Abstract: A system and method is provided for analyzing data obtained during manufacture of a web of paper or paperboard on a machine. The system comprises a computer including a database module, a statistical analysis module, and a processor for executing the modules. The database module contains measurements of quality parameters obtained from the web during manufacture. The statistical analysis module is executed by the processor to analyze the measurement data and estimate a target shift in at least one quality parameter that could be made if the controllable variations were removed. The target shift can be transformed into an economic amount (i.e., dollar value) by the statistical analysis module to assist the mill operator with making well informed, economic based decisions. The system further includes a diagnostic module capable of automatically identifying machine parameters that correlate to quality parameters that caused the web to fall outside the desired quality specifications.

Abstract: A vacuum pump (P0) provides vacuum to a paper machine deaeration tank (11) which has an inlet duct (10) through which the tank is supplied with wire water. A discharge duct (12) extends from the deaeration tank (11). There is an overflow (14) for the wire water in the discharge duct at the discharge end of the discharge duct (12). The overflow (14) of the discharge duct (12) is located below the deaeration tank (11) and opens to a free air space. The discharge duct (12) includes a branch duct (15a1) for a flow which is passed to the headbox (100).

Abstract: The present invention provides a drum type refining or washing apparatus in which the refining or washing efficiency of a pulp suspension or a food suspension is remarkably enhanced by the filtration function of a rotary drum and by the filtrate sucking force of a filtrate receptive cell.

Abstract: Method for determining a characteristic value for a binding force potential of paper fibers in a fibrous suspension. The method includes measuring an air content of the fibrous suspension and deriving the characteristic value from the measuring.

Abstract: The present invention relates to a method and apparatus for controlling the operation of an approach system of a paper machine or the like web formation apparatus. Especially preferably the method of controlling the operation of an approach system according to the invention is applicable to be used in connection with paper and paperboard machines as well as in connection with various apparatuses performing non-woven webformating.

Abstract: The present invention relates to the thickening of pulp suspensions. A low consistency pulp suspension is fed to a pre-thickener (10) through an inlet conduit (18). A layer of thickened pulp, formed on a filter surface (22), is pushed along the filter surface by a cleaning member to the discharge end of the pre-thickener and is discharged through the outlet (20). The cleaning member comprises a rotating shaft (30), on which shaft at least one screw thread (32) is fixed so as to leave a free space between the shaft and the screw thread. Essentially non-thickened pulp is allowed to flow through the apparatus via this space.

Abstract: The present invention relates to a wire pit. A characteristic feature of the wire pit (50) according to the invention is that its wall/walls (52′, 52″, 54′, 62) converge downwards so that the average flow direction of the liquid along the most part of the wire pit's (50) height deviates from vertical.

Abstract: The invention relates to an apparatus for passing stock to a headbox (100) of a paper machine or equivalent. The apparatus comprises a deaeration tank (11) which is provided with vacuum by means of a vacuum pump (Po) or another device. The deaeration tank (11) comprises an inlet duct (10) through which it is supplied with wire water. The deaeration tank (1) comprises a discharge duct (12) and, at the discharge end thereof, an overflow (14) for the wire water in the discharge duct (12). Said overflow (14) of the discharge duct (12) is located below the deaeration tank (11) and opens to a free air space, and that the discharge duct (12) includes a branch duct (15a1) for a flow which is passed to the headbox (100).

Abstract: The invention relates to a method, an apparatus and a screen for screening mechanical fibre pulp. According to the invention a short fibre material is separated using a gap screen, whereby said material can be very efficiently separated to form a specific fraction.

Abstract: In a method and an associated apparatus for discharging the whitewater from inside the loop of a continuous dewatering wire of a former, specifically a twin wire former in a paper machine the accumulating whitewater is collected by a collection tank, which is located within the loop; the collected whitewater is separated from the air, still inside the loop, by suctioning off of the area above the collection tank and the whitewater is removed from the collection tank through at least one channel that is connected to the collection tank and is located below the collection tank's water level.

Abstract: A device for adjusting the position of the wiper strip on the screen in a papermaking plant regulates the contact pressure with which the wiper strip bears on the screen. The wiper strip is fixed to a supporting bar and the supporting bar is configured such that it can be moved with respect to the screen counter to the action of a spring device, in particular an air spring, in order to adjust its position with respect to the screen. A plurality of holding bars are provided along the supporting bar, that can be adjusted in terms of their effective thickness in relation to pressing the wiper strip against the screen.

