Oxyflame - SFB/TRR 129

Predictions foresee an increasing electricity demand within the future decades. Simultaneously, reduction of pollutant emission is the overarching goal in order to minimize the impact of global warming. In order to ensure secure electricity supply and reduce pollutant emission, the development of novel ultra-low emission and highly efficient power plants as alternatives to conventional coal power plants is essential.

In this context, the oxyfuel combustion of biomass and coal is promising future technology. Different to conventional combustion processes with air, high flue gas recirculation is used to ensure an elevated concentration of water (H₂O) and carbon dioxide (CO₂) in the oxidizer of oxyfuel processes. The elevated CO₂ concentrations in the exhaust sets the fundament for an efficient usage of Carbon-Capture-and-Storage (CCS) technologies, which lead to significant reduction of CO₂ emission.

However, the elevated concentrations of H₂O and CO₂ in the oxidizer have tremendous effects on the combustion and transport processes under oxyfuel conditions. The collaborative research center TRR/SFB 129 "Oxyflame" targets to investigate the changes of the combustion process under oxyfuel conditions in detail. The essential goal is the development of physical and chemical models to predict the combustion processes under oxyfuel condition in order to establish a framework for usage of the oxyfuel technology in future power plant. Within the SFB/TRR 129, the ITV focuses on the gas phase chemistry of oxyfuel combustion and the heterogenous combustion of coal particles. The three main objects of the ITV are:

Development of chemical models to describe the gas phase chemistry under oxyfuel atmosphere

Sophisticated experimental methods are employed to investigate the combustion of pyrolysis products of biomass and coal and to elaborate emission formation pathways under oxyfuel conditions in reference flames. The experimental data are used to develop, validate, and optimize reaction mechanisms to predict the gas phase chemistry in oxyfuel atmosphere. These mechanisms are then used to simulate and predict the combustion processes and emission formation under oxyfuel conditions in power plants.

Modeling transient particel combustion in laminar and turbulent flows

The prediction of coal particle combustion requires models that capture the homogeneous and heterogeneous combustion of coal particles and the interaction of coal particles with the surrounding flow. Detailed simulations are used to predict the combustion of single coal particles up to particle clusters. The results generate a fundamental understanding of the particle combustion and form the baseline to derive numerical models to describe the particle combustion under oxyfuel conditions.

Analysis of model uncertainties and sensitivities

In order to compute the combustion and transport processes in a power plant, multiple models are required to describe the physical and chemical phenomena on different scales that often cover several orders of magnitude. The numerical models suffer from uncertainties regarding their predictive capabilities. For a meaningful interpretation of the numerical results, the knowledge of model uncertainties and the sensitivities of the models parameter is essential.