Abstract: A screening apparatus is disclosed having at least one housing attachment element and a main housing element, each of which has a hollow cylindrical and/or truncated-cone-shaped housing outer wall. The apparatus includes at least two coaxial, predominantly rotationally symmetrical screen baskets and a rotor having pulsation elements. An accepts chamber is disposed radially outside the screen baskets and the rotor and pulsation elements are disposed radially inside the screen baskets. An inlet of the housing is disposed centrally in the area between the screen baskets and an outlet channel allowing for access in the area between the two screen baskets. The invention is characterized in that at least in the area of the screen baskets, only one main housing element and one attachment element are provided and that the first screen basket is disposed in the attachment element and the second screen basket is disposed in the main housing element.

Abstract: A hydrodynamic device for generating negative pressure excursions in a pulp slurry during fine screening, includes at least one half-foil member disposed on a substantially cylindrical outer surface of a rotor. The rotor is mounted within and co-axial with a substantially cylindrical screen having a circumferentially continuous apertured zone to define an annular screening chamber between the rotor and the screen. The half-foil member is collectively at least axially co-extensive with the apertured zone and has a leading edge which, also collectively, is inclined at a spiral angle relative to the axis of the rotor such that, in one embodiment, during rotation, the leading edge of the half-foil member conducts large particles downwardly through the screening chamber. A selection of hydrodynamic foil configurations is provided in order to adapt to a wide range of pulp types and screening conditions.

Abstract: A fibre suspension is separated by a filter device having a hollow filter body (1) with a wall (2) of filter material, and a container (3). The entire fibre suspension to be separated is sprayed in the form of at least one liquid jet onto said wall (2) to force a fine fraction of the suspension containing most of said undesired particles through said wall of filter material into the hollow filter body, thereby leaving a created coarse fraction of the fibre suspension mainly containing fibres in the container outside the filter body. Relative displacement between the liquid jet and the filter material is provided. Said created coarse fraction is dewatered through the wall of filter material, and said dewatered coarse fraction is discharged from the container.

Abstract: A device for screening pulp suspensions includes a cylindric housing (1) with inject inlet (2), reject outlet (3) and accept outlet (4) and screening members in the form of a stator (5) and a rotor (8). The stator (5) as well as the rotor (8) include a plurality of annular elements (6 and 9, respectively), which are arranged in a mutual spaced relationship. The rotor (8) is located radially outside the stator (5), so that the rotor elements (9) are located directly in front of the spaces between the stator elements (6), and the axial length of the rotor elements is greater than the spaces between the stator elements. Thereby gaps (11) are formed between the stator elements and rotor elements.

Abstract: A manure separating apparatus includes a trough with angularly bottom surfaces that converge downwardly to a discharge opening. A drain screen is located above the bottom trough surfaces and includes somewhat similarly angled downward converging infeed and discharge surfaces. The infeed section of the drain screen is approximately twice as long and at a smaller angle to the horizontal than the discharge screen section. A manure/liquid slurry may be introduced at a top infeed end of the screen and moved downwardly along the infeed section of the screen by a paddle conveyor. Separation of solids occurs primarily along the infeed screen section. The slurry is then moved angularly upwardly along the discharge section of the screen for final dewatering. The discharge section is spaced above the trough bottom to avoid liquids on the trough bottom below to facilitate dewatering of the solids before discharge.

Abstract: In a screen for pressure sorters for fiber suspensions which is of rotationally symmetrical shape in relation to a screen axis and the screen wall of which is provided with screen opening channels connecting the screen inlet side with the screen outlet side and on its inlet and outlet sides with recesses into which the screen opening channels open, in order to improve the throughput capacity of the screen, to simplify its manufacture, to achieve good fatigue strength of the screen and to generate turbulences at the screen inlet side, each of the recesses on the inlet side extends over several screen opening channels and is in the form of a groove extending transversely to the circumferential direction of the screen, a recess is provided for each screen opening channel on the screen outlet side, and the largest width of the recesses on the outlet side is at least as large as the largest width of the grooves on the inlet side.

