Arrangement and method for adjusting blade gap in a refiner - Patents.com

Abstract

To provide an arrangement capable of precisely adjusting a blade gap in a refiner.SOLUTION: An arrangement and a method of adjusting a blade gap (12) in a refiner (1) are provided. The arrangement includes at least one loading device (16) that can be configured to move at least one of refining elements (3, 4, 6, and 7) of the refiner (1) with respect to at least one of other refining elements (3, 4, 6, and 7) of the refiner (1) so as to adjust blade gaps (12) between the refining elements (3, 4, 6, and 7), at least one vibration measuring device (20) for measuring vibrations of the refiner (1) during operation, and at least one control unit (21) that can be configured to adjust the blade gaps (12) between the refining elements (3, 4, 6, and 7) by controlling at least one loading device (16) to move at least one of the refining elements (3, 4, 6, and 7) with respect to at least one of other refining elements (3, 4, 6, and 7), on the basis of the measured vibrations of the refiner (1).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a refiner. More particularly, the present invention relates to adjusting the size of a blade gap between refining elements disposed substantially opposite each other within the refiner. [Background technology]

[0002] A refiner, for example a refiner for refining lignocellulose-containing fibrous material, comprises a number of refining elements arranged opposite each other. Typically, a refiner for refining lignocellulose-containing fibrous material comprises two refining elements arranged opposite each other, one of which is a fixed refining element and the other of which is a rotatable refining element arranged to rotate relative to the fixed refining element. Between the opposite refining elements there is a free distance, i.e. a refining chamber or blade gap, into which the lignocellulose-containing fibrous material to be refined is fed. In the blade gap, the lignocellulose-containing fibrous material undergoes a refining effect that is determined by the properties of the refining surfaces of the refining elements and the operating characteristics of the refiner, for example the rotation speed of the rotatable refining element and / or the pressure prevailing in the blade gap. Summary of the Invention [Problem to be solved by the invention]

[0003] In the usual refining of lignocellulose-containing fibrous materials, the intention is to affect the fiber properties without substantially affecting the fiber length of the fibrous material, i.e. without substantially affecting the fiber length or cutting the fibers to shorter lengths. Therefore, in this type of refining application, the adjustment of the blade gap has traditionally been based on the power control of the refiner's main motor. However, the power control of the refiner's main motor is not applicable in refining applications where a very accurate constant blade gap is essential, such as, inter alia, in the intention to affect the fiber length, i.e. cutting the fibers to shorter lengths, such as in the production of microfibril cellulose (MFC) or nanofibril cellulose.

[0004] It is an object of the present invention to provide a new arrangement and method for adjusting the blade gap in a refiner. [Means for solving the problem]

[0005] The invention is characterized by the features of the independent claims.

[0006] The present invention is based on the idea of ​​measuring vibrations of a refiner during operation and adjusting the blade gap between refining elements of the refiner by moving at least one refining element relative to at least one other refining element based on the measured vibrations of the refiner.

[0007] An advantage of the present invention is that the size of the blade gap can be adjusted very accurately by an arrangement which includes a very reasonable number of different devices.

[0008] Some embodiments of the invention are disclosed in the dependent claims. [Brief description of the drawings]

[0009] In the following, the invention will be explained in more detail by means of preferred embodiments with reference to the accompanying drawings. [Figure 1]FIG. 1 shows diagrammatically an arrangement for adjusting the blade gap in a refiner. [Diagram 2] FIG. 2 shows a schematic of a method for adjusting the blade gap in a refiner. [Diagram 3] FIG. 3 shows a schematic of another method for adjusting the blade gap in a refiner. For clarity, the drawings show simplified versions of some embodiments of the invention. Like reference numbers refer to like elements in the figures. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 1 is a highly schematic side view, partially in cross section, of a conical refiner 1. Refiner 1 may be used to refine wood-based fiber material containing lignocellulose. Refiner 1 has a first end Ea with a smaller diameter and a second end Eb with a larger diameter as indicated in the radial direction R of the refiner.

