WO2004052515A1

WO2004052515A1 - Apparatus for mixing

Info

Publication number: WO2004052515A1
Application number: PCT/SE2003/001905
Authority: WO
Inventors: Olof Melander; Peter Danielsson; Tomas WIKSTRÖM
Original assignee: Metso Paper Oy
Current assignee: Valmet Technologies Oy
Priority date: 2002-12-12
Filing date: 2003-12-08
Publication date: 2004-06-24
Anticipated expiration: 2005-06-12
Also published as: SE524454E; AU2003284823A1; SE524454C2; SE0203676D0; SE0203676L

Abstract

The present invention relates to an apparatus for mixing of a chemical medium in gaseous or liquid state with a pulp suspension, comprising a housing having a wall (2, 502) that defines a mixing chamber (4, 504), a first feeder (6, 506) for feeding the pulp suspension to the mixing chamber, a rotor shaft (8, 102, 206, 304, 400, 508, 604, 702), that extends in the mixing chamber, a drive device (9) for rotation of the rotor shaft, a rotor body (10, 104, 300, 510), that is connected to the rotor shaft and arranged to supply kinetic energy to the pulp suspension flow, during rotation of the rotor shaft by the rotation of the drive device, such that turbulence is produced in a turbulent flow zone (12, 512) in the mixing chamber, a second feeder (13, 513) for feeding of the chemical medium to the mixing chamber, and outlet for discharging the mixture of chemical medium and pulp suspension from the mixing chamber, and a flow-restraining element (15, 511) arranged to temporarily increase the flow velocity of the pulp suspension when the pulp suspension passes the flow-restraining element.

Description

APPARATUS FOR MIXING

The present invention relates to an apparatus for mixing of a chemical medium in gas gaseous or liquid state with a pulp suspension.

In treatment of pulp suspensions there is a need for intermixture of different mediums for treatment, for example for heating or bleaching purposes. Therefore it is desirable to disperse the medium in the pulp suspension during simultaneous conveyance of the pulp suspension through a pipe. Patent EP 664150 discloses an apparatus for this function. For heating of pulp suspensions, steam is added which condense and therewith give off its energy content to the pulp suspension. A bleaching agent is added in bleaching that shall react with the pulp suspension. In connection to the treatment of recovered fibre pulp printing ink is separated by flotation, which means that air shall previously be disintegrated in the pulp suspension such that the hydrophobic ink, or the printing ink, may attach to the rising air bubbles. In this connection it is desirable that the medium for treatment, e.g. air, is evenly and homogeneously distributed in the pulp suspension, preferably with tiny bubbles to achieve a large surface against the pulp suspension.

In all cases it is hard, with proportionately low addition of energy, to achieve an even intermixture of the medium in the flow of material. When heating pulp suspensions by supply of steam to a pulp pipe, problems often arise with large steam bubbles that are formed on the inside of the pipe, this as a consequence of a non- disintegrated gas with small condensation surface. When these large steam bubbles rapidly implodes, condensation bangs arises that causes vibration in the pipe and in following equipment. This phenomenon limits the amount of steam that can be added to the system and thus the desired increase in temperature. It is hard to achieve a totally even temperature profile in the pulp suspension when large steam bubbles exists. In order to remedy these problems, a large amount of energy can be supplied to carefully admix the steam in the pulp suspension. Another variant is to disintegrate the steam already at the supply in the pulp suspension. In intermixing of bleaching agent in a pulp suspension, relatively large amounts of energy are used in order to provide that the bleaching agent is evenly distributed and conveyed to all the fibres in the pulp suspension. The energy requirements are controlled by which bleaching agent that shall be supplied (rate of diffusion and reaction velocity) and also by the phase of the bleaching medium (liquid or gas) . The geometry at supply of the bleaching agent in vapour phase is important in order to avoid unwanted separation immediately after the intermixture.

