Patent Description:
In different stages of a pulp production process, the pulp has to be washed and/or dewatered. A very common approach for achieving dewatering is to use pulp filter equipment utilizing cylinder-based dewatering. This approach is based on the action of a perforated rotating cylinder surface, onto which a pulp to be dewatered/washed is provided. Liquid components of the pulp may pass the perforations of the cylinder surface, leaving a pulp with a higher concentration at the surface. This process becomes particular efficient if a pressure difference is applied between the volume outside and inside the cylinder surface.

In order to make the production more efficient, the cylinders may be long. Lengths of <NUM>-<NUM> meters are not uncommon. The equipment for pressurizing and the rotation control of the cylinders may essentially the same as for shorter cylinders, however, the throughput of pulp is increased considerably.

One problem with the use of long cylinders for pulp filtering purposes is that the efficiency of the dewatering /washing depends on the pressure distribution along the cylinder surface. Gases and liquids experiencing a pressure difference tend to select a path having as small flow resistance as possible. If the distribution of pulp over the surface of the cylinder is uneven, gases and liquids will tend to penetrate or escape the pulp predominantly at places where the pulp has a low consistency, i.e. where the pulp concentration is low. This means that an uneven distribution of pulp over the cylinder surface may give rise to unevenly dewatered/washed pulp.

The pulp is typically provided to the dewatering/washing arrangements by different types of pipe systems. When the pulp reaches the cylinders, the pulp has typically to be distributed over a much wider cylinder surface. Different arrangements of distributer screws have been used. The distribution action such screws is typically in the same order of magnitude as the speed of the rim of the screw. Since the speed of the screw typically in many applications is selected to be approximately the same as the pulp flow speed, the result of the distributer screw is typically limited, leading to that the pulp distribution still is very uneven. Furthermore, changes in pulp conditions, such as temperature, concentration, inlet flow speed etc. may influence the optimum screw speed. However, distributer screws are typically low-complexity arrangements having small or no possibilities to change the rotational speed.

<CIT> discloses a process for distributing an especially medium-consistent fibrous suspension in front of a dewatering device. It is distinguished in that the fibrous suspension is taken to the dewatering device in fluidized form and evenly distributed. Also disclosed is a device for implementing the process in which there is a closed device with a fluidizing rotor in front of the dewatering device.

<CIT> discloses an apparatus for washing and/or dewatering cellulose pulp including a movable permeable surface in a pulp transportation chamber having a chamber gap above the movable permeable surface, a pulp distributor for distributing pulp onto the movable permeable surface, a throttle having a throttle gap width and an adjustable throttle adjuster to remotely adjust the throttle gap width so that a volume of pulp flow into the pulp distributor is equal to or greater than the volume of pulp flow out of the distributor during operation.

<CIT> discloses a method for processing pulp in an apparatus for washing and dewatering pulp, and a system for controlling this apparatus, the apparatus comprising two rotatable press rolls having a permeable outer surface, and a vat, the press rolls defining a press nip between them. The processing is determined by a set of variable operating parameters, which are adjusted and/or maintained during operation in response to deviations of measured values of control parameters in relation to their respective predetermined threshold values. The variable operating parameters include rotation speed of the press rolls. The control parameters include vat pressure and/or linear load.

Furthermore, <CIT> discloses a distributor device for cellulose pulp of low and medium consistency that is used to form a uniform pulp web running from the distributor device in an apparatus treating the cellulose pulp. The distributor device has a cylindrical distributor housing arranged horizontally and transverse to the pulp web, and an inlet for the cellulose pulp at one end of the distributor housing and on the pulp web side. Pulp is fed with feed screws from the inlet and along the length of the distributor housing. The web is initially formed via the outlets defined along a generatrix in the jacket surface of the distributor housing. An optimum distribution of low-concentration pulp is obtained with the holes arranged along the generatrix in the jacket surface of the distributor housing. The holes have a defined hole diameter and are arranged at a distance from each other. The interaction with the feed screw makes it possible to keep the holes free from clogging.

A general object to find additional arrangements for improving the homogeneity of the pulp treatment in dewatering/washing arrangements.

The above object is achieved by methods and devices according to the independent claims. Preferred embodiments are defined in dependent claims.