Abstract: In the short circulation of a paper machine, a chemicals flow (F1) is fed into a fibre suspension flow in connection with a pipe expansion comprising a first pipe (1) and a second pipe (2) having a larger diameter than the first pipe, which pipes are connected to each other by means of an expansion step (3) perpendicular to the direction of flow. The chemicals flow (F1) can be passed so as to be mixed with the fibre suspension flow either in the second pipe (2) in an ideal mixing zone situated after the expansion step (3) or in the first pipe (1) so close to the expansion step (3) that the chemicals which are added have no time to react with the fibre suspension before the flow enters the expansion step (3).

Abstract: A screening apparatus for screening acceptable and rejectable material from a pressurized fiber suspension includes a housing and a rotor within the housing. The rotor has a top end. A screen basket is positioned generally concentrically around the rotor. A rotor blade ring is connected to the top end of the rotor and rotates with the rotor. A stationary defibering ring is positioned adjacent to the rotor blade ring.

Abstract: A screen, such as a drum screen or a flat screen, for screening or fractionizing pulp suspensions or the like suspensions of the pulp and paper industry. The screen comprises a reinforcement attached to the surface of the screen plate, such as a reinforcing ring (16, 18) attached to the surface of a drum screen (10). The reinforcement (17) is made of fiber-reinforced composite material. The invention also relates to a method of manufacturing the reinforcement of a screen plate of composite material. The composite material is preferably made of reinforcing fiber and plastic matrix material.

Abstract: The invention relates to a method and a device for degassing of suspension, specifically fiber stock suspension. The method according to the invention is characterized in that separated excess suspension is discharged sideways through an overflow having an overflow edge that is located in the tank outside wall and is positioned parallel to the tank axis. The device according to the invention is characterized in that the overflow includes at least one overflow having an overflow edge that is located in the tank outside wall and is positioned parallel to the tank axis and that at least one overflow system, for the purpose of discharging the separated excess suspension, is located following the overflow.

Abstract: In a method and an associated apparatus for discharging the whitewater from inside the loop of a continuous dewatering wire of a former, specifically a twin wire former in a paper machine the accumulating whitewater is collected by a collection tank, which is located within the loop; the collected whitewater is separated from the air, still inside the loop, by suctioning off of the area above the collection tank and the whitewater is removed from the collection tank through at least one channel that is connected to the collection tank and is located below the collection tank's water level.

Abstract: Process and apparatus for degassing a flowing fibrous paper suspension. The process includes separating the suspension into partial streams, spraying the partial streams into a degassing chamber under vacuum, and exposing the suspension to the degassing vacuum for at least 10 seconds. In this manner, gas within the suspension is separated from the suspension. The process also includes suctioning the separated gas out of the degassing chamber. The apparatus includes a degassing chamber structured to subject the suspension to a vacuum sufficient for degassing, an element arranged at an inlet of said degassing chamber for dividing the suspension into a plurality of partial streams, and a suction device for removing separated gas from said degassing chamber. The apparatus is structured and arranged so that the suspension is subjected to the degassing vacuum for a duration of at least 10 seconds.

Abstract: An apparatus for degassing an aqueous suspension containing pulp fibres, the apparatus comprising an elongated horizontal reservoir and a bypass manifold extending into the reservoir. The bypass manifold is placed inside the reservoir such that it it positioned substantially within the aqueous suspension at the bottom of the reservoir, the manifold thus decreasing the flow cross-sectional area of the aqueous suspension at the inlet end of the bypass manifold (2) in the reservoir.

Abstract: A washing system for washing a fiber suspension associated with a fiber stock preparation system, includes a plurality of rolls and a porous fabric carried by the plurality of rolls in a closed loop. The closed loop includes a lower run defining a washing zone, with the porous fabric moving in a running direction through the washing zone. The porous fabric has an upper surface in the washing zone which carries the fiber suspension thereon. A headbox is positioned with the closed loop and above the porous fabric at an upstream end of the washing zone. The headbox discharges a fiber suspension to be washed onto the upper surface of the porous fabric. An accept removal device is positioned within the closed loop and above the porous fabric at a downstream end of the washing zone. A plurality of showers, each having an inlet, are positioned within the closed loop and above the porous fabric in the washing zone between the headbox and accept removal device.

