Pressurized oxygen blown black liquor gasification, a new process for the recovery of energy and spentchemicals from chemical pulp mills, enables efficient power production or the production of motor fuels. Inthis paper, the experimental results of a 3 MW_(th) process development plant are presented and compared withthe results of a CFD model.The key parameters with the largest effect on gas composition are: operating pressure, oxygen-to-fuelequivalence ratio, black liquor load and black liquor preheating temperature.The experimental gas composition during normal operation of the gasifier does not agree with equilibriumcalculations. However, the agreement for the main components (CO, CO2 and H2) becomes very good if theCH4 and H2S concentrations are prescribed in the equilibrium code.The impurities present in the syngas were also investigated, the observation being made that the particlecontent in the gas after cooling was very low, and the only significant trace elements were Cl and N.A theoretical model for the gasifier has been implemented in the commercial CFD code Ansys-CFX. Theresults of the code agree well with the experiments for the major components in the gas, while the CH4concentration is under-predicted. A separate analysis with an equilibrium code (Factsage) shows that theCH4 content at equilibrium, under experimental conditions is very low, which agrees with the CFD code butdisagrees with the experiments. The reason for the disagreement between the experiments and the theoreticalmodels is assumed to be the limiting kinetics for CH4 conversion. A first approximation of the kinetics wasimplemented in the CFD code, which resulted in a very good agreement with the experiments.
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