JPH02169792A - Control device of paper machine - Google Patents

Abstract

PURPOSE:To prevent occurrence of inconvenience such as overdrying or overwetting and cutting accident, etc., by making a prediction part predict and calculate a disturbance part and a control part carry out feedforward control depending upon the disturbance part in change of grade, etc. CONSTITUTION:A controlled valuable is calculated by a controlled valuable calculation part 3 (target value following control device) depending upon a target value and a feedback value from a process and feedback control is carried out by a control part 4 depending upon the controlled valuable. When grade, etc., are changed, a disturbance part is predicted and calculated by a prediction part 2 (control device of disturbance suppression) and feedforward control is done by the control part 4 (synthesis device of steam pressure order value) depending upon the disturbance part.

Description

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

(Prior art) In a paper machine, a dryer section is arranged at the final stage of the paper drying process to dry the wet paper that has been squeezed out by the press device, and then the dryer section is placed at the final stage of the paper drying process to dry the wet paper that has been squeezed out by the press device. It is wound up by a winding device.

In this case, the dryer section includes ten or more to several dozen dryer cylinders, and when high-temperature steam is supplied to the inside of each of these dryer cylinders, the surface temperature thereof becomes high.

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

(Problem to be Solved by the Invention) By the way, in the above-mentioned paper machine, during steady operation, the disturbance added to the papermaking moisture process is small, so proportional-derivative (PI) control and proportional-derivative-integral control are performed. (P
The papermaking moisture process can also be sufficiently controlled by automatic operation using ID) control or the like.

However, when changing brands, etc., the bone dry basis weight and speed per second of the paper change significantly, so the water content in the paper changes greatly, and PI control, PID control, etc. cannot control it appropriately. As a result, problems such as over-drying or over-wetting of the paper, or paper cutting accidents may occur.

Therefore, in order to eliminate such inconveniences, when changing brands, etc., automatic operation is switched to manual operation, and the papermaking moisture process is directly controlled by a skilled operator.

However, such a method has problems in that it is difficult to save labor, requires a skilled operator, and lacks control reliability.

The purpose of the present invention is to automatically change the process control contents in response to changes in brands, etc., to prevent inconveniences such as over-drying or over-wet paper, or problems such as paper cutting accidents. It is an object of the present invention to provide a paper machine splitting device that can prevent this occurrence.

[Configuration of the Invention (Means for Solving the Problems) In order to achieve the above object, the paper machine splitting device according to the present invention is a paper machine splitting device that controls the process of a paper machine. a control amount calculation unit that calculates a control amount based on the value and the feedback value from the process; a prediction unit that predicts and outputs the external portion when the set value is changed; The method is characterized by comprising a control section that controls the process based on the output and the output of the control amount calculation section.

(Function) In the above configuration, under normal conditions, the control amount calculation section calculates the control amount based on the target value and the feedback value from the process, and the control section calculates the control amount based on the control amount. The process is subjected to feedback control. Then, when a brand or the like is changed, the prediction unit predicts and calculates the outer part, and causes the control unit to perform feed-forward control of the process based on this outer part.

(Example) Hereinafter, the present invention will be described in detail based on the illustrated example, but first, in order to facilitate understanding of the present invention, a moisture process in a paper machine will be briefly described.

First, one of the main properties of paper produced by a paper machine is the basis weight (symbol Bw,
unit g/m2) and ash content in solid content in paper (symbol ASH
1 unit %) and paper moisture content (symbol MP, unit %).

These are the basis weight BW, ash content ASH5, paper moisture content MP, bone dry basis weight (symbol BD, unit g/m2), ash content (symbol A, unit g/m2), moisture content (symbol M, unit g
/m2), and these relational expressions are expressed as follows.

In papermaking control, generally, the bone dry basis weight BD, ash iA, and moisture 1 are used as control variables, and when changing the bone dry basis weight BD, the type flow ff1FT is operated, and when changing the ash molecule iA, , when operating the sagging flow rate FC and changing the moisture content M, the dryer vapor pressure P is operated.

However, in this case, as shown in Fig. 3, these interfere with each other, so even if you change one of the bone dry basis ffi BD, ash content A, and moisture mm, the item flow rate FT and clay flow rate FC1 The speed per second VS and the dryer vapor pressure P must be controlled comprehensively.