The object with the present invention is to provide an apparatus for supplying and intermixing of a chemical medium in a pulp suspension in an effective way and that at least partly eliminates the above mentioned problem.

This object is achieved with an apparatus for mixing of a chemical medium in gaseous or liquid state with a pulp suspension according to the present invention. The apparatus comprises a housing having a wall that defines a mixing chamber and a first feeder for feeding the pulp suspension to the mixing chamber. Further, the apparatus comprises a rotor shaft, that extends in the mixing chamber, a drive device for rotation of the rotor shaft and a rotor body that is connected to the rotor shaft. The rotor body is arranged to supply kinetic energy to the pulp suspension flow, during rotation of the rotor shaft by the rotation of the drive device, such that turbulence is produced in a turbulent flow zone in the mixing chamber. The apparatus also comprises a second feeder for feeding of the chemical medium to the mixing chamber and an outlet for discharging the mixture of chemical medium and pulp suspension from the mixing chamber. The apparatus further comprises a flow-restraining element arranged to temporarily increase the flow velocity of the pulp suspension when the pulp suspension passes the flow- restraining element. The apparatus is characterised by that the flow-restraining element is integrated with the rotor shaft.

In that respect, in accordance with present invention, an even and effective intermixing of the chemical medium in the pulp suspension is provided.

Further features and advantages according to embodiments of the apparatus according to the present invention are evident from the claims and in the following from the description.

The present invention shall now be described more in detail in embodiments, with reference to the accompanying drawings, without restricting the interpretation of the invention thereto, where fig. 1 shows an apparatus in cross-section according to an embodiment of the present invention, fig. IB shows a cross-section A-A of the apparatus according to fig. 1A, fig. 2A-D illustrates alternative embodiments of flow-restraining disks integrated with the rotor shaft, fig. 3A-D shows schematically alternative embodiments of flow passages in an axial direction of a flow-restraining disk, fig. 4A-B shows alternative located patterns of flow passages for a flow-restraining disk, fig. 4C shows in one embodiment a flow- restraining disk in axial direction comprising concentrically rings which are coaxial with a rotor shaft, fig. 5A-C illustrates different alternative embodiments of rotor pins in cross-section of the rotor shaft, fig. 6A-D illustrates different alternative cross- sections of rotor pins, fig. 7A-C shows schematically alternative embodiments of a rotor shaft provided with axial flow- generating elements, fig. 8 shows an apparatus in cross-section according to an embodiment of the present invention, fig. 9A shows in a cross-section a rotor shaft extending through a feeding pipe, which is coaxially arranged with the rotor shaft, fig. 9B shows in a cross-section a rotor shaft extending through a feeding pipe, which is eccentrically arranged with the rotor shaft, fig. 10A-E illustrates in cross-section different alternative outlets of feeding pipes, fig. 11A shows a symmetrical arranging of an outlet of a feeding pipe around a rotor shaft, fig. 11B shows an asymmetrical arranging of an outlet of a feeding pipe around a rotor shaft, fig. 11C shows non-rotational symmetrical outlets of a feeding pipe around a rotor shaft, fig. 12 shows a chemical distribution element according to an embodiment, fig. 13 shows a chemical distribution element according to an alternative embodiment, fig. 14 shows a chemical distribution element according to yet an alternative embodiment.

