Control of fiber material processing

Abstract

This invention relates to a method for controlling an apparatus for processing fibrous material (1), wherein the apparatus has a housing (2) in which at least one first processing tool (3) and a second processing tool (4) are arranged, the processing tools (3, 4) being fixed to base plates (7, 8), having rotationally symmetrical shapes, coaxially arranged, rotating relative to each other about a common axis (5), defining a processing gap (6) through which the fibrous material (1) flows, and each having a processing profile (9) pointing toward the processing gap (6), wherein at least one base plate (7, 8) of the processing tool (3, 4) is axially movable to compensate for wear of the processing profile (9). The control of the apparatus is improved by determining the distance (s) between the base plates (7, 8) of the processing tools (3, 4) in the processing gap (6), and adjusting the value of the total power (PG) according to the change in the distance (s) between the base plates (7, 8) of the processing gap (6) in order to control the total power (PG).

Description

[0001] The invention relates to a method for controlling an apparatus for processing fiber materials, wherein the apparatus has a housing in which at least one first processing tool and a second processing tool are arranged. The processing tools are respectively fixed to a base plate and have a rotationally symmetrical shape and are arranged coaxially with each other and rotate relative to each other around a common axis. The processing tools define a processing gap through which the fiber material flows and each have a processing profile pointing to the processing gap, wherein at least one base plate of the processing tool is supported axially movably in order to compensate for the wear of the processing profile. In order to adjust the total power, the width of the processing gap is adjusted until a predetermined total power is reached.

[0002] Due to the relatively high consistency of the fibers during processing, intensive mechanical processing can be carried out in such plants (refiners, dispersers, pulpers), although the relatively movable processing tools do not come into contact but pass by each other at a short distance. Very considerable forces occur in this process. Plants of the aforementioned type are used, for example, to improve the quality of pulp, TMP (thermomechanical pulp) or fibrous material obtained from waste paper.

[0003] It has long been known to grind pulp fibers, ie fresh pulp and / or waste pulp, in order to be able to achieve the desired properties in the fibrous web produced therefrom, in particular with regard to strength, porosity, formation and surface.

[0004] In the case of refiners used in this process, the grinding surfaces are formed by replaceable grinding attachments which are screwed to the corresponding base plate due to the relatively rapid wear.

[0005] In order to achieve the desired fiber properties, in particular the degree of grinding, the grinding accessories must be adapted as closely as possible to the fiber material to be processed, also in order to prevent excessive wear of the accessories.

[0006] Furthermore, in order to increase the efficiency of the fiber treatment, efforts are made to make optimal use of the available grinding surface.

[0007] It is known from US 2004 / 0112 997 A1 as well as DE 2 939 587 A1 and DE 3 602 833 A1 to measure or calculate the idling power once before commissioning and to use it as a basis for machine control.

[0008] If the height of the processing profile of the processing tool decreases due to wear, this leads to a reduction in the idling power or pumping power. If the total power remains constant, this also leads to an increase in the specific power of the system, which is important for the desired processing intensity, and thus to over-processing of the fibers, in particular over-grinding. In the process, a constant total power is established by the axial displacement of the axially displaceable base plate.

[0009] If the gap is too small, there is a risk of high current consumption and contact with the handling tool.

[0010] Patent document DE 10 2016 207 726 A1 discloses determining the idling power during operation. However, for this purpose, the refiner must be idling or have water flowing through it, and the treatment gap must be opened and closed while the idling power is measured. The idling power measured in this case is then used as a basis for further operation.

[0011] The technical problem to be solved by the present invention is to realize a reliable and efficient operation of these devices by means that are as simple as possible.

[0012] According to the present invention, this technical problem is solved in the following manner, that is, during the operation of the equipment, the distance between the base plates of the processing tools of the processing gap is changed to control the total power, and in the process, the value of the total power is selected according to the measured distance between the base plates of the processing gap. The measured distance is also understood to be a distance change from an initial value in particular. This distance can be directly measured on the one hand, in the form of measuring the distance of the processing tools or the distance of the base plates on which the processing tools are fixed. But this distance can also be measured indirectly. For example, in one embodiment, the distance change can be inferred from the position of the drive device of the axially movable base plate for tracking the processing tools.