Furthermore, even if one of the item flow rate FT, clay flow rate FC, and dryer vapor pressure P is changed, for example, the water molecules fi M do not change immediately, and these changes in dryer vapor pressure A first-order lag occurs between the change in the water content M and the change in the water content M as shown in the following equation.

However, KM: Moisture process gain.

TM: First-order lag time constant.

S nila plus operator.

Δ: Symbol indicating minute change.

Therefore, in general, the item flow rate F7, clay flow it p C, dryer vapor pressure P, etc. are changed by taking such first-order delay into account.

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

As shown in this figure, the dryer section 15 includes a dryer hood 7, a plurality of dryer cylinders 8 disposed inside the dryer hood 7, and a dryer hood 7, a dryer hood 7, a dryer cylinder 8, a dryer hood 7, a dryer hood 7, a dryer cylinder 8, etc. It is equipped with a detector 9 for measuring the quantity A and the moisture iM, and when steam is supplied, it is supplied to each dryer cylinder 8 to increase the surface temperature thereof.

When the paper (wet paper) 10 compressed by the press section is carried in, it is sequentially dried by each dryer cylinder 8, and the paper 10 after the drying operation is continuously discharged.

Further, at this time, the basis weight BD, ash content A, and moisture content M of the paper 10 are measured by the detector 9.

In this case, the papermaking speed VS of the paper 10 is measured by a speedometer (not shown) attached to the pond part.

In this way, the dryer section 15 removes moisture from the paper 10 carried out from the press section, so that the moisture content of the paper 10 carried into the dryer section 15 (dryer entrance moisture content) and the moisture content from the dryer section 15 are The following equation holds true between the amount of moisture in the paper 10 to be discharged (dryer outlet moisture amount) and the amount of moisture evaporated from the paper 10 in the dryer section 15 (dryer evaporation amount).

Dryer evaporation amount = dryer inlet moisture amount - dryer outlet moisture amount... (5> Here, the dryer inlet moisture amount is paper production ff1Bo-Vs based on absolute dry tsubo fi BD D) WP (however, W
Assuming that P is proportional to the paper width (m), that the amount of dryer evaporation is proportional to the dryer vapor pressure P, and further assuming that the paper width WP is constant, the following equation can be obtained from the above equation (5).

b・P+C=a-BD・VS-M-VS
−= (6) However, a, b, c: constants obtained from the moisture process.

Also, from the characteristics shown in Figure 3, the change ΔBD in the absolute dry area iBD is the change ΔFT in the event flow iFT and the clay flow NF.
It can be expressed by the following equation using FC, the change in C, and ΔVs, the change in machine speed VS.

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

First, differentiate the above equation (6) with respect to time t, and use the differential symbol "
If 'd/dt' is rewritten as '°δ°', the following equation is obtained.

In 22, δMH=a・δB[), e−L2°S・AFC+3・e −””
-ΔVS...(7) However, K1, K2, K3: process gain.

TI, T2: First-order lag time constant.

Ll, L2, L3: Dead time from each operating end to the detector 9 as shown in FIG.

As can be seen from this equation (7), if one of the seed opening flow rate F, clay flow zr;'c, and machine speed VS changes,
The absolute dry area iBD changes after a predetermined time delay.

8M3=-□・δP s Then, the above equation (8) becomes δM=δM1+δM2+δM3,
...It can be expressed by the equation (10). Here, the factor (disturbance component) that changes the water molecule it M other than the dryer vapor pressure P is the variable δM1.6M2, so these long-term variables δM1 6M2 are as follows: 8M1≠0 6M2≠0...
(11), the change δM in the moisture content M in paper is δ
In order to become M・0...(12), δ town・-(8M1+δ town)...(
13) should hold true.

Therefore, from the above equation (8), if we calculate the change δI) in the dryer vapor pressure P that satisfies this equation (13), then δP= (a-VS-δBDNa・BD-
M)-δVsl-(14) is obtained.