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: A pressure sorter for a suspension flow includes a cylindrical housing having at least one inlet opening and at least one outlet opening with a defined pressure drop therebetween. A rotationally symmetric screen basket defining an axis is disposed within the housing. The screen basket has a plurality of openings defining a total screen perforation passage area. The axis of the screen basket is positioned offset a distance of 6 to 12% of the diameter of the screen basket. The axis of the screen basket is disposed in a plane which extends through the housing axis and is perpendicular to the housing outlet opening. A rotor and suspension sorting space are disposed centrically within the screen basket. An accepts space is disposed radially outward of the screen basket between the screen basket and the housing.

Abstract: This invention relates to a screen separator for separating metal adsorbent particles from a pulp and includes a screen separator for separating metal adsorbent particles from a pulp including an open topped and closed bottom cylindrical screen for axially vertical location, in use, in a tank containing pulp with the open top of the screen at or adjacent the full pulp surface level in the tank, an impeller which is located in the screen with its axis of rotation vertical, drive means, and a drive shaft connecting the drive means to the impeller with the impeller being adapted to drive pulp in the screen upwardly to a level above the surface level of the full pulp level in the tank when the impeller is rotated in the screen. The invention further extends to a method of separating the particles from the pulp by means of the separator and to a metal recover process which employs the separation method.

Abstract: Devices for screening pulp suspensions are disclosed including a cylindrical screen extending longitudinally within a housing, an inlet for feeding the pulp suspension into the interior of the cylindrical screen, an accept outlet for removing the accept portion of the pulp suspension after it has passed through the cylindrical screen, a reject outlet for removing a reject portion of the pulp suspension at the opposite end of the cylindrical screen with respect to the inlet, and a rotor concentrically positioned for rotation within the cylindrical screen such that an annular screen chamber is created between the rotor and the screen, the rotor including wings extending from its exterior such that the wings have a length circumferentially with respect to the rotor which ranges from about 2:1 to about 6:1 with respect to the distance between the rotor and the screen, and the leading edges of the wings being separated a greater distance from the rotor than the trailing edges of the wings.

Abstract: An apparatus and method for treating fiber suspension is especially applicable for pulp screening in the wood processing industry, particularly for the separation of light particles from fiber suspensions. The apparatus comprises an outer casing with conduits for inlet pulp, accepts, heavier rejects and lighter rejects; a filter cylinder and a rotor, the surface of which is provided with at least one protrusion; and an opening for guiding the light rejects through the surface of the rotor.

Abstract: Screening apparatus for separately removing knots and heavy reject particles from paper making stock comprises a generally cylindrical vertical housing having the interior thereof separated by a cylindrical perforated screening member into an annular screening chamber and an accepts space on the outer and inner sides of the screening cylinder respectively. Separate outlets for light and heavy reject particles are located at the top and bottom of the screening chamber, the supply flow of feed stock enters the screening chamber at the bottom thereof, and special provision is made to insure that maximum separation of the knots and other lighter reject particles from the heavy reject materials will be effected within the screening chamber with minimum contact with the screening cylinder itself.

Abstract: The invention concerns a sorter with at least two screen baskets in a housing unit. The invention is characterized in that with screen basket diameters of at least 600 mm the at least two screen baskets are contained side by side, spaced, in an arrangement such that their longitudinal center axes extend parallel to each other and their end sides or end surfaces are contained each in identical planes extending perpendicularly to the longitudinal center axes of the screen baskets.

Abstract: A self-cleaning filter comprises a filter element in a housing. A cleaning unit, movable with respect to the filter element, removes filtered-out solids from the upstream face of the filter element. The cleaning unit includes an axially movable cleaning element engageable with the filter element.

