Integrated fluid dynamics-process modelling of a coal-fired power plant with carbon capture

Oxyfuel combustion, where the fuel is combusted in a mixture of pure oxygen and recycled flue gases instead of air, is one of the leading options for carbon capture from coal-fired power plants. Accurate simulation of the operation of such plants is critical for successful development of the technology. A major challenge of such a simulation is how to account for the fundamental differences in gaseous physical and thermal properties; in particular the radiative and convective heat transfer coefficients. In this paper a combined CFD-process approach is developed whereby a detailed CFD model is utilised to represent the complex gas-phase combustion and radiative heat transfer to the furnace walls and the radiant section of the boiler. This is then combined with a full plant process simulation which includes modifications to the heat transfer components to account for differing gas compositions. The novel integrated calculations have been completed for air-firing and for oxyfuel under a range of conditions and a comparison reveals that there is a possible ‘working range’ of oxygen concentrations/recycle ratios under which the distribution of heat transfer in the system is similar to air firing and hence the steam conditions can be controlled to set-point temperatures and flows.