In fig. 1A-B is shown an apparatus according to an embodiment of the present invention, for mixing of a chemical medium in gas gaseous or liquid state with a pulp suspension. The apparatus comprises a housing with a wall 2 that defines a mixing chamber 4 and a first feeder 6 for supplying of pulp suspension to the mixing chamber. Further, the apparatus comprises a rotor shaft 8, which extends in the mixing chamber 4, a drive device 9 for rotation of the rotor shaft and a rotor body 10 that is connected to the rotor shaft 8. The rotor body is arranged to supply kinetic energy to the pulp suspension flow, during rotation of the rotor shaft by the rotation of the drive device, such that turbulence is produced in a turbulent flow zone 12 in the mixing chamber. The rotor body 10 preferably comprises one or more rotor pins 11. The apparatus also comprises a second feeder 13 for feeding of the chemical medium to the mixing chamber and an outlet (not shown) for discharging the mixture of chemical medium and pulp suspension from the mixing chamber 4. The apparatus further comprises a flow- restraining element 15 arranged to temporarily increase the flow velocity of the pulp suspension when the pulp suspension passes the flow-restraining element. The flow- restraining element 15 is integrated with the rotor shaft 8. The flow-restraining element 15 preferably comprises a flow-restraining disk 15' . Alternative embodiments of flow-restraining disks 100 integrated with the rotor shaft 102 is shown in fig. 2A-D. The rotor body 104 may suitably comprise a number of rotor pins 106, which extends from the rotor shaft 102, whereby the disk is fixed to the rotor pins 106 on the down-stream side of the rotor body as shown in fig. 2A, or on its upstream side as shown in fig. 2B. As shown in fig. 2C, the rotor body may comprise an additional number of pins 106', that extends from the rotor shaft on the down-stream side of the disk, whereby the disk 100 also is fixed to said additional pins 106'. Preferably, the disk comprise a number of concentrically rings 108, which are coaxial with the rotor shaft, and the rotor pins 106, 106' fixates the rings 108 in relation to each other, whereby flow passages 110 are defined by the pins and the rings. Fig. 2D shows rotor pins 106 and concentrically rings 100. Further, spacer elements 111 are arranged between the rotor pins 106 and the concentrically rings 100. The spacer elements are used in order to move the turbulent zone.

Now with reference to fig. 3A-D, the apparatus preferably comprises a flow-restraining disk 200 with on or more flow passages, arranged to temporarily increase the flow velocity of the pulp suspension when the pulp suspension passes the flow-restraining disk. The purpose of the disk is to create a controlled fall of pressure. The energy is used for static mixing and the disk is designed for varying pressure recovery depending on desired energy level. Fig. 3A-D shows different alternative embodiments of flow passages 202 in the axial direction of a flow- restraining disk 200. The flow area A of each flow passage increases or decreases in the direction of the flow, which in particular is shown in fig. 3A-B. Fig. 3A shows a divergent opening, i.e. that an open area enlarges in axial direction. Fig. 3B shows a converging opening, i.e. where the open area diminish in axial direction. As shown in fig. 3C-D, each flow passage can extend obliquely from the up-stream side of the disk against the centre axis C of the disk.

The flow-restraining disk 200 is preferably provided with a plurality of flow passages 202 as shown in fig. 4A-C, which passages can be arranged according to a number of alternative placement patterns. The disk is preferably circular or coaxial with the rotor shaft. The flow passages of the flow-restraining disk may for example form a Cartesian pattern (fig. 4A) which provides asymmetrical jet streams, or a polar pattern (fig. 4B) . Fig. 4C shows an alternative embodiment where the flow passages 202 of the flow-restraining disk 200 in axial direction are formed of concentrically rings 204 that are coaxial with a rotor shaft 206, and its rotor body 207, which may comprise one or more rotor pins 208, arranged on distance from and ahead of disk 200. Further, the flow-restraining disk may comprise at least one radial bar 210, that fixates the rings 204 relatively each other, whereby the flow passages 202 are defined by the rings and the bar.

