JPH07109079B2 - Paper machine controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a paper machine control device for suppressing a paper machine.

(Prior Art) In a paper machine, a drier is arranged at the final stage of the paper drying process, the wet paper squeezed by a press is dried, and the damp paper is placed downstream of the dryer. It is taken up by the take-up device.

In this case, the dryer unit includes dozens to several tens of dryer cylinders, and when high temperature steam is supplied into each of the dryer cylinders, the surface temperature thereof becomes high.

In this state, when the wet paper is carried in, the moisture is evaporated while being conveyed by each dryer cylinder, and the moisture is discharged from the outlet side.

(Problems to be solved by the invention) By the way, in the paper machine as described above, since the disturbance applied to the paper making water process is small during the steady operation, proportional / derivative (PI) control or proportional / derivative / integral (PI
D) The papermaking water process can be sufficiently controlled by automatic operation such as control.

However, when changing brands, etc.,
Since the papermaking speed is changed drastically, the amount of water in the paper will change greatly, and it will be difficult to control properly with PI control or PID control. Occasionally, problems such as cutting accidents occurred.

Therefore, in order to eliminate such an inconvenience, when the brand is changed, the automatic operation is switched to the manual operation, and the papermaking moisture process or the like is directly controlled by a skilled operator.

However, such a method has a problem that it is difficult to save labor, a skilled operator is required, and the certainty of control is poor.

The object of the present invention is to maintain the control in a steady state before and after a brand change and the like in a stable state, and automatically change the process control content when the brand etc. is changed (extracted). The purpose of the present invention is to provide a paper machine control device that can prevent inconveniences such as over-drying and over-wetting of paper, and troubles such as cutting accidents of paper.

[Structure of the Invention] (Means for Solving Problems) In order to achieve the above-mentioned object, the present invention provides a change in seed flow rate, a change in clay flow rate, and a change in machine speed due to a brand change. An absolute dry basis weight observing device for predicting and calculating the change in absolute dry basis weight at the entrance of the dryer based on the paper, and a paper resulting from a brand change from the predicted and calculated dry basis weight change and the machine speed change A disturbance suppression control device that generates a dryer vapor pressure correction value that cancels out the change in medium water content, and a dryer vapor pressure command value to match the paper return amount measured at the dryer outlet side with the paper moisture target value. A target value tracking control device to generate, a dryer vapor pressure correction value that is the output of the disturbance suppression device at the time of brand change and a dryer vapor pressure command value that is the output of the target value tracking control device are combined to the dryer part. Supply vapor pressure command value synthesizer It is characterized in that Bei.

(Operation) In the above configuration, in a normal state, the target value follow-up control device sets the dryer vapor pressure command value in order to match the paper moisture return amount measured at the dryer outlet with the paper moisture target value. Feedback control is performed to generate and supply to the dryer unit.

When the brand is changed, the absolute dry basis weight monitor changes the dry basis weight at the inlet of the dryer based on the changes in the seed mouth flow rate, clay flow rate, and machine speed that have been changed due to the brand change. The predicted amount is calculated, and the disturbance suppression control device generates a dryer vapor pressure correction value that cancels the change in water content in the paper due to the brand change from the predicted dry weight change and the machine speed change. The steam pressure command value synthesizer synthesizes the dryer steam pressure correction value output from the disturbance control device and the dryer vapor pressure command value output from the target value tracking control device, and supplies the synthesized value to the dryer unit.

(Examples) Hereinafter, the present invention will be described in detail based on the illustrated examples, but before that, in order to facilitate understanding of the present invention, a water process in a paper machine will be briefly described.

First, as one of the main properties of the paper constructed by the paper machine, the basis weight indicating the weight per unit area (symbol B _W , unit
g / m ² ) and the ash content in the solid content of the paper (symbol A _SH , unit%)
And the moisture content in the paper (symbol M _P , unit%).

And, these basis weight BW, ash content Ash, and moisture content in paper MP
Can be replaced by absolute dry basis weight (symbol BD, unit g / m ² ), ash content (symbol A, unit g / m ² ), water content (symbol M, unit g / m ² ), respectively, and their relationship The formula shall be expressed as follows:

In papermaking control, generally, the absolute dry basis weight B _D , the ash content A, and the water content M are used as control amounts, and when changing the absolute dry basis weight B _D , the seed mouth flow rate F _T is manipulated. When changing the ash content A, the clay flow rate F _C is operated, and when changing the water content M, the dryer vapor pressure P is operated.

However, in this case, as shown in FIG. 3, since they interfere with each other, even when one of the absolute dry basis weight B _D , the ash content A, and the water content M is changed, the seed flow rate F _T or , Clay flow rate F _C ,
The machine speed V _S and dryer vapor pressure P must be comprehensively controlled.