As can be seen from this equation (14), even if the bone dry basis weight BD and machine speed VS are changed due to brand changes, etc., these bone dry basis weight iBD, machine speed VS, and bone dry basis fi
BD, changes in machine speed Vs δBD, δVS, and water molecules iM
If the dryer vapor pressure P is changed by the value δp based on the constants a and b, the paper moisture iM can be kept unchanged.

However, this equation (14) is an ideal form when there is no first-order delay, so in reality, the equation (4) above is
Better results can be obtained by using equation (14) in consideration of the dynamic characteristics.

However, in this case, if the output of the detector 9 provided on the outlet side of the dryer section 15 is used as the absolute dry area iBD in the equation (14) and its variation δBD, then the "dryer" in the equation (5) Variable a in equation (6) corresponding to the input water content p
-BD/VS cannot be described accurately, so on the inlet side of the dryer section 15, these absolute dry area iBD and its change δ
However, in a normal moisture process, it is difficult to install a detector on the inlet side of the dryer section 15, so the absolute dry area iBD' on the inlet side of the dryer section 15, It is necessary to predict the amount of change δBO'.

In this case, various prediction algorithms can be used, but in this embodiment, the absolute dry area 'ti BD'' on the inlet side of the dryer section 15 is predicted by the following equation.

BD'=BDO+δBD'...
- (15) However, BD o: initial value of BD.

Also, the absolute dry basis weight BD' on the inlet side of the dryer section 15
The change amount δBD' in `` is predicted by the following equation obtained based on the above equation (7).

・ΔFC+3 ・e−”8・ΔVs −(
16) However, L4, L5, L6: Dead time from each operation end to the entrance of the dryer section 15 as shown in FIG.

Then, the absolute dry tsubo ff obtained by these predicted operations
If we rearrange the above equation (14) based on i B 04, ΔPF= (a'VS-8BCl'+ (a
-BDo-Ml-δVSI (17) is obtained.

In other words, when changing brands, if the dryer vapor pressure P of the dryer section 15 is corrected (feed-forward control) using the vapor pressure correction value ΔPF obtained based on equation (17), even when changing brands, the paper The moisture content M can be kept constant.

The present invention to which the above-described water content control principle is applied will be described in detail below.

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

The paper machine splitting device shown in this figure includes an FB control section (feedback control section) 17, an FF control section (feed forward control section) 18, a steam pressure command value synthesis device 4, and an adder/subtractor 16. Under normal conditions, the target value M
The moisture process 6 is feedback-controlled based on ref and the feedback value (moisture amount M) from the moisture process 6. When the brand or the like is changed, the amount of change in the amount of moisture M due to disturbance is predicted, and the moisture process 6 is controlled in a feed forward manner so that this change does not occur.

The FF control unit 18 is equipped with an absolute dry basis weight observation device 1 and a disturbance suppression splitting device 2, and the seed opening flow rate FT, clay flow rate FC1, machine speed VS, etc. are changed due to reasons such as a brand change. Then, based on these changes ΔF■ and ΔFC1ΔVs, a vapor pressure correction value ΔPF that makes the moisture content of the paper 10 constant, 31M, is determined, and this is sent to the vapor pressure command value synthesizer 4.
supply to.

The absolute dry basis weight observation device 1 is used to measure the type flow rate FT and clay flow 1Fl.
c. When the machine speed VS, etc. are changed, the calculation shown in equation (15) above is performed based on these changes ΔFT and △FC1ΔVS to calculate the change ΔBD''' in the absolute dry basis weight BD''.
is determined and supplied to the disturbance suppression splitting device 2.

The disturbance suppression splitting device 2 is configured to
When s etc. are changed, these changes ΔBD', △
Based on VS, the calculation shown in the equation <17) is performed to obtain a vapor pressure correction value ΔPF, which is then supplied to the vapor pressure command value synthesis device 4.

Further, the adder/subtractor 16 uses the target value M ref set by a setting device or the like and the feed/subtractor from the moisture process 6.
The difference with the water amount M to be backed up is calculated and supplied to the FB control unit 17.

The FB control unit 17 includes a target value follow-up control bag ¥13, and based on the difference supplied from the adder/subtractor 16,
Proportional, differential, and integral calculations are performed to calculate the dryer vapor pressure PB during normal operation, and this is supplied to the vapor pressure command value synthesizer 4.