Fig. 5A-C illustrates that a rotor body 300 according to the present invention may comprise a number of rotor pins 302, which extends from the rotor shaft 304 in its radial direction. Each rotor pin may be curved forward from the rotor shaft (fig. 5A) or backward (fig. 5B) relatively to the rotational direction of the rotor body (see arrow in fig. 5A-C) , which both embodiments aims to provide a radial conveyance of the mixture. According to an alternative embodiment shown in fig. 5C, each rotor pin may have a width b, as seen in the rotational direction of the rotor body, that increase along at least a part of the rotor body in direction against the rotor shaft 304. The embodiment according to fig. 5C decreases the opened area and by that the axial flow velocity increases. The rotor pins 302 can be provided with varying cross-sections as illustrated in fig. 6A-D. Each rotor pin may be designed with a circular cross-section as shown in fig. 6A, which is simple from a manufacturing viewpoint and a cost efficient design. The rotor pins 302 may also be provided with a triangular or quadratic cross-section, according to fig. 6B-C, which geometry creates a dead air space at rotation of the rotor shaft. According to yet an embodiment the rotor pins may be provided with a shovel- shaped cross-section according to fig. 6D, which results in a sling-effect at rotation of the rotor shaft. In addition, as evident from fig. 6C, each rotor pin may be designed with a helix shape, suitably with quadratic cross-section, in the axial direction of the rotor pin. Which one of the various designs of the cross-sections of the rotor pins 202 that are most preferable depends on the current flow resistance.

Fig. 7A-C shows alternative embodiments of a rotor shaft 400 provided with one or more axially flow generating elements 402. As is shown in fig. 7A, the axial flow- generating element can comprise a number of blades 404, which are obliquely attached relatively to the rotor shaft. Rotation of the rotor shaft causes an axial flow. If the elements are of various rotational orientations along the rotor shaft as shown in fig. 7A, different directions of flow are obtained as well. In addition, the axial flow-generating element can comprise a screw thread or a band thread 406, according to alternative embodiments shown in fig. 7B-C, which extends along the rotor shaft 400, that aims to force the fluid closest to the hub of the rotor shaft towards some direction. For the feeding, the height of the band can suitably be about 5-35 mm. According to an alternative embodiment the axial flow- generating element can comprise a relatively thin elevation of about 3-6 mm on the surface of the shaft, suitably about 3,8 to 5,9 mm. This scale of lengths is suitably when it corresponds to the characteristic size of the fibre-flocks for kraft pulp at current process conditions. Thus, this should be variable in the process. The size of the flocks can be said to be in inverse proportion to the total work that is added to the fibre suspension. Screw thread or band thread may be used also when the rotor shaft extends through the feeding pipe as shown in embodiments in fig. 9A-B, if the height of the band is relatively short.

In fig. 8 is shown an apparatus according to an embodiment of the present invention. The apparatus comprises a housing with a wall 502 that defines a mixing chamber 504 and a first feeder 506 for supplying of pulp suspension to the mixing chamber. Further, the apparatus comprises a rotor shaft 508, which extends in the mixing chamber 504, a drive device (not shown) for rotation of the rotor shaft and a rotor body 510 that is connected to the rotor shaft 508. The rotor body is arranged to supply kinetic energy to the pulp suspension flow, during rotation of the rotor shaft by the rotation of the drive device, such that turbulence is produced in a turbulent flow zone 512 in the mixing chamber. The apparatus also comprises a second feeder 513 for feeding of the chemical medium to the mixing chamber and an outlet (not shown) for discharging the mixture of chemical medium and pulp suspension from the mixing chamber 504. The apparatus further comprises a flow-restraining element 511 arranged to temporarily increase the flow velocity of the pulp suspension when the pulp suspension passes the flow-restraining element. The flow-restraining element 511 is integrated with the rotor shaft 508. The second feeder 513 may comprise at least one stationary feeding pipe 514, that extends from the wall 502 of the housing into the mixing chamber 504 and that has an outlet 516 for the chemical medium in or in close vicinity to said turbulent flow zone 512. The second feeder 513 may comprise a number of stationary feeding pipes 514, as evident from fig. 8, that extends substantially parallel to the rotor shaft 508 in the mixing chamber. Further, according to a not shown embodiment, the feeding pipes 514, respectively, may extend substantially radially to the rotor shaft 508 in the mixing chamber.

