REFRACTORIES FOR BLACK LIQUOR GASIFICATION

Improved alkali resistant refractories are needed for biomass and black liquorgasification (bblc) . one particular ly harsh application is linings for gasifiers used in thetreatment of black liquor (bl). bla ck liquor is a water solution ofthe non-cellulose portion of thewood (mainly lignin) and the spent pulping chemicals (na]coj. k]coj. and na]s). developmentofnew refractory materials for the black liquor gasification (blc) application is a critical issuefor implementation of this technology. factsage® thermodynamic sof tware was used to analyzethe phas es present in bl smelt and to predict the interaction of bl smelt with different refractorycompounds. the modeling included prediction of the phases f ormed under the operatingconditions of high temperature black liquor gasification (blc) process. at the operatingtemperature ofthe blg. factsage® predicted that the water would evaporate from the bl and thatthe organic portion of bl would combust. leaving a black liquor smelt composed of sodiumcarbonate (70-75%). potassium carbonate (2-5%). and sodium sulfide (20-25%). exposure ofaluminosilicates to this smelt leads to significant corrosion due to f ormat ion of expansive phaseswith subsequent cracking and spalling. oxides (21'0]. ceo]. la]o;. yeo}. li]o. mgo and cao)were determined to be resistant to black liquor smelt but non-oxides (sic and si jn4) would oxidizeand dissolve in the smelt. the other candidates such as mgai]04 and baai]04 were resistant tosodium carbonate but not to potassium carbonate. liaio] was stable with both sodium carbonateand potassium carbonate. candidate materials selected on the basis of the thermodynamiccalculations are being tested by sessile drop test for corrosion resistance to molten black liquorsmelt . sessile drop testing has confirmed the thermodynamic predi ctions fo r ai]oj. ceo]. mgoand cao. sessile drop testing showed that the thermodynamic predictions were incorrect for 21'0].