Operation of a papermaking machine with a machine operation interruption specification

Abstract

A method for determining a machine operation interruption specification for a papermaking machine (1) comprises the steps of: - providing (S10) a predicted operating period and / or a predicted maintenance or replacement period for a component of the papermaking machine; - predicting (S20) a value of a first parameter, which depends on a performance and / or wear of this component, for a plurality of future points in time; - predicting (S30) a value of a quality criterion, which depends on this parameter, for a plurality of future points in time on the basis of these predicted parameter values; and - determining (S40) a machine operation interruption specification for the papermaking machine with the aid of an optimizer on the basis of these predicted values of the quality criterion and the provided predicted operating period and / or maintenance or replacement period. The invention also relates to a method for operating the papermaking machine, a system, a papermaking machine installation and a computer program (product).

Description

[0001] Description

[0002] Operating a paper machine with a machine operation interruption specification

[0003] The present invention relates to a method and system for operating a machine for producing paper, cardboard, board or the like ("paper machine"), wherein a production operation of the paper machine is interrupted once or several times and one or more components of the paper machine are maintained or replaced during these machine operation interruptions, a method and system for determining a specification (for) such machine operation interruptions and a computer program or

[0004] Computer program product for carrying out a method described here.

[0005] Paper machine components such as drying cylinders, press cylinders, bearings, and the like, and especially fabric and / or screen baskets, require maintenance or replacement over time. For this purpose, appropriate machine downtimes must be utilized or planned.

[0006] One approach would be to provide for regular machine operation interruptions based on statistical operating times until failure or necessary maintenance of the respective component, i.e. to provide for a corresponding operation interruption for each component based on its statistical operating time until necessary maintenance or its statistical service life and to maintain or replace the component during this period.

[0007] However, this can in particular lead to the component having already lost an excessive amount of performance, for example water absorption capacity or the like, due to wear and tear before the machine operation is interrupted. This can lead either to a deterioration in production results or to increased production costs, for example higher heating requirements in drying cylinders or the like. The situation becomes even more complex when several components of the paper machine have to be serviced or replaced: for example, it can be more expedient to service or replace a component which, when viewed individually and in particular when weighing up its wear-related performance reduction against the time and material expenditure of maintenance or replacement, would already have to be serviced or replaced at a certain point in time, or which would not yet have to be serviced or replaced at a certain point in time, instead.to be serviced or replaced only during a machine operation interruption (which may be too early or too late for this component when viewed individually), during which one or more other components are also serviced or replaced, as this can, for example, reduce the number or total time of machine operation interruptions and thus improve production operations.

[0008] Accordingly, operating a paper machine using the approach of regular machine interruptions based on statistical operating times of individual components as explained above can be improved alone.

[0009] An object of an embodiment of the present invention is to improve the operation of a paper machine or to determine an advantageous machine operation interruption specification of the paper machine.

[0010] This object is achieved by a method having the features of claims 1 and 9, respectively. Claims 10-12 protect a system, a paper machine installation, and a computer program or computer program product for implementing a method described herein. The subclaims relate to advantageous developments.

[0011] According to one embodiment of the present invention, a method for determining a machine operation interruption specification (for) a paper machine comprises the steps:

[0012] - Providing a forecast operating time of a component of the paper machine and / or - a forecast duration (for) maintenance or replacement (“Maintenance or Replacement Duration”) of that component of the paper machine;

[0013] - predicting a value of a first one- or multi-dimensional parameter which depends, in particular directly or indirectly, on a performance and / or wear of that component, for several future points in time;

[0014] - predicting a value of a quality criterion dependent on this parameter for several future points in time based on these predicted parameter values; and

[0015] - Determining a machine downtime specification of or for the paper machine using an optimizer based on these predicted values ​​of the quality criterion and the provided predicted operating time and / or maintenance or replacement time.

[0016] In one embodiment, a machine operation interruption specification comprises the time(s) and / or duration(s) of one or more machine operation interruptions of the paper machine and / or components of the paper machine to be maintained and / or replaced during the (respective) machine operation interruption(s), in particular when, preferably in relation to an operating period, and / or for how long production operation of the paper machine is to be interrupted and which components are to be maintained and / or replaced during the (respective) machine operation interruption, in particular therefore a downtime planning and / or planning of maintenance and / or replacement intervals.

