EP2100997A2 - Machine for manufacturing and/or treating a sheet of fibrous material - Google Patents

Abstract

The machine has a press section (12) with multiple press nips (14,16). A control and regulating unit (18) is provided which is implemented in such a way that the individual press effect of a part of the press nips of press section is adjusted as a function of a pre-determined total press effect, particularly as a function of pre-determined target total press effect of the press section. The pre-determined target total press effect is observed in machine direction or in transverse direction.

Description

The invention relates to a machine for producing and / or treating a fibrous web, in particular paper or board web, with a press section comprising a plurality of press nips.

So far, the press nips of the individual press nips of a paper machine are adjusted manually according to the experience of the operator, which often takes into account the entire production area.

However, dewatering in a press depends on the applied pressure, speed and paper grade, which means that under most operating conditions the Niplast is set too high for the required moisture and moisture content. While dewatering above certain pressures is essentially no longer increasing, the energy consumption of the press and wear are directly dependent on the applied nip loads.

The invention has for its object to provide an improved machine of the type mentioned, with the energy consumption can be reduced to a minimum, especially in the press section without affecting the quality of the fibrous web.

This object is achieved in that a control and / or regulating device is provided, which is designed so that the individual pressing effects of at least a portion of the press nips of the press section as a function of a predeterminable total pressing action, in particular depending on a predetermined target total pressing action of the press section are adjustable.

Due to this design, the press nip load can be reduced to the minimum required to achieve a certain quality of the fibrous web. Thus, for example, a certain moisture of the fibrous web produced can be achieved with a minimum press nip. The energy consumption of the press or press section is thus reduced to a minimum. In addition, the felts are less squeezed, whereby their life is increased accordingly. The various press parts (for example, sheath) are subject to less wear, whereby their life is increased again accordingly. In addition, the volume of the end product in question can be substantially increased, which is particularly important for cardboard.

Preferably, the control and / or regulating device is designed so that a predetermined target total pressing action, viewed in the web running direction and / or in the cross machine direction, is compared with a particular online determined total actual pressing effect and the individual pressing effects of the respective press nips as a function of the difference be set between the predetermined target total pressing effect and the determined actual total pressing effect.

It is also particularly advantageous if the control and / or regulating device is designed such that the individual pressing effects of at least part of the press nips of the press section are influenced by predefinable weighting factors. In this case, preference is given to the individual pressing except for the pressing action of the last press nip in the web running direction Pressing effects of all press nips of the press section influenced by specifiable weight factors.

The weighting factors can be fixed, for example.

According to an alternative expedient embodiment of the machine according to the invention, the weighting factors determined for the various press nips can be predetermined depending on the operating state of the respective press, the respective felt moisture, the respective type of felt, the particular felt age, the type of paper, the weight per unit area and / or the like.

It is also particularly advantageous if the control and / or regulating device is designed so that the weighting factors are optimized, in particular online, with a view to achieving the lowest possible total pressing effect.

In this case, the control and / or regulating device may in particular be designed so that the weighting factors are advantageously optimized online with a view to minimizing the overall resulting in the press section pressing work.

In particular, the absolute line force, the force related to the maximum force, the absolute pressure, the pressure related to the maximum pressure and / or the like may be selected as a measure of the pressing work per press nip passage.

According to an expedient practical embodiment, the control and / or regulating device comprises means for compensating for changes in the operating state of the machine, in particular means for Compensation for changes in machine speed, paper grade, basis weight, press condition, felt moisture, felt type, felt age, and / or the like.

It is also particularly advantageous if the control and / or regulating device comprises a model scaling.

An advantageous embodiment of the machine according to the invention is characterized in that a device for measuring the actual moisture content of the fibrous web in the web running direction behind the press section is provided, that the target total pressing effect in dependence on a nominal moisture of the fibrous web in the area behind the Press section is selected and that the actual total pressing effect is selected as a function of the measured actual moisture content of the fibrous web.

In this case, the device for measuring the actual moisture content of the fibrous web is preferably arranged immediately after the press section.

According to a further preferred practical embodiment, the desired total pressing action is selected as a function of a desired dewatering amount of the press section and the actual total pressing action as a function of the actual dewatering amount of the press section.

