PRESS DIFFUSION CONTROLLER

Cellulosic pulp is treated to obtain simultaneous pulp flow and consistency control, utilizing a pressure-tight vessel (10) having a pulp inlet (12), pulp outlet (13), treatment liquid inlet (26), liquid extraction outlet (17), and movable screen (18) adjacent the liquid outlet (17). Pulp is fed into the pulp inlet (12) at a particular flow rate, and treated pulp is withdrawn through the pulp outlet (13) at a particular flow rate. The flow rate of the pulp being withdrawn is set and controlled by controlling the flow rate of the pulp fed into the pulp inlet (12). Liquid is withdrawn through the liquid outlet (17) at a particular flow rate, and the consistency of the pulp being withdrawn through the pulp outlet (13) is set and controlled by controlling the flow rate of liquid from the liquid outlet (17). Treatment liquid is fed into the liquid inlet (26), the nature of the pulp treatment and the qualities of the pulp being controlled by controlling the temperature and chemical makeup of the pulp introduced into the liquid inlet (26). A plurality of vessels (10, 10 min , 10 sec ) may be provided with the pulp withdrawn from each vessel fed to the subsequent vessel, and the liquid withdrawn from each vessel fed to the preceding vessel.