Abstract: An apparatus for screening pulp comprises a vessel, a cylindrical screen within the vessel, a rotor moving in the vicinity of the screen at a predetermined speed, an inlet for the unscreened pulp, an outlet for the screened pulp in the vessel. The rotor is non-cylindrical, for instance, elliptical, triangular, and in general, is multi-cam. The rotor has a contour surface which is achieved by attaching bars of the contoured shape to the surface of the rotor, for instance by welding. According to one embodiment, the contour surface of the rotor is discontinuous. The bars form a plurality of spaced protrusions instead of a single protrusion along the entire axial length of the rotor.

Abstract: A cylindrical element for filtering various substances and separating particles therefrom is shown wherein a wire is cylindrically wound in the form of a helix to form a helical slit between the adjoining peripheral margins of the wire thereby increasing to the maximum the area for filtering or separation treatment. The helical slit forms a linear treatment hole with improved filtering and separation deficiency. The cylindrically wound wire may be supported by actually extending support members having grooves therein or by cylindrically-shaped support members having openings of various sizes and shapes. An embodiment of the invention wherein the cylindrical element is mounted in a pipe is also shown.

Abstract: Screening apparatus for paper making stock comprises a generally cylindrical vertical housing having the interior thereof separated by a cylindrical perforated screening member into a screening chamber and an annular accepts chamber on the inner and outer sides of the screening cylinder respectively. The feed stock enters an inlet chamber below the screening chamber tangentially, and special provision is made for preventing heavy reject particles from circulating around the bottom of the inlet chamber. For this purpose, the inlet chamber is provided at a position spaced circumferentially downstream from the inlet port, with an outlet port into which high specific gravity particles are carried by centrifugal force along with the carrying liquid. A conduit leads from this outlet port back to the inlet chamber in order to maintain a continuous flow through this conduit.

Abstract: Rotor for pressure sorters for sorting fibrous suspensions, comprising a plurality of cleaning vanes provided for the circulation on the inlet side of a screen cylinder of the pressure sorter, these vanes being designed in sections as return regions and in sections as supply regions; the return regions are designed such that they urge the fibrous suspension portions adjacent the screen inlet side away from the screen cylinder, whereupon these fibrous suspension portions are diverted by the supply regions of the cleaning vanes towards the screen inlet side and fed back to the latter.

Abstract: A method and apparatus for treating a fiber suspension to thicken or screen it. The suspension is fed to the gap between a filter surface and a counter member, and accepts flow through openings in the filter surface. Rejects continue along the filter surface to a rejects outlet. Relative movement, preferably relative rotation, is effected between the filter surface and counter member. The suspension at the filter surface is coarser and/or of higher solids concentration than the accepts. This coarser suspension is subjected to a force component by a protrusion on the counter member surface that tends to move it away from the filter surface, in a guided manner (between the protrusion and a guide plate). A second protrusion in the form of a backwardly inclined plate forces fresh suspension toward the filter surface to take the place of the suspension just moved away from the surface.

Abstract: A backwash strainer including a body, a strainer element having an inlet side contained in the body, and a space defined between the body and the strainer element. The body includes an inlet to the strainer element and an outlet from the annular space. A nozzle for directing cleaning fluid against the inlet side of the strainer element for dislodging particulate matter from the inlet side of the strainer element mounts to the body. A backwash arm for collecting the cleaning fluid and dislodging particulate matter mounts to the body. The backwash arm is positioned adjacent to and is in close proximity to the inlet side of the strainer element and the nozzle. The backwash arm has an axially extending slot defined by two spaced members having ends positioned adjacent to the nozzle. The backwash arm and the nozzle together may be moveable about a central axis relative to the strainer element.

Abstract: An apparatus for screening pulp comprises a vessel, a cylindrical screen within the vessel, a cylindrical rotor moving in the vicinity of the screen at a predetermined speed, an inlet for the unscreened pulp, an outlet for the screened pulp in the vessel. The rotor has a contour surface which is achieved by means of a plurality of protrusions of contoured shape on the surface of the rotor, for instance by welding. The protrusions are spaced and are arranged along the entire axial length of the rotor.

