| A deposition model was developed to predict the deposit growth, properties, and heat flux through the deposit. Viscous flow sintering has long been recognized as the principal mechanism responsible for changes in the local properties of the deposit. Consequently, a transient description of sintering has been included in the model in order to estimate properties as a function of time at different positions in the deposit. An energy balance was used to determine deposit temperatures and the heat flux through the deposit. This balance accounts for variable physical properties and is solved iteratively with a prediction-correction technique at each time step during deposit growth.; This deposition model has been integrated into the comprehensive combustion code PCGC-3, and a computational strategy was developed to allow the integrated model to predict ash deposition in a utility boiler. The integrated deposition model was evaluated in a pilot-scale combustor by performing three-dimensional simulations of deposition in this combustor and comparing the predictions against experimental data. Simulations of ash deposition in a utility boiler demonstrated the ability of the integrated model to predict the potential of severe localized deposition, the effect of operating conditions on the deposit growth and properties, and the effect of slagging on boiler operation and performance. Once additional evaluations against experimental data in utility boilers are performed, this model will provide a useful tool for developing an optimal strategy for the management of ash deposition. |