It is also particularly advantageous if the desired total pressing action is selected as a function of a plurality of variables such as, in particular, the amount of dewatering, the change in humidity of the fibrous web, the change in humidity of a particular felt and / or the like and means for measuring the actual total pressing effect. Values of the respective sizes are provided. The tax and / or Control means comprise in particular means to at least partially weight the different sizes for determining the target total pressing effect or the actual total pressing effect differently.

The control and / or regulating device may in particular comprise a PI controller.

In certain cases, it is also advantageous if the control and / or regulating device comprises a fuzzy controller.

According to a preferred practical embodiment of the machine according to the invention, the control and / or regulating device is designed such that it determines the individual pressing effects of at least part of the press nips of the press section on the basis of a prediction of a maximum energy saving Niplast distribution which can be predefined, in particular, online Drainage influenced.

The control and / or regulating device preferably comprises a moisture content controller in order to set a predeterminable moisture content of the fibrous web after the press section via a corresponding adjustment of the pressing action of at least one press nip of the press section. Here, the moisture content controller is expediently designed so that the pressing action of at least a portion of the press nips of the press section can be influenced via predeterminable weighting factors.

Advantageously, the moisture content controller is designed so that, apart from the pressing action of the last press nip, as viewed in the web running direction, the pressing action of all press nips of the press section can be influenced by predeterminable weighting factors.

According to a further preferred practical embodiment of the machine according to the invention, the moisture content controller is designed such that it determines the pressing action of at least part of the press nips of the press section on the basis of a prediction of a maximum energy saving Niplast distribution for a predefinable drainage or, in particular, online. influenced a specified moisture content.

Thus, for example, it is possible to provide a moisture content controller which receives the moisture either from a moisture measuring device arranged directly behind the press or press section or, for example, from a moisture measuring device after the subsequent drying group.

1. 1. Abnehmendes Permeabilitätsmodell (Decreasing permeability model) $$\mathrm{m}\mathrm{=}{\mathrm{m}}_{\mathrm{0}}\mathrm{\cdot }{\left(\mathrm{1}\mathrm{+}\frac{\mathrm{A}\mathrm{\cdot }\mathrm{N}\mathrm{\cdot }{\mathrm{m}}_{\mathrm{0}}^{\mathrm{x}}\mathrm{\cdot }\mathrm{I}}{\mathrm{v}\mathrm{\cdot }{\mathrm{W}}^{\mathrm{2}}}\right)}^{\mathrm{-}\mathrm{1}\mathrm{/}\mathrm{n}}\mathrm{+}\frac{\mathrm{R}}{\mathrm{W}}\mathrm{,}$$
   
   mit
   m = Feuchtverhältnis nach der Presse bzw. Pressenpartie,
   m_o = eingehendes Feuchtverhältnis
   I (Pa.s) = Pressimpuls
   W (kg/m²) = Flächengewicht
   ν (m²/s) = kinematische Viskosität
   A (kg/m) = Permeabilitätskoeffizient
   n = Kompressibilitätsfaktor
   W (kg/m²) = Rückfeuchtungsausdruck $$\mathrm{Trockengehalt}=\frac{1}{1+\mathrm{m}}$$
   
2. 2. Begrenztes Konsistenz-Modell (Limited Consistency Model)
   $${\mathrm{c}}_{\mathrm{N}}={\mathrm{c}}_{\mathrm{L}}-{\left[\frac{\mathit{k}\mathit{\cdot }\mathit{I}}{\mathrm{\eta }\cdot {\mathit{<figure-callout\; id="2"\; label="W"\; filenames="imgf0003.png"\; state="\{\{state\}\}">W</figure-callout>}}^2}+\frac{1}{{\left({\mathit{c}}_{\mathit{L}}\mathit{-}{\mathit{c}}_{\mathit{i}}\right)}^2}\right]}^{-1/2},$$
   
   mit
   c_N = Trockenheit (Konsistenz) am Nip
   c_i = eingehende Konsistenz
   I (Pa.s) = Pressimpuls
   W (kg/m²) = Flächengewicht
   η (Pa.s) = Viskosität
   c_L = Begrenzende Konsistenz
   k (m⁴/kg²) = Anpassungskonstante $$\mathrm{c}\mathrm{=}\frac{\mathrm{1}}{\frac{\mathrm{1}}{{\mathrm{c}}_{\mathrm{N}}}\mathrm{+}\frac{\mathrm{R}}{\mathrm{W}}}$$
   

