Abstract: The invention refers to a rotary filter with a device for separating a liquid-solid mixture, particularly a pulp suspension, with several separate zones, at least one of which is of variable design. It is mainly characterized by the variable design for the length and/or position of the atmospheric zone and the vacuum zone.

Abstract: A drum having a longitudinal axis, and an outer periphery, has a multiplicity of longitudinal, drainage grooves formed therein, and a cylindrical sheath encloses the drum, the sheath having a multiplicity of holes formed therein. The drum is imperforate. A pair of the drums is employed in a twin-roll press as press rolls, and one thereof is used in a single roll press with a compaction baffle. In one embodiment, the press roll has its grooves formed in a herringbone pattern, the same pointed in the direction of rotation, to enhance drainage. In another embodiment, the longitudinal drainage grooves have increasing depth, toward a mid-length of the press roll where they open into inner-drum drainage conduits which discharge the filtrate adjacent the rotary axis of the press roll.

Abstract: A disc filter used in the pulp and paper industry meets modern requirements by axially dividing the tank and shaft (with the flow channels) into at least two separate and distinct portions, so that the treatment of pulp in several different stages using the same disc filter is possible.

Abstract: A suction head arranged between a filtrate channel and a barometric leg of a rotating filter having at least one filter means communicating with the filtrate channel. The filtrate channel is connected to the barometric leg through the suction head. In order to ensure continuous conveyance of air bubbles brought along the filtrate, the upper internal boundary of the suction head as regards flow towards the barometric leg is nowhere located at a level above the upper internal boundary of the barometric leg.

Abstract: An elongate scraper apparatus for scraping filter cake from a moving filter medium of a filter apparatus comprises an elongate bar or scraper having a length sufficient to substantially span the face of the filter medium upon which filter cake is deposited. The bar has a broad, continuous, smooth, front face that is parallel with the surface of the filter medium. The broad, front face of the bar or scraper allows substantial contact with the surface of the filter medium over the entire surface of the front face of the bar or scraper. The elongate bar or scraper further has a top face that forms a chisel edge at the top edge of the front face. The chisel edge points in a direction parallel with the surface of the filter medium. As the filter medium bulges outwardly, it applies uniform pressure on the broad face of the bar or scraper so that the bar or scraper flexes to conform to the contour of the bulging filter medium.

Abstract: In prior pressure washer drums, the filter deck was supported on the central shaft by spokes welded to the central hub which was in turn welded to the shaft. The extreme forces caused premature failure of the welded joints. The present invention provides a pressure washer drum in which sandwiched parallel plates having an array of apertures replace the spokes and central pipe and journals are supported on the hub by a bolting system rather than by welding.

Abstract: A circumferential seal for a disc filter valve to rotary collection pipe is formed by a radially compliant circumferentially restrained and tensioned seal disposed in a split "V" notch formed in a non-flooded zone between the stationary valve plate and the rotating collection pipe.

Abstract: A rotary filter valve is provided with a variable restriction of the timing plate which minimizes bypass gas entering the vacuum system during emergence of the filter elements from the submerged condition.

Abstract: A screen dram for the dewatering and/or washing of cellulose pulp, comprises a first cylinder (2) made from non-stainless material, which is rotatable about its axis (5); a cylindrical screen plate (6) arranged coaxially on the outside of the first cylinder, but at a distance from it, and between the screen plate and the first cylinder an annular chamber (7) which can receive liquid which has passed through the screen plate, which chamber contains passages (26) which extend in the axial direction towards one or both ends of the drum for the withdrawal of the screen liquid. The chamber (7) is lined with stainless steel (8) in the form of one or more cylindrical plate sections (8a, 8b . . . 8n). These, by virtue of shrink joints, can be joined to and bear in seal-tight arrangement against the cylindrical casing of the first cylinder. Preferably, the stainless steel contains at least 5% molybdenum.

Abstract: A washer drum is provided with unique cross bracing which prevents twisting, reduces vortex formation in radial inflow ports, and further provides support for the decking between closely spaced intermediate heads.

