| 摘要 |
The invention relates to an improved two vessel cooking system, wherein the first vessel is an atmospheric impregnation vessel and the second vessel is a pressurized digester, where hot black liquor is finally flashed off inside the impregnation vessel for steaming the cellulosic material and providing the impregnation liquor. According to the inventive method is an additional cleaner wash liquor heated and added to final cook zone in digester, while displacing a corresponding amount of hot black liquor before the final cook zone, and the heat value in the hot black liquor is recovered first in transport circulation before being used as source for flashing off steam used to steam the comminuted cellulosic material inside the impregnation liquor and final use as impregnation liquor. The invention results in a cooking process with high yield and improved delignification in final cooking phases and reduced COD content in the produced pulp without increasing steam consumption. |