[0017] A predicted operating time used in the present invention is, in one embodiment, a predicted or expected operating time of the (respective) component up to a specific state of this component, in one embodiment a failure of the component or a specific deterioration of the component or a corresponding risk thereof or the like, in a further development, in particular for a repairable or reusable component, a mean operating time between failures (“Mean Time Between Failures”, MTBF) orthe expected value of the operating time between two consecutive failures and / or for a (consumable) component that is not intended or cannot be repaired, a mean life (“Mean Time to Failure, MTTF”), generally a so-called “Mean Time before Failure”.

[0018] In one embodiment, the machine operation interruption specification is determined in such a way or with the proviso that, on the one hand, the quality criterion is optimized or - within the framework of the optimizer used - becomes optimal and, on the other hand, for example as an optimization constraint that prohibits exceeding the predicted operating time, or via a corresponding penalty function that worsens the quality criterion if the predicted operating time is exceeded, the predicted operating time is (if possible) not exceeded or exceeded as little as possible and / or the cumulative or total time of several operation interruptions is as short as possible.

[0019] By additionally considering a parameter that depends on the performance and / or wear of the component, an optimal compromise can be found between the earliest possible machine operation interruption, during which the performance of the component has not deteriorated or has only deteriorated slightly, particularly due to wear, and the latest possible machine operation interruption specification, so that machine operation is interrupted less frequently. This can improve the operation of the paper machine. Additionally or alternatively, the maintenance or replacement duration of the component can be shortened or extended with a correspondingly earlier or later machine operation interruption specification point, and / or by determining the machine operation interruption specification (also) based on the predicted maintenance or replacement duration, the operation of the paper machine can be interrupted for a shorter period overall, thus improving the operation of the paper machine.

[0020] In one embodiment, the method comprises the steps of: - providing (respectively) a predicted operating time and / or predicted maintenance or replacement time of one or more other components of the paper machine; and

[0021] - predicting (each) a value of at least one other one- or multi-dimensional parameter, which depends, in particular directly or indirectly, on a performance and / or wear of the (respective) other component, for several future points in time, preferably the same points in time for which the value of the one parameter for the one component is also predicted; where

[0022] - the values ​​of the quality criterion, which in this embodiment also depends on thisAn other parameter(s), are forecast for several future points in time on the basis of these forecast values ​​of thisAr other parameter(s); and

[0023] - the machine operation interruption specification of the paper machine is determined with the help of the optimizer also on the basis of these provided forecast operating times and / or maintenance or replacement times of the other component(s), preferably in such a way or with the proviso that on the one hand the quality criterion is optimized or - within the framework of the optimizer used - becomes optimal and on the other hand, for example as an optimization constraint that prohibits exceeding the forecast operating time(s) of the other component(s), or via a corresponding penalty function that worsens the quality criterion if the forecast operating time(s) are exceeded, the forecast operating time(s) is / are (if possible) not exceeded or exceeded as little as possible and / or the total time of the operation interruptions is / are as short as possible.

[0024] By additionally or in parallel considering two or more components, a more global view of the paper machine or the corresponding components can be taken into account for the first time when determining a machine downtime requirement, thus significantly improving the operation of the paper machine as a whole. In particular, in terms of the quality criterion, it may be better to maintain or replace a component earlier or later than would be optimal if this component were considered individually, for example, to avoid a machine downtime or shorten the overall duration of the downtime.

[0025] In one embodiment, one or more of the components are (each) a wear component to be replaced during the specified machine operation interruption; in a particularly advantageous development, this is a clothing or an arrangement of clothings in a press and / or dryer section of the paper machine. Additionally or alternatively, in one embodiment, one or more of the components are (each) a component to be serviced and subsequently used during the specified machine operation interruption; in a particularly advantageous development, this is a cylinder or an arrangement of cylinders in a press and / or dryer section and / or a bearing or an arrangement of bearings in the paper machine. Generally orAdditionally or alternatively, in one embodiment, one or more of the components (each) comprise at least one component, preferably clothing, of a press section and / or at least one component, preferably clothing, of a dryer section of the paper machine and / or one or more of the components (each) comprise at least one component, in particular a screen, in particular a screen basket, of a screen section of the paper machine, and can in particular each be such a component.

