In-depth Studies of OxyCoal Combustion Processes through Numerical Modelling and 3D Flame Imaging

Lead Research Organisation: Imperial College London
Department Name: Dept of Mechanical Engineering

Abstract

Coal will likely remain in an important position in the world energy mix in the foreseeable future because of its stability in supply and low cost in production. However, coal fired power generation industry has to substantially reduce its pollutant emission to survive in the future carbon constrained energy market. Oxycoal combustion with CO2 capture from flue gas is an emerging technology that can be adapted to both new and existing coal-fired power stations leading to a substantial reduction in carbon emission. Various assessments suggest that oxycoal technology is feasible and more favourable than other CCS (Carbon Capture and Storage) technologies, such as post-carbon capture. Currently, oxycoal combustion technology is still in its laboratory and technology demonstration stages and there is a significant knowledge gap in this new technology. A number of uncertainties exist in the combustion process where the changes in the heat transfer and combustion characteristics are, among others, the major concerns. Issues with system designs such as the optimum oxygen concentrations and its impact need to be investigated. Other complications include such as high concentrations of sulphur and mercury and changes in deposition and corrosion in the boiler and the downstream elements. If the technology is to be widely adopted in power generation industry for CCS then it is imperative that the impacts of these changes in the combustion processes are well understood, and that economic solutions to mitigating the problems encountered are identified.The proposed research aims to achieve an in-depth understanding of the oxycoal combustion processes, to develop key modelling capabilities for process prediction, and to provide guidelines to the power generation industry on design new and/or retrofitting existing power plant with oxycoal combustion technology. Because of the high costs of performing large scale tests, process modelling is commonly used as an alternative in technology development. In this project, advanced Computational Fluid Dynamics (CFD) techniques will be employed to perform detailed simulations on the oxycoal combustion processes. Because the oxycoal combustion is very different from the conventional air-coal combustion, new oxycoal specific CFD sub-programmes will be developed in order to achieve accurate modelling results. In parallel to the CFD modelling, well controlled practical measurements will be carried out to setup a comprehensive database on the oxycoal combustion and to provide validation to the CFD model development. In addition, a unique 3D flame monitoring system will be developed to monitor the oxycoal combustion flames. This integrated approach of advanced computational modelling, detailed experimental testing, and 3D flame imaging forms a mutual validating and complementary system to ensure a credible research output so that an in-depth understanding of the impact of oxycoal on flame characteristics, critical reaction kinetics, and devolatilsation and char reaction in the combustion processes may be achieved.The project consortium comprises of three academic centres of expertise from Leeds, Kent and the Imperial College. Three leading energy research institutes in China are joint force on the research. Collaborative research programmes have been arranged to carryout experimental testing and theoretical simulation in both UK and China. The project has also gained strong supported from leading power generation companies and commercial CFD developer providing practical advice on oxycoal combustion tests and combustion model development. The project provides a platform for the leading UK groups and leading Chinese partners to work together in tackling the significant issues related to the oxycoal combustion technology, which is expected to contribute significantly in cutting the CO2 and other greenhouse gases emissions in the power industry in both countries.

Publications

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Description A working set of models to represent coal combustion. Lagrangian particle transport and radiative heat transfer in an LES framework has been implemented and tested. The simulation results of the flow field were compared to experimental data for both a reactive and non-reactive case, and an overall good agreement emerged. A simple method for
replicating pyrometer measurements was developed for the LES and results obtained from the method were compared to the experimental data. Finally the species concentrations were compared to experimental results for CO2, O2 and N2. The results show the potentials of using LES for pulverized coal combustion and open the way for further developments on the coal combustion models and the applications to more complex burners.
Exploitation Route LES for pulverized coal combustion could be used for further developments on coal combustion models and applications to more complex burners.
Sectors Energy,Environment