Also, the seed port flow rate F _T , the clay flow rate F _C , the dryer vapor pressure P
Even if one of them, for example, the dryer vapor pressure P is changed, the water content M does not change immediately, and between these changes in the dryer vapor pressure and the water content M, the following equation is given. First-order delay occurs.

Where K _M : Gain of moisture process.

T _M : 1st delay time constant.

S: Laplace operator.

Δ: A symbol indicating a minute change.

Therefore, generally, the seed opening flow rate F _T , the clay flow rate F _C , the dryer vapor pressure P, etc. are changed in consideration of such a first-order delay.

Further, in a normal moisture process, a dryer unit 15 as shown in FIG. 4 is usually used.

As shown in this figure, the dryer unit 15 includes a dryer hood 7, a plurality of dryer cylinders 8 arranged in the dryer hood 7, a basis weight B _{D of the} paper 10 discharged from the dryer hood 7, , A detector 9 for measuring the ash content A and the water content M, and when steam is supplied, it is supplied to each dryer cylinder 8 to raise the surface temperature thereof.

Then, when the paper (wet paper) 10 squeezed by the pressing unit is carried in, the dryer cylinders 8 sequentially dry the paper 10, and the paper 10 after the drying work is continuously discharged.

At this time, the detector 9 measures the basis weight _{BD of the} paper 10, the ash content A, and the water content M.

In this case, the paper-making speed V _{S of the} paper 10 is measured by a speedometer (not shown) attached to another portion.

In this way, the dryer unit 15 removes the water content of the paper 10 carried out from the press unit, so that the dryer unit 15
The moisture content of the paper 10 (dryer inlet moisture content) loaded into the
The following equation is established between the water content of the paper 10 discharged from the dryer unit 15 (dryer outlet water content) and the water content evaporated from the paper 10 in the dryer unit 15 (dryer evaporation amount).

Dryer evaporation amount = Dryer inlet moisture amount-Dryer outlet moisture amount (5) Here, the dryer inlet moisture amount is the paper production amount B _D · V _S · W _P (however, based on the absolute dry basis weight B _D) Assuming that W _P is proportional to the paper width (m), the dryer evaporation amount is proportional to the dryer vapor pressure P, and further assuming that the paper width W _P is constant, the following equation is obtained from the above equation (5). .

b · P + C = a + B D · V S -M · V S ... (6) where, a, b, c: constant derived from moisture processed.

Further, variation △ B _D of bone dry basis weight B _D from the characteristic shown in FIG. 3, the variation △ F _T of Taneguchi flow F _T, the variation △ F _C clay flow F _C, Extract can be expressed by the following equation using a variation △ V _S speed V _S.

However, K ₁ , K ₂ , K ₃ : Process gain.

T _1, T _{2: 1-order} lag time constant.

L ₁ , L ₂ , L ₃ : Dead time from each operating end to the detector 9 as shown in FIG.

As can be seen from the equation (7), if one of the seed port flow rate F _T , the clay flow rate F _C , and the machine speed V _S changes, the absolute dry basis weight B _D changes with a delay of a predetermined time.

Next, the disturbance suppression control algorithm, which is the operating principle of the present invention, will be described.

First, the above equation (6) is differentiated at time t, and the differential symbol “d / dt” is rewritten by δ to rearrange it to obtain the following equation.

here, Then, the equation (8) can be expressed by the equation: δM = δM ₁ + δM ₂ + δM ₃ (10) Here, the elements (disturbance components) that change the water content M other than the dryer vapor pressure P are the variables δM ₁ and δM ₂ , so these variables δM ₁ and δM
_{Even if 2} is δM ₁ ≠ 0 δM ₁ ≠ ... (11), in order that the change amount δM of the water content M in the paper becomes δM = 0 (12), δM ₃ = − (δM ₁ + ΔM ₂ ) ... (13) should be satisfied.

Therefore, if the change amount δP of the dryer vapor pressure P that satisfies the equation (13) is obtained from the equation (8), Is obtained.

As can be seen from equation (14), due to changes in brands,
Even when the absolute dry basis weight B _D and the machine speed V _S are changed, the insulation basis weight B _D and the machine speed V _S, and the change ΔB _D in the absolute dry basis weight B _D and the machine speed V _S , By changing the dryer vapor pressure P by the value δp based on δV _S , the water content M, and the constants a and b, the water content M in the paper can be kept unchanged.

However, since this equation (14) is an equation of an ideal form when there is no first-order lag, etc., in reality, the dynamic characteristics are given to the equation (14) using the equation (4). Better results can be obtained when used with consideration.

