JP3003284B2 - Pulp concentration control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulp concentration control apparatus applied to a paper mill, and more particularly to a pulp concentration control apparatus for controlling a pulp concentration which determines quality in a waste paper dissolving step (pulp). The present invention relates to a pulp concentration control device that controls a supply amount of white water and a supply flow rate of white water.

[0002]

2. Description of the Related Art In a pulper used in a paper mill, waste paper as a raw material transferred while being measured by a conveyor is charged, and white water for dissolving the waste paper is charged. After being dissolved up to the next step, it is discharged to the next step.

[0003] Maintaining a constant concentration of pulp discharged from the pulper is important for maintaining the quality of the paper. The pulp concentration is controlled by controlling the input amount of waste paper (pulp), which is a raw material to be input into the pulper, and the supply amount of white water in consideration of the level in the pulper.

[0004] In this type of conventional pulp concentration control apparatus, the level in the pulper and the pulp concentration are controlled by independent control loops.

[0005]

For this reason, for example, when the level in the pulper is low and the pulp concentration is low, or when the level is high and the pulp concentration is high, if the level in the pulp is to be maintained, There were phenomena such as the deviation of the pulp concentration being further increased, and they interfered with each other, making it impossible to control the concentration. In such a state, there is a problem that it is necessary to switch from the automatic control state to the manual control.

[0006] The present invention has been made in view of the above points, and it is an object of the present invention to provide a pulp concentration control apparatus capable of performing automatic control operation in any control state and maintaining high quality. And

[0007]

According to the present invention for achieving the above object, waste paper as raw material weighed by a conveyor is supplied, white water for dissolving the waste paper is supplied, and a certain amount of waste water is supplied. A pulp concentration control device in a pulp configured to discharge pulp dissolved to a concentration to a next step, wherein a pulp concentration detecting means for detecting a pulp concentration discharged from the pulp and a level in the pulp are detected. A pulp level detecting means, and a pulp concentration signal and a pulp level signal are respectively taken on a horizontal axis and a vertical axis, and the center is defined as an optimal control zone, and the periphery of the optimal control zone is divided into at least six zones. A control table in which control conditions for shifting to the optimal control zone are set for each zone, and the pulp concentration detecting means Of pulp density signal, and inputs the level signal from the pulper level detection means, obtains the current zone by these two signals by referring to the control table, based on the set control condition in the zone, the current
Control means for controlling the amount of waste paper to be charged into the pulpper and the amount of white water supplied to the pulpper so as to shift from the current zone to the optimum control zone. It is a control device.

[0008]

In the control table, for example, six zones are divided according to the magnitudes of the pulp concentration signal and the pulp level, and each zone is controlled from the zone toward the central optimum control zone. Control conditions to be performed are set. The control means controls the amount of waste paper to be supplied to the pulper and the amount of white water supplied to the pulper based on the control conditions of the zone determined by the two signals that are currently input with reference to the control table.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration block diagram showing one embodiment of the present invention. In the figure, 1 is a pulp, and a screw AG for stirring the pulp is provided at the bottom. 2 is waste paper as raw material to be put into the pulper 1, 3A, 3
Reference numeral B denotes a conveyor for transferring the waste paper 2 to the pulper 1. A feeding amount measuring means 4 for detecting an input amount (transfer amount) to the pulper 1 is provided during the transfer of the waste paper. 5 is a drive motor for the conveyor 3A. Reference numeral 6 denotes a controller for controlling the input amount, which inputs a signal from the input amount measuring means 4 and sends out a control output to the drive motor 5, thereby adjusting the speed of the conveyor 3A and inputting waste paper into the pulper 1. The amount can be controlled. Reference numeral 7 denotes a pipeline for supplying white water for dissolving waste paper to the pulper 1. A flow meter 8 for detecting the flow rate of the white water and a valve 9 for adjusting the flow rate of the white water are provided on the way. Reference numeral 10 denotes a controller for controlling the supply amount of white water, which receives a signal from the flow meter 8 and sends a control output to the valve 9 to adjust the opening degree of the valve 9 and control the supply flow amount of white water. I can do it.

Reference numeral 11 denotes an output line for discharging pulp of a constant concentration toward the next step.
And a concentration detecting means 13 for detecting pulp concentration. Reference numeral 14 denotes a density controller, which receives a signal from the pulp density detection means 13 so that the pulp density becomes equal to the set value SVC set therein.
The valve 15 is adjusted to supply water. Reference numeral 16 denotes a pulper level detecting means for detecting the level in the pulper 1. Reference numeral 17 designates two signals, a pulp concentration signal PVC and a pulp level signal PVL, on the horizontal axis and the vertical axis, respectively, and sets the vicinity of the center as an optimal control zone and divides the periphery of the optimal control zone into at least six zones. This is a control table in which control conditions for performing control toward the optimal control zone are set for each zone, and are stored in advance in a memory or the like.

