JP5911873B2 - Method and configuration for treating pulp - Google Patents

Description

  The present invention relates to a method and configuration for treating pulp fed into a screen chamber in a pulp grinder.

  In chemical wood processing, the wood material is fed into the digester where the wood chips are processed so that the pulp (brown stock) is produced, and after the digester, the pulp is mainly fiber Is in a fibrous state, or it can be at least easily broken down into a fibrous state. The so-called brown stock discharged from the digester is washed and usually put into a delignification stage, where oxygen is usually used as delignification chemical. The delignification stage ends with a wash.

  Brown stock or oxygen delignified pulp discharged from the digester is typically screened in a screen chamber at an appropriate process stage. The purpose of pulp sieving is to separate material that is not needed for further processing, especially for the final product from the pulp. However, sieving is an operation that requires diluting the pulp to a concentration of about 1-4%, depending in part on the equipment used. Pulp is usually fed to the screen from the blow tank of the digester plant or from the tank following the oxygen delignification reactor where the pulp concentration is a medium concentration of 8-14%. In order to dilute the pulp from this discharge concentration to the few percent concentration required by the screen device, a dilution system is placed in the tank to pump the required amount of diluent. In most cases, the pulp is pumped through its top into the tank and the pulp is discharged immediately next to the diluent mixer positioned at the bottom of the tank. The pulp is preferably mixed with a diluent introduced via a mixer so that the pulp can be pumped from the tank to the subsequent process stage, i.e. into the screen apparatus. Mix quickly.

  The screen room consists of different types of screen devices such as nodule separation devices, screens, and nodule washers. The screen chamber can be positioned either after the digester or after the oxygen delignification stage or elsewhere in the pulp grinder where it is desired to increase the purity of the pulp. As mentioned above, the screen chamber is usually fed from a tank or tower, where there is a low concentration zone with a capacity of several tens of cubic meters. To homogenize the low concentration volume, a tank agitator and a reasonable amount of dilution water are used.

  In the smallest tank or tower with a diameter of about 3.5-7.0 m, the bottom portion can be made upright cylindrical, or initially somewhat narrowed and cylindrical under it. For larger towers, whose diameter is typically greater than 5.0 m, a so-called bottom strut can be placed in the center of the tower bottom. The purpose of the bottom strut is to lift the pulp over the bottom portion and to divide the bottom portion into an annular mixing zone. The shape of the prior art bottom strut may be either a uniformly converging cone (FIG. 1), a cylindrical strut, or a cylindrical strut with a converging cone converging upward at its upper end. it can. In all those towers with bottom struts, they are located on the bottom strut side so that the diluent mixer / multiple diluent mixers direct the flow to circulate along the annular mixing zone. The The bottom struts shall be of a rugged construction and when placed on the tower bottom they will be supported only by the tower bottom or the underlying foundation, in any case, by that very point, the tower bottom will be Otherwise, it should support the weight of the pulp in the tower. FIG. 1 shows a known high concentration having a tower wall 12, a bottom portion 20, a tower bottom 22, a bottom column 30, a mixer 40, a conduit 50 for feeding diluent and a discharge means 60 for diluted pulp. A pulp tower 10 (FIG. 2a of US Pat. No. 5,711,600) is shown. In the configuration of FIG. 1, the bottom portion 20 and the top portion of the tower 10 have a conical wall section 14 therebetween. The mixer 40 is arranged at a height of about 1.1 m from the bottom of the tower, so that the diluent is fed through the conduit 50 into the dilution zone at the bottom part at a height slightly higher than the mixer shaft.