[0026] Since such components, on the one hand, show a significant change in their performance with the operating time, for example, clothings lose a significant amount of drying or moisture absorption capacity, and thus impair the performance of the paper machine or have to be compensated by higher heating outputs or clog screens (baskets) and thus impair the quality and / or output, the present invention is particularly advantageous for the components mentioned (wear components, components to be maintained and subsequently reused, components, in particular clothings, of a press section or a dryer section or components, in particular screens (baskets), of a screen section),without being limited thereto. A particularly advantageous embodiment of the method comprises or consists of the following steps: a) providing (S10) a predicted operating time and a predicted maintenance or replacement time of a component of the paper machine; b) providing (S10a) a predicted operating time and, if appropriate, a predicted maintenance or replacement time of at least one other component of the paper machine; c) predicting (S20) a value of a first parameter, which depends on a performance and / or wear of the component, for several future points in time; d) predicting (S20a) a value of at least one other parameter, which depends on a performance and / or wear of the other component,for several future points in time; e) predicting (S30) a value of a quality criterion dependent on the first parameter for several future points in time based on these predicted first parameter values; f) predicting (S30a) a value of a quality criterion dependent on the other parameter for several future points in time based on these predicted other parameter values; g) predicting a quality criterion for several future points in time based on (S35) the predicted maintenance or replacement duration of the component and (S35a) optionally the predicted maintenance or replacement duration of the other component; h) Combining the predicted quality criteria (S30, S30a, S35, S35a) to form an overall quality criterion for several future points in time i) Determining (S40) a machine operation interruption specification of the paper machine using an optimizer on the basis of these predicted values ​​of the overall quality criterion,

[0027] The advantage of this variant of the method is that when determining the machine downtime specification, the individual components are not considered or optimized separately. Instead, an overall quality criterion is aggregated from the individual quality criteria, which is then optimized using an optimizer. Of course, the method is not limited to two components, but can easily be extended to multiple components, in particular three, four, five, or more.

[0028] By using an overall quality criterion, an optimal machine operation interruption specification for the current machine operation can be determined, which may well differ from the optimal machine operation interruption specifications of the individual components.

[0029] For this purpose, it is advantageous if the quality criteria of the individual components are selected in such a way that they can be combined with each other and aggregated into an overall quality criterion.

[0030] It is equally advantageous and feasible if the quality criteria and the overall quality criterion are a value that describes the economic costs of operating the paper machine. These economic costs can be, for example, operating costs (e.g., in € / hour or € / ton) or the equivalent of the amount of paper produced per unit of time (also, for example, in € / ton or € / hour).

[0031] The sum (or a weighted sum) of the individual quality criteria can then be used as the overall quality criterion.

[0032] By economizing the effects of operating time or maintenance or replacement time, the influence of different components can be made comparable.

[0033] Postponing a maintenance shutdown beyond, for example, the optimal time or the preferred maintenance intervals specified by the manufacturer can have very different effects on the many different components of the paper machine, and thus also lead to very different impacts on the quality criteria. This is illustrated by the following examples: Example 1: Press felt component:

[0034] If a press felt is operated beyond its optimum, the paper machine can continue to operate for a while. However, the reduced dewatering capacity reduces the "dry content after press" parameter. The paper comes out of the press moister and therefore requires more energy in the dryer section to reach the desired final dry content. The additional steam consumption in t / h and the resulting costs are then included in the quality criterion as an economic impact. However, if the press felt is operated beyond its maximum, the risk of felt tearing and / or the production of paper that is no longer saleable due to quality defects increases significantly. This can be factored into the quality criterion in the form of scrap costs or the accident costs of an unplanned machine downtime to replace a torn felt.

[0035] The maintenance downtime required for changing the felt can also be economized, e.g. over the usual duration of such a downtime and the resulting loss of production.

[0036] Similar considerations apply to other fabrics such as forming fabrics or drying fabrics.

[0037] Example 2: Screen basket in stock preparation.

[0038] The screen baskets are also usually changed at specific times. As with the fabrics, continued operation beyond the optimum is possible for a certain period of time. However, this usually affects the "reject rate" parameter. A higher proportion of fiber is rejected. This results in an increased demand for fiber material per ton of paper. The additional costs for these fibers can be included in the quality criteria for screen basket changes.