Abstract: The invention relates to a method and a device for screening and treating pulp. In the invention, the pulp is screened in a screen into an accepted fraction and a rejected fraction, the rejected fraction being treated after the screening by removing water from it. In order to reduce the energy consumption of the refining process, the rejected pulp fraction is screened by means of a means (13) rotating rapidly in a reject space (12) of a screen (1) in such a manner that the rapidly rotating means (13) effects a radial flow of the fine-grained material contained in the rejected fraction outwards through a perforated wall (14) surrounding the rotating means (13) into a space (15, 15a) from where the fine-grained material is discharged.

Abstract: A portable pressure screen apparatus is disclosed having a cylindrical shaped pressure housing defining upper and lower hingedly connected halves. The housing includes a slurry inlet aperture raised relative to a filtered slurry discharge port situated at the opposite end of the pressure housing from the slurry inlet aperture. A screen spans the interior of the housing, separating the interior into an upper chamber and a lower chamber. Collected particulate matter from the slurry inlet aperture is accumulated in the upper chamber and slurry filtered through the screen leaves the interior of the housing through the filtered slurry discharge port connected to the lower chamber. A support frame is employed to adjustably support the housing in a generally angled attitude relative to the horizontal.

Abstract: An improved screen plate for a pressure screening apparatus and a method for making the basket are disclosed wherein prestressed areas are provided at each end of each slot formed in the screen plate for minimizing crack propagation.

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: An improved apparatus and process for fractionating pulp suspensions consists of multiple interchangeable modular treating compartments stacked atop one another. Pulp suspension is fractionated in the first compartment, and one of the two resulting fractions flows gravitationally to a second compartment where it is fractionated further. Any of the resulting fractions may be fractionated still further in subsequent compartments as many times as desired. The treating compartments are interchangeable, so removal, addition, or replacement of compartments is relatively easy and quick. Fractionation in each compartment is carried out through centrifugal force.

Abstract: A method of treating a pulp suspension in a screening plant of a pulp mill wherein reject impurities are separated from defibered pulp by screening and/or cleaning, the cleaned pulp is thickened to a consistency of from about 10 to about 20%, the impurities are further treated in the screening plant by screening and defibering the accept fiber material for further screening and thickening and further reject impurities are removed from the screening plant after various screening stages, the method including effecting one or both of the pulp screening and cleaning stages in a closed, pressurized space in the screening plant and preventing the access of air to the pulp treated by effecting the thickening stages in a pressurized state and at the initial pressure of one or both of the preceding screening and cleaning stages.

Abstract: A high consistency pressure screen comprises a screen including a profiled inner surface and a rotor including a profiled outer surface rotating adjacent and spaced from the profiled screen to produce a positive-negative pulsation cycle of approximately 50%--50%.

Abstract: The invention relates to a method for controlling pressurized screening devices in which fiber pulp is fed to the pressurized screening device and is divided into the accepted portion of the fiber pulp passing through perforations of a cylindrical screenplate and the rejected portion which is removed from the screenplate, the perforated screenplate being treated by a device movable relative thereto and rotatable around the center axis of the screenplate, the fiber pulp being fed parallel with the center axis of the screenplate to baffle blade assembly comprising at least two baffle blades and also being rotatable around the center axis, wherein the speed of rotation of the baffle blade assembly and/or the radial dimension of the baffle blades are adjustable to control the screening. The invention additionally relates to pressurized screening devices for implementing the method.

