(57) Pulping apparatus for pulping high consistency paper pulp includes a tub 10 having
a bottom wall 13 and a generally cylindrical side wall 14 extending upwardly therefrom,
and a rotor 20 mounted centrally of the bottom wall for rotation about a vertical
axis and having a hub portion 21, a plurality of vanes 22 extending generally radially
outwardly from the hub and having pumping 27 and defibering faces 26 thereon, and
a plurality of helical screw flights 33 extending upwardly from the hub. Each flight 33 has
a concave undersurface 44 such that rotation of the rotor in the presence of high
consistency pulp causes the screw flights to draw pulp inwardly toward the axis of
rotation and push it downwardly to the defibering faces 26 of the vanes 22, and the
outer surface of each flight 45 being convexly curved and of substantially greater
surface area than its undersurface to provide an air foil effect further tending to
draw pulp into the path of the undersurface of the following flight. The screw flights
33 preferably include trailing portions 35 having raised peripheral ridges 40 extending
upwardly therefrom to prevent stock from flowing outwardly from the rotor until it
reaches the vicinity of the vanes. The trailing portions 35 of the screw flights 33
preferably have a width, measured in a radial direction, which is substantially the
same as the length of the vanes 22 such that pulp can be pushed downwardly and outwardly
into the entire path of the working faces 26-27 of the vanes.
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