In general, the press-load-moisture relationship may be based, in particular, on at least one of the following mathematical models, which may be implemented in the control and / or regulating device accordingly:

1. 1. Decreasing permeability model $$\mathrm{m}\mathrm{=}{\mathrm{m}}_{\mathrm{0}}\mathrm{\cdot }{\left(\mathrm{1}\mathrm{+}\frac{\mathrm{A}\mathrm{\cdot }\mathrm{N}\mathrm{\cdot }{\mathrm{m}}_{\mathrm{0}}^{\mathrm{x}}\mathrm{\cdot }\mathrm{I}}{\mathrm{v}\mathrm{\cdot }{\mathrm{W}}^{\mathrm{2}}}\right)}^{\mathrm{-}\mathrm{1}\mathrm{/}\mathrm{n}}\mathrm{+}\frac{\mathrm{R}}{\mathrm{W}}\mathrm{.}$$
   
   With
   m = wet ratio after the press or press section,
   m _o = incoming moisture ratio
   I (Pa.s) = pressing pulse
   W (kg / m ² ) = basis weight
   ν (m ² / s) = kinematic viscosity
   A (kg / m) = permeability coefficient
   n = compressibility factor
   W (kg / m ² ) = rewet expression $$\mathrm{dryness}=\frac{1}{1+\mathrm{m}}$$
   
2. 2. Limited Consistency Model (Limited Consistency Model)
   $${\mathrm{c}}_{\mathrm{N}}={\mathrm{c}}_{\mathrm{L}}-{\left[\frac{\mathit{k}\mathit{\cdot }\mathit{I}}{\mathrm{\eta }\cdot {\mathit{<figure-callout\; id="2"\; label="W"\; filenames="imgf0003.png"\; state="\{\{state\}\}">W</figure-callout>}}^2}+\frac{1}{{\left({\mathit{c}}_{\mathit{L}}\mathit{-}{\mathit{c}}_{\mathit{i}}\right)}^2}\right]}^{-1/2}.$$
   
   With
   c _N = dryness (consistency) on the nip
   c _i = incoming consistency
   I (Pa.s) = pressing pulse
   W (kg / m ² ) = basis weight
   η (Pa.s) = viscosity
   c _L = limiting consistency
   k (m ⁴ / kg ² ) = adaptation constant $$\mathrm{c}\mathrm{=}\frac{\mathrm{1}}{\frac{\mathrm{1}}{{\mathrm{c}}_{\mathrm{N}}}\mathrm{+}\frac{\mathrm{R}}{\mathrm{W}}}$$
   

Fig. 1

eine schematische Darstellung einer eine Tandem-NipcoFlex-Presse umfassenden Pressenpartie,

Fig. 2

eine vereinfachte schematische Teildarstellung einer beispielhaften Steuer- und/oder Regeleinrichtung,

Fig. 3

eine schematische vereinfachte Darstellung eines einer Steuer- und/oder Regeleinrichtung zugeordneten Controllers und

Fig. 4

ein Diagramm, in dem beispielsweise für ein Schuh-pressprofil ohne und ein Schuhpressprofil mit Rück-feuchtende der Trockengehalt über dem Pressimpuls dargestellt ist.

The invention will be explained in more detail below with reference to exemplary embodiments with reference to the drawing; in this show:

Fig. 1

a schematic representation of a press section comprising a tandem NipcoFlex press,

Fig. 2

a simplified schematic partial representation of an exemplary control and / or regulating device,

Fig. 3

a schematic simplified representation of a control and / or regulating device associated controller and

Fig. 4

a diagram in which, for example, for a shoe press profile without and a shoe press profile with rewet end of the dry content is shown on the press pulse.

Fig. 1 shows a schematic partial view of a double felted tandem NipcoFlex press 10 comprehensive press section 12 of a machine for producing and / or treating a fibrous web, which is in the present case, for example, a paper or board web.

The press section 12 or tandem NipcoFlex press 10 comprises a plurality of press nips 14, 16.

In addition, the relevant machine comprises a control and / or regulating device 18.

The press section 12 need not necessarily comprise such a tandem NipcoFlex press 10. This is only given as an example here. Generally, the press section 12 may comprise one or more press nips.