Abstract: An apparatus, for pressurized screening of a fiber/liquid suspension to separate the fibrous fraction into an accepts portion and a rejects portion, has a housing having an inlet with a heavy and large material trap, an accepts outlet, a rejects outlet, and a dilution liquid inlet. A hollow cylindrical screen having an open top and bottom communicates with the fibrous suspension inlet chamber and the rejects outlet chamber. Accepts fibers in the suspension pass through apertures in the screen to the accepts chamber and are discharged through the accepts outlet. Rejects discharge through the rejects chamber. A rotor having at least four regions, a closed top, and a bottom mounted drive mechanism is coaxially mounted within the screen. Hydrodynamic pulses are induced in the suspension in the screening region by a pattern of bumps and/or depressions impressed upon the rotor surface.

Abstract: A rotor is disposed concentrically within a cylindrical screen. The rotor carries a plurality of blades in close proximity to the screen to produce hydrodynamic pulses opposing fluid flow to clear the screen. Each blade includes a first portion affixed to the rotor, this first portion including an inclined face and a substantially raidally extending face. A second portion of the blade is removably affixed to the radially extending face of the first portion. The removable second portion extends radially beyond the first portion. After the removable portion has become worn from extended use, it can be removed and replaced with a new second portion. In a preferred embodiment, the thickness of the second portion of the blade is equal to or greater than the diameter of holes in the screen. It is also preferred that the length of the second blade portion extending beyond the first portion be greater than the diameter of holes in the screen.

Abstract: A stock screening apparatus has a material supply port which communicates with a material supply passage, and a first discharge port which communicates with a first discharge passage. The first discharge passage is located within a downward projected image of the material supply passage. In consequence, the stock which flows into a primary chamber flows in a vortex along the periphery of the primary chamber, and the foreign materials contained in this vortex, such as stones or metals, can thus be discharged through the first discharge passage when they are moved to the first discharge port. Also, a rotary shaft of a drum-shaped rotary body is disposed horizontally. An opening of the portion of the primary chamber located downstream of the drum-shaped rotary body and that of the secondary chamber are closed by a cover.

Abstract: Apparatus for screening papermaking stock comprises two annular flat screening plates arranged in parallel spaced relation to form a screening chamber therebetween which is bounded on its outer periphery by a cylindrical wall, and wherein a rotor includes vane portions which extend into this screening chamber to agitate the stock so that particles of sufficiently small size can pass through the screening plates into annular compartments outside the screening plates from which they flow into a peripheral chamber having an outlet port. The screening chamber includes an annular space which is surrounded by the accepts chamber and is radially beyond the vane portions of the rotor wherein reject material collects for discharge through an outlet tube which extends through the accepts chamber to the outside of the apparatus.

Abstract: An apparatus for separating undesired particles from a suspension flow of pulp and for dividing the suspension flow into fractions is described. The apparatus comprises a housing having a first chamber with an inlet for the suspension flow and a first outlet for the undesired particles, a second chamber with a second outlet and communicating with the first chamber through a first annular gap, and a third chamber with a third outlet and communicating with the second chamber through a second annular gap, the radial extension of the second gap being less than that of the first gap. First and second rotating discs are carried by a shaft for common rotation therewith. The first disc is disposed in the first chamber in front of the first gap to separate the undesired particles by means of teeth protruding from the first disc.

Abstract: Pressure screening apparatus for paper making stock embodies a cylindrical perforated screening member which defines screening and accepts chambers on the inside and outside thereof respectively in a closed housing which is filled with liquid stock under pressure in operation. A rotor member which operates in the screening chamber to keep the screening perforations open is specially constructed to provide it with sufficient buoyancy to counterbalance its weight when the apparatus is in operation and the housing is therefore filled with liquid stock. In the preferred form, the housing is mounted with the rotor axis horizontal, but it can also be made with the rotor axis vertical.

Abstract: A cylindrical screening basket for sorting and classifying fiber suspensions includes a wall which has an inner wall surface facing the fiber suspension and is provided with screen openings which lead into grooves arranged at the inner wall surface. The grooves extend essentially parallel to each other and transversely to the flow direction of the fiber suspension and are arched to define a downstream flank and an upstream flank, with the downstream flank having a sharper curvature than the upstream flank.