The vapor pressure command value synthesis device 4 includes the target value tracking dividing device 3.
Based on the dryer vapor pressure PB supplied from the disturbance suppression dividing device 2 and the steam pressure correction value ΔPF supplied from the disturbance suppression dividing device 2, the following equation is performed to calculate the steam pressure command value P.

p=w,・pe +w2Δ・PF
...(18) However, Wl, W2: Values indicating weighting coefficients, and usually each has a value of "1pa."

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

As described above, in this embodiment, when the brand, etc. is changed and the seed opening flow rate FT, clay flow rate Fc, machine speed VS, etc. are changed accordingly, disturbance suppression is performed accordingly. Since the vapor pressure correction value △PF is output from the dividing device 2 to correct the vapor pressure command value P output from the vapor pressure command value synthesis device 4, it is possible to change the brand name, etc. Even when a moisture disturbance ΔMD is generated from the disturbance process 6 and is superimposed on the steady moisture MMC of the moisture process 6, it is possible to prevent the water molecules fiM of the filter paper 10 discharged from the moisture process 6 from changing. can.

In addition, during steady state, the target value tracking division device 3 divides the moisture amount M fed back from the moisture process 6 and the target value M.
,. The dryer vapor pressure PB is calculated by performing proportional, differential, and integral calculations based on the difference with f, and the vapor pressure command value synthesizer 4 outputs the vapor pressure command value P corresponding to the dryer vapor pressure P8. The moisture content M of the paper 10 treated by the moisture process 6 is set to a target value M. It can always match C.

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

First, when the bone dry basis weight observation device 1 and the disturbance suppression dividing device 2 are not present, the bone dry basis weight BD and the papermaking speed VS are changed as shown in FIGS. 2(a) and (b). , and time t
1, the target value M,. , the value of "0.6" to "0.
9'', the vapor pressure command value P changes as shown in FIG. 2(C), and the moisture content M in the paper changes as shown in FIG. 2(d).

In addition, when using the bone dry basis weight observation device 1 and the disturbance suppression splitting device 2, in FIG.
), the bone dry basis weight BD and the machine speed VS were changed,
And at time t1, the value of target value M1゜f is "0.6"
If the value is changed from “0.9” to “0.9”, Fig.
The steam pressure command value P changes as shown in Fig. 2(f).
As shown in the figure, the water molecules fiM in the paper change.

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

(b) When using the bone dry basis weight observation device 1 and the disturbance suppression splitting device 2, the peak value of paper moisture HM should be improved by about 25% compared to when these are not used. Can be done.

(b) Also, when the Mlt11 measuring device 1 and the disturbance suppression splitting device 2 are used, the settling time can be improved by about 40% compared to the case where these are not used.

Furthermore, in the embodiment described above, the PF is calculated based on the vapor pressure correction value based on the equation (17), which ignores the first-order lag, but in reality, the first-order lag as shown in the following equation is taken into account. A working vapor pressure correction value ΔPTF having dynamic characteristics is calculated and used using the above equation.

+f, r・BD”・(n・Tcl−M−(n−Tc)
IIVs-(n-Tc)-Vsol] −
(19) However, VSO: initial value of machine speed VS.

[Effects of the Invention] As explained above, according to the present invention, when the brand etc. is changed, the process control contents are automatically changed in response to the change, thereby preventing overdrying of the paper or over-humidity. It is possible to prevent such inconveniences from occurring or accidents such as paper cutting.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of a paper machine splitting device according to the present invention, and FIGS. 2(a) to (f) are schematic diagrams showing the results of simulations conducted to explain the same embodiment, respectively. Figure 3 is a schematic diagram to explain the characteristics of a general paper machine, Figure 4 is a side view showing details of the dryer section used in the triyani process, and Figure 5 is a schematic diagram to explain each dead time. %formula%)

Claims (1)

[Claims] (1) In a paper machine splitting device that controls the process of a paper machine, a control amount calculation unit that calculates a control amount based on an input target value and a feedback value from the process, and a set value A prediction unit that predicts and outputs a disturbance component when changed, and a control unit that controls the process based on the output of the prediction unit and the output of the control amount calculation unit. Characteristic paper machine control device.