Bildung anorganischen Feinstaubs in turbulenter Kohlenstaubverbrennung

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The formation of fine particulate matter during coal combustion, especially of coal with high contents of sodium and silicon, is a worldwide social- and health relevant problem affecting the breathing air quality; no sufficient technical solution is available yet though. Existing particulate equipment (electrostatic precipitators) require an excessive effort to retain particles in the relevant size range of 0.1-2.5 µm. Thus, a further reduction of fine particulate emissions can only be achieved considering the entire process of fine particulate matter formation during coal combustion. However, the principle of fine particulate matter formation is far from being understood yet. Existing models are only valid for early combustion stages (pyrolysis) and were developed for laminar flow by now. Thus, up to now, no model for the formation of fine particulate matter exists that takes the complete turbulent burnout process into account. Hence, the turbulent flow field influences quantities, such as temperature or concentration of fine particle educts, that in turn affect the formation of fine particulate matter. Determination of characteristics of emitted particles requires the knowledge of particle history (temperature and local species concentrations), hence CFD-simulations are indispensable. In the proposed project, the model development for formation of fine particulate matter during turbulent coal combustion will be advanced using a complementary approach of CFD and experimental validation measurements. The investigated configurations will be increased in complexity with respect to flow field (laminar to turbulent) and particle load (starting with low particle load). In addition to model development, this project aims to reveal the essential variables determining the formation of fine particulate matter during coal combustion.