KRAFT COOKING WITH SPLIT SULFIDITY - A WAY TO BREAK THE YIELD BARRIER?

摘要

In recent years, a number of liquor making processes aimed atrnimproving both conventional and modified kraft cooking,rnhave been proposed. These innovations seek to produce tworn(or more) white liquors of chemical concentrations optimizedrnfor the different phases of the cook. The processes wouldrnenable the digester operator to feed the chips a hydrosulfiderichrnliquor early in the cook, followed by a hydrosufide-leanrn(or an alkali-rich liquor, or liquors), later in the cook.rnThe results of laboratory and other work aimed at elucidatingrnthe effects of this improved cooking regime for a variety ofrnbase kraft cooking technologies are reviewed. Specifically,rnthe effect on cooking selectivity, wood yield, and pulprnstrength are covered. The proposed liquor makingrntechnologies are described in conceptual terms and practicalrnprocess options, for integrating the new processes with arnvariety of conventional and modified pulping systems, arernoutlined.