[0011] The refiner 1 comprises a stationary refinement element 3, i.e. a stator 3, having a first end pointing towards a first end Ea of the refiner 1 and a second end pointing towards a second end Eb of the refiner 1. For the sake of clarity, the reference Ea is also used to denote the first end of the stator 3, and the reference Eb is also used to denote the second end of the stator 3. The stator 3 is supported on a frame structure 2 of the refiner 1. The frame structure 2 of the refiner 1 is shown in a highly simplified form in FIG.

[0012] The stator 3 comprises at least one stator blade element 4 having a refining surface. The stator blade element 4 thus forms a refining element in the stator 3 that exerts a refining effect on the material to be refined by the stator 3. The stator 3 may thus comprise a single stator blade element that provides the complete refining surface 5 of the stator 3. Typically, the stator 3 comprises two or more segment-like stator blade elements, which together form the complete refining surface 5 of the stator 3. Typically, the refining surface of each stator blade element 4, i.e. the refining surface 5 of the stator 3, comprises blade bars and blade grooves between the blade bars in a manner known to those skilled in the art. The blade bars and blade grooves of the refining surface 5 of the stator 3 are not shown for the sake of clarity in FIG. 1. In the embodiment of FIG. 1, the stator blade element 4 further comprises an opening 4a passing through the stator blade element 4.

[0013] The refiner 1 further comprises a rotatable refining element 6, i.e. rotor 6, having a first end facing towards a first end Ea of the refiner 1 and a second end facing towards a second end Eb of the refiner 1. Therefore, for the sake of clarity, the reference symbol Ea is also used to denote the first end of the rotor 6, and the reference symbol Eb is also used to denote the second end of the rotor 6.

[0014] The rotor 6 includes at least one rotor blade element 7 having a refining surface. The rotor blade element 7 thus provides a refining element in the rotor 6 that provides a refining effect on the material to be refined by the rotor 6. The rotor 6 may thus include a single rotor blade element that provides the complete refining surface 8 of the rotor 6. Typically, the rotor 6 includes two or more segment-like rotor blade elements that together form the complete refining surface 8 of the rotor 6. Typically, the refining surface of each rotor blade element 7, i.e. the refining surface 8 of the rotor 6, includes blade bars and blade grooves between the blade bars in a manner known to those skilled in the art. The blade bars and blade grooves of the refining surface 8 of the rotor 6 are not shown for clarity of FIG. 1. In the embodiment of FIG. 1, the rotor blade element 7 further includes an opening 6a that passes through the rotor blade element 7.

[0015] The rotor 6 comprises a hub 9 forming at least part of a rotor frame on which at least one rotor blade element 7 is supported. The hub 9 is shown in a highly simplified manner in Figure 1. The hub 9 of the rotor 6 is connected to a shaft 10 whose extension forms an axial direction of the refiner 1 and is indicated diagrammatically in Figure 1 by the arrow A. The shaft 10 is connected to a main motor 11 of the refiner 1. The main motor 11 is arranged to rotate the shaft 10, which in turn rotates the rotor 6, for example in a rotational direction indicated by the arrow RD in Figure 1. In view of the other parts of the refiner 1, the size of the main motor 11 is considerably reduced in Figure 1.

[0016] The stator 3 and the rotor 6 are arranged substantially opposite each other such that there is a refining chamber 12, i.e. a blade gap 12, between the stator 3 and the rotor 6. The refining chamber 12 or the blade gap 12 forms a volume in which the fibre material is refined. In FIG. 1 the size of the blade gap 12 relative to the other components of the refiner 1 is exaggerated. The free distance D between the opposing stator 3 and rotor 6 indicates the size of the blade gap 12. The refining effect brought to the fibre material to be refined in the blade gap 12 can be adjusted by adjusting the distance D between the stator 3 and the rotor 6, i.e. by adjusting the size of the refining chamber 12 or the blade gap 12.

