JPH0696833B2 - Freeness control method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the freeness of pulp discharged from a refiner device (referred to as "freeness" in the present application).
The present invention relates to a freeness control method for keeping a predetermined value.

[0002]

2. Description of the Related Art In a papermaking process, a refiner device is an important device for grinding pulp. Depending on the control result of this refiner device, the quality of paper strength, texture, air permeability, gloss, etc. It is known to have a great influence on stability, homogenization of products, operation start-up time and the like. Also, the control of this refiner device is
Various methods have been proposed to keep the freeness of pulp flowing out from the refiner device to a predetermined level.

As a conventional freeness control method for maintaining a predetermined freeness, a method for maintaining a constant electric load on the electric motor of the refiner device (hereinafter referred to as load control) has been adopted.

The above load control measures the electric load value of the electric motor of the refiner device, compares the measured value with a set value, widens the refiner disk gap when the measured value becomes higher than the set value, and conversely when the measured value becomes lower, the refiner. The disk gap is narrowed to control the electric load so as to maintain the set value.

However, although the above-mentioned load control can keep the freeness substantially uniform, the so-called indirect control cannot set an accurate freeness value, so that the outlet side (hereinafter referred to as the secondary side) of the refiner device is recently used. ), A freeness meter is installed, and an attempt has been made to use the measurement value measured by this freeness meter as a signal for correcting the above load control.

Further, in recent years, more accurate freeness control is demanded, and in addition to the measured values of the above-mentioned freeness meter, the flow rate, temperature, concentration, pressure, etc. of the raw material are measured and these measured values are added to the correction signal. Attempts have also been made.

[0007]

However, since the above-mentioned conventional freeness control method is an intermittent measurement in which the freeness meter cannot perform continuous measurement and performs sampling by sampling at regular time intervals, it is still necessary to measure external conditions. There is a problem that the freeness is unavoidably changed due to the change.

If correction signals for the flow rate, temperature, concentration, pressure, etc. of the raw material are added, the above problems can be solved to some extent.
When a number of conditions such as flow rate, temperature, concentration, pressure, etc. are calculated and combined with a predetermined calculation formula, a complex error may occur and a correction signal with an unexpected value may be generated, and these correction signals can be used sufficiently. I can't get credibility.

Therefore, the present invention has been made to solve the above-mentioned problems. Under various conditions, the refiner device calculates the amount of work actually functioning against the freeness fluctuation at the present time, and further, , The purpose of the present invention is to provide a freeness control method that can more accurately stabilize the freeness to a target value by calculating how much the actual work of this refiner device has excess or deficiency with respect to the target freeness. It is what

[0010]

In order to solve the above-mentioned problems, the structure of the present invention, which is based on the above-mentioned claims, has a freeness on the primary side and the secondary side of the refiner device. A meter is provided, and the difference between the measured values of both freeness meters is divided by the electric load value of the electric motor of the refiner device to calculate the work (delta freeness) of the refiner device per unit of electric load value, and it is also set separately. The difference between the target freeness value and the measured value of the secondary side freeness meter (current freeness deviation) is calculated, and the refiner disk gap is controlled by the control value obtained by the product of the delta freeness and the current freeness deviation. It is a technical measure that has been taken.

[0011]

Therefore, in the freeness control method of the present invention, the total work amount in which the freeness is changed by the refiner device is obtained by the difference between the measured values of the freeness meter on the primary side and the secondary side of the refiner device.

Since the refiner device can adjust the total work amount by adjusting the gap of the refiner disc, if the total work amount is divided by the gap adjustment amount of the refiner disc, a unit adjustment distance is obtained. The amount of work per hit can be calculated. However, since the work amount per unit adjustment distance is not in a linear proportional relationship at each position of the moving side disk, a complicated calculation formula is required. Therefore, in the present invention, the total work amount of the motor of the refiner device is calculated. The work amount (delta freeness) of the refiner device per unit of the electric load value is calculated by dividing by the electric load, and this delta freeness exhibits an action which is substantially the same as the work amount per unit adjustment distance.

In addition, a target freeness value set separately,
When the difference from the secondary side freeness meter measurement value (current freeness deviation) is calculated, this current freeness deviation indicates the excess or deficiency of the current work. Therefore, multiplying this value by the delta freeness makes the necessary adjustment of the refiner disk. Since the amount, in other words, the control value, is obtained, the freeness can be adjusted to the target value by adjusting the refiner disk interval with this value.