[0013] Since the idling power of the system decreases relatively strongly during the operating time of the treatment tool as the profile wear of the treatment tool increases, the total power, which is composed of the idling or pumping power and the specific power that is important for the target treatment intensity, should be adjusted accordingly. Unnecessary increases in the specific power and thus the treatment intensity of the fibers can thus be effectively and simply counteracted.

[0014] This is possible in particular because the usual width of the processing gap is many times smaller than the profile height of the processing tool, and the width of the processing gap can therefore be ignored in the control. When the fiber suspension is supplied, the formation of the processing gap is achieved in operation, and the processing gap width is adjusted until a predetermined total power is reached. Since the width of the processing gap is negligible compared to the profile height, the change in the gap width of the processing gap can also be ignored compared to the position change caused by the wear of the accessories, wherein the processing gap width can also be related to the flow rate. The profile height can therefore be determined by the measured distance / distance change or the change in the profile height can be determined from an initial value. For a device with one processing gap, the profile height is equivalent to half of the distance between the base plates, and for a device with two processing gaps, the profile height is a quarter of the determined distance value after deducting the width of the distance established by the non-profile component. It is also possible to determine the reduction in distance from the initial distance value and directly determine the reduction in profile height therefrom. The corresponding total power is formed according to the determined profile height and the desired processing intensity adjustment.

[0015] In one embodiment, it is provided that the wear of each fitting is indicated in a manner rounded to the nearest 0.1 mm, preferably to the nearest 0.5 mm. A displacement sensor or an incremental encoder is used as a sensor for determining the position or the change in position.

[0016] In order to simplify the control, the value of the total power should be selected only as a function of the measured distance between the base plates of the treatment gap or in combination with the desired grinding energy. In this case, the measured distance corresponds to the determination of the profile height. Preferably, the relationship between the profile height and the idling power associated therewith is stored in a characteristic curve family. This characteristic curve family can be read in by the operator before commissioning or can also be provided by the manufacturer of the device. Therefore, it is not necessary to determine the idling power during operation.

[0017] In a preferred embodiment, it is provided that in a device with a double gap, the rotor is mounted in a floating manner. Thus, the distance between the processing tools can be readjusted to the height of the contours for the two gaps by means of the axially displaceable processing tools.

[0018] When the total power is selected taking into account further values, such as the flow rate and the consistency and / or the quality of the fiber suspension, a more precise control is possible.

[0019] Advantageously, the value of the total power is adjusted at least in the case of a detected change in the distance between the base plates of the process gap of at least 1 mm. This corresponds to a reduction of 0.5 mm per process profile in the process gap.

[0020] However, it is usually sufficient to reselect the value of the total power at predetermined time intervals at most once a day, preferably at least once a week, depending on the measured change in the distance between the base plates in the process gap. Between these time intervals, the distance between the base plates and the wear of the process profiles is reduced in accordance with each other, so that the total power is kept constant at the respective current value.

[0021] When controlling or regulating the system, the idling power should also be taken into account if possible, which is dependent on the fiber material flow rate per unit time and, for example in the case of a refiner, is usually between 40 and 250, in particular 40 and 150 kWh per ton of dry weight.

[0022] After intervention in the system, for example by replacing only some of the accessories, the distance value measured when opening and / or closing the process gap can be used once as a new starting value for the idling power in order to establish a relationship with the stored characteristic diagram. In the subsequent control of the total power, in addition to the distance value, further links with other parameter values ​​can also be used for controlling the total power and thus also for controlling the specific power of the system.

[0023] Furthermore, it can be provided that the idling power is measured before each shutdown of the refiner. Furthermore, it can be provided additionally or alternatively that the idling power is determined only after a predetermined minimum operating time. This prevents the idling power from being determined every time in the case of frequent shutdowns of the plant several times a day. Due to the stored characteristic curves and the corresponding tracking of the total power, it is entirely sufficient to carry out the idling power determination every 1 to 2 weeks. This reliably prevents undesirably high grinding powers.

[0024] It has hitherto been common practice to determine the idling power of the installation during startup and to store it for control or to use a predetermined value for this purpose.

[0025] As the operating time of the respective processing tool increases and as a result the wear of the processing tool, in particular of the contour of the processing tool, increases, the current idling power of the device decreases. Therefore, the total power consumption must be reduced accordingly.

[0026] However, since the idling power was assumed to be constant in previous control / regulations, it could result in the total power consumed being set too high for the target processing intensity by 20% or more.