  The problem with these structures is still related to the uneven pulp discharge concentration. To overcome this problem, US Pat. No. 5,711,600 discloses a more advanced design of the bottom strut. According to this patent, it is essential that the diameter of the split member disposed therein is at least an order of magnitude larger than the diameter of the lower part of the column for the upper end of the column. In other words, the feature of the dividing member is that in the region of the dividing member, the cross-sectional area between the dividing member and the wall of the tower is smaller than the cross-sectional area in the bottom region of the column. This design still requires several mixers (the number of mixers can range from 2 to 6, depending mainly on the tower size) Connected with feed conduit for liquid. The mixers are placed in the bottom part of the tower so that they dilute the pulp and quickly circulate around the bottom struts. U.S. Pat. No. 7,622,018 describes at least a portion of the diluent required to dilute the pulp to the tower outlet concentration, in a certain region, substantially the height of the smallest cross-section of the tower (FIG. 2). A similar arrangement is described in which the dilution is further improved to be introduced between the tower wall and the strut (or another split member) in this position. The diluent is preferably introduced into at least two parts in the dilution part of the tower. One part is introduced into the thick pulp suspension at the same time that the suspension is removed from the storage part of the tower into the dilution zone, and the other part of the stirrer located in the dilution zone. Introduced with help. FIG. 2 shows an improved prior art high concentration pulp tower 10 according to US Pat. No. 7,622,018. The bottom portion 20 of the tower 10 includes a fixed bottom column 30. The upper end of the strut 30 is shaped so that the diameter of the split member 31, which is also fixed in it, is at least an order of magnitude larger than the diameter of the lower part of the strut 30. More generally, at the height of the dividing member 31, the cross-sectional area between the dividing member 31 and the wall 12 of the tower 10 is smaller than that in the bottom region of the column 30 below the dividing member. The dividing member 31 has an upper section 34 whose diameter is conical and converges upwards. In FIG. 2, the baffle plate 36 includes an annular feed tube 46 positioned between the bottom strut 30 and the tower wall 12, which feeds the diluent down the pulp into the dilution zone. Substantially simultaneously, a nozzle 48 is provided for introduction into the highly concentrated fiber suspension. The bottom part of the tower contains several dilution agitators 40. Pulp is discharged through conduit 60.

  The screen chamber feed tank can have an overall height of 6-30 meters and a diameter of 2-10 m, sometimes in the upper part of the screen chamber feed tank, for example when longer holding times are required from process requirements Is larger than the bottom part.

  In pulp mills with a production of 1000 admt / d, the low concentration mixing zone in the tank can be 3-6 meters in diameter and 2-6 meters in height. In a 3000 admt / d pulp mill, the mixing zone in the tank or tower can be 6-10 meters in diameter and 3-10 meters in height. A special tank agitator is used to homogenize the zone to be diluted of the tank. Normally, tank agitators operate within a concentration range of 2-5% concentration, but the performance of the agitator will be poor when the concentration is about 4.5-6% or higher.

  In conventional systems, the retention time of the pulp in the low-concentration mixing zone is usually 2-5 minutes, but in any case is shorter than 10 minutes. The tank stirrer is a method in which the concentration of the stock diluted in the tank becomes more uniform, the variation in the concentration of the stock from the tank becomes sufficiently small, and the flow can be handled in the screen chamber. Upset. Usually 1 to 4 tank agitators are required to obtain good mixing performance as appropriate. The number of tank agitators used for mixing depends on the production rate, but also on the capacity of the mixing zone.

US Pat. No. 5,711,600 US Pat. No. 7,622,018

  Conventional screen chamber mixing tanks are widely used, but they can also cause problems such as unexpected concentration fluctuations. Also, the mixing tank requires a lot of equipment and equipment for the agitator. The tank is not very energy efficient because of the agitator. A further problem is also their high space requirements and construction costs.

  The purpose of the new innovation is to eliminate the above mentioned problems and to make sure that the concentration of pulp fed to the sieving can avoid harmful concentration peaks, while being more energy efficient, saving space. It is to provide a screen chamber feed tank configuration.

  The object of the invention is achieved by the arrangements and methods described in the independent claims. Furthermore, other preferred embodiments of the invention become known in the dependent claims.

