Miscible liquids flow through a pulp fiber bed

The paper discusses displacement washing of kraft pulp, as part of miscible-displacement processes. If dissimilar miscible liquids are flowing through the porous fibre pad. dispersion is larger than that due to diffusion alone. For polyacrylamide solutions exhibiting slightly shear-thinning behaviour and for the water used as washing liquids. the influence of the wash liquid velocity, as well as mobility of displacing and displaced liquids on the longitudinal dispersion coefficient affecting washing efficiency was investigated. The presence of high molecular mass polyacrylamides in the washing liquid influenced the washing yield. as a function of polyacrylamides' ionicity. as Well as on the washing liquid's mobility.