[0027] In order to be able to store initial values ​​for the control in the memory after replacing at least one processing tool, it may be advantageous if the idling power is measured and entered by service personnel or if the idling power is measured by the control device itself, in particular when closing a processing interval.

[0028] Independently of this, the value for controlling the total power of the system should be selected such that the specific power of the system, which is relevant for the target processing intensity and is generated from the difference between the total power and the idling power, is constant over the operating time. This ensures a stable processing intensity. The specific power is considered constant if the deviation of the specific power from its arithmetic mean is less than 5%.

[0029] If the total power value is not re-determined continuously but at certain time intervals, the length of these time intervals should be selected so that any changes due to wear of the process profile are tolerable for the then increasing specific power. Changes of less than 5% of the last used idling power and / or position changes of less than 1 mm per gap are considered to be tolerable.

[0030] When determining the value of the total power as a function of the distance between the base plates of the treatment gap, the values ​​stored in the memory of the control device, in particular the characteristic diagram, should advantageously be used. The stored values ​​or characteristic diagrams are specified by the manufacturer of the system or determined in advance by the operator of the system in tests.

[0031] These values ​​stored in the memory are based on knowledge or experience of the idling power at the corresponding distance between the two base plates in the treatment gap and the wear of the treatment profile associated therewith. Taking into account the desired fiber treatment intensity and thus the specific power, a predetermined value for the controlled total power is derived as a sum.

[0032] For a simple construction of the device, one processing tool should rotate and the other processing tool should not rotate, wherein at least one processing tool is mounted so that it can move axially.

[0033] In a special embodiment, the processing tool and the base plate can also be designed in one piece.

[0034] It is also possible for the housing to have a plurality of, in particular two, parallel processing gaps arranged next to one another, which preferably each have a processing tool that rotates on an axis and a non-rotating processing tool.

[0035] In this case, two processing tools adjacent to the respective other processing gap are fastened to a common base plate, wherein the common base plate and at least one processing tool not fastened to the base plate are mounted so as to be axially displaceable.

[0036] The method according to the invention is particularly advantageously used in a refiner, in particular an LC (low consistency) refiner, in which the consistency of the fiber material is between 2 and 6%, in particular between 3.5 and 4.5%, of dry weight.

[0037] The fiber material can in particular also be TMP, a high-yield fiber suspension, MDF (medium density fiberboard) fiber material, wood chips or the like.

[0038] The present invention will be explained in detail below based on examples.

[0039] In the attached picture:

[0040] Figure 1 shows a schematic cross-sectional view of a refiner, and

[0041] Figure 2 Shows idling power P L The change and total power P G Adjustment over time t and over distance s between base plates 7 , 8 .

[0042] according to Figure 1 The paper fiber material 1 is pressed directly into the central, ie radially inner, region of the refiner attachment formed by the two processing tools 3 , 4 .

[0043] One processing tool 3 is stationary and is therefore designed as a stator, whereas the other processing tool 4 is rotatably mounted in the housing 2 of the refiner.

[0044] The processing tools 3, 4 each have a rotationally symmetrical shape, wherein two annular grinding surfaces are arranged parallel to one another. The processing gap 6 between the grinding surfaces is adjusted by axial displacement in order to achieve a predetermined total power. The processing intensity of the paper fiber material 1, also referred to as the fiber suspension, flowing into the gap is determined by the gap width of the processing gap 6. Compared to the height of the processing contour 9 of the processing tools 3, 4, this gap width of the processing gap 6 is negligible in its axial extension.

[0045] The rotating grinding surface 9 is moved in the direction of rotation by a shaft rotatably mounted in the housing 2. The shaft is driven by a drive device which is also present in the housing 2. In the example shown, the fiber suspension 1 to be ground enters the treatment gap 6 between the grinding surfaces of the two treatment tools 3, 4 via a central feed opening.

[0046] The fiber stock suspension 1 passes radially outwards over the cooperating grinding surfaces and leaves the connected annular space through the discharge opening.

[0047] The two grinding surfaces are respectively formed by a plurality of grinding plates, which extend over the circumferential sections of the corresponding grinding surfaces. The plurality of grinding plates are arranged side by side in the circumferential direction to generate a continuous grinding surface.

[0048] The grinding plate and thus the grinding surface has a processing contour 9 pointing toward the processing gap 6 , which processing contour is usually formed by a plurality of essentially radially extending grinding strips and grooves located between the grinding strips.