  With the new screen chamber feed tower for pulp, the mixing capacity is reduced, thus eliminating the need for conventional tank agitators. Diluent (water or filtrate) is fed into the upper area of the bottom part of the tower. Before the pulp to be diluted enters the discharge pump, the pulp is processed in a homogenization zone in which a rotating or stationary homogenizer is installed. The purpose of the homogenization zone is to equalize the concentration difference in the pulp suspension, so that the diluent is evenly distributed in the pulp suspension, i.e. the pulp concentration is homogenized. It is to mix the fiber suspension. After the homogenization zone, the pulp concentration is uniform and the pulp can be sent to sieving using a normal process pump (conventional centrifugal pump).

  A pulp tower (or tank) according to an embodiment of the present invention includes an upper portion into which pulp is fed and a bottom portion that is divided into a dilution zone, a homogenization zone and a discharge (pumping) zone. The upper part of the tower can act as a blow tank or a storage (holding) tank, the size of which depends on the requirements of the process if any buffering is required. The cross section of the tower is usually circular. The diameter of the top part is larger than the diameter of the bottom part of the tower. The difference between the top and bottom portions depends on process requirements, such as the holding time for storing pulp in the top portion of the tower.

  A device for injecting diluent into the pulp flowing downward in the tower is positioned substantially at a height that divides the tower into a top portion and a bottom portion, and a discharge device for the diluted pulp is Located in the bottom part. A device for homogenizing the concentration of the pulp stream to be diluted is arranged at a predetermined distance downstream of the dilution device in the pulp flow direction and upstream of the discharge device. Most of the diluent is added into the top area of the bottom portion of the tower. A small portion of the diluent can be added between the top dilution point and the homogenization zone.

  The dilution device defines a dilution point in the bottom portion of the tower having a diameter. According to an embodiment, the distance between the dilution device and the homogenization device is 1.5 to 10 times the tower diameter at the dilution point, at which point most of the diluent is added. The distance is therefore the distance between the first dilution point and the homogenization device.

  The distance between the dilution point and the homogenization point is determined by the required retention time, but is also determined by the homogenizer maintenance requirements.

  The retention time between the dilution point and the homogenizer should be long enough so that undiluted pulp does not enter the screen chamber feed pump. Considering various control systems and delays in the process, a retention time as short as 5-10 seconds should be sufficient, but in practical applications the retention time is usually 15-120 seconds, but preferably Is 20 to 60 seconds.

  According to an embodiment, the diluent can be fed using a normal pipe connection. The dilution is divided into the required number of connections around the mixing tank. The dilution device includes several feed nozzles / outlets located around the tower wall. Diluent is fed from the supply tank and directed inside towards the center of the tower. The pressure is such that the diluent is sprayed towards the pulp flowing down in the tower. The pressure control, outlet shape and number of outlets can be varied in several different ways, as will be apparent to those skilled in the art. However, its purpose is to provide maximum penetration into the pulp stream.

  According to another embodiment, the diluent can also be fed through a feed pipe that is routed through the dilution point. In this type of feed pipe, the diluent is directed into the pulp through several holes so that the diluent flows into the downwardly flowing pulp stream. The dilution device includes at least one pipe that extends inwardly from the pulp tower wall toward the center of the tower, and the pipe includes a number of outlet holes for adding diluent. Depending on the diameter of the dilution zone and the dilution rate, several of these types of dilution feed pipes can be provided through the dilution zone.

Homogenization capacity (i.e., the size of the homogenization zone) are small, usually up to 0.1 m ³ (100 liters) to 3M ^3, whereas the capacity of conventional mixing tanks, of 10 to 300 m ³ Within range. The retention time in the new configuration of the homogenization zone is typically only 2-10 seconds, whereas in conventional mixing tanks, the retention time is typically a few minutes.

  A homogenizer having rotating member (s) that generate disturbances in the homogenization zone will allow the suspension of the stock dilution liquid to flow uniformly to reduce the concentration fluctuations.

  When evaluating mixing with a conventional screen chamber feed tank, the volume space adjacent to the rotary stirrer blade represents only 0.5-3% of the total mixing volume. With the same calculations for the new tower and homogenization design, the volume space of the rotating homogenizer blade represents 15-20% of the total homogenization volume. This larger volume space will result in a more homogenous pulp stream, thereby avoiding harmful concentration peaks. The smaller space in the conventional stirrer tank makes the concentration peak easier to pass through the mixing zone.

