Professor Federal University of Espirito Santo Vitoria, Espirito Santo, Brazil
Industrial site arrangement, meteorological conditions, emission control technologies and the wide range of materials and specific conditions that compose the stockpiles may strongly affect the wind erosion and particles take-off. Due to the potential environmental impacts to nearby communities, it is essential the monitoring and accurate quantification of these emissions. It can be carried out by field measurements or by mathematical models using emission factors as recommended by the United States Environmental Protection Agency (USEPA) in AP-42 documentation. However, field campaigns may be prohibitive as a high number of factors influence the emissions and it changes several times during an operational day. The Computational Fluid Dynamics (CFD) is an important tool to address this outcome and to predict the flow field on the stockpiles. In the present work, numerical simulations of a full scale steel plant site were carried out to predict the emitted mass of stockpiles considering simultaneously the influence of: wind direction, wind magnitude (gust), existence of natural (green belts) and artificial (wind fences) barriers, porosity of the barriers, dust suppressants (water and polymer solution aspersion) and stored material characteristics (for instance, density and particle size distribution which affects the threshold friction velocity). Preliminary results indicate that the direction and magnitude of the wind gust influence the velocity distribution in the entire yard and may increase erosion levels on certain locations. The presence of green belts reduces the overall velocity distribution within the industrial site. The insertion of wind fences in areas already protected by green belts can cause an additional protection of the diffuse sources. Their efficiency is strongly dependent on the case. The tested porosity values of wind fences were 30 and 47\% not presenting, in average, considerable changes in the flow field on the piles under their influence. The application of dust suppressants on the surface of the pile increases the minimum velocity required for the particles to be emitted, making the erosion process more difficult. The effects of reducing or increasing emissions in a real industrial yard, considering all the factors already mentioned, are very heterogeneous. Therefore, the present results allow the analysis and selection of the possible scenarios in industrial yards looking for the most suitable combination leading to the optimization of yard management and environmental controls to reduce the emissions and their impact more efficiently in the environment and in the human health.
