ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Displacement of Black Liquor from Pulp Bed

F. Potůček and M. Pulcer

Department of Wood, Pulp, and Paper, Faculty of Chemical Technology, University of Pardubice, CZ-532 10 Pardubice

E-mail: Frantisek.Potucek@upce.cz

Received: 11 March 2004

Abstract: Brownstock washing was simulated using a laboratory displacement washing cell. The displacement of black liquor from the kraft pulp bed was described by the dispersion flow model containing one dimensionless parameter, the Peclet number, for alkali lignin and sodium as the tracers. To characterize washing operation, the traditional wash yield, dispersion coefficient, mean residence time of both solutes, as well as the holding time of wash liquid were evaluated. With respect to various size of lignin fragmented in black liquor and sodium ions, the rate of leaching from within the fibres is different for both solutes. Therefore, the displacement washing efficiency should be expressed not only by the traditional wash yield, but also by the amount of both solutes washed out at the wash liquor ratio equal to unity, and the total amounts removed during washing operation must be taken into account as well.

Full paper in Portable Document Format: 586a377.pdf

Chemical Papers 58 (6) 377–381 (2004)