The control and / or regulating device 18 is designed so that the individual pressing effects of at least a portion of the press nips 14, 16 of the press section 12 in response to a predetermined total pressing action, in particular depending on a predetermined target total pressing action of the press section 12 are adjustable.

Fig. 2 shows a simplified schematic partial representation of an exemplary control and / or regulating device for example, a tandem NipcoFlex press 10th

There are in the Fig. 2 to recognize a so-called Nipco-P-roll 20 and a so-called NipcoFlex roll 22, in the present case, the NipcoFlex roll 22 is arranged below. The pressing action in the nip formed between the two rolls 20, 22 can be influenced by supporting elements 24 and 26 assigned via the rolls 20, 22, which can be acted upon correspondingly by the control and / or regulating device 18.

As based on the Fig. 2 can be seen, the support elements 24 of the upper roller 20 are driven together in the present case. With the control of these upper support members 24 and the central support members 26 of the lower roller 22 can be controlled accordingly. In contrast, in the present embodiment, the edge-side support members 26 'of the lower roller 22 are controlled separately from the central support elements. However, the support elements 24, 26 or zones with support elements can also be controlled individually, so that the Pressing action in the cross machine direction by means of the control and regulating device 18 can be influenced.

Fig. 3 shows a schematic simplified representation of an embodiment of a controller 28 of the control and / or regulating device 18th

This controller 28 can be supplied as input signals, for example, a target total pressing effect and an actual total pressing effect, in the present case, the target total pressing effect, for example, based on a target total moisture and the actual total pressing effect, for example, based on a measured actual moisture of the fibrous web.

The controller 28 includes a controller 30, which is provided here for example as a PI controller. Basically, for example, a fuzzy controller is conceivable.

In the present embodiment, the controller 28 sets the loads of the individual press nips based on the measured humidity after the press section 12 and the difference with the setpoint. In a simplified embodiment of the controller 28 provided, for example, as a moisture controller, it acts on all nips, with the exception of the last nip considered in the web running direction, with predeterminable weighting factors.

According to an extended embodiment, the controller 28 may influence the individual nip loads based on an online optimization algorithm that makes a prediction of, for example, a maximum energy savings associated with maximum energy savings for a given dewatering or moisture content.

In the present embodiment, the controller 28 includes, as already mentioned, a controller 30, which may be, for example, a standard PI controller, the response time of this controller is for example in the minute range. The controller 28 is based in the present embodiment on a model scaling, for example, the nonlinearity of the control loop into account (see also Fig. 4 ).

In general, the control and / or regulating device 18 may be designed such that a predefinable desired total pressing effect is compared with an actual overall pressure determined in particular online, and the individual pressing effects of the relevant press nips as a function of the difference between the predefinable desired total pressing effect and the determined actual total pressure effect can be adjusted.

As based on the Fig. 3 can be seen, the controller 28 and the respective control and / or regulating device 18 may be designed so that the individual pressing effects of at least a portion of the press nips 14, 16 of the press section 12 (see also Fig. 1 and 2 ) are influenced by specifiable weight factors.

The weight factors can be fixed. However, it is also possible in particular for the weighting factors determined for the various press nips 14, 16 to be predeterminable depending on the operating state of the particular press, the respective felt moisture, the respective type of felt, the particular felt age, the type of paper, the basis weight and / or the like ,

In particular, the weighting factors can be optimized online with regard to the lowest possible total pressing effect. In this case, the weighting factors, in particular with regard to minimizing the be optimized overall in the press section 12 resulting press work.

For example, the absolute line force, the force related to the maximum force, the absolute pressure, the pressure related to the maximum pressure and / or the like can be selected as a measure of the pressing work per press nip passage.

As based on the Fig. 3 In particular, the controller 18 and controller 28 may also include means for compensating for changes in the operating condition of the machine, particularly means for compensating for changes in machine speed, paper grade, basis weight, condition of a particular press, the Felt moisture, felt type, felt age and / or the like.

As in Fig. 3 In particular, the control and / or regulating device 18 or the controller 28 may also include a model scaling.

In particular, a device for measuring the actual moisture content of the fibrous web in the web running direction behind the press section 12 can be provided. In this case, the desired total pressing effect, for example, depending on a desired moisture content of the pulp in the area concerned can be selected behind the press section 12, while the actual total pressing effect of the measured actual moisture of the web depends. In this case, the device for measuring the actual moisture is preferably provided immediately after the press section 12.

