RU1772273C - Method for automated control over process of production of multicomponent paper pulp - Google Patents

Abstract

The invention relates to the pulp and paper industry, namely, it allows to control the process of producing multicomponent paper pulp for the manufacture of paper with a complex composition. The essence of the invention lies in the fact that in addition to measuring the flow rate and concentration of each component and the total mass flow rate, the ash content of each component is additionally determined, based on the measured values of the concentrations and flow rate of the components, the total ash content of the paper pulp is calculated from its deviation from the set value, as well as depending on the mass ratios determined by the technological regulations and the unit cost of the components of the paper pulp composition, the conditional dry matter consumption of com components of the composition, then determine their desired mass ratio, the value of which regulate the ash content of the paper pulp 1 silt with

Description

The invention relates to methods for automatically controlling the process of obtaining paper pulp and can be used in the pulp and paper industry for the production of paper grades with a complex composition, for which, as a rule, the mass fraction of ash is of fundamental importance (ash)

A known method for automatically controlling the composition of the pulp by stabilizing the costs and volume ratios of the components.

The disadvantage of this method is that to set the weight ratios of the components of the composition, the operator must manually set the weight ratio of the main component, which is based on its subjective

ideas about the process This leads to situations when the required quality of the finished product is not ensured, in addition, there is an unreasonable overestimation of the cost of expensive components

There is also a known method for automatically controlling the pulp production process, selected as a prototype in which a predetermined ratio of component costs is determined automatically.

The required weight ratio of the main component-cellulose is determined by the following expression:

af} (. (1) where V is the speed of the paper machine,

VI x | Yu Yu v | Gs

bi is the coefficient (bi 0.25% / m / min), n is the step of control discreteness. As in the previous control method, the required weight ratio of the remaining components is redistributed depending on the main expensive component according to the following relationship:

  (, (2)

where K-2,3P,

P is the number of components of the composition.

The disadvantage of this method is the need and complexity of determining the tuning coefficient bi in formula (1) when changing the operating modes of the grinding apparatus, pressure box, suction boxes, changing the state of the mesh, etc.

In addition, this method is unacceptable for papers with a complex composition, because it does not take into account the need to maintain the ash content of the paper at a given level, as a result of which unacceptable fluctuations of this parameter and an increase in the cost of the final product are possible.

The aim of the invention is to improve the quality of finished products by stabilizing the ash content of paper and reducing the cost of its production.

This is achieved by the fact that in the known method, the ash content of each component is additionally determined, then, based on the weight ratios determined by the technological regulations, the measured values of the concentration and flow rate of the composition components, the total ash content of the paper pulp is calculated, and then, depending on the technological regulations defined the values of weight ratios and the cost of the components of the paper pulp composition, determine their predetermined ratio according to the following relationship:

B |

R

Zbi

I 1

100,

where bi is the conditional fraction of solids of the 1st component of the paper pulp, calculated from the linear system of equations by the Cramer method, as the ratio of the determinants of the system of equations including the above parameters, while ensuring the ash content of the paper pulp and minimizing the total cost.

The method is carried out as follows.

Measure the level in the mass pool,

flow rate and concentration of each component. Then, the readings of the concentration sensors are corrected by adapting their mathematical model to

laboratory measurement results.

The concentration sensor model has the form

YC a0 + aiXH;

iv Xc-bi (

(3)

where YC is the adjusted concentration value,

Хн - normalized concentration sensor reading.

1) 1, t) 2 — normalization coefficients, Xc — output signal from the concentration sensor,

a0.31 - adaptively adjustable model coefficients.

Model coefficients are calculated using the following formulas:

  - -11 + That T (4)

35

a, .1 + Y (1 + Xft)

  (1-A) + A AYc n-1J, n -,

where is the concentration value at the l-th step, calculated according to the model,

  the concentration value at the fifth step obtained by the laboratory method,

A - tuning filter coefficient (A 0.5-0.7),

y-tuning coefficient of convergence (y 1-2).

Similarly to what is done in the prototype, the concentration sensor model (3) may include signals of controlled disturbances (mass temperature, pressure, pH, flow rate, viscosity, etc.). Moreover, in the adaptation procedure of the model coefficients in accordance with formulas (4), only the number of coefficients changes.

Taking into account the corrected readings of concentration sensors and depending on

a predetermined ratio of all components, determine a predetermined flow rate of each component of the composition of the paper pulp:

Fi ° g,

, "1sA / Us1

 Ј (a, back / Us)) j i

“1, 05, Oz - weighting factors. This optimization criterion minimizes the cost of compositing and deviations of the ash content of the pulp from the task, provided that there are minimal deviations from the technological regulations,

Whereas the function

fifteen

howl- 2)

t 1

where Ft is the set value of the 1st component.

Go the total flow rate of the mass entering the mass pool,

ozzad. the set value of the ratio of the 1st component in the composition,

P is the number of components of the paper pulp composition,

Yei is the adjusted value of the concentration of the 1st component. It can be considered piecewise constant, the condition

The task on the total flow rate to minimize functional (8) is reduced to read from the condition of maintaining the task of finding a conditional extremum and a given level in the mass pool: it has the form

ft - weight ratio of J-ro component corresponding to the technological

p regulation (2D 1).

5J 1

“1, 05, Oz - weighting factors. This optimization criterion minimizes the cost of compositing and deviations of the ash content of the pulp from the task, provided that there are minimal deviations from the technological regulations,

Whereas the function

fifteen

howl- 2)

t 1

f - 1 + Ki (-,

(6) 25

Ym;

 a.