In general words, in a first aspect, a pulp distribution compartment arrangement for pulp filter equipment utilizing cylinder-based dewatering comprises a distribution compartment and a distributer screw. The distribution compartment has an exit opening. The exit opening has an elongated shape with a main extension in a first direction. An inlet to the distribution compartment is provided at a side of the distribution compartment opposite to the exit opening. The inlet enters the distribution compartment at an inlet position in the first direction. The distributer screw is rotatably arranged in the distribution compartment with a rotation axis parallel to the first direction. An elongated flow passage is defined between the distributer screw and a side wall of the distribution compartment. The side wall extends in a flow direction between the inlet and the exit opening. A throttle surface is provided at the side wall in a position along the first direction corresponding to the inlet position. The throttle surface provides a restriction of the elongated flow passage at the position in comparison to other positions in the first direction.

In a second aspect, a pulp filter equipment comprises a pulp dewatering arrangement having a pulp compartment provided in contact with a perforated cylinder. A pulp distribution compartment arrangement according to the first aspect is provided. The pulp distribution compartment arrangement is arranged with the exit opening in fluid contact with the pulp compartment and with the main extension of the exit opening being parallel to an axis of the cylinder.

In a third aspect, a pulp introduction method for pulp filter equipment utilizing cylinder-based dewatering comprises introducing a flow of pulp into a distribution compartment through an inlet. The pulp is passed the distribution compartment to an exit opening. The exit opening is situated at a side of the distribution compartment opposite to the inlet and has an elongated shape with a main extension in a first direction. The flow of pulp entering the distribution compartment at an inlet position in the first direction. A distributer screw rotatably arranged in the distribution compartment with a rotation axis parallel to the first direction is rotated. An elongated flow passage is defined between the distributer screw and a side wall of the distribution compartment. The side wall extends in a flow direction between the inlet and the exit opening. A throttle surface is provided at the side wall in a throttle position along the first direction corresponding to the inlet. The throttle surface provides a restriction of the elongated flow passage at the throttle position in comparison to other positions in the first direction.

One advantage with the proposed technology is that pulp is more evenly distributed over the width of a dewatering cylinder without requiring large amounts of additional supplied energy. Other advantages will be appreciated when reading the detailed description.

The invention, together with further objects and advantages thereof, may best be understood by making reference to the following description taken together with the accompanying drawings, in which:.

Throughout the drawings, the same reference numbers are used for similar or corresponding elements.

For a better understanding of the proposed technology, it may be useful to begin with a brief overview of typical pulp filter equipment utilizing cylinder-based dewatering.

<FIG> illustrates schematically parts of an embodiment of a prior art pulp filter equipment <NUM>. The pulp filter equipment <NUM> comprises a pulp dewatering arrangement <NUM> having a perforated cylinder <NUM> enclosed by a housing <NUM>. A pulp compartment <NUM> is defined between the perforated cylinder <NUM> and the housing <NUM>.

Incoming pulp <NUM> is provided, typically by an inlet pipe <NUM> to a pulp distribution compartment arrangement <NUM>, in which the pulp is distributed along the perforated cylinder <NUM> in the axial direction of the perforated cylinder <NUM>. The incoming pulp <NUM> may be provided to the pulp distribution compartment arrangement <NUM> from any direction, as indicated by the alternative inlet pipe illustrated by broken lines. The pulp thus enters, as indicated by the arrow <NUM>, the pulp compartment <NUM> and follows the rotation of the perforated cylinder <NUM>. Gas and liquid (as typically also some minor amounts of pulp) passes the perforations of the perforated cylinder <NUM>, as indicated by the arrows <NUM>. The perforated cylinder is rotated in a rotational direction R, transporting the pulp within the pulp compartment <NUM> around the perforated cylinder <NUM>.

If the pulp filter equipment <NUM> is intended for washing purposes, washing liquids <NUM> can be introduced in washing sections <NUM> at different positions around the pulp filter equipment <NUM>.

The pulp, typically reduced in liquid content <NUM>, is excited from the pulp filter equipment <NUM> through an outlet <NUM>. In washing applications, however, the pulp exiting the outlet <NUM> may even have an increased liquid content compared to the pulp entering the arrangement.

