Abstract: A cylindrical screen within which rotates a rotor fitted with means causing pressure variations and/or turbulence. The rotor (1) consists of one or several cylindrical surface segments (2) which when geometrically developed are right triangles of which the two perpendicular sides (3, 4) resp. correspond to the cylinder base (3) and to the height (4) and of which the oblique side (5) constitutes the hypothenuse.

Abstract: The invention concerns a rotor for the pressurized, hydrodynamic purification of paper pulp from old papers in known purifying equipment comprising a cylindrical screen, characterized in that it comprises a generally cylindrical case extending along a longitudinal axis of rotation 6 and comprising a sequence of n identical elements 8 arrayed side-by-side along the longitudinal axis 6, the screen-side wall evincing a shoulder 14 on either side of which it winds spirally around the longitudinal axis over at least 360.degree., the base and the top of the shoulder subtending a very slight angular gap .OMEGA. relative to said axis in such manner that the shoulder side 14 slopes toward the screen surface, the slope angle .alpha. relative to the radial plane through the shoulder base being between 5 and 80.degree., the elements 8 being mutually shifted in the direction of rotation around the axis 6 by an angle .beta. with a magnitude of at least 360.degree./n, where n is at least 3.

Abstract: Good deinking of waste paper can be obtained at high consistency by first pulping at high pH, then lowering the pH, adding alkaline cellulase and letting the cellulase act during continued pulping and/or maceration. The improved deinking results in higher whiteness and better cleanliness (fewer ink particles) in paper made from the treated pulp after separation of ink particles. This cellulase treatment results in better operation of certain equipment such as thickeners and in better drainage of the pulp during paper making.

Abstract: Cylindrical sieve for paper pulp strainer of the type of thin sheetmetal is formed by juxtaposition of U-shaped sectional elements (2) made from a metal strip. The element (2) has a first flange (3), a bottom (4), followed by a second flange (5) bent over toward the exterior of the U-shaped element on itself so as to define a space (6) in the fold thus formed, intended to receive and hold the first flange (3') of the adjacent element (2'). The base of the U-shaped element is pricked to form depressions or slots.

Abstract: Process of making and mounting an end rim of a cylindrical sieve (1) for paper pulp strainer and classifier characterized by the fact that the rim is of one piece, molded directly on the end of the cylinder with a hardenable or thermosetting plastic material.

Abstract: The device comprises a closed chamber (1) equipped with an inlet pipe (3) for the aerated liquid, an outlet pipe (4) for the deaerated liquid, and an air evacuation pipe (5); and a rotor having a shaft extending into the chamber. The shaft carries means (7) for centrifugation of the liquid and means (8,9,10) for intensive agitation of the centrifuged liquid.The device works according to the following process: continuously, the liquid is introduced into the closed chamber and it is vigorously centrifuged there in with the aid of mechanical means (7) and simultaneously subjected to intensive agitation with the aid of second mechanical means (8,9,10).The released air gathers freely at the center of the chamber whence it is evacuated, as the deaereated liquid is evacuated through the outlet pipe.

Abstract: Sieve for paper pulp strainer and classifier of the kind formed by the juxtaposition of elements of U-shaped cross section comprising a perforated flat bottom (2) and two sidewalls (3) characterized in that the elements (1) of U-shaped cross section are disposed so as to form a notable cylindrical revolving wall, provided with slots or holes, whether or not associated with grooves and bars (obstacles).

Abstract: A screening device is provided with a screening element having a plurality of perforations going therethrough. Each perforation has an inlet and an outlet.The screen element includes a plurality of step-type obstacle members positioned in the vicinity of the inlets of the perforations to produce turbulence in a flow of a fluid passing through the perforations. Each obstacle member has a shielding member positioned substantially above the inlet so that a gap is defined between the shielding member and the screening element. The shielding element extending over the inlet of the perforation forms an entry baffle above the outlet.At least one blade having a hydrodynamic profile rotates at high speed above the shielding element.

Abstract: The invention relates to a multiple liquid injector composed of several identical elementary injection tubes 2, disposed in a rim around a central tube. Each tube 2 has an inlet conduit 3, itself comprising a converging truncated cone 6 and a cylinder 7, followed by an aeration zone 4 comprising an aeration chamber 8 fed tangentially by a conduit 9 perpendicular to the tubes 2, a jet centering funnel 10, followed by mixing cylinder 11, and lastly a diverging outlet conduit 12.

Abstract: A valve arrangement has an outflow seat section defined by at least a tubular side wall. The outflow seat section has a free end with an engaging part extending along the entire periphery of the side wall. The engaging part is adapted for close engagement with an engaging surface of a movable obturating plate. The engaging surface is substantially parallel to a plane of the engaging part and remains substantially parallel to this plane during movement of the obturating plate toward and from the free end of the outflow seat section. During operation of the valve arrangement the engaging surface of the obturating plate simultaneously engages the entire plane of the engaging part of the outflow seat section causing closing of the valve arrangement.

Abstract: The aeration of dispersions, especially the aeration of fiber suspensions in a flotation apparatus 1, is performed with a ring injector 2 to which air is delivered through air feed ducts 11 in the mixing section 4. The annular gap forming in the ring injector 2 is thus aerated inside and out. The center core 7, which tapers in the direction of the greatest free cross section Q4 of the ring injector 2, is provided with a fin 56 which prevents the rotation of the dispersion.