Abstract: An anti rewet deck is provided for press rolls used to increase consistency of fibrous pulp slurry from approximately 4 percent up to about 30 to 50 percent. This is accomplished by biasing the location of the drainage holes in the roll shell to the forward edge of the drainage compartments within the roll shell. To avoid the necessity for handing of the rolls, a mechanism is provided for accomplishing the purposes of minimizing rewet at practical production rates by providing baffle plates which effectively orient the draining pattern in the desired direction. Such baffles can be permanently or removably installed once the desired handing of the rolls is determined.

Abstract: The invention concerns a drum washer. The washer has a shaft formed by two cones (46) placed with their bases against one another. The shaft can be used as a supporting structure for the drum. Vanes (48) can also be placed on it for assisting in collecting washing liquid falling from the upper part of the drum separately from the washing liquid ending up on the bottom of the drum. The washer is especially suitable for washing cellulose pulp.

Abstract: A separation device for suspensions comprises a housing (1), a filter body (3) with a wall of filter material situated in the housing, spray means (14) adapted to spray jets of a suspension to be separated directly onto one side of the wall of filter material, and means (4, 6) for displacing the filter body relative to the spray means. According to the invention the filter body forms a substantially circular cylindrical drum (3) with a vertical center axis, the circumferential wall of the drum comprises said wall of filter material. Further, said displacement means (4, 6) is adapted to turn said cylindrical drum about said vertical center axis during operation.

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: A pressure filter includes a pressure vessel having a pressure chamber and a circumferential edge; a turntable rotatably mounted within the pressure vessel about a horizontal axis; a plurality of filters non-rotatably mounted to the turntable and spaced apart from each other at the circumferential edge of the pressure vessel and rotatable around the horizontal axis through a center of the pressure vessel such that the plurality of the filters continuously dip into and out of a solid solution in a bottom of the pressure chamber. A blow-off station is positioned above the solid suspension in the pressure chamber for freeing filter cake that has dried on the plurality of filters. A filter cake conveyor conveys the blown-off filter cake through a pressure lock in the pressure vessel.

Abstract: A disc filtering apparatus for filtering liquids, such as fiber pulps suspensions, includes hollow filter discs, each of which has two opposed side walls of filter material. A plurality of circumferentially spaced support arms extend within each hollow filter disc, for supporting the side walls of filter material. Between the support arms, each side wall of filter material is supported by at least one wire member extending substantially along the filter disc and attached to the support arms.

Abstract: An improved drum structure for a corrugated deck type rotary drum filter is provided that increases filter efficiency by eliminating transverse filtrate flow in the drain channels of the drum. Each drain channel is divided into sub-channels using at least one solid grid. The sub-channels drain into a single bucket associated with the drain channel. A drain slit is provided above each sub-channel in the corrugated material that covers the outer surface of the drum.

Abstract: A method and apparatus for filtering pulp fibers from a pulp slurry, using a combination of vacuum, hydrodynamic and hydrostatic forces in order to achieve a more effective deposition of pulp fibers onto the filter surface and enhanced flow of filtrate through the cylinder. The apparatus is in the form of an improved vacuum filtration system, in which the filtrate outlet tube is disposed along the axis of rotation of the rotary cylinder and the filtrate inlet and outlet ports of each filtrate conduct are radially offset from one another in the direction of intended rotation of the cylinder. During various phases of filter operation, vacuum forces generated by the vacuum source cooperate with either hydrodynamically or hydrostatically generated forces, which together act upon columns of filtrate in the filtrate conduits as the cylinder rotates.

Abstract: A disc filter including at least one filter disc (3) partly submerged in a vessel (1) for liquid or suspension to be filtered, said filter disc including a plurality of substantially annularly disposed filter sectors (4) and being rotatable about a collecting through (6) for solid substance deposited on the outside of the filter sectors (4) and falling down therefrom. Each filter sector has a filtrate outlet (16) by means of which the interior of the filter sector communicates with an axial channel (8) for discharge of filtrate. The filtrate outlet (16) is arranged at the edge (22) of the filter sector (4) trailing upon rotation of the filter disc and being connected to the side (12) of the axial channel (8) leading in the direction of rotation. Hereby the filter sectors (4) may be arranged to extend radially outside as well as radially inside the axial channels (8).

