CN109154142B

CN109154142B - Method for controlling a device for treating fibers

Info

Publication number: CN109154142B
Application number: CN201780027240.2A
Authority: CN
Inventors: C.马科纳托; P-W.塞普克
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2016-05-04
Filing date: 2017-04-27
Publication date: 2021-02-05
Anticipated expiration: 2037-04-27
Also published as: WO2017191030A1; DE102016207726A1; EP3452657B1; EP3452657A1; CN109154142A

Abstract

The invention relates to a device for treating a fibre (1) at least partially as a function of the idle power (P) of the device_L) The method for controlling comprises a housing (2) in which a first treatment tool (3) and a second treatment tool (4) are arranged, wherein the treatment tools (3, 4) are fixed on substrates (7, 8), respectively, have a rotationally symmetrical shape, are arranged coaxially to one another, rotate relative to one another about a common axis (5), and define a treatment gap (6) through which the fibers (1) flow radially, wherein the gap width of the treatment gap can be varied by an axial displacement of at least one substrate (7, 8) of the treatment tools (3, 4). The control of the device is thereby improved in that, over the service life of at least one treatment means (3, 4), the idle power (P) is measured several times in the presence of fibers (1) or water, respectively_L) Is stored in the memory of the early controller and is evaluated by the controller, alone or in combination with other values.

Description

Method for controlling a device for treating fibers

The invention relates to a method for controlling an apparatus for treating fibers at least partially as a function of the idle power of the apparatus, wherein the apparatus has a housing in which a first treatment tool and a second treatment tool are arranged, which are each fixed on a substrate, have a rotationally symmetrical shape, are arranged coaxially to one another, rotate relative to one another about a common axis and define a treatment gap through which the fibers flow in the radial direction, the gap width of the treatment gap being variable by an axial displacement of at least one substrate of the treatment tools.

Due to the relatively high consistency of the fibres during the treatment, a strong mechanical treatment is achieved in such an apparatus (refiner), although the treatment tools, which are movable relative to each other, do not come into contact but pass each other at a small distance. Significant forces occur here.

An apparatus of the above-mentioned type is applied, for example, to the quality improvement of pulp, TMP pulp or fibers obtained from waste paper.

It has long been known that pulp fibers, i.e. virgin pulp and/or old paper fibers, should be ground 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.

In the refiners used for this purpose, the grinding surface is formed by replaceable grinding fittings screwed to the respective base plate on account of relatively rapid wear.

In order to achieve the desired fiber properties, in particular the degree of abrasion, the abrasive fitting must be matched as well as possible to the fibers to be treated and in order to avoid excessive wear of the fitting.

Furthermore, the optimum use of the available abrasive surface is promoted for the efficiency of the fiber treatment.

Documents US 2004/0112997 a1 and DE 2939587 a1 and DE 3602833 a1 disclose that the idling power is measured or calculated once before the device is put into operation and used as a basis for machine control.

In any case, the efficiency of the process is reduced in the case of an excessively large gap. If the gap is too small, too high a current consumption and the risk of contact of the processing tool are also created.

The object of the invention is to provide a device which is safer and more efficient to operate by means of measures which are as simple as possible.

The object is achieved according to the invention in that at least one value of the idling power is measured several times during the service life of at least one treatment tool in the presence of fibers or water during the opening and/or closing of the treatment gap, respectively, is stored in a memory of the controller and is evaluated by the controller individually or in combination with other values.

It is clear here that the idle power of the device changes during the running of the processing tool. With increasing wear of the profile of the processing tool, the idle power drops relatively sharply.

However, the idling power, which is dependent on the fiber throughput per unit time and is usually between 40 and 250, in particular 40 and 150kWh, is of great importance when controlling or regulating the plant.

The value of at least one measured idle power with an open and/or closed treatment gap should therefore be used directly or indirectly, for example by means of an average value or a correlation with other parameter values, for the control of the total power and further for the control of the specific power of the plant.

The idle power of the installation should usually be determined at the time of use and stored for control or use for this purpose as a preset value.

The total power consumption is composed of the idle power of the plant and the dedicated power which is important for the intensity of the process sought.

The current idling performance of the system is reduced by the previously experienced operating time of the individual processing tools and the increased wear of the processing tools, in particular the wear of the profile of the processing tools. And thus the overall power consumption is correspondingly reduced.

However, since the idle power is regarded as constant in the previous control/regulation, the total power consumed for the required treatment intensity is set too high, by 20% or even more.

Furthermore, when the process gap is closed, the power is too high due to the reduced idling power due to wear and accordingly a post-calibration is necessary, or even damage to the process tool can result.

If the determination of the free-wheeling power is to be made as accurately as possible, it is advantageous if the measurement of the free-wheeling power is carried out with a constant gap width.

On the other hand, more idle power measurements can be carried out in a shorter time with a change in the gap width.