The arrangement and procedures around different kinds of pulp filter equipment <NUM> are, as such, well-known by anyone skilled in the art and is therefore not further described in detail. Only features and conditions that are of interest for the present ideas are discussed further below.

<FIG> illustrates a part of an embodiment of a pulp filter equipment <NUM> with a part of a wall of a distribution compartment <NUM> of a pulp distribution compartment arrangement <NUM> and a part of the housing <NUM> removed (as well as the distributer screw). The pulp distribution compartment arrangement <NUM> thus comprises the distribution compartment <NUM>. The distribution compartment <NUM> has an exit opening <NUM>, which has an elongated shape with a main extension in a first direction X. This first direction X is parallel with the rotational axis of the perforated cylinder <NUM>.

An inlet pipe <NUM> is attached to an inlet <NUM> of the distribution compartment <NUM>, to which inlet pipe <NUM> incoming pulp <NUM> may be provided in any direction, as illustrated by the alternative arrows. The inlet <NUM> is situated at an opposite side of the distribution compartment with respect to the exit opening <NUM>. The inlet <NUM> is typically considerable narrower than the distribution compartment <NUM> in the first direction X, and an inlet position <NUM> of the inlet <NUM> along the first direction X can be defined. The purpose of the pulp distribution compartment arrangement <NUM> is, as the name indicates, to distribute the pulp, as indicated by arrows <NUM>, as evenly as possible over the entire width of the perforated cylinder <NUM>.

<FIG> illustrates the pulp distribution compartment arrangement <NUM> in a cross-sectional side view. The incoming pulp <NUM> is distributed <NUM> in the interior <NUM> of the distribution compartment <NUM>. For assisting in this distribution, there is provided a distributer screw <NUM> (which was excluded in <FIG>), which is rotatably arranged around a rotation axis <NUM> parallel to the first direction X. In this example, the distributer screw <NUM> has a first threading 31A, which is arranged for supporting pulp flow in the direction from the inlet position <NUM> towards one of the ends of the distribution compartment <NUM>, when the distributer screw <NUM> is rotated in the intended direction. The distributer screw <NUM> has also a second threading 31B, which is arranged for supporting pulp flow in the direction from the inlet position <NUM> towards the other end of the distribution compartment <NUM>, when the distributer screw <NUM> is rotated in the same intended direction. The distributer screw <NUM> thus assists in forcing the pulp out from the center towards the ends of the distribution compartment <NUM>.

<FIG> illustrates the same pulp distribution compartment arrangement <NUM> in a perpendicular cross-sectional side view, seen along the first direction. Here it is seen that the distributer screw <NUM> is arranged relatively close to one side wall of the distribution compartment <NUM>, thereby leaving an elongated flow passage <NUM> open at the other side. The elongation of the flow passage <NUM> is directed along the first direction, i.e. perpendicular to the view in <FIG>. The flow passage <NUM> is defined between the distributer screw <NUM> and a side wall <NUM> of the distribution compartment <NUM>. The side wall <NUM> extends in a flow direction between the inlet <NUM> and the exit opening <NUM>.

The distributer screw <NUM> of <FIG> is intended to be rotated in a counterclockwise direction as illustrated, which means that any pulp flow at the right side of the distributer screw <NUM> is counteracted, but the pulp flow in the flow passage <NUM> is facilitated.

Having a very slow rotation of the distributer screw <NUM> will cause the pulp flow to be faster than the rotation speed, which causes friction losses between the distributer screw <NUM> and the pulp in the flow passage <NUM>. At the same time, the distribution action is also low. By increasing the rotational speed, the distribution action will increase, and the friction will decrease, at least up to the point where the pulp flow in the flow passage <NUM> has a same speed as the rotational speed of the distributer screw <NUM>. An even higher speed will probably increase the friction again, causing additional energy losses. Depending on the pressure conditions in the distribution compartment and the pulp compartment in the pulp filter equipment <NUM>, and on the pulp condition, such as e.g. concentration, viscosity, temperature etc., there are different optimum speeds for the distributer screw <NUM>. However, control of the speed of the distributer screw <NUM> is often difficult to perform due to the complexity in the relation between optimum speed and pulp condition. Furthermore, a distributer screw <NUM> including speed control may be considerably more expensive than a constant speed arrangement.