Abstract: A method and apparatus for fibrous suspensions in the wood processing industry and more specifically to a so-called drum cylinder, the basic construction of which comprises a vessel, into which suspension being thickened is supplied and a wire-surface cylinder rotating in the vessel. The drum filter is characterized in that the closure member of the drum filter has a channel for leading gas from the filtrate tubes through the compartments of the distribution chamber to the outside of the closing member. The method is characterized in that the operation phase of the filter cylinder is divided into five separate stages. In the first stage, when the cylinder descends on to the vessel, air and the initial filtrate are discharged from the filtrate components and the formation of the pulp web on the wire surface begins. In the second stage, filtrate is discharged with vacuum and the formation of the pulp web continues.

Abstract: A continuously operable centrifuge for spinning off sugar massecuite has an upwardly conically expanded strainer basket (20) mounted for rotation about a vertical axis (16). A downwardly conically expanding massecuite distributor (40) rotating with the basket reaches into a floor region of the strainer basket substantially coaxially to the strainer basket. The lower rim of the distributor forms a throw-off edge. Inside and in the upper region of the massecuite distributor (40), a distributing cup (30) is for distributing massecuite. The peripheral wall of the massecuite distributor (40) is formed by several ring elements (41), (42, 43) which partly overlap in the axial direction leaving an annular gap (44, 45). The product distributor is surrounded by a downwardly conically expanding stationary bell (51) which forms a further gap or gap space between itself and the rotating rings.

Abstract: A drum filter is provided including a rotatably mounted, generally cylindrical drum with a filter and vacuum drainage associated therewith. The deck structure comprises a plurality of circumferentially spaced, axially extending, and radially projecting imperforate members affixed at one end to the outer peripheral surface of the drum and having an outer end on which said filter is supported. The members each include a pair of circumferentially spaced, axially extending, and radially projecting imperforate surfaces. Perforate members are preferably formed in a substantially "U" shaped cross-sectional configuration comprising a pair of sidewall members connected to a floor member, which in turn is joined to and supported on the outer peripheral surface of the filter drum. The opposed surfaces of the members together define filtrate slots which form open axially extending channels adapted to receive at least a substantial portion of the filtrate after the drum rotates past the twelve o'clock position.

Abstract: A filter sector for a filter disk of a rotating filter, including folded or currugated means having ridges and valleys extending in a longitudinal direction of said means to form filtrate channels, and a filtering medium covering said means. Said means includes at least two elements (9, 10), each having parallel riges (12, 11') and valleys (11, 12') and said at least two elements are located in an at least partly overlapping relationship, such that filtrate channels (13) of one element (9) intersect with filtrate channels (14) of the other element (10). Preferably, the filter sector includes two at least substantially equally shaped elements and said elements are disposed such that there is communication between filtrate channels (13, 14) of said elements (9, 10) in zones of said partly overlapping relationship.

Abstract: A filter for continuous filtering of a suspension under pressure and/or vacuum comprises a vessel (1) having a center axle (2) on which filter discs (3) are arranged at a distance from each other along the central axle. The filter discs consist of filter sectors having surrounding filter cloth and internal channels and between the filter sectors and an outlet from the vessel (1) there is a connection in the central axle (2). Moreover, a scraper (7) is arranged for removing the filter cake (8) on the filter cloth obtained during the filtering operation and a vertical outlet pipe (12) receives the scraped-off filter cake material. The central axle (2) is formed with only one common channel for the filtrate and the gas from all filter sectors in the vessel (1) and consists of a tube.

Abstract: Compressible material is compacted into a plug by a device including a housing, solid outer wall, and restricting adjustable portion at an outlet. A root wall is rotated about an axis and conveys the material to be compressed in a channel having solid sidewalls. Without significant extraction of liquid from the material, the material is compressed until discharged in a compacted plug form from the housing outlet. A pneumatic cylinder provides an adjustable force for effecting the compaction adjacent the housing outlet. Examples of compressible materials that may be acted upon in the practice of various industrial processes include wood chips, high consistency paper pulp (cellulose pulp), wax and fibrous waste (for making artificial fireplace logs), and mud and straw (for producing building blocks or bricks).

Abstract: An assay filter unit where the filter of the unit is sealed into the body of the unit to prevent any passage of material to be assayed round the edge of the filter but is removable by breaking out a filter support grid along a predetermined line of weakness, together with the filter, for assay of material retained on the filter.

