Method for distributing cellulosic pulp through a reactor at a constant upward velocity

A method for the chemical treatment of cellulosic pulp comprising:

• (a) introducing a mixture of untreated cellulosic pulp and one or more treatment chemicals axially into a frusto-conical bottom chamber connected to a vertical, cylindrical reactor vessel, wherein said chamber has an inner wall and contains a distributor comprising a cone located coaxially therein, wherein the vertex of said cone is oriented downward;
• (b) passing said mixture through the volume between said cone and the inner wall of said bottom chamber and distributing said mixture into said reactor vessel, thereby promoting flow of said mixture upward through said vessel at a constant velocity;
• (c) reacting said pulp with said treatment chemicals while said mixture flows upward through said reactor;
• and
• (d) withdrawing treated cellulosic pulp from the upper end of said reactor vessel;
• wherein all the components in said reactor are static and immobile during the introduction and distribution of the mixture, and during chemical treatment of the mixture.