An alternative approach to assist in pulp distribution within a pulp distribution compartment is illustrated in <FIG>. This embodiment of a pulp distribution compartment arrangement <NUM> for pulp filter equipment utilizing cylinder-based dewatering comprises a distribution compartment <NUM>. The exit opening <NUM> from the distribution compartment <NUM> has an elongated shape with a main extension in a first direction (perpendicular to the plane of paper in the illustration). The inlet <NUM> to the distribution compartment <NUM> is situated at a side of the distribution compartment opposite to the outlet opening <NUM>. The inlet <NUM> enters the distribution compartment <NUM> at an inlet position in the first direction. The distributer screw <NUM> is rotatably arranged in the distribution compartment <NUM> with a rotation axis <NUM> parallel to the first direction. An elongated flow passage <NUM> is thereby defined between the distributer screw <NUM> and a side wall <NUM> of the distribution compartment <NUM>. The side wall <NUM> extends in a flow direction between the inlet <NUM> and the exit opening <NUM>. The side wall <NUM> is in this embodiment depicted as a straight side wall, which extends in a vertical direction. A side wall according to the invention can, however, be a curved side wall, which extends in other directions.

This embodiment further comprises a throttle surface <NUM> provided at the side wall <NUM> in a position along the first direction corresponding to the inlet position. This position is defined as a position of a most prominent part of the throttle surface, typically a center of the throttle surface and is referred to as the throttle position. The throttle surface <NUM> provides a restriction of the elongated flow passage <NUM> at this throttle position in comparison to other positions in the first direction.

In this embodiment, the throttle surface <NUM> is provided at the side wall <NUM> at a level of the distributer screw <NUM> in the flow direction. This may be advantageous, since already the distributer screw <NUM> provides some flow restrictions, which then can be enhanced by the throttle surface <NUM>. However, in other embodiments, the throttle surface <NUM> may be provided at other positions along the flow direction, but before the pulp compartment <NUM> at the perforated cylinder <NUM> is reached.

In the embodiment of <FIG>, the distributer screw <NUM> is provided close to the opposite wall, with respect to the throttle surface <NUM>. However, in other embodiments, the distributer screw <NUM> may be positioned closer to the throttle surface <NUM>. The pulp flow <NUM> may the also have a component at the opposite side of the distributer screw <NUM>.

In a particular other embodiment, a respective throttle surface may be provided at both side walls on opposite sides of the distributer screw <NUM>.

<FIG> illustrates another side view of the embodiment of a pulp distribution compartment arrangement <NUM> of <FIG> with the distributer screw removed. Here, it is easily seen that the inlet <NUM> enters the distribution compartment <NUM> at an inlet position <NUM> in the first direction X. A throttle position is preferably positioned at the inlet position <NUM>. The throttle surface <NUM> restricts the width of the flow passage, which means that the local pressure in this region increases. The flow of pulp <NUM> within the pulp distribution compartment arrangement <NUM> typically follows a path striving towards lower pressures, and the tendency for the flow of pulp to go from the inlet position <NUM> towards the ends of the distribution compartment <NUM> increases. This results in a more even distribution of the pulp along the entire exit opening <NUM>. The pulp flow <NUM> into the pulp compartment of an associated pulp filter equipment thus takes place over the entire width.

The throttle surface <NUM> can be designed in many different ways. <FIG> illustrates a side view of a side wall <NUM> and a throttle surface <NUM>, where the upstream end of the throttle surface is constituted by an inclined flat surface. The downstream part of the throttle surface <NUM> is the provided at a constant distance from the side wall <NUM>. In <FIG>, the throttle surface <NUM> is provided with an inclined surface both at the upstream and downstream ends. In <FIG>, a throttle surface with a rectangular cross-section is illustrated. In <FIG>, the throttle surface <NUM> consists of a single inclined surface. As any person skilled in the art understands, the shape of the throttle surface <NUM> can be varied in many different ways.