Abstract: A seal for a rotating center valve vacuum filter drum has a non-flat cross section with an elastomeric core and a chemical resistant sheathing. The seal is installed under tension so that, as wear occurs during operation, positive sealing contact is maintained. The non-flat cross section provides a nesting relationship with the center valve slot and stationary shoe to resist any tendency to wander out of the slot.

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: A filtration apparatus including a rotatable drum and a filter member defining at least a part of the side wall of the drum. A liquid containing solid particles, such as used wash water from a vehicle washing facility, is introduced into the drum by a sump pump or the like and a motor including an electrically-operated brake rotates the drum at a sufficient speed to force a liquid filtrate or filtered water outwardly through the filter member and cause a layer of relatively dry solids to collect on the inner surface of the filter member. Operation of the drum motor is terminated at the same time or shortly after operation of the sump pump is terminated and the brake is energized at the same time.

Abstract: An appratus for treating medium consistency pulp in connection with different treatment apparatuses, such as washers. According to the prior art the treatment of pulp, for example, the washing process, starts at a low consistency, approximately 1-3% so that it is necessary always to dilute pulp before washing, whereby the water consumption of the plant increases and the need of power in, for example, pumping and in the treatment generally increases. The present invention makes it possible to treat medium consistency pulp, because the feeding means is able to spread the pulp as an even layer on the perforated surface of the treating apparatus.

Abstract: A method for recovering crystals from a slurry by supplying the slurry to a rotary sucking filter while rotating a cylindrical filter medium thereof to effect a sequence of operations of sucking filtration, washing and further sucking filtration, which method comprises conducting a sucking filtration while pressurizing the slurry side so as to maintain such a temperature and pressure that the filtrate of the rotary sucking filter will not reach a condition of supersaturation, whereby stuffing of the filter medium due to deposition of crystals from the mother liquor with increase in the slurry viscosity is prevented and the recovery of the crystals are realized efficiently over a long period of time. This method is suitable for recovering crude and purified crystals of terephthalic acid and can be applied also for the recovery of general crystilline products, such as hydroquinone, resorcin and so on from slurries of them.

Abstract: An apparatus for treating pulp includes a pressure-proof outer casing for a suspension to be treated. A shaft is rotatably arranged in the outer casing and a number of disks are arranged substantially radially on the shaft within the casing. The disks are formed by a number of sectors each having two opposite filter surfaces for allowing liquid from the suspension to be drained therethrough and a liquid compartment between the filter surfaces for the drained liquid or filtrate, so that a substantially annular filter surface is formed. The liquid compartment is in communication with a liquid discharge member. The apparatus further includes members for dividing the annular filter surfaces into two or more portions. The members are stationary relative to the casing, so that the members are used for separating different treatment stages of fiber suspension from one another.

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: Method and equipment for filtration of a suspension so that the suspension to be filtered is fed from a feed part (4) onto the filter face of a filter member (5), which moves relative the feed part. The pulp layer is formed on the outer face of the filter member and the filtrate flows into the interior of the filter member, and the pulp layer is removed from the filter member at the removing point. After the pulp removing point (17), before the feed point (4), one or several cleaning points (12) are provided wherein liquid is made to flow through the filter member (5) from the inner face of the filter member to the outer face. The flow rate of the liquid that flows through the cleaning point or points is adjusted higher than the rate of any liquid flow that may flow through the rest of the filter member from the inside-face side to the outside-face side.

Abstract: An improved cylindrical rotary screen having as a screen member a composite element comprising a radially inner layer of fine mesh screening supported on a radially outer layer of apertured, expanded metal sheeting. The radially inner layer of fine mesh screening is provided as a number of removable modular panels which are longitudinally slidable in and out of the open discharge end of the cylindrical screen. The rotary screen provides excellent filtration yet is simple to manufacture and maintain.

Abstract: This invention relates to a vacuum water drawing windlass for making paper and in particular to one mainly including a tubular member, a bushing fitted on each end of the tubular member, a controlling disc rigidly engaged with the other side of each bushing, a case fixedly engaged with each controlling disc, a shaft inserted into each end of the tubular member and two brackets for supporting the tubular member whereby the paper production may be increased and the quality of the paper may be improved.

