Apparatus for washing cellulose with a rotary drum

Abstract

An apparatus for washing cellulose, wherein the cellulose is conducted through between a rotary drum and a stationary shell encircling it, in the form of a layer supported by the permeable mantle surface of the drum. The principle of operation of the apparatus is: conducting washing liquid through the shell, through compartments located under the mantle surface of the drum and serving as washing liquid collectors, and through a valve system composed of a rotary part associated with the drum and a stationary part placed thereagainst, several times through the cellulose layer so that when the apparatus is operating the washing liquid at the same time moves in the direction opposite to the direction of rotation of the drum, stepwise, through the apparatus. It is essential in the invention that the valve system is composed of annular parts located at one end of the drum, their radius substantially equalling that radius on which the compartments under the mantle surface of the drum are located from the shaft of the drum, and that the part of the valve system rotating along with the drum comprises an aperture by which the ends of the compartments are joined to the valve system. By this design, the delay occurring in the washing liquid transfer has been reduced and the controllability of the washing process has been improved.