Inorganic fine particulate matter formation during turbulent pulverized coal combustion

The formation of fine particulate matter during combustion, especially of coals with high contents of sodium and silicon, is a worldwide social- and health relevant problem, severely affecting air quality. Yet, no sufficient technical solution is available. Existing equipment (electrostatic precipitators) requires an excessive effort to retain particles in the relevant size range of 0.1 – 2.5μm. Thus, a further reduction of fine particulate emissions can only be achieved considering the entire process chain of fine particulate matter formation during (coal) combustion. However, the principle of fine particulate matter formation is far from being understood. Existing models are only valid for early combustion stages (pyrolysis) and were developed for laminar flow. Thus, up to now, no model for the formation of fine particulate matter exists that takes the complete turbulent burnout process into account. Nevertheless, the turbulent flow field influences quantities – such as temperature or the local concentration of fine particle educts – which in turn affect the formation of fine particulate matter. Thus, the determination of characteristics of emitted particles requires the exact knowledge of particle history (temperature and local species concentrations), requiring a combination of detailed laboratory experiments and CFD-simulations. The investigated configurations are 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.

This Sino-German project is a joint collaboration between WSA at RWTH (funded by DFG) and the Chinese part is the Department of Energy and Power Engineering at Tsinghua University (funded by the NSFC).