Abstract: A method and an apparatus for washing a fiber pulp mixture, whereby water and, with it, ash and other particle-type impurities are removed from the fiber pulp mixture. The fiber pulp mixture is fed between two wires in a dewatering section so that water and ash are removed from the fiber pulp through both wires, after which the wires and the fiber pulp between them are led to run along a curved surface to remove any extra water by means of the tension of the wires and centrifugal force.

Abstract: A hydrocyclone and a process for discharging impurities from a suspension containing paper fibers using a hydrocyclone having a radially inner area. The hydrocyclone includes an inflow for introducing the suspension to be purified, an accepted stock outflow for discharging the purified suspension, a separating part, a reject discharge device for discharging impurities of the suspension, at least one element for adding a diluting liquid at an addition point which is located in a radially inner area of the hydrocyclone, wherein the at least one element has at least one aperture opening axially and opposite to a discharge direction of the impurities. The process includes adding a diluting liquid into the suspension in the radially inner area of the hydrocyclone, wherein the diluting liquid is added in a flow direction opposite to an axial discharge direction of the impurities.

Abstract: A process arrangement for the short circulation in a paper or board machine including stock chests for component stocks, metering pumps for component stocks, cleaning devices, pumps, a headbox and a wire section as well as a system of pipes connecting these elements, together with regulation devices. After the metering pumps, the component stock flows are passed into a closed mixing volume in which the component stocks are mixed and diluted with a first dilution water flow. From this closed mixing volume, the stock is passed in a closed space by a first feed pump of the main line of the process through a screen and a centrifugal cleaner to the suction side of a second feed pump of the main line, where a second dilution water flow is passed to the stock. The second feed pump feeds the stock through a machine screen to the inlet header in the headbox.

Abstract: The present invention provides an apparatus for decontaminating aqueous paper pulp, the apparatus comprising a decontaminating cell (12). The decontaminating cell (12) has an upper light contaminate collection hood (30) and/or a lower heavy contaminate collection trough (40). Paper pulp is provided to the cell (12) under a pulp head sufficient to purge the contaminates therefrom.

Abstract: A casing has a pulp slurry inlet, a reject outlet and an accept stock outlet and accommodates a rotor. The rotor has a hollow cylinder with scraper blades at its outer periphery. A screen plate is disposed outside of the scraper blades to provide between them a passage facing to the screen plate. The hollow cylinder is formed with pulp slurry outlets. Rotation of the hollow cylinder causes the pulp slurry to be circulated outside and inside of the hollow cylinder, so that separation of the pulp slurry into accept stock and reject is repeatedly carried out by the screen plate.

Abstract: The invention relates to a method and an arrangement for producing a flow of stock in a moulding tank (1). In this, stock is pumped into the moulding tank (1) at the bottom (1a) and allowed to flow up over the brim (1b) thereof. During its rise in the moulding tank (1), the flow of stock pumped in is distributed by at least one grating placed essentially horizontally and provided with flow openings. An arrangement for performing the said method comprises a line (2a, 2b), connected to the moulding tank (1) and a machine vat for ready prepared stock, for delivering fresh stock to the moulding tank (1) by means of a pump (5) connecting with the line (2a, 2b). The line (2b) opens out in an area close to the bottom (1a) of the moulding tank (1) in such a way that an upwardly directed flow of stock is obtained. The pump (5) is adapted to deliver excess stock so that excess stock is allowed to flow over the brim (1b) of the moulding tank (1).

Abstract: An improved double acting deaeration vessel is most desirably used in the pulp and paper industry. The deaeration vessel removes gas from a fiber suspension without requiring fine adjustment of the final consistency of the suspension fed to the deaeration vessel. In the same gas volume where the fiber suspension is treated in the deaeration vessel a second partition wall forming a second weir is provided, and the vessel jacket is provided with one or more inlets for a second fluid medium to be introduced into the vessel, with an outlet for the substantially gas free second fluid medium. A common outlet is provided in the common gas volume for gas separated from both the fiber suspension in the second fluid medium, as well as an outlet for the fraction of the second fluid medium separated by the weir.