Abstract: The invention relates to a method and a screening apparatus (1) for screening pulp. In the method, the maximum length of fibres and shives flowing through holes (4a) in a screen drum (4) is adjusted by moving blades (8) with a sharp front edge close to the surface of the screen drum (4) in such a manner that the sharp edge (8a) of the front face moving closest to the drum surface strikes shives or long fibers passing through the hole (4a) and pulls them back. The rate of travel of the blades (8) is so adjusted that the pulp flows in the hole (4a) only over a distance corresponding to the predetermined fiber length during the interval between the front edge of two successive blades (8). The screening apparatus (1) comprises blades (8) moving in parallel with the surface of the screen drum (4). The front edge of the blades defines in cross-section a sharp angle, the point of the angle defined by the front edge moving closest to the surface of the screen drum (4).

Abstract: Screen cylinders, and methods of making the same for use in removing contaminant particles from papermaking stock, have a seamless cylinder body and the openings or slots therethrough are formed by directing a focused laser beam at an outer surface while focusing the beam intermediate the outer an dinner surfaces to form an opening or slot with tapered walls. Wear bars may be applied to the inside surface as a bead of weld material. The seamless cylindrical body is formed by centrifugal casting or by cold roller extrusion.

Abstract: Aqueous slurries of particulate materials, particularly wood pulp slurries produced during the recycling of newsprint and other paper products, are processed to recover an accepts fraction in a rotary filter having a hollow cylindrical rotor. The rotor is modified to prevent plugging by outwardly tapering the inner wall of the rotor from its upstream towards a downstream end, so as to cause heavy particles tending to accumulate on the wall to flow towards the downstream end and not accumulate. At the downstream end, vane-like hub supports are provided angularly offset from the axis of the rotor to impart motion to the slurry passing through the rotor to assist in circulation of the slurry within the filter housing.

Abstract: A cylindrical screen member of a centrifugal pulp screen used in paper manufacturing is disclosed. The pulp is agitated and impelled to pass through a plurality of parallel radial through-holes of the screen member by the centrifugal force imparted by a rotor. Each through-hole of the screen member has a cross-section elongated in a direction transverse to a horizontal line and inclined at an angle with respect to a vertical line. The pulp particles can linearly pass through the through-holes and flow out through the screen member smoothly. Therefore, the likelihood of blockage is reduced, and the power necessary to drive the rotor is economized.

Abstract: An apparatus for screening a suspension of fibrous cellulose material containing undigested wood comprising a shaft rotating in a housing and an elongate screen disposed in a screening chamber. This screen comprises a stationary screening member and a rotating screening member connected to the shaft. Each of the screening members comprises a plurality of parallel rings disposed with predetermined axial distance from each other to form circumferential openings, the rings of the stationary screening member and the rotating screening member being arranged to partially close each other's openings between the rings to define circumferential screening gaps therebetween. According to the invention the stationary screening member is in the form of a unitary body rigidly connected to the housing so that at least circumferential movement is prevented. The rotating screening member is likewise in the form of a unitary body but it is connected to the shaft for common rotation therewith.

Abstract: The invention relates to a method and a device for screening and treating pulp. In the invention, the pulp is screened in a screen into an accepted fraction and a rejected fraction, the rejected fraction being treated after the screening by removing water from it. In order to reduce the energy consumption of the refining process, the rejected pulp fraction is screened by means of a means (13) rotating rapidly in a reject space (12) of a screen (1) in such a manner that the rapidly rotating means (13) effects a radial flow of the fine-grained material contained in the rejected fraction outwards through a perforated wall (14) surrounding the rotating means (13) into a space (15, 15a) from where the fine-grained material is discharged.