[0017] The refiner 1 further comprises a first feed passage 13 at a first end Ea of the refiner 1, via which a first fibre material fraction, indicated generally by arrow FM1, is fed into a first feed chamber 6' provided by the internal volume of the rotor 6 on the side of the first end Ea of the rotor 6. The refiner 1 further comprises a second feed passage 14 at a second end Eb of the refiner 1, via which a second fibre material fraction, indicated generally by arrow FM2, is fed into a second feed chamber 6'' provided by the internal volume of the rotor 6 on the side of the second end Eb of the rotor 6. The first fibre material fraction FM1 and the second fibre material fraction FM2 may be of the same or different quality.

[0018] The operation of the refiner 1 of FIG.

[0019] The first fiber material fraction FM1 is fed via the first feed passage 13 to the first feed chamber 6' and further via the opening 6a in the first feed chamber 6' into the blade gap 12. The first fiber material fraction FM1 is refined when the rotor 6 is rotated. The second fiber material fraction FM2 is fed via the second feed passage 14 to the second feed chamber 6'' and further via the opening 6a in the second feed chamber 6'' into the blade gap 12, where the second fiber material fraction FM1 is refined. The opening 6a thus connects the first feed chamber 6' and the second feed chamber 6'' to the blade gap 12. The first fiber material fraction FM1 and the second fiber material fraction FM are thus subjected in the blade gap 12 to the refining effect provided by the refining surfaces 5, 8 of the stator 3 and the rotor 6 when the rotor 6 is rotated. The first fiber material fraction FM1 and the second fiber material fraction FM refined in the blade gap 12 are discharged from the blade gap 12 through the openings 4a of the stator blade element 4 into a discharge chamber 15 behind the stator blade element 4. The openings 4a thus connect the blade gap 12 to the discharge chamber 15. The flow of the first fiber material fraction FM1 and the second fiber material fraction FM2 into and out of the blade gap 12 is shown diagrammatically by the arrows FM1 and FM2, respectively. As diagrammatically shown by the arrows with reference sign FM1+FM2, the refined first fiber material fraction FM1 and the second fiber material fraction FM2 are discharged from the discharge chamber 15 out of the refiner 1 via a discharge passage 16 for further processing. The refining effect experienced by the fiber material fractions FM1 and FM2 can be adjusted by adjusting the distance D between the stator 3 and the rotor 6, i.e. by adjusting the size of the refining chamber 12 or the blade gap 12.

[0020] FIG. 1 shows diagrammatically a loading device 16 which may be coupled to the shaft 10 of the refiner 1 for moving the rotor 6 back and forth in the axial direction A, as shown diagrammatically by the arrow AD, to adjust the distance D between the stator 3 and the rotor 6, i.e. to adjust the size of the refining chamber 12 or the blade gap 12.

[0021] The loading device 16 of FIG. 1 comprises an actuator 17 connected directly or indirectly via a connecting element 19 to the shaft 10 of the rotor 6 as shown in FIG. 1. The actuator 17 is configured to move the rotor 6 towards the first end Ea of the refiner 1 in order to reduce the distance D between the stator 3 and the rotor 6, i.e. to reduce the size of the blade gap 12, or towards the second end Eb of the refiner 1 in order to increase the distance D between the stator 3 and the rotor 6, i.e. to increase the size of the blade gap 12, depending on the operation of the actuator 17. The actuator 17 can be, for example, an actuating cylinder, such as a ball screw actuator or a planetary screw actuator. Instead of the shaft 10 of the rotor 6, the actuator 17, and thus the loading device 16, can be arranged to be connected to the rotor 10 by some other means.

[0022] 1 further includes an adjusting device 18 connected to or arranged in conjunction with the actuator 17 for controlling the operation of the actuator 17 to control the movement of the rotor 6. The adjusting device 18 is configured to operate the actuating cylinder 17 to move the rotor 6 towards the first end Ea of the refiner 1 to reduce the distance D between the stator 3 and the rotor 6, or to move the rotor 6 towards the second end Eb of the refiner 1 to increase the distance D between the stator 3 and the rotor 6.