In case the feeding pipe 602 extend parallel to the rotation shaft according to the embodiment in fig. 9, the rotation shaft 604 may extend through the feeding pipe 602, whereby an annular outlet for chemical medium is defined by the rotor shaft 604 and the feeding pipe 604. In that respect, a feeding pipe 602 can extend coaxially as shown in fig. 9A, or eccentrically to a rotor shaft 604 as shown in fig. 9B, whereby an annular outlet 600 for the chemical medium is defined by the rotor shaft 604 and the feeding pipe 602.

According to the embodiment in fig. 8, the outlet 516 of the feeding pipe is suitably of rotational symmetrical design, such as a circular form as shown in fig. 10A. The outlet of the feeding pipe may also be of other non- rotational symmetrical design, e.g. elliptical according to fig. 10B-C, triangular form according to fig. 10D, or rectangular form as shown in fig. 10E.

In case the second feeder comprises a number of stationary feeding pipes 514 according to the embodiment in fig. 8, the outlets 516 of the feeding pipes can be situated symmetrically, on equal distance R from the rotor shaft 8, as shown in fig. 11A, or asymmetrically around the rotor shaft 508, with different distance Rl and R2, respectively, from the rotor shaft 508, as shown in fig. 11B. In case the outlets 516 of the feeding pipes, respectively, are non-rotational symmetrical designed, at least one of the outlets 516 be provided with an orientation of rotation VI in relation to the centre of rotor shaft that differs from the corresponding orientations of rotation V2 of the other outlets, as evident from fig. llC.

Again, with reference to the apparatus according to the embodiment shown in fig. 1A-B, the second feeder may comprise a chemical distribution element 14 integrated with the rotor body 10 and arranged to distribute the chemical medium to or to close vicinity to said turbulent flow zone 12. Preferably, the rotor body 10 comprises a number of rotor pins 11, which extends from the rotor shaft 8. The chemical distribution element 14 comprises at least one chemical outlet 16, suitably situated up-stream of the rotor pins. Further, according the apparatus in fig 1A-B, the second feeder 13 may comprise a stationary cylindrical body 18, which is coaxial with the rotor shaft 8, and that the rotor body 10 comprises a sleeve 20 that sealingly surrounds the cylindrical body 18, whereby the cylindrical body is provided with a channel for the chemical medium that communicates with the chemical distribution element 14. The second feeder 13 can suitably comprise a connection pipe 22, that extends through the wall 2 of the housing to the stationary cylindrical body 18 and that is connected to the channel therein.

As evident from fig. 12-14, a chemical distribution element according to the embodiment of the apparatus shown in fig. 1A-B may comprise at least one distribution pipe 700 that extends radial from the rotor shaft 702, whereby a chemical outlet 704 is arranged on the distribution pipe 700.

As illustrated in fig. 14, the chemical outlets 704 may be directed (which is shown by the arrows in fig. 14) against a rotor pin 706. According to an alternative embodiment, as shown in fig. 12 and 13, the chemical distribution element may also comprise at least one chemical outlet 704 arranged on at least one of the rotor pins 706. In that respect, the chemical outlet can be directed (as shown by arrows in fig. 12 and 13) in the opposite flow direction F of the pulp suspension along the rotor shaft 702, or directed transverse the pulp suspension (not shown) from the rotor shaft 702. As evident from fig. 12, the chemical distribution element can comprise a plurality of chemical outlets 704 arranged on at least one of the rotor pins 706, whereby at least one chemical outlet 704' is directed in the opposite flow direction of the pulp suspension along the rotor shaft and at least one chemical outlet 704'' is directed transverse the flow direction F of the pulp suspension from the rotor shaft 702. The chemical outlets 704 may be designed as cylindrical apertures. Other design, e.g. spray nozzle shape, can be used in order to improve the chemical distribution and prevent the pulp suspension from penetrating upstream in the chemical outlets 704.