  At the same time as the mixing volume is small, the energy input can be more evenly divided and less mixing energy is required to achieve the required mixing quality. When comparing a conventional screen chamber feed tank configuration with a tank agitator and a new system in which a homogenizer is used, the installed power can be reduced by 50-80%, for example 66%. A rotating homogenizer typically includes a shaft that is mounted in the wall of the tower and includes an extension that mixes the pulp stream when rotated. Lower power consumption can be achieved because of the smaller capacity for mixing and because of the lower rotational speed. The homogenizer can operate within a rotational speed range of 600-1200 rpm. The circumferential speed of the homogenizer is 5 to 20 meters / second, usually 10 to 15 meters / second. For a 5000 admt / d pulp line, the power provided to a conventional tank agitator can be 4 * 90 kW = 360 kW, but for a homogenizer, the power provided can be only 110 kW.

  Also, the required amount of disturbance can be generated by using a stationary structure in the homogenization zone. A homogenizer is a device or structure in the tower that performs a process that equalizes the flow of pulp and diluent flowing through the bottom portion of the tower. Also, a combination of a rotating homogenizer and a stationary homogenizer structure is possible.

  In a stationary homogenizer, the flow rate is increased by increasing the flow rate by reducing the flow, i.e. by reducing the cross-sectional area, whereby the introduced diluent is mixed into the flowing pulp. It will be. The stationary homogenizer preferably comprises a protrusion or an annular flange or ring disposed on the inner wall of the tank.

  A stationary homogenizer can include disturbance enhancing devices such as baffles, ribs, pins, small clumps, etc., placed in the homogenization zone, in addition to the squeezing device.

  In the case of a stationary homogenizer, it may be preferable to use a vertical strut or bar between the discharge (pumping) zone and the homogenization zone. The struts are located in the bottom part of the tower. It has a lower end supported by the bottom of the tower. The struts extend through a discharge (pumping) zone and through a homogenization zone where a stationary homogenizer element is secured to the tower wall. The strut diameter is determined so that homogenization is optimal. The struts themselves can include structures such as obstacles or extensions to enhance pulp stream homogenization.

  The design using a rotating and / or stationary homogenizer will depend on the required mixing quality, which will be assessed by the concentration variation after the screen chamber feed pump and the total energy used for the application. Can do.

  In a further embodiment of the inventive configuration, it further comprises a structure for at least one flow directing element, such as a cylindrical pipe, a rectangular bar or a beam, which converts the diluted pulp stream into the homogenization zone. Positioned after the dilution point but on the homogenizer to guide. The pipe or bar can be mounted so that it is normally positioned horizontally across the tower. It is fixed to the tower wall at both ends. The distance and location of the inductive element from the homogenizer is such that the flow to the homogenization zone is uniform and the pulp can flow freely down, but the flow is directed to the location that gives the best homogenization result To be determined.

  After homogenization of the pulp stream, a normal process pump capable of delivering 3-8% strength pulp can be used to discharge the pulp from the bottom of the tower through the outlet to the screen. Depending on the concentration and / or location of the screen chamber in the process, it may be necessary to provide a gas removal function in the screen chamber feed pump. The pulp feed concentration is typically 8-14% in the upper part of the tower. The bottom portion of the tower according to the inventive arrangement and method lacks an agitator that mixes and dilutes the pulp. In the new tower, the diluent necessary to obtain the discharge (pumping) concentration is introduced into the pulp before the homogenization device.

  In screen chamber operation, screening concentration stability is a requirement that must be considered in conventional screen chamber applications, but also in the inventive system. In conventional systems, the screen chamber feed tank may experience an unexpected concentration peak and the screening concentration may be too high, making the screen chamber operation difficult. In the system of the invention, the mixing (homogenization) capacity of the screen chamber feed tank is essentially smaller than in conventional systems. Due to the short retention time, it should be necessary to have a faster response from concentration control. Conventionally, concentration control of the screen chamber is performed using a densitometer that controls the dilution flow into the screen chamber feed tank and into the suction side of the screen chamber feed pump. This type of concentration control can cause concentration peaks to be screened, which can cause serious problems such as screen clogging, pressure and flow fluctuations.