Abstract: The rotor of a sorter has a circumference which, in cross section perpendicular to the rotor axis of rotation, is essentially composed of circular arcs. Depending on sorter size, the number of circular arcs amounts to between two and eight. The eccentricity of the circular arcs relative to their center, based on the rotor axis of rotation, amounts to preferably between 4 and 10 mm. This makes it possible to obtain slight rotor stresses at a good sorting efficacy, preferably also with a mean substance density of more than 3% of fiber suspensions. The difference between the smallest and greatest rotor spacing e=f.sub.max -f.sub.min amounts to maximally 60 mm, preferably 20 mm.

Abstract: An improved efficiency screen plate for screening pulp in a pressure screening apparatus is disclosed wherein various design parameters are established which increase screen performance, particularly in screening medium consistency pulp. The basket is formed of thin, sheet-like material formed without machining into an undulating pattern. Undulation frequencies, slot location, turbulence bar frequency, and turbulence bar height are established for increasing screen performance.

Abstract: The pressurized screening device designed for screening fiber pulps, especially paper pulp is provided with a screenplate with perforations, cleaning members being in connection with and moving relative to the screenplate, devices for generating the relative motion between the screenplate and the cleaning members, piping firstly for introducing fiber pulp into the pressurized screening device, secondly for conducting the accepted fiber pulp into the next process stage and thirdly for discharging rejected pulp from the pressurized screening device preferably to be returned into the pressurized screening device, and guiding devices for shifting the flow direction of unscreened fiber pulp to a direction substantially perpendicular to the screenplate. The guiding devices include a combination of several compartments for guiding the flow of fiber pulp which are comprised of side walls, a back wall and baffle blades.

Abstract: A paper pulp screening apparatus wherein a modular cylindrically-shaped screen plate is formed of a thin material of uniform thickness bent to form an undulating shape to increase the screening area, and the screen plate is supported by cylindrical-backing members to give the plate strength, with the plate being formed into various complex shapes. Manufacturing methods for forming the undulating shapes are disclosed.

Abstract: A method for keeping a screen surface or a filter surface clean, wherein a pressure fluid is introduced from a conduit to a secondary side of a screen/filter drum, which fluid flows, during an underpressurized stage caused by blades of a rotor rotating on a primary side of the screen/filter drum, through the screen/filter drum from the secondary side to the primary side thereby rinsing the openings of the drum and making them clear.

Abstract: A paper pulp screening apparatus wherein a modular cylindrically-shaped screen plate is formed of a thin material of uniform thickness bent to form an undulating shape to increase the screening area, and the screen plate is supported by cylindrical-backing members to give the plate strength, with the plate being formed into various complex shapes. Manufacturing methods for forming the undulating shapes are disclosed.

Abstract: A screening apparatus comprises a pair of stationary concentric screens with a plurality of foils rotating therebetween and adjacent thereto, the individual foils being radially aligned. The screening apparatus comprises a tangentially disposed slurry inlet and a diametrically and tangentially disposed heavy rejects outlet at the end of a heavy rejects trap. The light reject/accepts slurry flows into the screening zone and, after separation, is discharged at an end of the screening apparatus by way of respective light rejects and accepts outlets. The accept outlet is located axially with respect to the screen cylinders and rotating foils so the pressure pulses are virtually eliminated in the screening process. The apparatus may be constructed for vertical or horizontal rotation of the foils.

Abstract: Fiber suspension, such as paper pulp flowing to the headbox of a paper machine, is acted upon by apparatus which affects the axial direction and magnitude of the speed of the fiber suspension during screening to optimize results. A rotor cooperates with a screen cylinder, the rotor having a plurality of projections arranged along its axial length. The axial length of the rotor preferably has different axially extending circumferential zones. The projections have non-axial surfaces which act on the suspension to change the axial forces. Different shapes of projections are preferably provided in the different zones so that the axial forces vary in dependence upon the distance from the inlet to the screen casing, and the discharge outlet from the screen casing.