[0049] Means known per se for axially moving the non-rotating processing tool 3 are not shown. The amount of axial movement is measured by a displacement sensor 10. The rotating processing tool 4 does not change its axial position. The amount of axial movement can also be measured by an incremental encoder not shown on the drive device in order to adjust the axial position of the non-rotating but axially movable processing tool 3.

[0050] Furthermore, the processing tools 3 , 4 are fixed to the respective base plates 7 , 8 .

[0051] In contrast to the example shown here, the treatment gap 6 can extend not only perpendicularly to the rotation axis 5 but also obliquely thereto, as in a conical refiner. Furthermore, the housing 2 can also comprise a plurality of treatment gaps 6 , in particular two.

[0052] Figure 2 Explain the actual idling power P of the refiner L The change in the distance S, which decreases with increasing operating time t and therefore also with increasing wear of the processing contour 9 of the processing tool 3 , 4 .

[0053] Here, the total power P supplied to the processing equipment G From idling power P L and the specific power P responsible for the treatment intensity of the fiber suspension 1, i.e. the grinding power S composition.

[0054] When the idling power is known, the total power is adjusted to a predetermined value corresponding to the desired processing intensity. S If the operating time of the treatment tools 3, 4 is significantly longer than that required for the target treatment intensity of the fiber suspension 1, the used idling power P is adjusted accordingly, depending on the measured distance s between the base plates 7, 8 or the distance between the treatment tools 3, 4, using stored values ​​or stored characteristic diagrams. L .

[0055] By varying the distance s between the base plates 7, 8 of the processing tools 3, 4 of the processing gap 6 during operation, the total power P used by the apparatus can be controlled simply and efficiently. G It is essential to the invention that the total power P is selected as a function of the distance s between the base plates 7 , 8 of the process gap 6 . G The value of .

[0056] Here, the total power P G The value of is preferably selected such that the specific power P of the device which is important for the target processing intensity S Be as constant as possible in terms of runtime.

[0057] The total power P is selected according to the distance s between the base plates 7 , 8 of the treatment gap 6 G When using the values ​​of , the values ​​stored in the memory of the control device are used. These values ​​are specified by the manufacturer of the device or determined by the operator of the device during experiments.

[0058] Total power P G The value specified for the control device can be as follows Figure 2 The distance s between the base plates 7 , 8 according to the process gap 6 is continuously adjusted as shown by the dashed line.

[0059] But alternatively according to Figure 2 For total power P G The total power P can also be readjusted at certain time intervals according to the distance s between the base plates 7 and 8 of the treatment gap 6. G Alternatively, it can also be provided that the total power is adjusted according to the change s. The idling power corresponding to the distance s is used as the basis for the adjustment.

[0060] Between the corresponding adjustments, the total power P G The predetermined value of remains constant. S Minor increases during this period can be tolerated.

[0061] Idle power P which is important for controlling processing equipment L The value of is updated by the measured distance.

[0062] Under customary operating parameters such as pressure, flow and consistency, during opening and / or closing of the treatment gap 6, an idling power P is carried out in the presence of the fibrous material 1. L This verification can be arranged every 1-2 weeks, or even once a day.

[0063] For this purpose, the idling power P of the treatment equipment is measured when the treatment gap is opened and / or closed. L And check the idling power P L In this way, a fault in the distance measurement can also be reliably detected if the measured value of the idling power deviates significantly from the value stored for the corresponding distance.

[0064] When the treatment system is put into operation or when the treatment tools 3, 4 or their accessories are replaced, the idling power P is measured when the treatment gap 6 is closed. L And it is stored in the memory as an initial value for control.

[0065] For at least approximately true idling power P L The knowledge of the specific power and the corresponding total power to be regulated has an impact not only on the specific power but also on the total power to be regulated when the idling power is below the predetermined minimum PL In the case of , it is inferred that there is a correspondingly high wear in the processing tools 3, 4, which makes it necessary to replace the processing tools. It can also be provided that when a predetermined distance value is fallen below, the user is prompted so that the user can plan and prepare for the grinding accessory replacement that will be needed soon.

