shaking arm s to the sloped sidewall 30 may reduce the components and especially moving components in the vessel further combining the agitator and anti compression ring reduces the mechanical components in contact with the material and thus reduces the components that might disrupt the flow of material through the vessel fig3 shows an exemplary discharge device 36 formed in a lower portion of the vessel in which the sidewall transitions from a cylindrical wall to a wall having a one dimensional convergence and side relief such that a diamond shaped indention is formed on opposite sides of the discharge device the discharge device 36 may comprise horizontal feed screws 38 mounted adjacent the bottom of the discharge device a discharge device 36 in a bottom section of the vessel may be a flow promotion device such as described in u s pat nos 5 500 083 5 628 873 and 5 617 975 as an alternative to a horizontal feed screw a rotating scraper 40 that may be of conventional design may be arranged in a lower section of the vessel the scraper may push the cellulosic material to a central discharge point 42 at the bottom on the vessel a.