Computer Fluid Dynamics ( CFD) analysis is known for applying the finite volume method (FVM) to problems of fluid flow, heat transfer, among others, using concepts from numerical methods and Thermofluid Dynamics. The discrete element method (DEM) is applied when the objective is to analyze the displacements and rotations of discrete bodies. To understand the differences between the methods, see this content in a previous blog article. In this article, learn how Kot Engenharia applied both concepts to the analysis of an ore transfer system.
CFD-DEM analysis of an ore transfer system
A transfer chute is a component commonly found between conveyor belts used to direct the flow of material in the unloading process. A client company installed a new chute in its plant with the aim of reducing dust generation and emissions to the outside environment. However, the new chute did not perform as well as it should have, and the scope of Kot's work was to identify the phenomena responsible for the generation and release of dust due to the transfer of ore to the environment.
Initially, the behavior of the bulk flow was evaluated using DEM in specific software. It was concluded that there was no risk of clogging, as shown in Figure 1.
Figure 1: Material flow in the chute - SOURCE: Kot Collection.
The same software was used for a coupling between CFD and DEM, with the aim of evaluating the air flow inside the chute. Thus, it was possible to see the formation of vortices in the internal region and a zone of high turbulence, which increases the generation of dust. These results are shown in Figure 2.
Figure 2: Air flow during kick discharge - SOURCE: Kot Collection.
In order to gain a more detailed understanding of the phenomenon observed, the air flow on the material receiving conveyor was studied. This conveyor has its own dust control system, with a transition to the belt cover, which has the same function. The analysis was carried out using a computational fluid dynamics tool, which uses FVM as its basis.
It was observed that the dust control system serves its purpose well. However, in the transition region between the system and the conventional belt cover, factors favorable to dust generation were noticed, since there is no enclosure. The formation of vortices can be seen in Figure 3. At the exit of the cover, it is visible that the phenomenon is mitigated.
Figure 3: Cross-sections at the roof inlet and outlet - airflow pressures (P) and velocities (U) - SOURCE: Kot Collection.
The turbulence regions along the covered area of the conveyor were also analyzed, as shown in Figure 4, where the lines represent the air flow. Once again, it can be seen that the transition region is the most critical point in terms of air currents.
Figure 4: Air flow in the roof area - SOURCE: Kot Collection.
As such, the chute and the transition region from the dust control system to the roof are responsible for the high generation and leakage of dust. Kot Engenharia presented the causes of these problems and developed solutions, which involve geometric changes to adapt the flow and methods of achieving better recirculation of the air flow.
Kot Engenharia has the experience and resources necessary to carry out simulations involving DEM and CFD analysis, such as the case described in this article. Contact our team for more information!
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