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Ενεργειακή ανάλυση συστημάτων συνεχούς μεταφοράς εξορυγμένων υλικών

Biotakis Georgios

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Year 2023
Type of Item Diploma Work
Bibliographic Citation Γεώργιος Μπιωτάκης, "Ενεργειακή ανάλυση συστημάτων συνεχούς μεταφοράς εξορυγμένων υλικών", Διπλωματική Εργασία, Σχολή Μηχανικών Ορυκτών Πόρων, Πολυτεχνείο Κρήτης, Χανιά, Ελλάς, 2023
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This study investigates the possibility of converting a conveyor belt system, used for the transportation of bulk materials, into an energy storage system. By harnessing the gravitational potential energy of the material at a certain height and utilizing its movement on inclined conveyor belts, the gravitational energy is converted into electrical energy using regenerative motors. This energy storage system is based on the same principle as the hydro-pumped storage system, but instead of using water reservoirs, it employs piles of loose bulk materials (such as sand, gravel, or other fragmented materials) at different elevations. It can provide a solution for energy storage in areas where water pumping is not feasible, and it can also be utilized in former mining areas, where sufficient quantities of loose bulk materials and suitable height differences are available.Based on existing computational models for calculating the required operating power of conveyor belts according to ISO 5048 and DIN 22101, this study examines which parameters affect the performance and storage capacity of such a system. Sensitivity uncertainty analysis is used for this investigation. The key decision parameters are defined as the travel length, conveyor belt width, conveyor belt incline, and belt speed, while the parameters with uncertainty include the motor efficiency factor, the belt filling factor, the coefficient of friction, the specific weight of the transported material, and the resistance coefficient due to friction on the idlers.Two scenarios were examined, corresponding to an optimized conveyor belt system and a typical one, and the effect of uncertainty parameters on the system performance was calculated. The results showed that the conveyor belt's filling factor and the motor system's efficiency factor had the greatest impact on the performance indicators of the energy storage system. The calculated value for the energy storage factor ranged from 0.68 to 0.90 for the optimized system and from 0.44 to 0.75 for the typical system. These values are comparable to other existing energy storage systems (pumped storage, compressed air, batteries, and flywheels). Furthermore, energy storage systems based on conveyor belt operation have lower construction costs, longer lifespans, no storage losses, and do not produce waste during their operation.Finally, the analysis results of an existing downhill conveyor belt system installed in a quarry, that is used not only to transport materials but also to recover energy during its operation, showed that the system's performance is lower than the theoretically calculated. This deviation is due to the fact that the existing system was not designed as an energy storage system but rather as a material transportation system.

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