(H-pb

b -, .. o}

,,

(9)

 N p -Back

where n is the step of discreteness of control,

Kt, K2 - tuning factors,

, is the current and set value of the level in the mass pool at the nth 30th step.

The ash content of the pulp consisting of P components is determined by the expression

where 1 is an additional parameter of the function

 G F Y A) Lagrange,

, ci i) The determinant and the column vector of free A and p, (7) members of this system of equations has

view

I (FiYci)

I 1

where AI is the ash content of the 1st component (1). The predetermined weight ratio of the components of the paper pulp composition is determined based on the following optimization criteria

40

45

AND

F d.ZHbiU-;

where bi Fi -YC |,

Az is the preset ash content of BuSlovna the fraction of solids of the 1st component of the composition of paper pulp, constant mass (0 Az 1) .55 is divisible from the system of equations (9)

C | -specific value of the 1st component by the Cramer method, calculated from paper pulp formulations, mule

Ym;

 a.

(H-pb

b -, .. o}

,,

AND

. .., fi2.

,, K, C2)

fifty

. „(, T

.; 2-,. (YU)

bi

A 5 (11)

where 1-1.P;

D | - a determinant obtained from A by replacing the 1st column with a column composed of free members B (formula (10)}.

The predetermined ratio of each of the components of the composition is calculated by the formula;

bi

p 2 bi

I 1

- -100

(12)

Without violating the generality of reasoning, we can put q0 1. in this case, the bi values acquire the meaning of the desired weight ratios in fractions of unity.

The drawing shows a diagram of the implementation of the method.

Positions 1-7 indicate the flows of components that make up the composition of the paper pulp,

8- mixing box.

9-mass pool,

10-machine pool,

10-17 - actuators, control valves

18-24 - flow sensors, 25-31 - concentration sensors,

32- level sensor

33 - task on the ash content of paper pulp,

34 - ash content of the components of the paper pulp composition,

35 - unit cost of the components of the composition,

36 - weight ratios of components corresponding to the technological regulations,

37- task on the level in the mass pool,

38 - concentration of the components of the composition, determined by laboratory methods,

39 - flow control unit of the composition components,

40 - unit for determining the total flow rate,

41 - block correction of readings of concentration sensors,

42- unit for calculating tasks on expenses,

43 - block calculation tasks on the total flow in the mixing box,

44 - unit for calculating predetermined weight ratios,

45- control computing device.

Consider an example implementation of the method as applied to the process for making paper pulp for a base paper of decorative facing materials. 8 in this case in the mixing box 8

serves seven components:

1- coniferous cellulose,

2- deciduous cellulose,

3 - marriage, 4 - osprey,

5- kaolin,

6 - melamine-formaldehyde resin,

7- suspension of a coloring pigment mixture.

From a mixing box 8 paper

the mass is fed into the mass pool 9, after

what does it enter the engine pool 10.

By signals from flow sensors 18-24 V

block 39 calculates and issues

control actions on the drive mechanisms of the control flaps 11-17, and in block 40, the total consumption of components in the mixing box 8 is calculated.

8block 41 readings from concentration sensors 25-31. taking into account the results of laboratory tests 38, they are corrected in accordance with formulas (3) and (4).

Further, taking into account the readings of the level sensor 32, as well as the values of the total flow rate and tasks at level 37, in block 43, the task by the total flow rate of the components into the mixing box is calculated using formulas (6).

Based on the tasks calculated in blocks 43 and 44 on the total flow rate and the weight ratio, as well as taking into account the corrected readings of the concentration sensors, in block 42, the formula for the consumption of components is calculated by formula (5).

8 block 44 according to the signals from the flow sensors 18-24, as well as taking into account the task on the ash content of the pulp 33, the ash content of the components of the composition 34, the specific cost 35 and the weight ratios determined by the technological regulations, the paper ash content is calculated using formula (7) mass, after which the conditional for solids of the components of the composition (bi) is determined from the system of equations (9) by the formula (11) and their predetermined weight ratio is calculated by the formula (12).

At the same time, the following parameters are manually entered into the control computing device 45 (drawing):

ash paper task; the ash content of the components of the composition: the unit cost of the components of the composition;

weight ratios corresponding to the technological regulations;

task by level in the mass pool;

laboratory concentration of the components of the composition.

All of these parameters are entered into device 45 using a numeric keypad.

The ash content of each component of the composition is determined by laboratory analysis in accordance with GOST 7629-77.

Claims (1)

SUMMARY OF THE INVENTION A method for automatically controlling the process of producing multicomponent paper pulp, including measuring the flow rate and concentration of each component, determining the total mass flow rate entering the mass pool, and measuring the level therein, correcting the concentration of the pulp components by the deviation from the set value and correcting - a set value of the flow rate of each component entering the mass pool, depending on the total flow rate and the level of mass, characterized in that, in order to increase and the quality of the finished product and reducing the cost of its production, the ash content of each component is determined, based on the measured values of the concentration and consumption of the components, the total ash content of the paper pulp is calculated, by the value of its deviation from the set value, as well as depending on the mass ratios determined by the technological regulations and the unit cost of the components of the paper pulp composition, the conditional dry solids consumption of the components of the composition is calculated, then their predetermined mass ratio is determined according to the following dependence; B | Sbi i i 100, where bi FI -Yd is the conditional consumption of solids of the 1st component of the paper pulp, calculated by the Cramer method as the ratio of the determinants of a linear system of equations including the above parameters; FI - set value of the flow rate of the 1st component of the composition; Yci is the adjusted value of the concentration of the 1st component; p is the number of components of the paper pulp composition.