Similarly, the shape of the throttle surface <NUM> along the first direction X may also be designed in many different ways. <FIG> indicates a shape having a broadest with in the vicinity of the inlet position <NUM> and which gradually narrows towards the ends of the distribution compartment <NUM>. <FIG> illustrates a throttle surface <NUM> having a rectangular shape as seen in a direction perpendicular to the first direction X and the inlet pulp flow. <FIG> illustrates a throttle surface <NUM> having a reduced vertical extension in the vicinity of the ends. Also here, as any person skilled in the art understands, the shape of the throttle surface <NUM> can be varied in many different ways.

Also the protrusion from the side wall can be designed in different ways. In a preferred embodiment, the restriction of the elongated flow passage decreases monotonically from the throttle position in at least one direction along the first direction. By "monotonically decreasing" is understood the common mathematical definition, i.e. that the restriction is constant or decreasing in every section from the throttle position outwards. In other words, the restriction of the elongated flow passage is largest at the throttle position and lacks any section with increasing restriction when moving outwards along the first direction from the throttle position.

This monotonic behaviour is preferably maintained over at least <NUM>% of a distance between the throttle position and an end wall of the distribution compartment. Close to an end wall of the distribution compartment, end effects may occur. Such end effects may result in that there is a build-up of pressure within the pulp close to the end wall. In such cases, it may be advantageous to cause pulp to instead move inwards, away from the end wall. Consequently, in such cases, the restriction of the elongated flow passage may even increase close to the end wall. In most applications, such end effects are only present outside the above mentioned <NUM>% of a distance between the throttle position and an end wall of the distribution compartment.

<FIG> illustrates one such example. Here, in the diagram, the protrusion of the throttle surface <NUM> is plotted against the position along the first direction. A flat mid-section covers the inlet position <NUM>. At each end, the protrusion is gradually, in this particular case linearly, decreasing. This restriction is thus monotonically decreasing from the inlet position <NUM> towards the respective ends. In this particular embodiment, the throttle surface is a piecewise flat surface.

<FIG> illustrates another example of a throttle surface causing a restriction that monotonically decreases from the inlet position <NUM> towards the respective ends. In this case, the decrease is gradual in a non-linear fashion. As any person skilled in the art understands, the shape of the throttle surface <NUM> can be varied in many different ways.

Also the amount by which the throttle surface protrudes is of importance. A larger protrusion cases a larger flow restriction and typically increases the tendency to force the pulp flow towards the sides. In order to give a reasonably effect for most design variations, the width of the flow passage <NUM> is preferably reduced by at least <NUM>%. By using a ratio between on one hand a smallest distance between the throttle surface and the distributer screw and on the other hand the largest distance between the side wall and the distributer screw, one definition of the flow passage reduction can be defined. Preferably, such a ratio is less than <NUM>, more preferably less than <NUM>, even more preferably less than <NUM> and most preferably less than <NUM>. This enables a noticeable influence on the flow characteristics of the pulp within the pulp distribution compartment arrangement.

In a particular embodiment, the distributer screw <NUM> is arranged in a similar manner as in <FIG>. In other words, the distributer screw extends outside the inlet position <NUM> on both sides along the first direction X. In a further embodiment, the distributer screw has a threading in a first direction at one side of the throttle position and a threading in a second, opposite, direction at the opposite side of the throttle position. Preferably, as mentioned above, the restriction decreases monotonically from the throttle position in both directions along the first direction.

The mechanical construction of the throttle surface can be of many different kinds. A solid or hollow volume of solid material can in one be attached to the side wall. Alternatively, the side wall may be re-shaped to give the protrusion. In other words, the throttle surface may be integrated directly into the side wall. The throttle surface may also be formed by arranging e.g. a number of flat or curved plates to the side wall and to each other. Another approach is to form the throttle surface by a sheet supported by a throttle surface support. The sheet may be rigid or elastic.

As mentioned in the background, different pulp conditions may require different conditions within the pulp distribution compartment arrangement to achieve a proper pulp distribution. In <FIG>, a pulp filter equipment <NUM> is illustrated, having a throttle surface <NUM> according to the ideas presented above. The distributer screw is removed in this illustration to increase the visibility. The pulp dewatering arrangement <NUM> of the filter equipment <NUM> may in one embodiment be a pulp press-washing equipment. The pulp dewatering arrangement <NUM> of the filter equipment <NUM> may in another embodiment be a pulp press-dewatering equipment.

