Abstract: An arrangement in a pulp grinder comprising a grindstone (1), a feed chute (2), and a piston to feed wood (3) against the grindstone (1). The arrangement comprises separate pushing members (6), which are arranged to push the wood (3) against the grindstone (1) at essentially the entire width of the feed chute when the percussion piston is moved back to the stroke position to allow the feed of a new batch of wood.

Abstract: The invention relates to a method for controlling a multi-step screening apparatus (1), the method comprising controlling other accept, reject and dilution flows in relation to the flow measured in the accept channel (7a) of the first screening step (3a). Thus a simpler control unit (9) can be used and accept of higher quality can be obtained than before. The invention further relates to an apparatus for controlling a multi-step screening apparatus (1), said apparatus comprising a control unit (9) arranged to measure the flows of all accept, reject and dilution water channels (7a-7c, 5a, 5b, 11a, 11b) and to adjust the flow of the other channels on the basis of the flow of the accept channel of the first step.

Abstract: An apparatus for cleaning a fiber mass suspension, the apparatus comprising a receptacle and an inlet channel and an outlet channel for feeding the suspension into and for discharging it from the receptacle. In addition, the apparatus comprises air feed means for feeding air into the lower portion of the receptacle. The apparatus comprises at least one partition wall dividing the receptacle into spaces in such a way that the suspension may flow between the spaces at the lower portion and the upper portion of the partition wall, respectively. The air feeding means are positioned to feed air into one aeration space, whereby the air separates impurities from the suspension and makes the suspension flow on different sides of the partition wall upwards and downwards, respectively, so that a spiral flow is created around the partition wall from the inlet channel into the outlet channel.

Abstract: An arrangement for providing continuous grinding in a pulp grinder comprising a feed chute and a piston in the feed chute moving lengthwise of the feed chute for pressing the wood in the feed chute against a grindstone. The arrangement comprises rotary feed members between the piston and the grindstone on the sides of the feed chute for pushing the compressed wood further against the grindstone. Also, the arrangement comprises a closing member that can be pushed between the compressed wood and the piston to prevent the wood from moving backward with the piston as the piston is moved to the initial position, ready for the stroke, to allow the feed of a new batch of wood.

Abstract: An arrangement in a pulp grinder comprising a grindstone, a feed chute extending to the grindstone, a piston moving in the feed chute, an auxiliary piston and closing members. In the arrangement, there are recesses on the front of the piston and apertures in the auxiliary piston so that the closing members can be pushed from both sides of the feed chute through the auxiliary piston to the recesses of the piston so that they settle behind the wood pressed by the piston.

Abstract: A method and apparatus for controlling a multi-step screening apparatus (1) controls other accept, reject and dilution flows in relation to the flow measured in the accept channel (7a) of the first screening step (3a). Thus a simpler control unit (9) can be used and accept of higher quality can be obtained than before. The apparatus has a control unit (9) aranged to measure the flows of all accept, reject and dilution water channels (7a-7c, 5a, 5b, 11a, 11b) and to adjust the flow of the other channels on the basis of the flow of the accept channel of the first step.

Abstract: A method and an arrangement for treatment of reject material separated at screening of fibre pulp prepared by grinding wood. In the method reject material is fed against the surface of a grindstone (3) of a pressure grinder immediately before a normal grinding zone (6). The arrangement comprises a reject feeding equipment (12) placed immediately before the normal grinding zone (6) through which the reject material is fed to be ground again.

Abstract: In a method and pressure screen for screening fiber suspension, fiber suspension is passed through two successive screening stages (A, B) provided in the same pressure screen so that accept from the first screening stage (A) is passed to the second screening stage (B), and accept from the second screening stage (B) is removed from the pressure screen. Reject from the second screening stage (B) is returned to the supply side of the first screening stage (A) for rescreening. The pressure screen has a first screen cylinder (9) having an inlet space (V1) into which fiber suspension is introduced. A second screen cylinder (10) is provided at a distance from the first screen cylinder. Accept passed through the first screen cylinder (9) is passed into the inlet space (V5) of the second screen cylinder through a channel within the rotor (3) by pumping blades (5) attached to the rotor.

Abstract: A method of making a screen cylinder, in which method mesh wires (2) are arranged next to one another and attached inside the ring-shaped supporting rods (3) to provide a cylindrical mesh surface, and a screen cylinder which includes mesh wires (2) arranged next to one another to provide a cylindrical mesh surface, the mesh wires being attached to the supporting rods (3) surrounding them. In the method, supporting rings (4) are positioned around the supporting rods (3) without fastening the supporting ring (4) to the supporting rod (3), and the supporting ring (4), when it is put in place, is tightened such that it presses the supporting ring (3) in the radial direction of the mesh cylinder. The mesh cylinder is made of a supporting ring (4) which is positioned around the supporting rod (3) without fastening it to the supporting rod (3) and which is tightened around the supporting rod (3) so firmly that it presses the supporting rod (3) in the radial direction of the screen cylinder.

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 device for separating solids from suspension comprises two filtering belts pervious to water travelling in the same direction and arranged to be supported and guided each by their respective liquid withdrawing surfaces provided with holes which form therebetween a prefiltering chamber converging in the direction of travel. The prefiltering chamber comprises in the beginning a supply inlet for supplying suspension to be treated into the chamber, as well as sealing elements defining the chamber at its sides in directions perpendicular to the direction of travel of the belts. The sealing elements are formed by rigid walls rigidly joined to the liquid withdrawing surfaces, such that the prefiltering chamber has a substantially closed housing-like construction.

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 pulping and screening materials containing fiber pulp includes an upper pulping section for breaking down the materials and a lower screening section for prescreening of the broken materials. The pulping section includes a feeding chamber delimited by a housing, a rotor unit in the feeding chamber, a drive unit for rotation of the rotor unit and a first perforated screenplate in a bottom portion of the pulping section through which an accepted portion of the broken material is fed into the screening section. The screening section includes a space also delimited by a housing and positioned on the opposite side of the first perforated screenplate and a stationary partition wall for dividing the space into a first and a second partial space. At least a portion of the partial wall defines a second perforated screenplate. The first partial space communicates with the feeding chamber for receiving the accepted portion of the broken material.

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 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 decker comprises a tank having a thickening drum mounted rotatably therein and including a filtering shell. The inside of the drum communicates with an inlet for feeding mass, whose consistency is to be increased during the thickening process and outlets for discharging the thickened mass after the thickening process. The filtrate separated from the mass being thickened, is arranged in a flow communication from the inside of the thickening drum through the filtering shell of the drum to the bottom portion of the tank. At least one separating member is placed in the bottom portion of the tank outside the drum and forms a partition point or partition line situated transversely with regard to the direction of rotation of the drum and at a predetermined, angular distance from the horizontal plane coinciding with the axis of rotation.

Abstract: A thickener has a receptacle in which a thickening drum having an axial filtering wall is mounted in a receptacle for rotation about an axis. A liquid-and-solid-materials mass to be thickened is introduced into the one axial end of the thickening drum. Thereby the solid materials contained in the mass to be filtered form a filtering layer on the inner surface of the a filtering wall and liquid filtrate from the mass flows through the filtering layer and wall into the receptacle. At least one barrier plate radially divides the inner space of the thickening drum into axially sequential spaces, the barrier plate being fixed within the thickening drum for rotation therewith. The barrier plate is provided with at least one opening axially therethrough for flow of the mass to be thickened and at least one opening axially therethrough for air flow in the axial direction of the thickening drum. The thickened mass is then discharged from the other axial end of the thickening drum.