reduced visibility [3]

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Conclusion