Numeral 20 denotes a control means, which is a pulp concentration detecting means 1
3 and the level signal PVL from the pulp level detection means 16 are input, and the control table 17 is referred to based on the control conditions set in the zone determined by the two input signals. The apparatus is configured to control the amount of waste paper to be supplied to the pulper and the amount of white water supplied to the pulper, and includes a level controller 21. The control means 20 controls the set value SVw of the input amount controller 6 for the input amount control in accordance with the obtained control condition.
Also, the setting value SVf of the controller 10 for white water control is changed to an optimum value. This control means 2
0 may be configured in a calculator together with each controller.

FIG. 2 is a conceptual diagram showing an example of the control table 17. Here, the pulp concentration signal PVC is plotted on the horizontal axis (X axis), and the pulp level signal PV is plotted on the vertical axis (Y axis).
L is taken, and the vicinity of the center surrounded by the broken line is the optimum control zone (H zone). The zones A, B, C, D, E, and F are provided around the optimal control zone. Although the G and I zones are shown, these zones are considered to be included in the A, D, B, and C zones. Zone A has low pulp concentration,
This is the case where the pulper level is also low, where the production increases and the level control sensitivity is too high. As the nature of pulper, the lower the pulp concentration, the higher the emission. Therefore, when the control state is at this position, the control condition is set so that the control state shifts as indicated by arrow S-1. That is, the set values SVw and SVf are changed so that the amount of waste paper is gradually increased and the white water is also gradually increased. Zone B is a case where the pulp concentration is high and the pulper level is high, where the production amount is reduced and the level control sensitivity is too low. The nature of the pulper is that the higher the pulp concentration, the lower the emissions. Therefore, when the control state is at this position, the control condition is set such that the control state shifts as indicated by arrow S4. That is, the amount of waste paper is gradually reduced,
Each set value SVw, so that white water gradually decreases
Change the SVf.

In zone C, the pulp concentration is high and the pulp level is low, in which the production increases and the level control sensitivity is too high. As the characteristics of the pulp, the pulp concentration and the pulp level may be controlled in the same phase. Therefore, if the control state is in this position,
The control condition is set such that the control state shifts as indicated by arrow S-3. That is, the set values SVw and SVf are changed so that the amount of waste paper is increased very slowly and the white water is also increased very slowly.
Zone D is, on the contrary, a case where the pulp concentration is low and the pulper level is high, where the production amount is reduced and the level control sensitivity is too low. As the characteristics of the pulp, the pulp concentration and the pulp level may be controlled in the same phase. When the control state is at this position, the control condition is set so that the control state shifts as indicated by arrow S-2. In other words, the set values SVw and SVf are changed so that the amount of waste paper is decreased very slowly and the white water is also decreased very slowly.

The E or F zone is where the pulp concentration is almost optimally controlled, but the pulper level is too high or too low. The character of the pulper is in an excessively responsive state. When the control state is at this position, the control condition is set such that the control state shifts as indicated by arrow S-6 or S-5. That is, the level control is performed by slowly changing the set value SVf of the white water flow rate according to the deviation due to the fluctuation of the pulper level.

As described above, in the control table, the conditions for shifting the control state toward the H zone which is the optimum control zone for each zone (in this example, the set value SVw of the amount of waste paper, the white water flow rate) (The condition for sequentially changing the set value SVf) is set.

The operation of the above-configured device will be described below. FIG. 3 is a conceptual diagram showing an operation state of the control means 20 when the control state is in the optimum control zone H. In this state, in the control means 20, the level controller (LIC) 21 performs a predetermined operation (for example, PI operation) on a signal from the level meter 16 and a deviation signal of the level set value SVL, and outputs the operation result MV. It is given as a flow rate set value SVf of the white water flow rate controller 22. The white water flow controller 22 receives the signal PVf from the white water flow detecting means 8 as an input, and sets a flow set value S given from the level controller 21.
A predetermined calculation is performed on the deviation from Vf to control the flow rate of white water supplied to the pulper 1. Thereby, the level control in the pulper 1 is performed first.

The moving average calculating means 23 receives the signal PVf from the white water flow rate detecting means 8 and receives the moving average value PVfo.
Is calculated. The pulp input amount calculating means 24 receives the moving average value PVfo and the pulp concentration signal SVc and basically controls the concentration ratio with respect to the white water flow rate.
The set value SVw of the pulp input amount is calculated by the equation (1).

