Metod för förgasning av svartlut i sodapannor

摘要

Black liquor is burned in a recovery boiler having upper and lower furnace portions with multiple combustion air levels. The black liquor is sprayed in above the lower furnace level. Oxygen enriched air is added into the lower furnace at least one level below the black liquor sprays to create improved reducing conditions in said lower furnace. Some combustion air from the lower furnace is redistributed into the upper furnace to significantly reduce the upward gas velocity below the black liquor sprays. Reducing conditions in the lower furnace are optimized at a controlled temperature to improve emissions control. Preferred Features: The oxygen enriched air also reduces power requirements and the lower gas velocity limits carry over allowing the burning of more black liquor. In a new recovery boiler, a higher specific capacity can be achieved with lower noxious emissions. Oxygen enriched air may also be added to the upper furnace section to improve reburning conditions and limit NOx production while reducing outlet gas velocities.