In order to increase the accuracy of the measurement, it is generally advantageous if the value of the idle power is measured several times, preferably at defined time intervals, for example several seconds, and stored in a memory when the processing gap is open and/or closed.

A significant improvement in the measurement accuracy can be achieved in that at least one first average value is formed from at least a part of the measured values of the idling power when the process gap is open and/or closed and is stored as the current idling power in a memory.

However, when the process gap is only slightly open, a large measurement error for the idling power may still result. In order to exclude this value during the averaging, a second average value should be formed at least from a part of the value of the idling power measured during the opening and/or closing of the process gap and stored in the memory as the current idling power instead of the first average value, wherein, however, values deviating by more than 20% from the respective first average value are ignored.

In view of the relatively frequent provision of values for the current idle power, the old values should be ignored in order to enable control of the device as a function of one or more last measured values of the idle power and/or a first average value thereof and/or a second average value thereof.

In the case of a process gap which remains closed for a predetermined maximum operating time (for example 24 hours), the process gap is additionally opened and closed again for determining the idling power in order to obtain the most instantaneous value of the idling power.

In order to be able to store the initial values for the controller in the memory after the at least one process tool has been replaced, it is advantageous if the idle power is measured and entered by maintenance personnel or if the idle power is measured by the controller itself when the process gap is closed.

In general, the main parameters, such as pressure, flow rate of the fiber suspension and material density, should be in the normal operating range when determining the idle power.

In order to achieve a simple construction of the apparatus, one treatment tool should be rotated and the other treatment tool not rotated, wherein at least one rotating tool is axially movably supported. In a special embodiment, the processing tool and the substrate can also be designed in one piece.

The method according to the invention is particularly advantageously applied in refiners, especially LC (low consistency) refiners, where the material density of the fibres lies between 2 and 6, preferably 3.5 and 4.5%.

The fibers may be, inter alia, TMP, high-yield pulp (Hochausbeute-Zellstoff), MDF fibers, chips made of wood or other materials.

The invention is explained in more detail below with the aid of examples. In the drawings:

FIG. 1: showing a schematic cross-section through a refiner, an

FIG. 2: showing the true idle power P over time t_LrealVariation and total power P of_GAnd (4) adjusting.

The papermaking fibers 1 are pressed according to fig. 1 directly into the central, i.e. radially inner region of the refiner counter-piece, which is formed by the two processing tools 3, 4.

One treatment tool 3 is stationary and thus constructed as a stator, while the other treatment tool 4 is rotatably supported in the casing 2 of the refiner.

The processing tools 3, 4 each have a rotationally symmetrical shape, wherein two circular grinding surfaces are arranged parallel to one another and the gap spacing between the grinding surfaces can be set by axial displacement of the usually rotating processing tool 3.

The rotating grinding surface can be moved in the direction of rotation by a rotatably mounted shaft. The shaft is driven by a drive which is also present in the housing 2.

The fibre suspension 1 to be ground reaches the grinding gap 6 between the grinding surfaces of the two processing tools 3, 4 through the inlet via the middle in the embodiment shown here.

The fibre suspension 1 flows radially outwards through the co-acting abrasive surface and leaves the adjoining annular chamber through the outlet opening.

The two grinding surfaces are each formed by a plurality of grinding plates, which each extend over a circumferential section of the respective grinding surface.

The abrasive plates are arranged one after the other in the circumferential direction to form a continuous abrasive surface.

The abrasive plate and thus the abrasive surface is typically formed by a plurality of substantially radially extending abrasive strips 9 and grooves between the abrasive strips.

Means known per se, with which the rotating processing tool 4 is moved in the axial direction and the extent of this axial movement is measured, are not shown. The non-rotating processing tool 3 does not change its axial position.

Furthermore, the processing tools 3, 4 are fixed on the respective substrates 7, 8. Unlike the embodiment shown here, the treatment gap 6 can extend not only vertically but also, in the case of a conical refiner, obliquely relative to the axis of rotation 5.

FIG. 2 shows the true idling power P of the refiner_LrealThe change in the operating duration t, the actual idling power, decreases substantially continuously with increasing operating duration t and thus with increasing wear of the processing tools 3, 4.

The total power P input to the processing device is then_GFrom idling power P_LrealAnd a specific power P for the treatment intensity, i.e. the grinding power, of the fibers 1_SAnd (4) forming.

To avoid dedicated power P_SThe idle power P stored for controlling the treatment device is significantly higher than the power required for the treatment intensity sought for the fibers 1 during the operating time of the treatment tools 3, 4_LUpdated several times during the operating time period t, i.e. compensated for the actual idling power P_Lreal。

This is shown in fig. 2 by the dedicated power P for the operating time period t_SConstant means the total power P_GSimultaneous and in-phase with stored idle power P_LIn the same range and thus with the true idling power P_LrealIn a very similar manner.