SVw = PVfo · SVc · K1 · K2 (1) where K1 is a moisture correction coefficient of the input pulp. In this zone, for example, 1.00 to 1.10 K2; a time delay correction coefficient is 1.00. １．２1.20 The input amount controller 6 is provided with the set value SVw of the pulp input amount obtained by the equation (1), and controls the conveyor speed, that is, the supply amount of waste paper to be input to the pulp 1. Thereby, the input amount of pulp is controlled so as to be always proportional to the fluctuation of the flow rate of white water.

FIG. 4 shows the operation state of the control means 20 when the control state is in the zones A, C and F and the control is performed in the directions of arrows S-1, S-3 and S-5. FIG. This conceptual diagram differs from FIG. 3 in that the flow rate set value SVf given to the white water flow rate controller 22 is changed in relation to the pulper level signal SVL in each zone. . That is,
In the graph GF showing the relationship between SVL and SVf, the inclination angle β (the angle formed with the X axis) is selected as follows according to the case where control is performed in the direction of each arrow.

In the direction of arrow S-1, β1, in the direction of arrow S-3, β3, in the direction of arrow S-5, β5. FIG. 5 shows that the control state is in zones D, B, and E. And the arrow S
FIG. 7 is a conceptual diagram showing an operation state of the control means 20 when control is performed in the directions -2, S-4, and S-6.
Also in this conceptual diagram, the flow rate set value SVf given to the white water flow rate controller 22 changes in a relationship determined in each zone with respect to the pulper level signal SVL. That is, in the graph GF showing the relationship between SVL and SVf, the inclination angle β (the angle formed with the Y axis)
Are selected as follows according to the case where control is performed in the direction of each arrow.

In the direction of arrow S-2, β2, in the direction of arrow S-4, β4, in the direction of arrow S-6, β6. FIG. 6 shows the state of control in each zone. It is an operation waveform diagram. In this way, no matter what zone the control state is located in (especially in the A zone or the B zone where conventional control is difficult), these control preset in each zone According to the conditions, the control of the flow rate of the white water supplied to the pulper and the control of the amount of waste paper are performed so as to always enter the optimum control zone.

In the above description, the amount of waste paper is controlled by controlling the drive motor of the conveyor. However, the movement of the conveyor is controlled on / off to adjust the operation time. May be controlled by the

[0023]

As described above in detail, according to the present invention, even if the control state is located in any zone, the state automatically shifts to the optimum control state, so that high quality can be maintained. A pulp concentration control device can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram showing one embodiment of the present invention.

FIG. 2 is a conceptual diagram illustrating an example of a control table.

FIG. 3 is a conceptual diagram showing a configuration of an operation state of a control unit when a control state is in an optimum control zone H;

FIG. 4 is a diagram showing a control state in zones A, C, and F, and an arrow S
FIG. 7 is a conceptual diagram showing an operation state of a control unit when control is performed in the directions of -1, S-3, and S-5.

FIG. 5 is a diagram showing a control state in zones D, B and E, and an arrow S
FIG. 8 is a conceptual diagram showing the configuration of an operation state of a control unit when control is performed in the directions of −2, S-4, and S-6.

FIG. 6 is an operation waveform diagram showing a state of a control state in each zone.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pulper 2 Waste paper 3A, 3B Conveyor 4 Input amount measuring means 5 Drive motor 6 Input amount control controller 7 White water supply line 10 White water flow rate control controller 11 Output line 12 Delivery pump 13 Pulp concentration detecting means 14 Concentration controller 16 Pulper level detecting means 17 Control table 20 Control means 21 Level controller

Claims (1)

(57) [Claims] 1. A method in which waste paper as raw material measured on a conveyor is supplied, white water for dissolving the waste paper is supplied, and pulp dissolved to a certain concentration is discharged to the next step. A pulp concentration control device for detecting a pulp concentration discharged from the pulp; a pulp level detection device for detecting a level in the pulp; a pulp concentration signal and a pulp level signal In order to take the two signals on the horizontal axis and the vertical axis, respectively, and to set the vicinity of the center as an optimal control zone, divide the periphery of the optimal control zone into at least six zones, and to shift to the optimal control zone in each zone. A pulp concentration signal from the pulp concentration detection means, and a pulp level detection method. Inputs the level signal from the current through these two signals by referencing the control table
Seeking the zones, based on the set control condition in the zone, the transition from the current zone to the optimal control zone
Pulp concentration control device, characterized in that a control means for controlling the amount of white water to be supplied to the input amount and pulper waste paper to be introduced into the pulper as.