However, in this case, if the absolute dry basis weight B _{D of the} equation (14) and the change δB _D of the output of the detector 9 provided on the outlet side of the dryer unit 15 are used, the equation (5) is obtained. Since it is not possible to accurately describe the variables a, B _D, and V _S in Eq. (6) corresponding to the “dryer inlet water content”, these absolute dry basis weights B _D and their changes at the inlet side of the dryer unit 15 It is necessary to measure δB _D , but in a normal moisture process, the dryer section 15
Since it is difficult to install a detector on the inlet side of the dryer, the absolute dry basis weight B _D ^* on the inlet side of the dryer unit 15 and its change δ B _D
^* It is necessary to predict and.

In this case, various prediction algorithms can be used, but in this embodiment, the absolute dry basis weight B _D ^* at the inlet side of the dryer unit 15 is predicted by the following formula.

B _D ^* = B _D0 + δ B _D ^* (15) However, B _D0 : The initial value of B _D.

Further, the change amount ΔB _D ^* of the front dry basis weight B _D ^* on the inlet side of the dryer unit 15 is predicted by the following equation obtained based on the equation (7).

However, L ₄ , L ₅ , L ₆ : Dead time from each operation end to the inlet of the dryer unit 15 as shown in FIG.

Then, the insulation basis weight B _D obtained by these prediction operations
By rearranging the above equation (14) based on ^* , Is obtained.

That is, at the time of brand change, if the dryer vapor pressure P of the dryer section 15 is corrected (feed forward control) by the vapor pressure correction value ΔP _F obtained based on this equation (17),
Even when the brand is changed, the water content M in the paper can be kept constant.

Hereinafter, the present invention to which the above-mentioned water content control principle is applied will be described in detail.

FIG. 1 is a block diagram showing an embodiment of a paper machine controller according to the present invention.

The paper machine controller shown in this figure has an FB controller (feed
Back control unit) 17, FF control unit (feed / forward control unit) 18, vapor pressure command value synthesizer 4, and adder / subtractor 16
In a normal state, the water process 6 is feed back controlled based on the target value Mref and the feed back value (water content M) from the water process 6. Then, when the brand or the like is changed, the change amount of the water content M due to the disturbance is predicted, and the water process 6 is feed-forward controlled so that this change does not occur.

The FF control unit 18 includes an absolutely dry basis weight observing device 1 and a disturbance suppression control device 2, and for reasons such as brand changes, the seed flow rate F _T , the clay flow rate F _C , the machine speed V _S, etc. When is changed,
Based on these changes ΔF _T , ΔF _C , and ΔV _S , a vapor pressure correction value ΔP _F that keeps the water content M of the paper 10 constant is obtained, and this is used as the vapor pressure command value synthesizer 4 Supply to.

When the seed flow rate F _T , the clay flow rate F _C , the machine speed V _S, etc. are changed, the absolute dry basis weight observing device 1 changes these changes ΔF _T , △
F _C, △ based on V _S, the amount (15) by performing the calculation shown in Equation bone dry basis B _D ^※ change in △ B _D seek ^※, and supplies it to the disturbance suppression control unit 2.

When the absolute dry basis weight B _D ^* , the machine speed V _S, etc. are changed, the disturbance suppression control device 2 uses the changes ΔB _D ^* , ΔV _S to show the formula (17) above. Calculated vapor pressure correction value △
P _F is determined and supplied to the vapor pressure command value synthesizer 4.

Further, the adder / subtractor 16 calculates the difference between the target value Mref set by the setter and the like and the water amount M fed back from the water process 6, and supplies this to the FB control unit 17.

The FB control unit 17 includes a target value follow-up control device 3 and performs a proportional / differential / integral calculation based on the difference supplied from the adder / subtractor 16 to calculate a dryer vapor pressure P _B during normal operation. Then, this is supplied to the vapor pressure command value synthesizer 4.

Based on the vapor pressure command value synthesizer 4, the dryer vapor pressure P _B supplied from the target value follow-up controller 3 and the vapor pressure correction value ΔP _F supplied from the disturbance suppression controller 2, The calculation shown is performed to calculate the vapor pressure command value P.

P = W ₁ · P B + W ₂ · ΔPF (18) However, W ₁ and W ₂ : are values indicating the weighting coefficient, and usually each is a value “1”.

Then, the vapor pressure command value P is supplied to the water process 6 to evaporate the water from the paper 10 and reduce the water amount M to a predetermined value or less.

As described above, in this embodiment, the brand and the like are changed, and in response to this, the seed flow rate F _T , the clay flow rate F _C , the machine speed
When V _S or the like is changed, in response to this, the disturbance suppression control device 2 outputs the vapor pressure correction value ΔP _F , and the vapor pressure command value synthesizer 4 outputs the vapor pressure command value. Since P is corrected, the brand etc. is changed, the moisture disturbance ΔM _D is issued from the disturbance process 6 in response to this, and even when this is superimposed on the steady moisture amount M _C of the moisture process 6. The water amount M of the paper 10 discharged from the water process 6 can be kept unchanged.