[0023] Conventionally, the adjustment of the blade gap is based on the power control of the main motor 11 of the refiner 1. The reason is that in normal refining, the intention is to only affect the properties of the fibers in the lignocellulose-containing fibrous material without substantially affecting the fiber length or cutting the fibers to shorter lengths. However, the power control of the main motor 11 of the refiner 1 is intended to affect the fiber length by cutting the fibers to shorter lengths and is not applicable in refining applications where a precise and constant blade gap is desired. Examples of this kind of refining applications are e.g. the production of microfibril cellulose (MFC) or nanofibril cellulose (NFC).

[0024] According to the solution disclosed herein, an arrangement for adjusting a blade gap in a refiner includes at least one loading device configured to move at least one refining element of the refiner relative to at least one other refining element of the refiner in order to adjust the blade gap between the refining elements, at least one vibration measuring device for measuring vibrations of the refiner in operation, i.e., during operation, and at least one control unit configurable to adjust the blade gap between the refining elements by controlling the at least one loading device based on the measured vibrations of the refiner, thereby moving the at least one refining element relative to the at least one other refining element.

[0025] With reference to the embodiment of FIG. 1 , an arrangement for adjusting the blade gap 12 in the refiner 1 includes a loading device 16 coupled to the rotor 6 for moving the rotor 6 relative to the stator 3, the loading device 16 being capable of moving the rotor 6 back and forth in an axial direction A, as indicated diagrammatically by the arrows AD.

[0026] The arrangement of Figure 1 further includes a vibration measuring device 20 for measuring vibrations of the refiner 1 during operation. The vibration measuring device 20, which may be a vibration measuring sensor such as an acceleration sensor, is preferably located on a non-moving part of the refiner 1, such as a frame structure 2 of the refiner 1, as shown in Figure 1. According to one embodiment, the vibration measuring device 20 is located on a fixing point of a stator blade element on a casing at the feed end of the refiner 1, which fixing point provides a robust location for the vibration measuring device 20.

[0027] The arrangement of Figure 1 further comprises a control unit 21 which is configurable to control the loading device 16 based on the measured vibrations of the refiner 1 to adjust the blade gap 12 between the oppositely arranged refining elements 3, 6 by moving the rotor 6 relative to the stator 3. Control signals from the control unit 21 to the loading device 16, and in particular to an adjustment device 18 of the loading device 16, are indicated diagrammatically by arrows CO-16.

[0028] According to one embodiment of the arrangement, the at least one control unit is configured to control the at least one loading device to move the at least one refining element towards the at least one other refining element, receive vibration measurement signals representative of measured refiner vibrations from the vibration measurement device, compare the received vibration measurement signals with settable conditions for the refiner vibration, and control the at least one refining element to move away from the at least one other refining element according to a settable distance corresponding to a vibration measurement signal that satisfies the settable condition for the refiner vibration.

[0029] According to this embodiment and with reference to the embodiment of figure 1, the control unit 21 is configured to control the loading device 16 so that the rotor 6 is moved towards the stator 3. At the same time, the control unit 21 receives from the vibration measuring device 20 a vibration measurement signal VMS representative of the vibrations of the refiner 1 during operation. The control unit 21 comprises a vibration monitoring unit and a possible amplification unit for the vibration measurement signal VMS. The control unit 21 is configured to compare the measured vibration measurement signal VMS with settable conditions SET-V set for the vibrations of the refiner 1, the conditions SET-V being intended to provide reference limit values ​​set for the vibrations of the refiner 1. The conditions or reference limit values ​​SET-V set for the vibrations of the refiner 1 may represent certain characteristics of the vibration measurement signal VMS, such as the amplitude or frequency of the vibration measurement signal VMS. The characteristics of the vibration measurement signal VMS depend at least on the distance between the stator 3 and the rotor 6, and when the refiner 1 is in operation and the rotor 6 approaches the stator 3, at least the amplitude of the vibration measurement signal VMS tends to increase.

