| The use of the high sulfur coals in electric generation and various industrial activities are blamed for the production of acid rain. The moderate-to-high sulfur content of many U.S. coals, especially Illinois coals, is of particular concern as current and newer more stringent regulations require reductions in sulfur dioxide emissions. Much of the mineral matter, pyrite and other ash producing minerals are liberated in finely ground coal. A significant amount of these undesirable materials can be physically removed from coal when liberated as individual particles. The percentage of these materials that can be removed depends on the fineness of coal grinding. The main purpose of this research was to design and construct an aerodynamic separator to classify particles by density and then investigate its performance. The concept of the operation of the aerodynamic separator is based on the principle that particles of different densities, but essentially the same size, follow different trajectories when injected into a uniform air flow field. An analytical model of the flow field for predicting particle trajectories is developed herein. The classification of particles by density in the flow field model is then investigated. The effect of the initial velocity, direction, location and shape of the particle on its trajectory can then be evaluated via the analytical model. Finally, the aerodynamic separator is designed based on the predicted trajectories. In the testing phase of the apparatus the particle distributions were initially studied by collecting data of the weight distributions coal from Illinois Coal Sample Bank and silica sand. In the second phase of the experimental research, coal was separated from the heavier impurities specifically pyritic sulfur. Finally, based on the experimental results obtained, the initial velocity profiles of feed particles were selected. These profiles are chosen such that the predicted particle trajectories span over the experimental particle distribution results. Hence, an analytical model capable of generating particle distributions in the aerodynamic separator was developed, tested and presented in this report. |