  If concentration control is configured so that some of the diluent is also sent downstream of the concentration measurement point close to the next screen, the problematic concentration peak should be smaller and the screening concentration is Can be kept between the required values. According to an embodiment of the invention, the tower outlet comprises a pump for transporting the pulp diluted from the tower to the screen device, and a feeder for adding diluent to the pulp to control the pulp concentration. The supply is positioned between the pump and the screen device. Up to 5-10% of the diluent can be added to the discharged pulp.

  The structure and method of the developed invention will be described in more detail with reference to the drawings.

1 shows the bottom part of a prior art pulp tower. FIG. 1 shows the bottom part of a prior art pulp tower. FIG. It is a figure which shows the screen chamber sending tower by the Example of this invention. It is a figure which shows the bottom part of the screen chamber feed tower by the Example of this invention. FIG. 5 is a cut-away view along the cross-section AA of FIG. 4 illustrating, by way of example, a stationary homogenizer that can be used in connection with embodiments of the present invention. FIG. 5 is a cut-away view along the cross-section AA of FIG. 4 illustrating, by way of example, a stationary homogenizer that can be used in connection with embodiments of the present invention. It is a figure which shows the device for introduce | transducing a dilution liquid. 1 is a diagram illustrating a control system that can be applied with respect to the present invention. FIG. 6 shows a screen chamber feed tower according to a further embodiment of the invention. FIG. 6 shows a screen chamber feed tower according to a further embodiment of the invention.

  FIG. 3 shows a screen chamber feed tower according to an embodiment of the present invention. The tower 100 includes a tower wall 102, a top portion 104, a bottom portion 106 and a tower bottom 108. The top of the tower can be equipped with a device or conduit 110 for exhausting gas. In this embodiment, the diameter of the top portion 104 is greater than the diameter of the bottom portion 106. The upper part of the tower can serve as a blow tank or a storage (retention) tank, the size of which depends on the requirements of the process if any buffering is required. Pulp is fed into the tower through conduit 112 from a digester or oxygen delignification reactor.

  The bottom portion 106 is divided into a dilution zone 107 and a homogenization zone 109, which is positioned after dilution in the direction of the pulp flow. In the upper part of the bottom part, a conduit 114 is arranged to introduce diluent into the pulp flowing downward in the tank. A homogenization device is placed in the homogenization zone positioned below the dilution zone. The purpose of the homogenization zone is to mix the pulp suspension so that its concentration is homogenized. In this embodiment, both a rotating homogenizer 116 and a stationary homogenizer 118 are provided. Connected to the tower through its wall is a pump 120. The pump 120 is adjacent to or connected to the bottom. It pumps diluted and homogenized pulp from the tower discharge zone 121 to the screen.

  The rotating homogenizer 116 includes a shaft 124 equipped with drive means 122 and a blade or extension 126. The blade is rotated so that the diluent is evenly distributed in the pulp suspension. This is just one preferred design of the homogenizer. Also, other designs that can homogenize the pulp concentration can be used. The feature is that when using a homogenizer, the installed power can be reduced by 50-80%, for example 66%. Low power consumption can be achieved because of the smaller capacity for mixing and the low rotational speed. For a 5000 admt / d pulp line, the power provided to a conventional tank agitator should be 4 * 90 kW = 360 kW, but with a homogenizer, the power provided should be only 110 kW.

  In the tower according to FIG. 3, a stationary homogenizer 118 is also provided, which is a restriction in the form of an annular flange or ring. It further enhances the disturbance in the pulp suspension and thus makes possible concentration differences uniform.

  According to a preferred embodiment, the dilution point 114 in the bottom part of the tower has a diameter D, and the distance C between the dilution device 114 and the homogenization device 116 is 1.5 at the dilution point of the tower diameter D. 10 times.

