The gasification of black liquor has the potential to both reduce the capital costs of chemical recovery equipment and provide additional electrical power to the mill. IPST is supporting development of gasification processes for black liquor through its research programs. We have commissioned a pressurized gasification pilot plant to study important technical issues related to black liquor gasification. These include the impact of pressure on gasification rates; the problems associated with residual tar and condensable organic matter in the product gas; the forms of sodium and sulfur in the gasifier products; the fate of the minor species such as potassium, chloride, and nitrogen; and the evaluation of materials for black liquor gasifiers. Our new pilot plant is capable of processing black liquor solids continuously, at pressures to 80 bar (1200 psi) and temperatures to 1500°C (2700°F). Work is now under way to evaluate the impact of pressure on residual tar and condensable organic matter and on sulfur gas species in the product gas.

Another gasification study deals with catalytic destruction of tar and condensable organic matter from black liquor gasifiers. This work has shown that cyclic and heterocyclic organic compounds, such as benzene and anthracene, are present in the product gas from black liquor gasification at temperatures at least to 1100°C. Catalysts for thermal degradation of these compounds are being evaluated. Promising catalysts will be evaluated at the pilot level at a commercial black liquor gasifier site.