[0039] Here, too, there is a maximum point at which the risk of a breakdown increases disproportionately. The maintenance downtime required for changing the screen basket can also be minimized, for example, by reducing the usual duration of such a downtime and the resulting production loss.

[0040] Example 3: Bearings for rotating components

[0041] For bearings, for example, for rollers in a press or former, exceeding the optimal replacement time will usually not have a direct impact on production costs. However, the risk of a failure continuously increases, leading to extremely high costs for the operator due to very long machine downtime and very high repair costs. This "failure risk" parameter can also be converted into a quality criterion, for example, by creating a curve for the increase in the failure risk, which is multiplied by the predicted or recorded costs for resolving a failure.

[0042] The maintenance downtime required for the bearing change can also be economized, e.g. over the usual duration of such a downtime and the resulting production loss.

[0043] These three examples alone demonstrate how universally applicable versions of the proposed method can be. Furthermore, completely different components and the parameters resulting from their operation can be compared and weighed against each other using economization.

[0044] It is possible for the components under consideration to all come from the same section of a paper machine. Alternatively, they can also come from different sections, such as stock preparation, the headbox, the forming section, the press, or the drying section, as well as the reeling or coating sections.

[0045] It is particularly advantageous if the components come from interconnected sections. If the sections are decoupled from one another, such as a winder or an offline coating machine, the advantages of the described method are less pronounced, as these sections can be stopped and serviced separately and independently of the rest of the paper machine. This is not possible, for example, with the press and dryer section or the stock preparation and headbox, as these sections are directly linked to one another in the production process. Thus, with components from interconnected sections, the advantage of an optimized, coordinated machine downtime specification is particularly significant.

[0046] In one embodiment, one or more of the parameters, each of which depends on the performance and / or wear of a component of the paper machine and on the basis of which the value of the quality criterion is predicted, depend on a performance function and / or on a replacement or maintenance effort of the corresponding component and / or on a production and / or process speed of the paper machine and / or on an energy requirement of one or more components of the paper machine, in a further development of the entire paper machine, and can in particular specify these. By taking such parameters into account when (determining) a machine operation interruption specification, the operation of the paper machine can be particularly advantageously improved.

[0047] In one embodiment, the values ​​of one or more of the parameters are (each) predicted based on a value of the (corresponding) parameter for one or more past points in time. This allows the parameters to be predicted particularly reliably, easily, and / or precisely.

[0048] In one embodiment, one or more of the variables used according to the invention, in particular one or more of the parameters, are evaluated during or for the optimization (each) with a cost function, which in a further development (each) can be linked to a corresponding list. This allows, in particular, advantageous scaling or scalability to be realized. For example, time periods, material expenditure, energy requirements, and production (rate) or process speed can be advantageously weighted against each other in the quality criterion using appropriate cost functions. According to one embodiment of the present invention, a method for operating the paper machine comprises the steps, preferably the multiple repetition of the following steps:

[0049] - Carrying out production operation of the paper machine;

[0050] - Interruption of production operations;

[0051] - servicing one or more components of the paper machine and / or replacing one or more components of the paper machine during this machine shutdown; and

[0052] - Carrying out a production operation of the paper machine according to this machine operation interruption specification; wherein the time(s) and / or duration(s) for the machine operation interruption(s) and / or components to be maintained and / or replaced ("machine operation interruption specification") is / are determined according to a method according to one of the preceding claims, in a further development. The or at least one of the further production operation(s) can in particular continue the (respectively) previous production operation.

[0053] Likewise, the further production operation(s), or at least one of the further production operations, can also be a different type of production operation than the one preceding it. Thus, a period of non-production between two different types of production operations of the paper machine is also referred to as a (machine) interruption of operation of the paper machine within the meaning of the present invention.

