Black liquor, a biomass-based fuel formed in the papermaking process has traditionally been burned in recovery boilers to generate steam and electricity and recover the inorganic chemicals. Pressurized black liquor gasification offers an attractive alternative to the recovery boiler that has the potential to add a net electrical power of the order of 1000 MW to the Swedish power grid at full integration. Chemrec AB, one of the leading actors has developed an entrained down flow reactor. A development plant has been designed and is to be taken into operation during 2004, At the laboratory of Energy Technology Centre (ETC) in Pitea, Sweden. The plant will operate at 30 bar (a) and 30 tons/day black liquor will be gasified. The entrained flow reactor consists of two parts. In the gasification reactor black liquor is supplied together with an oxidant. Combustible fuel gases and inorganic smelt is formed. The smelt and fuel gases are transported to the quench cooler in the lower part where it is rapidly cooled by spray nozzles. The smelt is separated from the fuel gases by gravitation. At LTU a CFD model of the quench has been developed using the commercial code FLUENT 6. The simulations were performed in steady state using the segregated solver. A non structured mesh with approximately 48000 cells was used in the study. The results show that the model is predicting the flow pattern, velocity field and temperature field. The separation of smelt from the gas flow shows that droplets larger then 100 μm will be collected in the bottom of the quench but smaller droplets will travel with the gas flow to the quench outlet. Further work is required in order to make the model more complete. Radiation needs to be included as well as important chemical reactions. The model also needs to be validated against measurement data when the development plant is in operation.