Claims

1. Apparatus for mixing of a chemical medium in gaseous or liquid state with a pulp suspension, comprising a housing having a wall (2, 502) that defines a mixing chamber (4, 504), a first feeder (6, 506) for feeding the pulp suspension to the mixing chamber, a rotor shaft (8, 102, 206, 304, 400, 508, 604, 702), that extends in the mixing chamber, a drive device (9) for rotation of the rotor shaft, a rotor body (10, 104, 300, 510), that is connected to the rotor shaft and arranged to supply kinetic energy to the pulp suspension flow, during rotation of the rotor shaft by the rotation of the drive device, such that turbulence is produced in a turbulent flow zone (12, 512) in the mixing chamber, a second feeder (13, 513) for feeding of the chemical medium to the mixing chamber, and an outlet for discharging the mixture of chemical medium and pulp suspension from the mixing chamber, and a flow- restraining element (15, 511) arranged to temporarily increase the flow velocity of the pulp suspension when the pulp suspension passes the flow-restraining element, characterised in that the flow-restraining element (15, 511) is integrated with the rotor shaft (8, 102, 206, 304, 400, 508, 604, 702) .

2. Apparatus according to claim 1, characterised in that a flow-restraining element (15, 511) comprises a flow- restraining disk (15', 100, 200) with one or more flow passages (110, 202) arranged to temporarily increase the flow velocity of the pulp suspension when the pulp suspension passes the flow-restraining disk.

3. Apparatus according to claim 2, characterised in that the rotor body (10, 104, 300, 510) comprise a number of rotor pins (11, 106, 106', 302, 706), that extends from the rotor shaft (8, 102, 206, 304, 400, 508, 604, 702), whereby the disk (15', 100, 200) is fixed to the rotor pins on the down-stream side of the rotor body.

4. Apparatus according to claim 3, characterised in that the rotor body (10, 104, 300, 510) comprise an additional number of pins (11, 106, 106', 302, 706), that extends from the rotor shaft (8, 102, 206, 304, 400, 508, 604, 702) on the down-stream side of the disk, whereby the disk (15', 100, 200) is also fixed to said additional pins.

5. Apparatus according to claim 3 or 4, characterised in that the disk comprise a number of concentrically rings (108, 204), which are coaxial with the rotor shaft (8, 102, 206, 304, 400, 508, 604, 702), and the rotor pins (11, 106, 106', 302, 706) fixates the rings in relation to each other, whereby said flow passages (110, 202) are defined by the pins and the rings .

6. Apparatus according to any of claims 3-5, characterised in that spacer elements (111) are arranged between the disk (15', 100, 200) and the rotor pins (11, 106, 106', 302, 706) .

7. Apparatus according to any of claims 2-6, characterised in that each flow passage (110, 202) extend obliquely from the up-stream side of the disk (15', 100, 200) against the centre shaft (C) of the disk.

8. Apparatus according to any of claims 2-7, characterised in that the flow area (A) of each flow passage (110, 202) increases or decreases in the direction of the flow.

9. Apparatus according to any of claims 2-8, characterised in that the disk (15', 100, 200) is provided with a plurality of flow passages (110, 202) that form a Cartesian or polar pattern.

10. Apparatus according to any of claims 2-9, characterised in that the disk (15', 100, 200) is circular or coaxial to the rotor shaft (8, 102, 206, 304, 400, 508, 604, 702) .

11. Apparatus according to any of claims 1-10, characterised in that the rotor body (10, 104, 300, 510) comprise a number of rotor pins (11, 106, 106', 302, 706), which extends from the rotor shaft (8, 102, 206, 304, 400, 508, 604, 702) .

12. Apparatus according to claim 11, characterised in that each rotor pin (11, 106, 106', 302, 706) is curved forward from the rotor shaft (8, 102, 206, 304, 400, 508, 604, 702) or backward relatively to the rotational direction of the rotor body.