[0054] According to one embodiment of the present invention, a system, in particular hardware and / or software, in particular program technology, is set up to carry out a method described here and / or comprises:

[0055] - means for providing a predicted operating time of a component and, in a further development, of one or more other components of the paper machine and / or for providing a predicted duration (for) maintenance or replacement of said component(s) of the paper machine;

[0056] - means for predicting a value of a first parameter depending on a performance and / or wear of one component and, in a further development, of another parameter depending on a performance and / or wear of the (corresponding) other component(s), for a plurality of future points in time;

[0057] - means for predicting a value of a quality criterion dependent on said first and, where appropriate, said other parameter(s) for several future points in time on the basis of these predicted parameter values; and

[0058] - Means for determining a machine operation interruption specification of or for the paper machine with the aid of an optimizer on the basis of these predicted values ​​of the quality criterion and the provided predicted operating time(s) and / or maintenance or replacement time(s), in particular a corresponding optimizer.

[0059] According to one embodiment of the present invention, a paper machine installation comprises one or more paper machines and a system for determining a machine operation interruption specification (for) this paper machine(s) and / or for operating this paper machine(s) according to a method described herein.

[0060] A means within the meaning of the present invention can be designed in hardware and / or software, in particular at least one, in particular digital, processing unit, in particular a microprocessor unit (CPU), graphics card (GPU) or the like, preferably connected to a memory and / or bus system for data or signals, and / or one or more programs or program modules. The processing unit can be designed to execute instructions implemented as a program stored in a memory system, to detect input signals from a data bus, and / or to output output signals to a data bus. A memory system can have one or more, in particular different, storage media, in particular optical, magnetic, solid-state, and / or other non-volatile media. The program can be designed in such a way that it embodies the methods described here oris capable of executing, so that the processing unit can execute the steps of such methods and thus in particular can determine a machine operation interruption specification of one or more paper machines and / or operate this paper machine(s). In one embodiment, a computer program product can have, in particular be, a storage medium, in particular a computer-readable and / or non-volatile one, for storing a program or instructions or with a program or instructions stored thereon. In one embodiment, execution of this program or these instructions by a system, in particular a computer or an arrangement of several computers, causes the system, in particular the computer(s), to execute a method described here or one or more of its steps, or the program or instructions are configured to do so.

[0061] In one embodiment, one or more, in particular all, steps of the method are fully or partially computer-implemented, or one or more, in particular all, steps of the method are fully or partially automated, in particular by the system or its means. In one embodiment, the optimizer comprises an optimization algorithm and / or is performed on or by a computer or with computer support.

[0062] Further advantages and features emerge from the subclaims and the exemplary embodiments. The following shows, partly schematically:

[0063] Fig. 1: a system for determining a machine operation interruption specification of a paper machine and operating the paper machine according to an embodiment of the present invention; and

[0064] Fig. 2: A method for operating a paper machine, comprising determining a machine operation interruption specification of the paper machine according to an embodiment of the present invention. Fig. 1 shows a system for determining a machine operation interruption specification of a paper machine 1 and operating the paper machine 1 according to an embodiment of the present invention in the form of a correspondingly programmed computer 2.

[0065] Fig. 2 shows a method for operating a paper machine comprising determining a machine operation interruption specification of the paper machine according to an embodiment of the present invention.

[0066] In advance of or while the paper machine is already in production, the time and / or duration of one or more future machine operation interruptions and the components of the paper machine to be maintained and / or replaced during this time (“machine operation interruption specification”) are determined.

[0067] For this purpose, in a step S10, a predicted operating time, preferably the mean time before failure, in particular MTBF or MTTF, and / or a predicted maintenance or replacement time of several components of the paper machine are provided, for example the MTBF and / or a predicted replacement time of one or more clothings of a press section and / or one or more clothings of a dryer section and / or one or more screen baskets of a screen section of the paper machine.

[0068] In a step S20, values ​​of a one- or multi-dimensional parameter Xi, which depends directly or indirectly on the performance and / or wear of one of these components, are determined for several future times t k , t k +i , ... predicted.

[0069] For example, the performance of a fabric deteriorates over time and may be compensated for by higher heating requirements and / or slower operation of the paper machine. Thus, such a fabric parameter can indicate the increased heating requirements caused by the deterioration in performance of the respective fabric, or the reduced process speed caused by or to compensate for the deterioration in performance of the respective fabric, possibly evaluated with corresponding costs, particularly for improved scalability. The same applies analogously to the screen baskets.

