Computational Fluid Dynamics (CFD) can be considered to be a real research and engineering tool for process design and development. Commercial CFD software contain many possibilities to model different sub-processes including evaporation and combustion. To improve these sub-models, a very detailed physical single particle combustion model for black liquor combustion is presented and experimentally validated in this book. This book contains a broad review on available research publications in the field of black liquor combustion, descriptions of detailed modeling techniques and observations on new conversion mechanisms. It gives new ideas on how to model combustion of thermally large particles. It should be useful reading for researchers and engineers working with numerical modeling of different conversion processes related to combustion, process chemistry and metallurgy.