Abstract: A paper-making screen apparatus for separating foreign matters from paper-making raw materials is formed of a screen having a first annular end plate located at an end; a second annular end plate located at the other end thereof, having a plurality of openings for male screws; a plurality of interval keeping members secured to the first and second end plates to keep an interval therebetween, and having female screws on the side facing the second end plate; a plurality of male screws engaging the female screws; and a plurality of rod-shaped members connected to the first and second end plates, and annularly arranged parallel to each other at certain intervals.

Abstract: A stock liquor pressure pulsation absorbing apparatus of an active type is able to absorb pressure pulsations in an ordinarily demanded frequency range of 0.01 to 100 Hz. A by-pass pipe (2) extracts a portion of a stock liquor from a master pipe (1) for supplying the stock liquor to a paper machine headbox. A control pump (7) returns a portion of the stock liquor so extracted into the by-pass pipe. A detector (3) detects a stock liquor pulsation pressure at a branch point, or on an upstream side thereof, of the by-pass pipe and master pipe for controlling the control pump. The pressure pulsation, including the low frequency range, of the stock liquor is thereby absorbed accurately and precisely, variations in the basis weight are made small and a stable supply of final products with a high quality can be attained.

Abstract: Apparatus for treating pulp, comprising a stand (1); a rotatably mounted drum (3); feeding and discharging members (6, 8) for the pulp; a wall member (2) which surrounds the jacket (40) of the drum in order to delimit therebetween a material space (5) with which the feeding member communicates via an inlet (7), which material space includes two treatment zones (24, 25); a delivery member (26) for delivering liquid to the treatment space via the wall member; a press member (22, 23) arranged downstream of each delivery member in order to exert a press force against the pulp; a collecting chamber (18, 19) inside the drum in connection with each treatment zone and press member for receiving liquid which is pressed through the jacket. According to the invention, the drum is supported by two support rollers (12, 13) which extend through the drum on either side of its vertical center plane and are in contact with the inner side of the drum, the support rollers being rotatably mounted on the stand (1).

Abstract: The present invention relates to a device for distributing liquid, especially washing liquid for washing paper pulp, in a diffuser having at least one screen plate (1), comprising an apparatus for supplying the washing liquid and at least one elongated nozzle (2, 5) which can be connected to the apparatus and which extends down in front of the screen plate and is arranged to supply the liquid. The nozzle is provided with openings (7 to 12) for washing liquid which open out at different predetermined levels, and whose location is designed to provide an even distribution of washing liquid along the height of the screen plate. A channel (13 to 18) for supplying washing liquid can be arranged to each opening (7 to 12) in the nozzle (2, 5).

Abstract: For distributing stock evenly across the face of a tube bank in a papermaking machine, the stock supply header has an increasing change in cross-sectional area per unit width traveling from the inlet end to the recirculation end of the header. The header top wall converges toward the bottom wall, while the rear wall converges toward the front wall. The change in cross-sectional area down the header from the inlet end to the recirculation end is thus closely matched to an ideally parabolic shape.

Abstract: The invention is directed to a paper-making machine for making a paper web from a fiber suspension. The paper-making machine includes a headbox having an entrance, a fluid conduit connected to the headbox entrance, and a deaeration device with an exit connected to the fluid conduit. The deaeration device includes a housing and a pipe. The housing including an inner surface defining an inner chamber. The pipe is disposed at least partially within the housing and is configured to receive the fiber suspension. The pipe has a plurality of outlets disposed within the inner chamber of the housing. Each of the outlets is configured to output a stream of the fiber suspension against and at an acute angle relative to the inner surface of the inner chamber. A vacuum source is connected to the housing and is in fluid communication with the inner chamber.

Abstract: Separation and discharge of contaminants and defibration of undefibered waste paper can be effected in a single apparatus which has a generally cylindrical casing, a rotor concentrically arranged in the casing and a cylindrical main screen plate concentrically surrounding the rotor. Stock is separated by the main screen plate into that passing from inside through the main screen plate to outside and that not passing through it. The stock passing through the main screen plate is sent as accept stock to a next process. The stock not passing through the main screen plate is passed through a gap of a defibering section provided by defibration stator and rotor for defibration of undefibered waste paper and is further separated into the stock passing through an auxiliary screen plate and that not passing through it. The stock passing through the auxiliary screen plate is sent back through a circulation pathway in the rotor to inside of the main screen plate.