  FIG. 4 shows the bottom portion of the tower 106, where pulp flows from the top portion, passes through the bottom portion (arrow), and is discharged from the tank.

  The tower includes a dilution device 128 that includes an opening 130 in the tower wall through which diluent is fed into the pulp stream. The opening is positioned around the tower and connected to conduit (s) for supplying liquid into the opening. Two or more openings 130 are disposed around the tank at a predetermined distance from each other.

  A homogenization zone 109 is provided after the dilution point 107. Homogenization is achieved by protrusions arranged on the inner surface of the tank. By squeezing the flow, i.e. by using the protrusion 132 to reduce the cross-sectional area, the flow rate is increased, and thanks to the squeeze, the disturbance is greater, and the diluent introduced thereby causes the diluent to flow into the flowing pulp. Will be further mixed. The protrusion extends at a predetermined distance X in the vertical direction so that its cross-sectional area is reduced at the bottom of the tower. After the protrusion, the cross-sectional area of the bottom part widens again.

  FIG. 5 shows a cross-sectional drawing of a stationary homogenization. FIG. 5a is a cut-away view along the cross-section AA of the embodiment of FIG. FIG. 5a shows a protrusion 132 disposed on the inner surface of the tank. FIG. 5b shows a disturbance enhancing device such as a plate 134 or protrusion with different types of shapes, such as rectangles and triangles.

  FIG. 6 shows another embodiment for the dilution device 136. Diluent (arrow 140) can be fed through the feed pipe 138, which is piped so that it extends at least partially through the tower and hence through the dilution zone. In this type of feed pipe, the diluent is led into the pulp through a number of holes 142 so that the diluent flows into the pulp flowing downward.

  FIG. 7 shows a control system, which can be applied with respect to an embodiment of the present invention. Concentration control is configured such that a portion of the diluent is also sent downstream from the concentration measurement point QIC proximate to the next screen 148. Therefore, this fine adjustment can be used to keep the sieving concentration between the required values. Most of the diluent is pumped through line 144 to the bottom portion 106 of the tank, but some liquid (from 5 to 10%) can also be introduced through line 146 into the entrance of screen 148. The feed line 150 includes a concentration measurement QIC and diluent conduit 146 to adjust the feed concentration and maintain it at a set point. In the event of a production disturbance, the concentration is measured, and by reacting rapidly to the concentration increase that can occur by adding diluent via line 146, the concentration is essentially kept at a set point and stabilized. it can.

  FIG. 8 shows a screen chamber feed tower according to a further embodiment of the invention. The tower shown in FIG. 8 corresponds to the tower of FIG. 3, but it comprises two homogenizers 116 attached to the tower wall. Further, the tower further includes a structure for at least one flow directing element. This figure also shows a cut-away view along the cross-section BB. In this embodiment, a cylindrical pipe 123 is placed horizontally across the tower. Pipe 123 is positioned after dilution point 114 but above homogenizer 116 to direct the pulp stream to be diluted to homogenization zone 109. The pipe 123 is mounted so that it is secured to the tower wall 102 at both ends thereof. The distance and location of the pipe from the homogenizer 116 is such that the flow to the homogenization zone is uniform and the pulp can flow freely down, but that flow is where the best homogenization results are given. Should be determined to be guided to

  FIG. 9 shows a screen chamber feed tower according to a further embodiment of the invention. In the case of a stationary homogenizer, it may be preferable to use a vertical strut or bar between the discharge (pumping) zone and the homogenization zone. The tower shown in FIG. 9 corresponds to the embodiment according to FIG. 4, but the struts 131 are arranged in the bottom part of the tower. The lower end of the column 131 is supported by the bottom 108 of the tower. The struts extend through the discharge (pumping) zone 121 toward the diluting device 128 and also through the homogenization zone 109 where the stationary homogenizer element 132 is secured to the tower wall. The strut contributes to the aperture. The diameter of the strut 131 is determined so that homogenization is optimal. The struts themselves can further include structures such as obstacles or other extensions (ribs, pins, small chunks, etc.) that increase the level of disturbance and thus increase the homogenization of the pulp flow.