13. Apparatus according to claim 11 or 12, characterised in that each rotor pin (11, 106, 106', 302, 706) has a width (b) , as seen in the rotational direction of the rotor body (10, 104, 300, 510), that increase along at least a part of the rotor body in direction against the rotor shaft (8, 102, 206, 304, 400, 508, 604, 702) .

14. Apparatus according to any of claims 11-13, characterised in that each rotor pin (11, 106, 106', 302, 706) has a circular, quadratic or shovel-shaped cross- section.

15. Apparatus according to any of claims 11-13, characterised in that each rotor pin (11, 106, 106', 302, 706) has a helix shape.

16. Apparatus according to claim 15, characterised in that each rotor pin (11, 106, 106', 302, 706) has a quadratic cross-section.

17. Apparatus according to any of claims 1-16, characterised in that the rotor shaft (8, 102, 206, 304,

400, 508, 604, 702) is provided with an axially flow generating element (402) .

18. Apparatus according to claim 17, characterised in that the axial flow-generating element (402) comprise a number of blades (404), which are obliquely attached relatively to the rotor shaft (8, 102, 206, 304, 400, 508, 604, 702) .

19. Apparatus according to claim 17, characterised in that the axial flow-generating element (402) comprise a screw thread or a band thread (406), which extends along the rotor shaft (8, 102, 206, 304, 400, 508, 604, 702).

20. Apparatus according to any of claims 1-19, characterised in that the second feeder (13, 513) comprises at least one stationary feeding pipe (514, 602), that extends from the wall (2, 502) of the housing into the mixing chamber and that has an outlet for the chemical medium in or in close vicinity to said turbulent flow zone (12, 512) .

21. Apparatus according to claim 20, characterised in that the feeding pipe (514) extend substantially radial to the rotor shaft (8, 102, 206, 304, 400, 508) in the mixing chamber (4, 504) .

22. Apparatus according to claim 20, characterised in that the feeding pipe (514, 602) extend substantially parallel to the rotor shaft (8, 102, 206, 304, 400, 508, 604) in the mixing chamber.

23. Apparatus according to claim 22, characterised in that the rotor shaft (8, 102, 206, 304, 400, 508, 604) extends through the feeding pipe (602), whereby an annular outlet (600) for the chemical medium is defined by the rotor shaft (8, 102, 206, 304, 400, 508, 604) and the feeding pipe.

24. Apparatus according to claim 19, characterised in that the second feeder (13, 513) comprise at least one stationary feeding pipe (514, 602), that extends from the wall (2, 502) of the housing into the mixing chamber and that has an outlet for the chemical medium in or in close vicinity to said turbulent flow zone (12, 512), that the feeding pipe (514 602) extends substantially parallel to the rotor shaft (8, 102, 206, 304, 400, 508, 604) in the mixing chamber, that the rotor shaft (8, 102, 206, 304, 400, 508, 604) extend through the feeding pipe (602), whereby an annular outlet (600) for chemical medium is defined by the rotor shaft (8, 102, 206, 304, 400, 508, 604) and the feeding pipe, and that the feeding pipe (602) extend coaxially or eccentrically to the rotor shaft (8, 102, 206, 304, 400, 508, 604).

25. Apparatus according to claim 20 or 21, characterised in that the outlet (516) of the feeding pipe is of rotational symmetrical design.

26. Apparatus according to claim 25, characterised in that the outlet (516, 600) of the feeding pipe has circular form.

27. Apparatus according to claim 20 or 21, characterised in that the outlet (516, 600) of the feeding pipe has elliptical, triangular, or rectangular form.

28. Apparatus according to claim 20, characterised in that the second feeder (13, 513) comprises a number of stationary feeding pipes (514, 602) .

29. Apparatus according to claim 28, characterised in that the feeding pipes (514) extend substantially radial to the rotor shaft (8, 102, 206, 304, 400, 508, 604) .