Abstract: Process for damping pressure pulsations and apparatus for performing the process. The process of this invention serves for the damping of pressure pulsations in a fluid, particularly a fiber suspension, flowing in a closed system wherein the pressure pulsations to be damped are measured at a measuring site and compensated at a correction site, with a throttle position being located between the measuring and the correction sites, with the damping of the imparted pressure impulses occurring at the correction site, which pressure impulses are opposite to the measured pressure pulsations, with the time periods thereof being about the same as those of the measured pressure pulsations. Several apparatuses for performing the process are also set forth.

Abstract: An apparatus and process for the solvent pulping and washing of pulp using vessels purged of oxygen free gas when the process is arrested or terminated. The washing is accomplished by first continuously passing the pulp to a pressure diffuser, then to a first multi-stage drum displacer washer, and then to a second multi-stage drum displacer. In the pressure diffuser the lignin is washed out of the pulp, utilizing as wash liquid a mixture of solvent and water having a solvent concentration equal to or higher than that required by the extraction process within the digester, and at a pressure at least about 350 psi. The pressure in the second and third stages is lower, and water is the wash liquid in the third stage. Alcohol can be recovered from the spent wash liquid of the first wash stage, so that all but about ten gallons or less of alcohol per ton of pulp is recovered.

Abstract: The invention concerns a rotor with impulse elements running in the vicinity of a rotationally symmetric screen basket and with blade elements which are run radially within the impulse elements with or by the rotor, notably for use in screen graders. The invention is characterized in that a pump impeller is formed by the mutual coordination and design of the blade elements.

Abstract: A screen aperture blinding prevention and liquid overflow prevention and level control apparatus for a knot drainer senses liquid level within the knot drainer and compares the sensed level to a setpoint level. Differences in the two levels generate control signals of appropriate magnitude and direction, and those control signals are transmitted to a valve whose degree of responsiveness and openness is adjusted to change the outflow rate of accepts liquor from the accepts chamber of the rejects separator. In addition, passive level control is provided in the discharge line for establishing accept flooded screen apertures regardless of variations of inflow and outflow rates during operation while active level control to create accept flow rate greater than, less than, or equal to inlet flow rate is provided by the combination of siphonic loop, barometric leg and control values for accepts outflow and for backwash nozzle flow.

Abstract: The invention concerns a drum washer. The washer has two plates (14; 18) located after each other in parallel with the drum, and the pulp to be washed is conducted between these plates. Between the plates there is a gap (22) closed by a flap valve (25) by way of which gap washing liquid is conducted through the mat. The washer is especially suitable for washing cellulose pulp.

Abstract: The stock stream of a pre-cleaned paper stock suspension is sub-divided into extremely small partial jets in a chamber of a compartment. Each such partial jet or stream has a throughflow volume of approximately 50 liters/min. to 80 liters/min. and is directed with great turbulence against an impact wall within the closed chamber of the compartment at jet velocities in the order of about 10 m/sec. to 12 m/sec. and at an absolute pressure of about 0.5 to 0.8 bar absolute, the partial jets then being completely sprayed at such impact wall. The paper stock suspension which is to be deaerated has as large as possible surface area, so that the air is efficiently released at a negative pressure or vacuum of approximately 0.05 bar prevailing in the chamber and then can be suctionally removed. The division of the stream of the paper stock suspension into partial jets is accomplished by a distributor through which extends a predetermined number of throughflow openings defined by bores.

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 present invention relates to the treating of fiber suspensions in the pulp and paper industry and particularly to a method and apparatus for washing fiber suspensions.The method is characterized in that the fiber suspension is fed into the treatment apparatus, the desired process is carried out and the suspension is discharged from the apparatus in such a way that the fiber suspension is fed directly from the conduit to the treatment ducts mounted between the end plates of the rotational parts of the washer thus forming substantially extensions of the conduit. The fiber suspension is treated in the ducts and thereafter the treated suspension is discharged from the ducts by feeding yet untreated suspension to the apparatus.The apparatus includes a plurality of axially elongated treatment ducts (9) arranged in the form of a ring around an axis of rotation. The ducts are radially limited by filter surfaces (10, 11) and in the direction of the end walls divided by partition walls (8).