[0030] The control unit 21 is configured to control the loading device 16 to move the rotor 6 towards the stator 3 until the vibration measurement signal VMS reaches a set condition SET-V for the characteristics of the vibration measurement signal VMS. In response to the vibration measurement signal VMS fulfilling the set condition SET-V for the vibration of the refiner 1, the control unit 16 is configured to control the loading device 16 to move the rotor 6 away from the stator 3 by a distance corresponding to a settable distance SET-BW set for the distance the rotor 6 should be away from the stator 3 to obtain a desired blade gap size SET-D or a set value SET-D for the size of the blade gap 12. A specific control signal CO-16 set for controlling the operation of the loading device 16 provides a specific movement of the rotor 6 in the axial direction A of the refiner 1 due to the known mechanical coupling between the loading device 16 and the rotor 6, so that the size of the blade gap 12, i.e. the distance D between the stator 3 and the rotor 6, can be precisely adjusted.

[0031] According to one embodiment of the arrangement, the at least one control unit is configurable to control the at least one loading device such that at least one purification element is moved towards at least one other purification element until the purification elements contact each other.

[0032] According to this embodiment, with reference to the embodiment of Fig. 1, the control unit 21 is configured to control the loading device 16 such that the rotor 6 is moved towards the stator 3 until the stator 3 and the rotor 6 come into contact with each other. When the refining surface 8 of the rotor 6 comes into contact with the refining surface 5 of the stator 3, the size of the blade gap 12, i.e. the distance D between the refining surface 8 of the rotor 6 and the refining surface 5 of the stator 3, is zero, which the control unit 21 can detect from the vibration measurement signal VMS based on the condition SET-V set for the vibration measurement signal VMS. In response to the vibration measurement signal VMS indicating that the refining surface 8 of the rotor 6 and the refining surface 5 of the stator 3 have come into contact with each other, the control unit 21 is configured to control the loading device 16 to move the rotor 6 away from the stator 3 according to a predetermined distance SET-BW set in the control unit 21.

[0033] Here, the settable predetermined distance SET-BW may correspond to a set value SET-D for the size of the blade gap 12. The control unit 21 is configured to move the rotor 6 away from the stator 3, taking into account the mechanical coupling between the loading device 16 and the rotor 6 after the stator 3 and the rotor 6 come into contact with each other, such that the size of the blade gap 12, i.e. the distance D between the refining surface 5 of the stator 3 and the refining surface 8 of the rotor 6, corresponds to the set value SET-D set for the distance D between the refining surface 5 of the stator 3 and the refining surface 8 of the rotor 6. By moving the rotor 6 towards the stator 3 until the rotor 6 and the stator 3 come into contact with each other and then moving the rotor 6 away from the stator 3 by a distance corresponding to the set value SET-D set for the distance D between the refining surface 5 of the stator 3 and the refining surface 8 of the rotor 6, the size of the blade gap 12 can be adjusted very precisely. An embodiment of such a method is disclosed diagrammatically in FIG. 2.

[0034] The set value SET-D for the size of the blade gap 12 may vary depending on the actual refining application. Typically, the set value SET-D may be 0.0005-0.2 mm. In the case of the production of microfibril cellulose (MFC) or nanofibril cellulose (NFC), the size of the blade gap 12 may be, for example, 0.001-0.02 mm.

[0035] According to one embodiment of the arrangement, the at least one control unit can be configured to control the at least one loading device to periodically move the at least one refining element towards the at least one other refining element after the at least one refining element is moved away from the at least one other refining element in response to a vibration measurement signal satisfying a settable condition for vibration of the refiner.

[0036] According to this embodiment, with reference to the embodiment of figure 1, the control unit 21 is configured to control the loading device 16 in order to move the rotor 6 back towards the stator 3 after it has been moved away from the stator 3 in response to a vibration measurement signal VMS fulfilling a set condition SET-V for the vibrations of the refiner 1. The intention of moving the rotor 6 back towards the stator 3 is to substantially maintain the size of the blade gap 12 at its set value SET-D in response to wear of the refining surfaces 5, 8 of the stator 3 and of the rotor 6.

[0037] According to one embodiment of the arrangement, the control unit is configurable to control the at least one loading device to periodically move the at least one purification element towards the at least one other purification element according to a settable distance at a settable time interval.