Abstract: An apparatus for treating, e.g., washing or filtering, fiber suspensions having a consistency of 8-20%, the apparatus including at least on rotatable filtering surface, an arrangement for feeding the suspension to a treatment region of the apparatus, and an arrangement for discharging the suspension from the treatment region, the feeding arrangement including at least one pressure chamber for fluidizing the suspension, at least one inlet duct for introducing the suspension to the chamber, and at least one feed duct for transferring the suspension from the pressure chamber to the treatment region.

Abstract: A filter section for a roatatable filter of the kind including a plurality of sections (5) assembled into an annular filter disk. Each section (5) comprises two mutually spaced plate-shaped elements (6,7) which are at least partially perforated and provided with protrusions (8) keeping a filter cloth (9) spaced from the plate-shaped elements. The space between the plate-shaped elements (6,7) is in communication with a discharge conduit (2) for filtrate. At least one substantially radial drainage channel (12) is arranged between the plate-shaped elements (6,7), this channel communicating with the outlet (13) of the section. The space between the plate-shaped elements (6,7) at the side of the drainage channel (12) is filled with a hardened compound (11), and the plate-shaped elements (6,7) are provided with openings (10) towards the channel (12).

Abstract: A sorting apparatus for sorting fiber suspensions heavily laden with rubbish and other contaminants, which sorter has two successive sorting units each having a ring-shaped strainer space, which are likewise successive, and an accepts space with a rotationally symmetric strainer between the accepts space and strainer space. The first sorting unit is pressurized above atmospheric pressure; diluting water is fed to the second unit strainer space; and a rotating plate is mounted between the first and second sorting units to control the flow between the strainer spaces.

Abstract: A rotary drum filter has a plurality of longitudinally extending division grids mounted about the outer circumference of a drum. A plurality of corrugated sheets are provided, with the leading and trailing edges of each sheet mounted to circumferentially adjacent pairs of division grids to define filtrate compartments. An equivalent number of perforated filter plates are also provided. Each filter plate is attached to the top of a corrugated sheet and has a leading edge that is set back from the leading edge of the attached sheet. A seal member is positioned at the leading edge of each corrugated sheet and has a first leg extending between the filter plate and the corrugated sheet. The seal member further includes a second leg which abuts the leading edge of the corrugated sheet so as to block the open ends at the leading edge of the corrugated sheets.

Abstract: A vacuum filter for the separation of solids from liquids, comprising an endlessly circulating array of troughs which constitute a common horizontal filter surface, on which an endless filter cloth is laid, in which each trough has an elastic sealing strip on that rimless edge which extends along the trough bottom transversely to the direction of movement. A good vacuum seal between two successive troughs with easy replaceability of the sealing strip is provided wherein the sealing strip is releasably clamped by a spring-loaded movable clamping bracket against the leading and/or rear edge of one of the adjacent troughs.

Abstract: An improved method and apparatus for filtration includes an outer stationary body, an inner rotating body defining a gap with the outer body for receiving a fluid sample, the surface of one of the bodies defining the gap being a filter. The rotation of the inner body creates Taylor vortices which continuously displace occluded solute on the filter surface. The filter can be a membrane. In one embodiment the device may be used to filter very small volumes of fluid such as are handled in clinical and other laboratories.

Abstract: Apparatus for gas-producing treatment, particularly fermentation and digestion, of organic material contained in a suspension comprises a horizontal, rotatably mounted treatment drum having an inlet for the suspension at one end and an outlet for the treated suspension at the other end. A plurality of baffles extending in axial planes throughout the length of the drum are secured to the interior side of the drum and extend from there towards the central region of the drum. In each of a number of angular drum positions, the number being equal to the number of baffles, one of the baffles defines jointly with the wall of the drum a downwardly open gas collection space which is spaced from the vertical plane containing the axis of rotation of the drum. The gas collected therein causes an uneven distribution of the suspension within the drum and thereby causes a turning moment acting on the drum.