[0070] In a step S30, the value of a quality criterion dependent on these parameters, for example a possibly weighted sum of the corresponding (evaluated) heating effort increase(s) and / or process speed reduction(s), for the future times t k , t k +i , ... predicted.

[0071] In a step S40, an optimization algorithm or an optimizer running on a computer determines the time and / or duration for one or more future machine operation interruptions and the components to be maintained and / or replaced during these machine operation interruptions on the basis of these predicted values ​​of the quality criterion and the provided predicted operating time and / or maintenance or replacement time of the components, preferably in such a way that, on the one hand, an increase in heating expenditure and / or a reduction in process speed to compensate for the deterioration in performance of the clothing is minimized and / or the total time of the operation interruptions is as short as possible and, on the other hand, that the MTBF or MTTF are not exceeded, in particular taking into account the respective maintenance or replacement time.

[0072] If, in a highly simplified example, a first covering has an average lifetime of Xi hours and a second covering has an average lifetime of x2> Xi hours, the replacement of which yi ory2> yi hours and the quality criterion deteriorates by Ai as a result of a deterioration in the performance of the first covering with increasing usage per hour and by A2 as a result of a deterioration in the performance of the second covering with increasing usage per hour, the optimization can, for example, show that it is optimal to replace the first and second covering together in one operational interruption lasting y2, at an operating time that is no more than or less than Xi hours after the last replacement, even though the second covering has not yet reached its average service life and the replacement of the first covering alone would be possible in a shorter operational interruption yi, if an overall assessment is carried out, taking into account in particular the deterioration in the performance of the second covering and the cumulative orA total downtime with separate replacement of the first and second coverings during separate downtimes leads to a correspondingly better value for the quality criterion. Similarly, with regard to the quality criterion, it may be better to accept the performance deterioration of the second covering and replace it later together with a third covering if this results in a better value for the quality criterion, particularly due to the shorter replacement period yi for the first covering.Even this very simple example shows the power of an inventive determination of a machine operation interruption specification, since the complex relationships between different components, in particular their predicted operating times and / or maintenance or replacement times and the influence of their performance and / or wear on an (overall) quality criterion, can significantly improve the operation of the paper machine, since performance deteriorations due to longer operating times of individual components are taken into account in relation to more frequent maintenance or earlier replacement and (thereby) the maintenance or replacement of various components can be carried out optimally.

[0073] In step S50, a production operation of the paper machine is carried out and continued in a further development. This production operation is interrupted at one of the times determined in step S40 for the duration determined therein (Fig. 2: step S60), and the corresponding component(s) of the paper machine are serviced or replaced (Fig. 2: step S70). Subsequently, another production operation of the paper machine is carried out, and in a further development, the previous production operation is continued (Fig. 2: step S80).

[0074] In the present disclosure, "has an X" generally does not imply an exhaustive list, but is a shortened form of "has at least one X" and also includes "has two or more X" and "has Y in addition to X." Although exemplary embodiments have been explained in the preceding description, it should be noted that a multitude of modifications are possible. In particular, as already indicated, the determination of (new) machine operation interruption specifications can also take place during production operation, and thus, values ​​of parameters can be particularly advantageously predicted based on past points in time. Furthermore, it should be noted that the exemplary embodiments are merely examples that are not intended to limit the scope of protection, applications, or structure in any way.Rather, the foregoing description provides the person skilled in the art with a guide for the implementation of at least one exemplary embodiment, whereby various changes, in particular with regard to the function and arrangement of the described components, can be made without departing from the scope of protection as it results from the claims and combinations of features equivalent to these.

[0075] List of reference symbols Paper machine Computer

Claims

Patent claims 1. A method for determining a machine operation interruption specification of a paper machine (1), the method comprising the steps of: - Providing (S10) a predicted operating time and / or a predicted maintenance or replacement time of a component of the paper machine; - predicting (S20) a value of a first parameter depending on a performance and / or wear of said component for several future points in time; - predicting (S30) a value of a quality criterion dependent on this parameter for several future points in time on the basis of these predicted parameter values; and - Determining (S40) a machine operation interruption specification of the paper machine using an optimizer on the basis of these predicted values ​​of the quality criterion and the provided predicted operating time and / or maintenance or replacement time.