[0038] According to this embodiment, with reference to the embodiment of FIG. 1, the control unit 21 is configured to control the loading device 16 to intermittently move the rotor 6 towards the stator 3 according to a set value SET-T set for a time interval, after which the control unit 21 is configured to control the loading device 16 to move the rotor 6 towards the stator 3. The set value SET-FW is configured to determine how far the rotor 6 is moved towards the stator 3 in one go. The set value SET-FW represents the amount of wear of the refining surfaces 5, 8 of the stator 3 and the rotor 6 during the time interval SET-T. According to this embodiment, the wear of the refining surfaces 5, 8 of the stator 3 and the rotor 6 can be accurately compensated and the size of the blade gap 12 can be kept substantially constant at its set value SET-D. An embodiment of such a method is disclosed diagrammatically in FIG. 3.

[0039] The set value SET-FW for compensation of the wear of the refining surface and the set value SET-T for each time interval can vary depending on the actual refining application. Typically, the set value SET-FW varies between 0.001 and 0.01 mm and can be based on estimated or empirical values ​​for the wear of the refining surface during the time interval SET-T. Depending on the implementation, the set value SET-FW represents an intended movement of the rotor 6 in the axial direction A of the refiner 1 or an intended change in the size D of the blade gap 12, the latter being converted by the control unit 21 into a specific intended movement of the rotor 6 in the axial direction A of the refiner 1. The set value SET-T can be, for example, from several minutes to several tens of hours. From time to time, the control unit 21 controls the loading device 16 to move the rotor 6 towards the stator 3 until it contacts the stator 3, and then controls the loading device 16 to move the rotor 6 away from the stator 3 according to a distance corresponding to a set value SET-D set for the size of the blade gap 12, thereby eliminating possible deviations in the size of the blade gap 12, for example due to the wear of the refining surface differing from the predicted wear of the refining surface.

[0040] According to one embodiment of the arrangement, the arrangement includes a position measurement device for providing a position measurement signal representative of a position of the at least one refining element relative to the at least one other refining element, and the at least one control unit is configurable to receive the position measurement signal from the position measurement device and to control the position of the at least one refining element relative to the at least one other refining element based on the position measurement signal.

[0041] According to this embodiment, with reference to the embodiment of Fig. 1, the arrangement comprises a position measuring device 22 for providing a position measurement signal PMS representative of the position of the rotor 6 relative to the stator 3. The control unit 21 is configured to receive the position measurement signal PMS from the position measuring device 22 and to control, based on the position measurement signal PMS, the position of the rotor 6 relative to the stator 3 by means of the loading device 16. According to this embodiment, the position of the rotor 6 relative to the stator 3 can be accurately determined and controlled, as the position measurement signal PMS provides a feedback signal for the position of the rotor 6 relative to the stator 3.

[0042] According to one embodiment of the arrangement, the loading device includes at least one servo motor, the at least one servo motor including a position measuring device for measuring a rotational position of a shaft of the servo motor, and the at least one control unit is configured to receive a position measurement signal representing the measured rotational position of the servo motor shaft from the position measuring device, determine a position of the at least one purification element relative to at least one other purification element based on the measured rotational position of the servo motor shaft and a coupling between the at least one purification element and the servo motor shaft, and further control the position of the at least one purification element relative to the at least one other purification element based on the position measurement signal.

[0043] According to this embodiment, with reference to the embodiment of figure 1, the loading device 16 comprises as adjustment device a servo motor 23, which comprises a position measuring device 22 for measuring the rotational position of a shaft 23' of the servo motor 23. The control unit 21 is configured to receive a position measurement signal PMS representative of the measured rotational position of the shaft 23' of the servo motor 23 from the position measuring device 22 and to determine the position of the rotor 6 relative to the stator 3 based on the measured rotational position of the shaft 23' of the servo motor 23 and on the mechanical coupling of the rotor 6 with the shaft 23' of the servo motor 23. In addition, the control unit 21 is configured to control the position of the rotor 6 relative to the stator 3 based on the position measurement signal PMS. The servo motor 23 with the position measuring device 22 provides a means by which the position adjustment of the rotor 6 relative to the stator 3 can be performed very accurately.

[0044] In the above disclosed solution, the size of the blade gap 12 can be adjusted very accurately by means of an arrangement including a very reasonable number of different devices.