Abstract: A two stage liquid filtration apparatus including a first pre-filter stage for removing heavy small particulate contaminants from the liquid with a first housing defining an inlet and an outlet and a screening means dividing a central chamber therethrough to allow contaminants like sand to fall downwardly therefrom for pre-filtration thereof. The liquid is then carried to a second stage filter which is a rotary filtration means for further removing contaminants through a rotatable cylinder with internal baffles for discharging the waste at one end of the cylinder and discharging the filtered water downwardly about the periphery of the cylinder. The cylinder is formed of a filtration media. A liquid reservoir is positioned below the cylindrical filter which includes a tank means for receiving filtered liquid and a heating means for controlling the temperature thereof.

Abstract: The subject valve discharge system comprises a discharge valve member that includes a valve closure segment at an inlet end thereof for insertion in the discharge valve housing. It further includes valve connecting means at a discharge end thereof. The respective discharge valve member and the discharge valve housing together define a gap therebetween. The discharge elbow defines a flow passage therethrough and includes elbow inlet and outlet ends. The elbow inlet end includes elbow connecting means. Discharge valve mounting means are connected to the respective discharge valve member and the elbow connecting means, respectively. The valve mounting means is self-adjustable during use for axial movement in response to the axial movement of the discharge system which is responsive to the axial movement of the rotary drum filter. In this way, the gap setting is maintained at a substantially constant, fixed clearance.

Abstract: The improved rotary vacuum filter discharge flow assembly provides a discharge filtrate stream having a substantially increased filtrate flow velocity, a reduced vacuum loss, a reduced level of turbulence and air entrainment to means defining an axially-extending valve-receiving space in communication with a remote filtrate collection area. The subject assembly, which is located at one end of a rotary vacuum filter, includes a plurality of radially-disposed, inlet conduit means connected to and in communication with the rotary vacuum filter discharge flow assembly and comprises a plurality of radially-disposed discharge conduit means for transporting the discharge filtrate stream from the inlet conduit means to the valve-receiving space means. Each of the discharge conduit means are connected at one end to one end of the inlet conduit means, and are joined at the other end to respective adjacent discharge conduit means for defining the valve-receiving space means.

Abstract: An apparatus for washing cellulose, wherein the cellulose is conducted through between a rotary drum and a stationary shell encircling it, in the form of a layer supported by the permeable mantle surface of the drum. The principle of operation of the apparatus is: conducting washing liquid through the shell, through compartments located under the mantle surface of the drum and serving as washing liquid collectors, and through a valve system composed of a rotary part associated with the drum and a stationary part placed thereagainst, several times through the cellulose layer so that when the apparatus is operating the washing liquid at the same time moves in the direction opposite to the direction of rotation of the drum, stepwise, through the apparatus.

Abstract: A continuous contacting device is disclosed wherein a fluid stream may be contacted with particulate exchange materials. The device includes a plurality of rotating chambers filled with particulate material. Fluid is supplied individually to these chambers through a plurality feed ports which are in periodic fluid communicating relation with each of the chambers. A plurality of fixed discharge ports which are likewise in periodic fluid communicating relation with each of the chambers is also provided. A process for continuously contacting fluids with the solid particulates is also disclosed.

Abstract: A rotary drum vacuum filter suitable for processing pulp slurries is provided with a vacuum expression belt. The invention provides a method and apparatus for tracking and controlling the belt during operation. The belt is positioned by a moveable frame for expressing filtrate from the pulp web and in operation a control unit monitors lateral movement of the belt with respect to the drum. When drifting occurs the belt is adjusted horizontally during operation to counter drift. The adjustment can be repeated as necessary. If continued drift cannot be corrected then the belt is moved vertically to an inoperative position.

Abstract: A filter for continuous filtering of suspension under pressure includes a pressure vessel, a shaft rotatably journalled in the pressure vessell and disc filters elements arranged on the shaft. The filter elements are composed of sectors and inlet filtrate channels in each sector are connected to axially extending channels in the shaft, one axial channel for each sector. The axial channels are connected to a filtrate valve formed to divide the filtering cycle corresponding to one rotation revolution for the filter elements in a number of filtering zones, at least one in liquid phase and one in gaseous phase. A separate filtrate outlet from the pressure vessel is connected to each filtering zone and means is controlling the difference pressure over the filtering zones independent of each other.