In one embodiment, the throttle surface is adjustable, thereby enabling provision of different restriction sizes and/or shapes. In embodiments based on a sheet supported by a throttle surface support, the throttle surface support can be adjustable. In a further embodiment, the throttle surface support is adjustable from outside the pulp distribution compartment arrangement <NUM>, thereby enabling provision of different restriction sizes and/or shapes during operation.

In a particular embodiment, the pulp distribution compartment arrangement <NUM> further comprises a control unit <NUM>. The control unit <NUM> has an input for information associated with sensor readings. Typically, sensors <NUM> are connected by wired connections <NUM> or wireless connections to the input of the control unit <NUM>. The control unit <NUM> is thereby configured to adjust the throttle surface <NUM> e.g. by the throttle surface support in dependence of the information associated with sensor readings. This can be achieved by sending signals to an adjustment arrangement of the throttle surface <NUM>, e.g. by wired connections <NUM> or wireless connections.

The information associated with sensor readings may in one embodiment comprise measurements related to pulp flow. In other words, at least one the sensors <NUM> may be a sensor responsive to properties associated with pulp flow. Examples of such sensors are e.g. pressure sensors, flow speed sensors, temperature sensors, conductivity sensors etc. The information associated with sensor readings thus typically comprise information concerning pulp properties and/or flow information of a flow of pulp. In other words, at least one the sensors <NUM> may be a sensor responsive to properties associated with pulp flow.

Seen from a pulp filter equipment <NUM> view, the pulp distribution compartment arrangement <NUM> is a pulp distribution compartment arrangement having a control unit <NUM>. The pulp treatment equipment <NUM> then further comprises at least one sensor, connected to the control unit and arranged for providing the information associated with sensor readings.

As mentioned above, in one embodiment, at least one of the sensors is a sensor responsive to properties associated with pulp flow. Preferably, in one further embodiment, the sensor responsive to properties associated with pulp flow is arranged to measure such conditions within the pulp compartment <NUM>. In another embodiment, the sensor responsive to properties associated with pulp flow is arranged to measure such conditions at the exit opening from the distribution compartment.

In one embodiment, , the sensor responsive to properties associated with pulp flow is arranged to measure pulp properties and/or flow information of a flow of pulp <NUM> to be entered into the inlet <NUM>.

The controllability of the throttle surface <NUM> can be implemented in many different ways. <FIG> illustrates schematically one approach to provide a throttle surface <NUM> with variable protrusion. In this embodiment, the throttle surface <NUM> comprises three sections of planar plates hinged to each other. The center plate is joined to two throttle surface supports <NUM> in a hinged manner. A guiding pin <NUM> attached to the center plate of the throttle surface <NUM> is provided through a guide opening <NUM> to ensure the vertical positioning of the throttle surface <NUM>. In <FIG>, the ends of the throttle surface supports <NUM> that are not hinged to the throttle surface <NUM> are moved vertically, thereby causing the enter plate of the throttle surface <NUM> to be moved closer to the side wall <NUM>. The moving of the throttle surface supports <NUM> can e.g. be controlled by a control unit, such as illustrated in <FIG>.

<FIG> illustrates an alternative embodiment. Here, a flexible surface sheet <NUM> is supported on a rigid plate <NUM>, which in turn is attached to throttle surface supports <NUM>. The throttle surface supports <NUM> are linearly movable by motor units <NUM>. By moving the throttle surface supports <NUM> in and out, the protrusion of the flexible surface sheet <NUM> can be adapted, as illustrated in <FIG>.

As any person skilled in the art understands, the approach for controlling a shape and/or protrusion of the throttle surface <NUM> can be varied in many different ways.

The shape and design of the pulp distribution compartment arrangement may also vary in other aspects. In <FIG>, an embodiment with an asymmetric inlet of pulp is shown. The inlet <NUM> is here situated at one end of the distribution compartment <NUM>. The distributer screw <NUM> is in this embodiment only requested to drive the pulp in one direction, to the right as illustrated in the figure. The distributer screw <NUM> therefore only presents one threading <NUM>. The throttle surface <NUM> here starts at the left side of the distribution compartment, as illustrated and protrudes at least a part of the distance towards the right side.