Abstract: In the inventive method and apparatus for the continuous discharge of water and fine particles from a suspension, particularly fibrous pulp, the pulp or suspension is thickened without forcing the removal of water through a relatively thick, uncontrollably gathered fiber mat. In the method, the suspension to be thickened is fed into a filtering chamber, the suspension is continuously mixed for equalizing consistency differences, the liquid is continuously removed from the suspension through a filter and the thickness of a fiber mat which forms on the filter surface is controlled by subjecting the mat to shear stresses. In a thickening apparatus for practicing this method, at least one of co-operating surfaces--i.e. the filtering surface (8) and its counter-surface (10)--is provided with loosening members (12) for non-mechanically limiting the thickness of a fiber mat forming on the filtering surface and thereby preventing the uncontrolled formation of such a mat on the filtering surface (8).

Abstract: The invention relates to a centrifugal pump particularly adapted for pumping fibrous suspensions from within a reservoir, wherein the pump includes a rotor arranged wholly within the reservoir for cooperation with the bottom wall thereof to effect fluidization of suspension and discharge of the fluidized suspension from the reservoir for passage through the pump, wherein an entrained gas, such as air, is withdrawn from the pump by means of a unique pump-out mechanism disposed rearwardly of a shroud of an impeller of the pump and including pump-out vanes and a repeller shroud cooperating with the impeller shroud and pump-out vanes to define radially opening flow paths, wherein flow openings extend across the impeller shroud for flow communication with the radially opening flow paths. The mechanism may also include repeller vanes carried by the repeller shroud to extend rearwardly of pump-out vanes.

Abstract: A method and apparatus for the removal of light material from a fiber suspension particularly suitable for removing light compressible plastic material such as expanded polystyrene and similar material from the short circulation of a paper machine. The plastic particles containing fiber suspension is divided in a degassing tank into reject and accept flows by the assistance of vacuum. The light reject containing flow is separated from the main flow by an overflow device and recirculated to the wire pit or corresponding device. A separation device such as a vibrating screen, vibrating drum, curved screen or inverted cyclone is provided within the light reject flow return duct for removing the detrimental plastic or other light material from the short circulation and for preventing the accumulation thereof in the wire pit.

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: 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 method and apparatus for pumping a liquid-fiber suspension, and specifically for pumping high consistency fiber suspensions in the pump and paper industry. The method of pumping a liquid-fiber suspension includes the moving of the suspension into a pump, separating a portion of the liquid part of the suspension from the liquid-fiber suspension during the pumping operation and directing the separated liquid to the suspension at a point somewhere between a situs in advance of the pump inlet and the pump outlet. This method is enabled by an apparatus, in which at least part of the surfaces of the pump (1) is provided with filter surfaces (6, 7, 8, 9, 10), through which the liquid separated from the suspension is returned either into the pump, directly in front of the suction opening (11) of the pump (1) or to some other suitable place in the vessel containing the suspension.

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 fibers of recycled paper are cleaned by agitating the slurry containing the fibers to maintain the fibers in suspension, and contacting the slurry with wash water to remove ink and other contaminants. The apparatus includes a passageway having screens forming opposite sides of the passageway. Agitators are within the passageway, and create enough turbulence to prevent fibers from settling or agglomerating. Channels adjacent to each screen carry wash water, and pump pressure creates a pressure differential across the screens to cause the wash water to contact the slurry and to be removed from the passageway.

Abstract: The present invention relates to a method and apparatus for the continuous discharge of water from suspension, especially from fibrous pulp, whereby pulp is caused to thicken without having the water to be removed through a thick uncontrollably gathered fiber mat.In accordance with the invention the suspension to be thickened is fed into a filtering chamber, the suspension is formed as a layer that is continuously being mixed for equalizing the consistency differences, the liquid is continuously removed from the suspension and the thickness of the fiber mat being formed on the filter surface is controlled by subjecting said mat to shear stresses.The above described method is realized by an apparatus, in which at least one of the co-operating surfaces, the filtering surface (8) and its counter surface (10), is provided with means (12) for non-mechanically limiting the thickness of a fiber mat on the filtering surface, whereby a uncontrolled formation of a fiber mat on the filtering surface (8) is prevented.