Rotor for pressurized hydrodynamic purification of paper pulp and equipment fitted with this rotor

Equipment for the hydrodynamic purification of paper pulp comprising a closed tank 1, 25 containing at least one cylindrical, stationary screen 5, 29 separating two chambers, and a rotor 7, 31 coaxial (6, 30) with the screen, characterized in that the rotor further comprises a generally cylindrical case extending along a longitudinal axis of rotational 6, 30 and comprising a sequence of n identical elements 8, 80 located side-by-side along the longitudinal axis 6, each 8, 80 being cylindrical, a side wall of each element 8, 80 having a step 14, 37, said step forming a base edge 12, 35 and a top edge 13, 36, on either side of the step, the side wall gradually spirally winding around the longitudinal axis 6, 30 over at least 360.degree. from said top edge to said base edge such that the distance between the screen and side wall increases gradually from said top edge to said base edge, the base edge 12, 35 and the top edge 13, 36 of the step subtending a very small angle .OMEGA. with said longitudinal axis in such manner that the step 14, 37 slopes toward the surface of the screen 5, 29, an angle .alpha. of this slope relative to a radial plane 15, 38 extending through the base of the step to the axis, being between 5.degree. and 80.degree., the elements 8, 80 being mutually rotationally offset about the axis 6, 30 by an angle .beta. measured between the radial planes of adjacent elements, the angle .beta. of a magnitude of at least 360.degree./n, where n is at least 3.

A centripetal rotor for the pressurized hydrodynamic purification of paper pulp from old papers in known purification equipment using a cylindrical screen, comprising:

• a generally cylindrical case extending along a longitudinal axis of rotation 30 and comprising a sequence of n identical elements 80 located side-by-side along the longitudinal axis 30, each element 80 being cylindrical, an inner side wall 34 of each element 8, 80 having a step 37, said step forming a base edge 35 and a top edge 36, on either side of the step, the side wall gradually spirally winding around the longitudinal axis 30 over at least 360.degree. from said top edge to said base edge such that the distance between the screen and side wall increases gradually from said top edge to said base edge, the base edge 35 and the top edge 36 of the step subtending a very small angle .OMEGA. with said longitudinal axis in such manner that the step side 37 slopes toward the surface of the screen 29, an angle .alpha. of this slope relative to a radial plane 38 extending through the base of the step to the axis, being between 5.degree. and 80.degree., the elements 80 being mutually rotationally offset about the axis 30 by an angle .alpha. measured between the radial planes of adjacent elements, the angle .beta. of a magnitude of at least 360.degree./n, where n is at least 3, an outer body wall 33 of the tubular body being cylindrical and of circular cross section.