The desired overall pressing action may in particular also be selected as a function of a desired dewatering quantity of the press section 12, while the actual total pressing effect is selected as a function of the actual amount of dewatering of the press section 12.

It is also conceivable, for example, to select the desired total pressing effect as a function of a plurality of variables, in particular the amount of dewatering, the change in humidity of the fibrous web, the change in humidity of a respective felt and / or the like, and means for measuring the actual values for determining the actual total pressing action of the sizes concerned.

As based on the Fig. 3 In addition, the control and / or regulating device 18 or the controller 28 may moreover comprise means for weighting, at least in part, differently, the various variables for determining the desired total pressing effect or the actual total pressing effect.

The controller 28 may be e.g. to act a moisture content controller, by a corresponding adjustment of the pressing action of at least one of the press nips 14, 16 of the press section 12 a specifiable moisture content of the fibrous web after the press section 12 is adjustable. In this case, the moisture content controller may in particular be designed so that the pressing action of at least a portion of the press nips 14, 16 of the press section 12 can be influenced via predeterminable weighting factors.

Fig. 4 shows a diagram in which, for example, for a shoe press profile (profile A) and a shoe press profile with rewet (profile B), the dry content T is shown above the pressing pulse. The resulting nonlinearity of the control loop can be determined, for example, by the model scaling of the controller 28 (cf. Fig. 3 ).

For example, the respective machine speed and paper grade compensation may be based on a spreadsheet format or an N-dimensional neural network, allowing the controller 28 to be easily set for the correct work area.

• der Feuchtegehalt soll beim Arbeitspunkt konstant bleiben
• die Summe der in den einzelnen Nips aufgebrachten Leistungen bzw. Pressleistungen soll insgesamt auf ein Minimum reduziert sein: Pressleistung_Nip1 + Pressleistung_Nip2 ... + Pressleistung_Nipn ⇒ Minimum.

For the weighting of the individual control loops, in the control and / or regulating device 18 or the controller 28, for example, an optimization algorithm can be implemented which accomplishes the following:

• the moisture content should remain constant at the operating point
• the sum of the power and press power applied in the individual nips should be reduced to a minimum overall: press _{power Nip1} + press _{power Nip2} ... + press _{power Nipn} ⇒ minimum.

In the case of a press with variable cross-machine direction compressive load (for example Nipco F), a feed forward estimation and feedback on the basis of an algorithm implemented in the control and / or regulating device 18 or controller 28 may be used the humidity measurement, the press nips are controlled or regulated. In the same way, it is also possible to compensate for the moisture changes resulting in the transverse direction, for example via a steam blow box.

LIST OF REFERENCE NUMBERS

10

Tandem NipcoFlex Press

12

press section

14

press nip

16

press nip

18

Control and / or regulating device

20

roller

22

roller

24

support element

26

support element

28

controller

30

regulator

32 a-c

Nip Control

KE

box relief

SD

system pressure

DS

Pressure in support elements

GPWS

Total pressure effect (should)

GPWI

Total pressing effect (is)

MSK

Model scale

Gk

speed compensation

sk

side compensation

Nip-Gw

Nip weighting

T

dryness

Claims (23)