The updating of the value of the idling power PL stored for controlling the treatment plant is generally done in the presence of the fibre 1 during the opening and/or closing of the treatment gap 6 at normal operating parameters, such as normal pressure, flow and material density.

For this purpose, the treatment gap is opened and/or closedIdle power P of time-to-time processing equipment_LMeasured several times and at certain time intervals of about 2s each and as idle power P_LThe value of (c) is stored in a memory.

Subsequently, the idling power P measured when the process gap 6 is opened or closed is used as a reference_LThe value of (d) constitutes a first average value. From idling power P_LConstitute a second average value and are stored, wherein values deviating more than 20% from the respective first average value are ignored.

If the second mean value is calculated for the opening of the process gap 6 and for the closing of the process gap, a common second mean value for the controller is formed by the two.

By using idling power P_LAs a basis for controlling the processing device, larger measurement errors can be excluded. The situation is considered to be that, as the closed process gap 6 is approached, the power consumption increases and is significantly higher than the idling power P_L。

Of importance for the control of the plant is only the idling power P_LOr the last stored result of the respective average value, i.e. older values in the memory of the controller may be overwritten/deleted.

If the process gap 6 is not open for a longer time span, for example a maximum of 24h, the controller is dedicated to determining the current idling power P_LWhereas the opening and closing of the process gap 6 is carried out. It can be avoided that the true idling power P_LrealToo significant a deviation from the idling power P stored in the control unit of the treatment plant_L。

Idle power P when the treatment plant is put into operation or the treatment tools 3, 4 or the mating parts thereof are commissioned or replaced_LMeasured when the process gap 6 is closed and stored in memory as an initial value for the controller.

For at least approximately true idle power P_LThe acquisition of (b) in the processing tools 3, 4 influences not only the dedicated power but also the control of the gap adjustment.

Furthermore, the idle power can be lower than the preset lowest idle power P_LA correspondingly high wear in the processing tools 3, 4 is inferred, which requires the processing tools to be replaced.

Claims

1. A refiner for treating fibres (1) at least partly according to the idling power (P) of the refiner_L) Method for carrying out a control, wherein the refiner has a housing (2) in which a first treatment tool (3) and a second treatment tool (4) are arranged, which are each fixed on a base plate (7, 8), have a rotationally symmetrical shape, are arranged coaxially to one another, rotate relatively about a common axis (5) and define a treatment gap (6) through which the fibers (1) flow radially, the gap width of the treatment gap being variable by an axial movement of at least one of the base plates (7, 8), characterized in that, over the service life of at least one of the first and second treatment tools, the idling power (P) is measured a plurality of times in the presence of fibers (1) or water_L) Is stored in a memory of the controller and is evaluated by the controller, alone or in combination with other values.

2. Method according to claim 1, characterized in that the idling power (P) is measured with a constant gap width_L) The numerical value of (c).

3. Method according to claim 1, characterized in that the idle power (P) is measured with a change in the gap width_L) The numerical value of (c).

4. Method according to any of the preceding claims, characterized in that the value of the idling Power (PL) is measured a number of times and stored in a memory when the process gap (6) is open and/or closed, respectively.

5. Method according to claim 4, characterized in that the value of the idling Power (PL) is measured several times at determined time intervals and stored in a memory when the process gap (6) is opened and/or closed, respectively.

6. Method according to claim 4, characterized in that at least the idling power (P) measured when the process gap (6) is open and/or closed is measured_L) A part of the values of (b) constitutes at least one first average value and is stored in a memory.

7. Method according to claim 6, characterized in that at least the idling power (P) measured when the process gap (6) is open and/or closed is measured_L) A part of the values of (b) constitutes a second average value and is stored in a memory, wherein values deviating more than 20% from the respective first average value are ignored.

8. Method according to claim 7, characterized in that the idling power (P) is measured according to one or more of the last measured idling powers_L) And/or the first average value of the idle power and/or the second average value thereof, to achieve control of the refiner.

9. Method according to claim 1, characterized in that at least one idle power (P) measured when the process gap (6) is open and/or closed is measured_L) Is directly or indirectly used for the total power (P) of the refiner_G) And (4) controlling.

10. Method according to claim 1, characterized in that the treatment gap (6) is determined for idle power (P) after a predetermined maximum operation time of the refiner has been exceeded_L) Is opened and reclosed.

11. Method according to claim 1, characterized in that after replacing at least one of the first and second processing tools, the idle power (P) is_L) Measured and stored in memory as an initial value for the controller.

12. Method according to claim 11, wherein the idle power (P) is after replacement of at least one of the first and second processing tools_L) Is measured when the process gap (6) is closed and stored in a memory as an initial value for the controller.

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

14. The use according to claim 13, wherein the refiner is a low consistency refiner.