Claims

1. A method for controlling an apparatus for processing fiber material (1), wherein: The device comprises a housing (2) in which at least one first processing tool (3) and a second processing tool (4) are arranged, the processing tools (3, 4) being respectively fixed on base plates (7, 8), having a rotationally symmetrical shape, being arranged coaxially with each other, rotating relative to each other about a common axis (5), defining at least one processing gap (6) through which the fiber material (1) flows, and respectively having a processing profile (9) pointing towards the processing gap (6), wherein at least one base plate (7, 8) of the processing tools (3, 4) is supported so as to be axially movable in order to compensate for the wear of the processing profile (9), characterised in that during operation of the device, the distance between the base plates (7, 8) of the processing tools (3, 4) in the processing gap (6) is measured, and the total power (P) is selected in this case as a function of the distance (s) between the base plates (7, 8) in the processing gap (6). G ) value.

2. The method according to claim 1, characterized in that The total power (P) is selected solely according to the distance (s) between the base plates (7, 8) of the treatment gap (6). G ) value.

3. The method according to claim 1, characterized in that The total power (P) is selected in combination with other values ​​as a function of the distance (s) between the base plates (7, 8) of the process gap (6). G ) value.

4. The method according to any one of the preceding claims, characterized in that The total power (P) is adjusted at least when a change of at least 1 mm in the distance between the base plates (7, 8) of the process gap (6) is detected. G ) value.

5. The method according to any one of claims 1 to 3, characterized in that The total power (P) is adjusted at predetermined time intervals, every 1 to 2 weeks, according to the distance (s) between the base plates (7, 8) of the treatment gap (6). G ) value.

6. The method according to claim 1, characterized in that After replacing at least one of the processing tools (3, 4), the idling power (P L ) and stores it in the memory as an initial value for control.

7. The method according to claim 6, characterized in that The measurement of the idling power is carried out when the process gap (6) is closed.

8. The method according to claim 6, characterized in that The specific power (P S ) remains constant over the running time, the specific power is determined by the total power (P G ) and the idling power (P L ) is produced, and the changed idling power is taken into account here.

9. The method according to claim 1, characterized in that: The total power (P G ), the value stored in the memory of the control device is used.

10. The method according to claim 9, characterized in that The total power (P G ), a characteristic curve group stored in the memory of the control device is used.

11. Use of a method according to any one of the preceding claims in a refiner.

12. The use according to claim 11, characterized in that: The method is used in a LC refiner.

13. An apparatus for processing fiber material, wherein: The device comprises a housing (2) in which at least one first processing tool (3) and a second processing tool (4) are arranged, the processing tools (3, 4) being fixed on base plates (7, 8), respectively, having a rotationally symmetrical shape, being arranged coaxially with each other, rotating relative to each other around a common axis (5), defining at least one processing gap (6) through which the fiber material (1) flows, and respectively having a processing profile (9) pointing towards the processing gap (6), wherein at least one base plate (7, 8) of the processing tools (3, 4) is supported axially movably in order to compensate for the wear of the processing profile (9), characterized in that a sensor is provided for determining the position of the axially movable processing tool, and a characteristic curve family is stored in a memory, wherein the characteristic curve family contains the correlation between the idling power and the distance change of the processing tools (3, 4), wherein the idling power (P L ) is adjusted accordingly using stored values ​​or a stored family of characteristic curves according to the measured distance (s) between the base plates (7, 8) or the distance between the processing tools (3, 4).

14. The device according to claim 13, characterized in that The device comprises a wear indication of the processing tool (3, 4), wherein a signal is triggered in the event of falling below a predetermined distance value or a predetermined distance change.

15. An apparatus for processing fiber material, wherein: The device comprises a housing (2) in which at least one first processing tool (3) and a second processing tool (4) are arranged, the processing tools (3, 4) being respectively fixed on base plates (7, 8), having a rotationally symmetrical shape, being arranged coaxially with each other, rotating relative to each other about a common axis (5), defining at least one processing gap (6) through which the fiber material (1) flows, and respectively having a processing profile (9) pointing towards the processing gap (6), wherein at least one base plate (7, 8) of the processing tools (3, 4) is supported axially movably in order to compensate for wear of the processing profile (9), characterized in that a sensor is provided for determining the position of the axially movable processing tool, and a characteristic curve group is stored in a memory, wherein the characteristic curve group contains the correlation between the idling power and the distance change of the processing tools (3, 4) in order to select the total power (P) according to the distance (s) between the base plates (7, 8) of the processing gap (6). G ) value.

16. The device according to claim 15, characterized in that The device comprises a wear indication of the processing tool (3, 4), wherein a signal is triggered in the event of falling below a predetermined distance value or a predetermined distance change.

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