Machine for producing and / or treating a fibrous web, in particular paper or board web, with a press section (12) comprising a plurality of press nips (14, 16),
characterized,
that a control and / or regulating device (18) is provided, which is designed so that the individual press effects at least a portion of the press nips (14, 16) of the press section (12) in dependence on a predeterminable total pressing action, in particular in response to a predeterminable desired total pressing action of the press section (12) are adjustable. Machine according to claim 1,
characterized,
that the control and / or regulating device (18) is designed so that a predetermined target total pressing action, considered in the web running direction and / or in the transverse direction, is compared to a particular online determined actual total pressing effect and the individual pressing effects of the respective press nip in dependence be set by the difference between the presettable target total pressing effect and the determined actual total pressing effect. Machine according to claim 1 or 2,
characterized,
in that the control and / or regulating device (18) is designed such that the individual pressing effects of at least part of the press nips (14, 16) of the press section (12) are influenced by predeterminable weighting factors. Machine according to claim 3,
characterized,
that the control and / or regulating device (18) is designed so that up to the pressing action of the considered in the web running direction of the last press nip the individual pressing effects of all the press nips (14, 16) of the press section (12) are influenced by predetermined weighting factors. Machine according to claim 3 or 4,
characterized,
that the weighting factors are fixed. Machine according to claim 3 or 4,
characterized,
in that the weighting factors determined for the various press nips (14, 16) can be predetermined as a function of the operating state of the respective press, the respective felt moisture, the respective felt type, the respective felt age, the type of paper, the basis weight and / or the like. Machine according to one of the preceding claims,
characterized,
in that the control and / or regulating device (18) is designed so that the weighting factors are optimized, in particular online, with regard to the lowest possible total pressing effect. Machine according to claim 7,
characterized,
in that the control and / or regulating device is designed so that the weighting factors are optimized, in particular online, with a view to minimizing the pressing work resulting overall in the press section (12). Machine according to claim 8,
characterized,
in that the absolute line force, the force related to the maximum force, the absolute pressure, the pressure related to the maximum pressure and / or the like are selected as a measure of the pressing work per press nip passage. Machine according to one of the preceding claims,
characterized,
in that the control and / or regulating device (18) comprises means for compensating for changes in the operating state of the machine, in particular means for compensating changes in the machine speed, the type of paper, the basis weight, the state of a particular press, the felt moisture, the felt type, the felt age and / or the like. Machine according to one of the preceding claims,
characterized,
that the control and / or regulating device (18) comprises a model scaling. Machine according to one of the preceding claims,
characterized,
in that a device for measuring the actual moisture content of the fibrous web in the web running direction behind the press section (12) is provided, that the desired total pressing effect is selected as a function of a desired moisture content of the fibrous web in the relevant area behind the press section (12) and the actual total pressing effect is selected as a function of the measured actual moisture content of the fibrous web. Machine according to claim 12,
characterized,
that the means for measuring the actual humidity of the fibrous web is arranged directly after the press section (12). Machine according to one of claims 1 to 11,
characterized,
in that the desired total pressing action is selected as a function of a desired dewatering quantity of the press section (12) and the actual total pressing effect as a function of the actual dewatering quantity of the press section (12). Machine according to one of the preceding claims,
characterized,
in that the setpoint total pressing effect is selected as a function of a plurality of variables such as, in particular, the amount of dewatering, the change in humidity of the fibrous web, the change in humidity of a respective felt and / or the like, and means for measuring the actual values of the relevant variables are provided for determining the total actual pressing action , Machine according to claim 15,
characterized,
in that the control and / or regulating device (18) comprises means for weighting, at least in part, differently, the various variables for determining the desired total pressure effect or the actual total pressure effect. Machine according to one of the preceding claims,
characterized,
that the control and / or regulating device (18) comprises a PI controller. Machine according to one of the preceding claims,
characterized,
in that the control and / or regulating device (18) comprises a fuzzy controller. Machine according to one of the preceding claims,
characterized,
in that the control and / or regulating device (18) is designed such that it brings about the individual pressing effects of at least part of the press nips (14, 16) of the press section (12) on the basis of a prediction of a maximum energy saving produced, in particular, online Niplast distribution influenced for a given drainage. Machine according to one of the preceding claims,
characterized,
in that the control and / or regulating device (18) comprises a moisture content controller (28) in order to obtain a corresponding setting the pressing action of at least one press nip (14, 16) of the press section (12) to set a predetermined moisture content of the fibrous web after the press section (12). Machine according to claim 20,
characterized,
that the moisture content controller (28) is carried out so that the pressing action of at least part of the press nip (14, 16) of the press section (12) via predetermined weight factors can be influenced. Machine according to claim 21,
characterized,
that the moisture content controller (28) is designed so that up to the pressing action of the considered in the web running direction of the last press nip, the press effect of all the press nips (14, 16) of the press section (12) via predetermined weight factors can be influenced. Machine according to one of the preceding claims,
characterized,
in that the moisture content controller (28) is designed such that it determines the pressing action of at least a portion of the press nips (14, 16) of the press section (12) on the basis of a prediction of a maximum energy saving Niplast distribution, in particular given online, for a predefinable Dewatering or a specified moisture content influenced.

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