Further, in the steady state, the target value tracking control device 3 controls the amount of water M fed back from the water process 6 and the target value M.
_Since the dryer vapor pressure P _B is calculated by performing proportional / differential / integral calculation based on _ref and the difference, the vapor pressure command value synthesizer 4 outputs the vapor pressure command value P corresponding to the dryer vapor pressure P _B. , Paper 10 treated by Moisture Process 6
It is possible to always make the water content M of the target value M _ref coincide with the target value M _ref .

Next, the effects of the above-described embodiment will be described by using the experimental results obtained when simulation is performed using a computer.

First, in the absence of the absolute dry basis weight observing device 1 and the disturbance suppression control device 2, the absolute dry basis weight B _D and the machine speed V _S are changed as shown in FIGS. 2 (a) and 2 (b). If the value of the target value M _ref is changed from "0.6" to "0.9" at time t1, the vapor pressure command value P changes as shown in FIG. The water content M in the paper changes as shown in (d).

When the absolute dry basis weight observing device 1 and the disturbance suppression control device 2 are used, the absolute dry basis weight B _D and the machine speed V are as shown in FIGS. 2 (a) and 2 (b). _S and are changed, and time
When the value of the target value M _ref is changed from “0.6” to “0.9” at t1, the vapor pressure command value P is changed as shown in FIG. 2 (e).
Changes and the water content M in the paper changes as shown in FIG. 2 (f).

As is clear from these simulation results, the following effects can be obtained in this embodiment.

(B) When the absolute dry basis weight observing device 1 and the disturbance suppression control device 2 are used, the peak value of the water content M in the paper should be improved by about 25% as compared with the case where they are not used. You can

(B) When the absolutely dry basis weight observing device 1 and the disturbance suppression control device 2 are used, the settling time can be improved by about 40% as compared with the case where these devices are not used.

Further, in the above-described embodiment, the vapor pressure correction value ΔP _F is obtained based on the equation (17) in which the first-order delay is ignored,
Actually, the used vapor pressure correction value ΔP _TF having a dynamic characteristic is calculated and used by an expression including the first-order delay as shown in the following expression.

However, S _S0 : Initial value of machine speed V _S.

[Effects of the Invention] As described above, according to the present invention, when a brand or the like is changed, the control in a steady state before and after the brand or the like is changed is maintained in a stable state, and the corresponding It is possible to automatically change the control contents of the process so that inconveniences such as overdrying and overwetting of the paper and accidents of cutting the paper do not occur.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a paper machine controller according to the present invention, and FIGS. 2 (a) to (f) are schematic diagrams showing the results of simulations carried out to explain the same embodiment. FIG. 3 is a schematic diagram for explaining the characteristics of a general paper machine, FIG. 4 is a side view showing details of a dryer section used in a dryer process, and FIG. 5 is a schematic diagram for explaining each dead time. Is. 2 ... Prediction unit (disturbance suppression control device) 3 ... Control amount calculation unit (target tracking control device) 4 ... Control unit (vapor pressure command value synthesis device)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Yamaguchi, Aomori Prefecture, Hachinohe City, Oji, 3rd Aomori Valley, Aomori Yachi, Mitsubishi Paper Mills, Ltd. (72) Inventor, Hiroaki Kobayashi, Hachinohe City, Aomori, Aomori Valley, 3rd Aomori Valley Mitsubishi Paper Mills, Ltd. Hachinohe Mill (72) Inventor Minoru Taniguchi, Aomori, Aomori, Aomori Prefecture, No. 3 Aomori Yachi No. 3 Mitsubishi Paper Mills, Hachinohe Mill (72) Hashimoto Nobuaki, Hachinohe, Aomori, Aomori Valley, Aomori Valley Address Mitsubishi Paper Mills, Ltd. Hachinohe Mill (56) References JP-A-55-116894 (JP, A) JP-A-55-84495 (JP, A)

Claims (1)

[Claims] 1. The flow rate of seeds changed due to a change in brand,
An absolute dry basis weight observer that predicts and calculates the variation in absolute dry basis weight at the entrance of the dryer unit based on each change in clay flow rate and machine speed, and the predicted calculated absolute dry basis weight change and the machine speed. A disturbance suppression control device that generates a dryer vapor pressure correction value that cancels the moisture content in the paper caused by the brand change from the change amount, the amount of returned moisture content in the paper measured at the dryer outlet, and the target moisture content in the paper. Target value tracking control device that generates a dryer vapor pressure command value to match the above, and when the brand is changed, the dryer vapor pressure correction value that is the output of the disturbance suppression device and the dryer vapor pressure command that is the output of the target value tracking control device And a vapor pressure command value synthesizing unit for synthesizing the value with the steam pressure command value synthesizing unit, and supplying the same to the dryer unit.