Although the present invention has been described with respect to what is presently considered to be the most practical and preferred embodiments, the present invention should not be limited to the disclosed embodiments, but is within the spirit and scope of the appended claims. It should be understood that various modifications and equivalent arrangements are intended to be included.

Claims (14)

A processing device for pulp fed into a screen chamber of a pulp crusher,
A tower having upright walls and a bottom;
A pulp inlet in the upper part of the tower;
A dilution device for feeding diluent into the pulp flowing down in the tower, wherein the dilution device is substantially positioned at a height that divides the tower into the top and bottom portions A dilution device,
A processing apparatus comprising a discharge device for diluted pulp, disposed in the bottom portion of the tower,
Homogenizing device for homogenizing the consistency of the pulp to be the diluent is at a predetermined distance downstream of the dilution device in the direction of flow of the pulp to be the diluent, which and disposed upstream of the discharge device,
The homogenizing device includes at least one throttle member that restricts the flow of the diluted pulp, and a shaft that is mounted on the upright wall of the tower with at least one rotating member. A processing device. The dilution device defines a dilution point in the bottom portion of the tower having a diameter;
The processing apparatus according to claim 1, wherein a distance between the dilution device and the homogenization device is 1.5 to 10 times the diameter of the tower at the dilution point. The processing apparatus according to claim 1, wherein the at least one rotating member has an outer peripheral speed of 5 to 20 meters / second . 2. The dilution device according to claim 1, characterized in that it comprises several feed nozzles or openings for the flow of the diluted pulp , which are arranged around the upright wall of the tower. Item 4. The processing device according to any one of Items 3 to 3 . The dilution device includes at least one pipe extending inwardly from the upright wall of the tower toward the center of the tower;
The processing apparatus according to claim 1 , wherein the pipe includes a plurality of outlet holes for adding the diluent. The bottom portion of the tower includes a homogenization zone;
There, the diluted pulp stream is homogenized by the homogenization device,
6. The processing apparatus according to claim 1, wherein a capacity of the homogenization zone is 0.1 to ³ m ³ . 7. The discharge device according to any one of the preceding claims, characterized in that the discharge device comprises an outlet for the homogenized pulp to be further homogenized in the bottom part of the tower. Processing equipment. The outlet is connected to a conduit;
The conduit comprises a pump for transporting the pulp from the tower to a screen device and a feeder for adding diluent into the pulp to control the concentration of the pulp;
The processing apparatus according to claim 7 , wherein the feeder is positioned between the pump and the screen device. 9. A processing apparatus according to any one of claims 1 to 8 , characterized in that a flow directing element is arranged between the dilution device and the homogenization device. A method for treating pulp fed into a screen chamber of a pulp grinder,
Pulp with a concentration of 8-14% is fed into the tower with an inlet in the upper part of the tower,
The pulp flows from the top portion of the tower to its bottom portion;
A diluent is introduced into the pulp at the bottom portion of the tower where a dilution zone is defined ;
In the processing method, the reduced pulp is discharged from the bottom of the tower where a discharge zone is defined ,
The pulp and the diluent comprise a rotating device in a homogenization zone to equalize the concentration of the pulp stream and produce the pulp with the reduced concentration , and Processed by a homogenizing device that utilizes the effect of squeezing ,
The homogenization zone, characterized in that it is positioned between the discharge zone and the dilution zone, the process method. The processing method according to claim 10 , wherein the diluent added to the pulp flowing in the tower is introduced upstream of the homogenization zone. The processing method according to claim 10 , wherein the pulp is homogenized in the homogenization zone having a capacity of 0.1 to ³ m ³ . The pulp is discharged from the tower and pumped to a screen device;
11. A processing method according to claim 10 , characterized in that a part of the diluent is added upstream of the screen device to control the concentration of the discharged pulp . The processing method according to claim 12 , wherein up to 10% of the diluted solution is introduced into the discharged pulp .

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