Kraft Black Liquor Steam Gasification with Direct Causticization

Abstract:

Steam gasification of kraft black liquor char was performed at 860℃ in a tube furnace with direct causticization using anatase titanium dioxide and recycled sodium tri-titanate. The organic carbon in the black liquor char could be completely gasified within 6 min, approximately equal to the complete conversion time of sodium carbonate in black liquor char to sodium penta-titanate at these conditions, and the generated dry gas had a high heating value of nearly 10MJ/m3. The main component of solid product was sodium penta-titanate, and the sodium tri-titanate recycled from hydrolysis of sodium penta-titanate had satisfactory reactivity compared to fresh titanium dioxide. No agglomeration of solid product was observed through the process of reactions. About 20% of total sulfur in black liquor retained in the gasified residual solid in the form of non-reduced state.