Abstract
The furnace of a pulverised coal-fired utility boiler with a thermal output of 210MW, with dimensions of 8m x 8m x 29m and 12 burners located on three levels, is considered. Coal combustion is described by a five-step-reaction scheme. The model covers two heterogeneous reactions for pyrolysis and char combustion and three gas phase reactions for the oxidation of volatile matter. A standard k, e-model is used for the description of turbulence. The interaction of turbulence and chemistry is modelled using the Eddy Dissipation Concept (EDC). The transport equations for mass, momentum, enthalpy and species are formulated in general curvilinear co-ordinates enabling an accurate treatment of boundaries and a very good control over the distribution of the grid lines. The discretisation is based on a non-staggered finite-volume approach and the coupling of velocities and pressure is achieved by the SIMPLEC method. Numerical diffusion is minimised by the use of the higher-order discretisation scheme MLU. The accuracy of the predictions is demonstrated by comparing the computational results with in-furnace measurements of carbon monoxide, carbon dioxide and oxygen concentrations and of temperatures.
Published Version
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