2. Method according to claim 1, characterized by the steps: - providing (S10) a predicted operating time and / or a predicted maintenance or replacement time of at least one other component of the paper machine; and - predicting (S20) a value of at least one other parameter, which depends on a performance and / or wear of said other component, for several future points in time; wherein - the values ​​of the quality criterion which also depends on this other parameter are forecast for several future points in time on the basis of these forecast values ​​of this other parameter; and - the machine downtime specification of the paper machine is also determined with the help of the optimizer on the basis of this provided forecast operating time and / or maintenance or replacement time of the other component.

3. A method for determining a machine operation interruption specification of a paper machine (1), the method comprising the steps of: Providing (S10) a predicted operating time and a predicted maintenance or replacement time of a component of the paper machine; Providing (S10a) a predicted operating time and, if applicable, a predicted maintenance or replacement time of at least one other component of the paper machine; Predicting (S20) a value of a first parameter depending on a performance and / or wear of the component for several future points in time; predicting (S20a) a value of at least one other parameter depending on a performance and / or wear of the other component for several future points in time; Predicting (S30) a value of a quality criterion dependent on the first parameter for several future points in time on the basis of these predicted first parameter values; Predicting (S30a) a value of a quality criterion dependent on the other parameter for several future points in time on the basis of these predicted other parameter values; Predicting a quality criterion for several future points in time based on (S35) the predicted maintenance or replacement duration of the component and (S35a) optionally the predicted maintenance or replacement duration of the other component; Combining the predicted quality criteria (S30, S30a, S35, S35a) into an overall quality criterion for several future points in time Determining (S40) a machine operation interruption specification of the Paper machine using an optimizer based on these predicted values ​​of the overall quality criterion 4. Method according to one of the preceding claims, characterized in that at least one quality criterion, in particular all quality criteria and the overall quality criterion, is a value that describes economic costs in the operation of the paper machine.

5. Method according to one of the preceding claims, characterized in that at least one of the components is a wear component to be replaced during the machine operation interruption specification and / or at least one of the components is a component to be maintained during the machine operation interruption specification and subsequently to be used further.

6. Method according to one of the preceding claims, characterized in that the component and the other components come from different sections of the paper machine.

7. Method according to one of the preceding claims, characterized in that at least one of the parameters which depends on a performance and / or wear of a component of the paper machine depends on a performance function and / or on a replacement or maintenance effort of this component and / or on a production and / or process speed of the paper machine and / or on an energy requirement of at least one component of the paper machine.

8. Method according to one of the preceding claims, characterized in that the values ​​of at least one of the parameters are predicted on the basis of a value of a parameter for one or more past points in time.

9. A method for operating a paper machine (1), comprising the steps, preferably repeated several times: - carrying out (S50) a production operation of the paper machine; - Interruption (S60) of production operations; - servicing at least one component of the paper machine and / or replacing at least one component of the paper machine during this machine operation interruption (S70); and - Carrying out (S80) a further production operation of the paper machine after this machine operation interruption; wherein a specification of the time and / or the duration for the machine operation interruption and / or the component to be maintained and / or replaced is determined according to a method according to one of the preceding claims.

10. System (2) for determining a machine operation interruption specification of a paper machine (1) and / or for operating a paper machine (1), which is set up to carry out a method according to one of the preceding claims and / or comprises: - means for providing a predicted operating time and / or a predicted maintenance or replacement time of a component of the paper machine; - means for predicting a value of a first parameter depending on a performance and / or wear of said component for several future points in time; - means for predicting a value of a quality criterion dependent on this parameter for several future points in time on the basis of these predicted parameter values; and - means for determining a machine downtime target of the paper machine using an optimizer on the basis of these predicted values ​​of the quality criterion and the provided predicted operating time and / or maintenance or replacement time.

11. Paper machine installation comprising at least one paper machine (1) and a system (2) for determining a machine operation interruption specification of this Paper machine and / or for operating a paper machine according to one of the preceding claims.

12. Computer program or computer program product, wherein the computer program or computer program product contains instructions, in particular stored on a computer-readable and / or non-volatile storage medium, which, when executed by one or more computers or a system or a paper machine installation according to one of the preceding claims, cause the computer(s) or the system or the paper machine installation to carry out a method according to one of the preceding claims.

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