[0045] The precise adjustment of the size of the blade gap 12 is particularly important in the production of microfibril cellulose (MFC) or nanofibril cellulose (NFC). In this specification, the term "nanofibril cellulose" means a group of separate cellulose microfibrils or bundles of microfibrils derived from plant-based, especially wood-based, fibrous materials. Synonyms of nanofibril cellulose (NFC) include, for example, nanofibrillated cellulose, nanocellulose, microfibril cellulose, cellulose nanofibers, nanoscale cellulose, microfibrillated cellulose (MFC) or cellulose microfibrils. Depending on the degree of comminution, the particle size of the separate cellulose microfibrils or bundles of microfibrils is a few nanometers (nm) or a few micrometers (μm). The average length of the separate cellulose microfibrils or bundles of microfibrils can be, for example, 0.2 to 200 μm and the average diameter can be, for example, 2 to 1000 nm.

[0046] The arrangement for adjusting the size of the blade gap disclosed herein may additionally comprise a measurement sensor intended to measure the gap between the opposing refining elements, typically arranged on one of the opposing refining elements and may be used, for example, for the calibration of the vibration-based adjustment of the size of the blade gap.

[0047] In the embodiment of FIG. 1, the refiner 1 is a conical refiner with a single stator and a single rotor, but the solution disclosed herein for adjusting the blade gap of the refiner can also be applied to conical refiners with any number of stators and / or rotors. The refining surface of the refiner stator and / or rotor can include openings as shown in FIG. 1 or the refining surface can be substantially uniform without any openings. The feeding of the fibrous material to be refined can take place only at one end of the refiner or at one side of the refiner if the fibrous material to be refined is fed to the refiner through openings in a fixed refining element. As is clear from the above, in a conical refiner, when adjusting the blade gap, the movement of the refining element takes place in the axial direction A of the refiner and the change in the size of the blade gap takes place at a given angle between the axial direction A and the radial direction R of the refiner depending on the rise angle of the conical structure of the refining element.

[0048] Moreover, instead of a conical refiner, the solution disclosed herein can also be implemented in a disc refiner comprising a disc refiner which comprises a disc refiner element extending in the radial direction of the refiner, i.e. in a direction substantially perpendicular to the axial direction of the refiner. In a disc refiner, when adjusting the blade gap, the movement of the refiner element and the change in the size of the blade gap 12 occurs in the axial direction A of the refiner. The refiner element which is moved in the disc refiner can also be either a fixed refiner element or a rotating refiner element. The disc refiner may also have any number of stators and / or rotors. The basic structure and working principle of a disc refiner is known to a person skilled in the art of refiners and will not be disclosed in more detail here.

[0049] Moreover, instead of conical and disc refiners, the solution disclosed herein is also applicable to cylindrical refiners comprising a number of cylindrical stators and / or rotors. In cylindrical refiners, the adjustment of the blade gap is usually performed by adjusting the diameter of the stator, so that the movement of the refining elements and the change in the size of the blade gap occurs in the radial direction R of the refiner. In cylindrical refiners, the loading device may be arranged to be operatively connected to the stator in order to change the diameter of the stator in response to a respective control signal applied to the loading device by the control unit, thereby moving the stator or stator blade elements towards the rotor or rotor blade elements. The basic structure and working principle of cylindrical refiners are also known to those skilled in the art of refiners, and therefore will not be disclosed in more detail herein.

[0050] In the above examples, the refiners disclosed were intended, inter alia, to refine lignocellulose-containing fibrous material. In addition to refiners for refining lignocellulose-containing fibrous material, the solutions for adjusting the blade gap size disclosed herein may also be applied to refiners intended to refine other materials, such as minerals, natural and synthetic polymers, carbon, coal, metals or any mixtures or alloys thereof.

