Simulation and Experimental Studies on Belt Conveyor Drive System For Energy Conservation In Underground Mines

Abstract

Transportation of extruded material from the underground to the surface is a significant area concentrating underground mining technologies. With available technology, belt conveyors are mostly adopted for transporting extruded materials. The conveyor belt system's efficiency directly relates to underground mines' productivity, which is a significant area of research that is needed. A conveyor system's efficiency can be estimated in terms of energy consumption and the specific energy consumed. In the present study, the belt conveyor system's efficiency is illustrated considering three different ways, i.e., field investigation, simulation, and experimentation. Under field investigations, data relevant to three different field belt conveyors (FBCs), namely Gantry (FBC1), 5L (FBC2), and Surface (FBC3) from the production department of GDK-1&3 incline, The Singareni Collieries Company limited, Ramagundam, Telangana, India was collected. Collected data includes energy consumption and a specific energy for each belt conveyor system. These systems possess different varying dimensions along length and height. The data was processed, energy calculations such as energy consumption and specific energy of all three belt conveyors were estimated. This study illustrates how the length of the belt, inclination, and drive motor affect the belt conveyor system's energy consumption. To further improvise the energy losses, simulation studies on the field's data were carried out for predicting both energy consumption and specific energy. The simulation was carried out using MATLAB 2018b under two categories. These include a non VFD (variable frequency drive) and VFD-based simulation models. To develop a simulation model reference voltage vector was consider as input. Upon comparison of both models, it was observed that a VFD- based simulation model could significantly reduce both energy consumption and specific energy, i.e., incorporation of a VFD to the belt conveyor system reduces energy consumption, in turn, specific energy. The minimization in annual energy consumption and specific energy achieved on interfacing VFD were found to be 9.4% (2390kWh), 2.31% (2041kWh) and 7.3% (7797kWh) for energy consumption and 10.4% (0.20866 kW/ton-km), 2.55% (0.02166kW/ton-km) and 5.93% (0.12384 kW/ton-km) for specific energy with respect to FBC1, FBC2 and FBC3. viii A simulation model was also developed for the laboratory belt conveyor (LBC) considering length and three different heights, namely, LBC1, LBC2, and LBC3), individually for both non VFD and VFD incorporations. To simulate a VFD, the principle of working of a proportional integral (PI) control was thoroughly studied, and the structural design was simulated. The study revealed similar observations as field data simulations. The minimization in annual energy consumption and specific energy achieved on interfacing VFD were found to be 9.9%, 9%, and 7.6% for energy consumption and 12.2%, 11.5%, and 10.2% for specific energy for LBC1, LBC2, and LBC3. In order to validate the simulation study, an experiment on a LBC system was carried out. The experimentation was done for three different simulated elevations and variable loadings from 20% to 100% of the rated belt capacity. Readings for both non VFD and VFD unit incorporations were recorded. It was observed that the results of incorporating a VFD unit to the belt conveyor system reduce the energy consumption and specific energy. With the use of VFDs, the reduction in energy consumption for LBC1, LBC2, and LBC3 are 9.6%, 8.55%, and 7.2%, respectively. And, the reduction in specific energy for LBC1, LBC2, and LBC3 are 11.5%, 11.3%, and 9.89%, respectively. Statistical analysis is also carried using Minitab V 18. Linear regression models are developed to predict the specific energy. Models are developed individually for both non VFD and VFD incorporations. Linear regression models are developed for laboratory belt conveyor system. A graph of actual vs. predicted specific energy are plotted for each of the said systems. The specific energy of the belt conveyor system depends on various factors; the speed of the belt, supply voltage to the motor, applied force, the mass of the material, and applied input and output powers. However, its significance on the specific energy of the belt conveyor has been varied with and without connecting the controller.