BATCH PROCESS FOR PREPARING KRAFT PULP

摘要

Methods for discharging spent cooking liquors from a batch digester containing cooked lignocellulose- containing material in spent cooking liquor are disclosed, including supplying a first portion of washing liquid to the digester to displace a first portion of the spent cooking liquor at a temperature and dry solids content which substantially corresponds to the temperature and dry solids content of the spent cooking liquor at the end of the batch digestion, supplying a second portion of washing liquid to the digester to displace a second portion of the spent cooking liquor having a temperature and dry solids content substantially lower than that of the spent cooking liquor in the digester, and maintaining the first and second portions of spent cooking liquor separate from each other. Methods of producing kraft pulp in batch digesting processes using this method are also disclosed.