Method of decreasing black liquor viscosity

摘要

A method of decreasing the viscosity and improving the evaporability of sulfate black liquor from the cellulose cook includes raising the temperature of the black liquor above the cooking temperature so as to split the macro-molecular lignin fraction contained in the liquor. The temperature of the black liquor is maintained at the raised level for 1 to 60 minutes, preferably for 1 to 5 minutes.