[0051] It is obvious to a person skilled in the art that with the advancement of technology, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

1. 1. A mechanism for adjusting a blade gap in a refiner, the mechanism comprising: at least one loading device configured to move at least one refining element of the refiner relative to at least one other refining element of the refiner to adjust a blade gap between the at least one refining element of the refiner and the at least one other refining element of the refiner; at least one vibration measurement device for measuring vibrations of the refiner during operation; at least one control unit configurable to adjust the blade gap between the at least one refining element and the at least one other refining element by controlling the at least one loading device to move the at least one refining element relative to the at least one other refining element based on the measured vibration of the refiner; Including, The at least one control unit is controlling the at least one loading device to move the at least one refining element towards the at least one other refining element; receiving a vibration measurement signal from the vibration measurement device representative of a measured vibration of the refiner; comparing the received vibration measurement signal with configurable conditions for vibration of the refiner; controlling the at least one loading device to move the at least one refining element away from the at least one other refining element according to a configurable distance in response to the vibration measurement signal satisfying the configurable condition for vibration of the refiner; [0033] the at least one control unit may be configured to control the at least one loading device such that the at least one refining element is periodically moved towards the at least one other refining element according to a settable distance at settable time intervals after the at least one refining element is moved away from the at least one other refining element in response to the vibration measurement signal satisfying the settable condition for vibration of the refiner; A mechanism, wherein a set value for the configurable distance represents an amount of wear of a refining surface between the at least one refining element and the at least one other refining element during the configurable time interval.

2. 2. The mechanism of claim 1, wherein the at least one control unit is configurable to control the at least one loading device to move the at least one purification element toward the at least one other purification element until the at least one purification element and the at least one other purification element contact each other, and in response to the contact, the at least one control unit is configured to control the at least one loading device to move the at least one purification element away from the at least one other purification element.

3. the mechanism includes a position measurement device for providing a position measurement signal indicative of a position of the at least one refining element relative to the at least one other refining element; The at least one control unit is receiving a position measurement signal from the position measurement device; controlling a position of the at least one refining element relative to the at least one other refining element based on the position measurement signal; The mechanism according to claim 1 or 2, which is configurable to:

4. the loading device including at least one servo motor including a position measuring device for measuring a rotational position of a shaft of the servo motor; The at least one control unit is receiving a position measurement signal from the position measuring device representative of a measured rotational position of a shaft of the servo motor; determining a position of the at least one refining element relative to the at least one other refining element based on the measured rotational position of the shaft of the servo motor and a coupling of the at least one refining element and the shaft of the servo motor; controlling a position of the at least one refining element relative to the at least one other refining element based on the position measurement signal; The mechanism according to claim 1 , which is configurable to:

5. 5. The mechanism of claim 1, wherein the vibration measurement device is a vibration measurement sensor configured for attachment to a frame structure of the refiner.

6. The mechanism according to claim 1 , wherein the at least one refining element moved by the at least one loading device is a rotor of the refiner.

7. 1. A method for adjusting a blade gap in a refiner, the method comprising: moving at least one refining element towards at least one other refining element; measuring vibrations of the refiner during operation; comparing vibration measurement signals representative of vibration of the refiner during operation with configurable conditions for vibration of the refiner; adjusting a blade gap between the at least one refining element and the at least one other refining element based on the measured vibration of the refiner by moving the at least one refining element relative to the at least one other refining element and moving the at least one refining element away from the at least one other refining element according to a settable distance corresponding to a vibration measurement signal that satisfies a settable condition for the vibration of the refiner; after moving the at least one refining element away from the at least one other refining element in response to a vibration measurement signal satisfying the settable condition for vibration of the refiner, periodically moving the at least one refining element toward the at least one other refining element according to a settable distance at a settable time interval, a set value for the settable distance representing an amount of wear of a refining surface between the at least one refining element and the at least one other refining element during the settable time interval; The method includes:

8. 8. The method of claim 7, comprising the step of moving the at least one purification element toward the at least one other purification element until the at least one purification element and the at least one other purification element contact each other, and in response to the contact, the at least one purification element is moved away from the at least one other purification element.

9. providing a position measurement signal indicative of a position of the at least one refining element relative to the at least one other refining element; controlling a position of the at least one refining element relative to the at least one other refining element based on the position measurement signal; The method of claim 7, comprising:

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