Modeling of Particle-Turbulence-Chemistry Interaction in oxy-fuel-Processes
In the Oxyflame subproject B6 the interaction between particles, the gas phase flow and the combustion process is investigated numerically. For this purpose, the method of Large Eddy Simulation (LES) is adopted using the academic CFD-Code FASTEST-3D. The disperse phase is modeled by tracking a large number of particles following an Euler-Lagrange approach.
In coal combustion, various subprocesses such as devolatilization, ignition and combustion of volatiles in the gas phase and char burnout take place at different time scales. Further, the presence of the disperse phase also influences the turbulent flow field and the combustion process itself.
Because particles are burnt in an environment of oxygen and recirculated flue gas, essentially only carbondioxide and water vapour are present. Therefore, special emphasis is put on the reaction kinetics. The different material properties of the gas phase such as specific heat capacity and emissivity in comparison to air fired systems do not only increase heat transfer by radiation, but also affect the combustion behavior fundamentally.
The objective of this subproject is the development of models and methods for an accurate description of interaction effects between particle transport, gas phase turbulence, gas phase combustion and heterogeneous particle reaction in an oxy-fuel environment in the context of transient LES.