<FIG> illustrates yet another embodiment of a pulp distribution compartment arrangement <NUM>. Here, the pulp distribution compartment arrangement <NUM> comprises more than one inlet <NUM> to the distribution compartment <NUM>, in this particular embodiment three. The inlets <NUM> are positioned at different positions along the first direction X. The pulp distribution compartment arrangement <NUM> also comprises more than one throttle surface <NUM>, one for each inlet <NUM>. The throttle surfaces <NUM> are provided at the side wall <NUM> at a level of the distributer screw <NUM> in the flow direction and in a respective position <NUM> along the first direction X corresponding to a respective inlet <NUM>. The distributer screw <NUM> is provided with threadings 31A and 31B, alternating in threading directions, adapted to assist in distributing pulp away from each inlet <NUM>.

Also, the distribution compartment <NUM> itself may be of varying design. <FIG> illustrates schematically the outer shape of a distribution compartment <NUM>. In this embodiment, the distribution compartment <NUM> presents a sloping upper wall, giving an interior <NUM> volume that is higher in the vicinity of the inlet <NUM> compared to the ends. Such shaping may also facilitate the distribution of the pulp.

As indicated above, the pulp distribution compartment arrangement <NUM> according to the embodiments presented above is advantageously used in a pulp filter equipment <NUM>. The pulp filter equipment <NUM> comprises a pulp dewatering arrangement <NUM> having a pulp compartment <NUM> provided in contact with a perforated cylinder <NUM>. The pulp distribution compartment arrangement <NUM> is arranged with the exit opening <NUM> in fluid contact with the pulp compartment <NUM> and with the main extension X of the exit opening <NUM> parallel to an axis of the cylinder <NUM>.

The pulp dewatering arrangement <NUM> is in one embodiment a pulp press-washing equipment. The pulp dewatering arrangement <NUM> is in another embodiment a pulp press-dewatering equipment.

<FIG> illustrates a flow diagram of steps of an embodiment of a pulp introduction method for pulp filter equipment utilizing cylinder-based dewatering. In step S10, a flow of pulp is introduced into a distribution compartment through an inlet. In step S20, the pulp is passed through the distribution compartment to an exit opening. The exit opening is situated at a side of the distribution compartment opposite to the inlet and has an elongated shape with a main extension in a first direction. The flow of pulp enters the distribution compartment at an inlet position in the first direction. A distributer screw, rotatably arranged in the distribution compartment with a rotation axis parallel to the first direction, is rotated in step S30. Thereby, an elongated flow passage is defined between the distributer screw and a side wall of the distribution compartment. The side wall extends in a flow direction between the inlet and the exit opening. In step S40, a throttle surface is provided at the side wall in a throttle position along the first direction corresponding to the inlet. Thereby, the throttle surface provides a restriction of the elongated flow passage at the throttle position in comparison to other positions in the first direction.

Claim 1:
A pulp distribution compartment arrangement (<NUM>) for pulp filter equipment (<NUM>) utilizing cylinder-based dewatering, comprising:
- a distribution compartment (<NUM>);
- an exit opening (<NUM>) from said distribution compartment (<NUM>), said exit opening (<NUM>) having an elongated shape with a main extension in a first direction (X);
- a inlet (<NUM>) to said distribution compartment (<NUM>) at a side of the distribution compartment opposite to said exit opening (<NUM>), said inlet (<NUM>) entering said distribution compartment (<NUM>) at an inlet position (<NUM>) in said first direction (X);
- a distributer screw (<NUM>) rotatably arranged in said distribution compartment (<NUM>) with a rotation axis (<NUM>) parallel to said first direction (X);
whereby an elongated flow passage (<NUM>) is defined between said distributer screw (<NUM>) and a side wall (<NUM>) of said distribution compartment (<NUM>), said side wall (<NUM>) extending in a flow direction between said inlet (<NUM>) and said exit opening (<NUM>),
characterized by
- a throttle surface (<NUM>) provided at said side wall (<NUM>) in a throttle position along said first direction corresponding to said inlet position (<NUM>);
whereby said throttle surface (<NUM>) provides a restriction of said elongated flow passage (<NUM>) at said throttle position in comparison to other positions in said first direction (X).