30. Apparatus according to claim 28, characterised in that the feeding pipes (514, 602) extend substantially parallel to the rotor shaft (8, 102, 206, 304, 400, 508, 604).

31. Apparatus according to claim 29 or 30, characterised in that the outlets (516) of the feeding pipes are situated symmetrical or asymmetrical around the rotor shaft (8, 102, 206, 304, 400, 508, 604).

32. Apparatus according to any of claims 28-31, characterised in that the outlets (516) of each of the feeding pipes (514) are of a rotational symmetrical design.

33. Apparatus according to claim 32, characterised in that each feeding pipe (514) has a circular form.

34. Apparatus according to any of claims 28-31, characterised in that the outlets (516) of each of the feeding pipes (514) are of a non-rotational symmetrical design.

35. Apparatus according to claim 31, characterised in that the outlets of each of the feeding pipes (514) are of a non-rotational symmetrical design and at least one of the outlets (516) is provided with an orientation of rotation (VI) in relation to the centre of rotor shaft that differs from the corresponding orientations of rotation (V2) of the other outlets.

36. Apparatus according to claim 34 or 35, characterised in that the outlet of each feeding pipe (514) has elliptical, triangular, or rectangular form.

37. Apparatus according to any of claims 1-19, characterised in that the second feeder (13) comprises a chemical distribution element (14) integrated with the rotor body (10, 104, 300) and arranged to distribute the chemical medium to or to close vicinity to said turbulent flow zone (12) .

38. Apparatus according to claim 37, characterised in that the rotor body comprise a number of rotor pins (11, 106, 106', 302, 706), which extends from the rotor shaft (8, 102, 206, 304, 400, 702) .

39. Apparatus according to claim 38, characterised in that chemical distribution element (14) comprises at least one chemical outlet (16, 704) situated up-stream of the rotor pins (11, 106, 106', 302, 706).

40. Apparatus according to claim 38, characterised in that chemical distribution element (14) comprise at least one distribution pipe (700) that extends radial from the rotor shaft (8, 102, 206, 304, 400, 702), whereby the chemical outlet (16, 704) is arranged on the distribution pipe.

41. Apparatus according to claim 40, characterised in that the chemical outlet (16, 704) is directed against the rotor pins (11, 106, 106', 302, 706).

42. Apparatus according to claim 38, characterised in that the chemical distribution element (14) comprise at least one chemical outlet (16, 704) arranged on at least one of the rotor pins (11, 106, 106', 302, 706).

43. Apparatus according to claim 42, characterised in that the chemical outlet (16, 704) is directed in the opposite flow direction (F) of the pulp suspension along the rotor shaft (8, 102, 206, 304, 400, 702).

44. Apparatus according to claim 42, characterised in that the chemical outlet (16, 704) is directed transverse the flow direction (F) of the pulp suspension from the rotor shaft (8, 102, 206, 304, 400, 702) .

45. Apparatus according to claim 38, characterised in that the chemical distribution element (14) comprise a plurality of chemical outlets (16, 704) arranged on at least one of the rotor pins (11, 106, 106', 302, 706), whereby at least one chemical outlet is directed in the opposite flow direction (F) of the pulp suspension along the rotor shaft (8, 102, 206, 304, 400, 702) and at least one chemical outlet is directed radial out from the rotor shaft.

46. Apparatus according to any of claims 39-45, characterised in that the second feeder (13) comprise a stationary cylindrical body (18), which is coaxial with the rotor shaft (8, 102, 206, 304, 400, 702), and that the rotor body (10, 104, 300) comprises a sleeve (20) that sealingly surrounds the cylindrical body, whereby the cylindrical body is provided with a channel for the chemical medium that communicates with the chemical distribution element (14) .

47. Apparatus according to claim 46, characterised in that the second feeder (13) comprise a connection pipe (22), that extends through the wall (2) of the housing to the stationary cylindrical body (18) and that is connected to the channel therein.