Since the above-mentioned delta freeness is obtained by the difference between the measured values of the freeness meter on the primary side and the secondary side of the refiner device, all conditions such as flow rate, temperature, concentration and pressure are practical. Therefore, even if the refiner device is controlled only by the control value obtained by the product of the delta freeness and the current freeness deviation, even if this control value is used as the correction signal for the load control, Further, even if it is added to one of the correction signals for the load control, the freeness is held more stably as compared with the conventional one.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the figure, reference numeral 1 is a conventionally known refiner device. In the illustrated example, a cone-type refiner device is used as the refiner device 1, and the raw material feed path 2 is provided on one end side.
Although not shown in the drawing, the product take-out path 3 is connected to the other end side, and although not shown in the figure, a pair of discs are provided oppositely, and at least one of the two discs is rotated by the electric motor 4 (usually , Rotate one, and rotate both in the opposite directions.)
As in the prior art, one of the two disks can be moved by the adjusting device 5 so that the disk interval can be adjusted.

Then, the raw material flows into the refiner device 1 from the raw material feeding passage 2, passes between both discs, is mechanically ground by the rotation of the discs, and flows out from the product taking-out passage 3. It is the same as before.

According to the method of the present invention, freeness gauges 10a and 10b are provided on the primary side and the secondary side of the refiner device 1, and the difference between the measured values of the both freeness gauges 10a and 10b is measured by the electric motor 4 of the refiner device 1. The work amount (delta freeness) of the refiner device 1 per electric load value unit is calculated by dividing by the load value.

As the above-mentioned freeness meters 10a and 10b, the one as shown in FIG. 2 can be used. The structure will be described with the freeness meter 10a provided on the product take-out path 3 side. A main body closed container section 12 communicating with the product take-out path 3 via a net 11 is erected on the upper surface side of the product take-out path 3.
Three electrodes 12a, 12b, 12c, which are airtight from above and have different lower end positions, are inserted in each.

Further, cleaning water supply nozzles 13a and 13b are attached to the main body airtight container portion 12 so that cleaning water can be sprayed and cleaned at the end of the freeness measurement.

Further, internal pressure adjusting devices 14a and 14b are connected to the main body closed container portion 12 so that the internal pressure can be set to a predetermined value. Usually, the internal pressure of the main body closed container portion 12 is taken out from the product take-out path 3. The internal pressure adjusting device 14a side is communicated with the main body closed container 12 so that the internal pressure is higher than the internal pressure, so that the state in which there is no filtered water is maintained. When measuring the freeness, the solenoid valve 15 is switched and the low pressure side internal pressure adjusting device 14b side is communicated with the main body hermetic container portion 12 to reduce the pressure. Although this depressurization is omitted in the figure, a pressure detector is attached to the product take-out path 3 so that the set pressure of the low-pressure side internal pressure adjusting device 14b becomes lower than the internal pressure of the product take-out path 3 to keep the depressurization constant. I am devising. Then, when the pressure inside the main body closed container portion 12 is reduced, the filtered water rises from the net body 11,
When the two electrodes 12a, 12b both come into contact with the filtered water at the first water level L1, a timer housed in the control panel 30 described later operates, and at the second water level L2, the three electrodes 12a, 12b, 12c.
When all of them touch the drainage water, the timer is stopped and the freeness is measured by the time when the timer is activated.

Since the internal pressure of the main body closed container 12 and the internal pressure of the product take-out path 3 may fluctuate during measurement, the internal pressures of both may be measured every unit time (for example, 0.2 seconds).
More accurate freeness can be measured by obtaining the average value of the internal pressures and correcting the difference in the average value of the internal pressures.

Then, the measurement values of both the freeness meters 10a and 10b are calculated by the calculation circuit of the control panel 30 to obtain the difference between them. This difference (tentatively called the total work) is
The refiner device 1 actually corresponds to the work amount in which the freeness is changed.

In the refiner device, one of the two disks is moved by the adjusting device 5 to adjust the disk interval to adjust the work amount (total work amount). Once the quantity is determined, it can be used as a control signal for disk adjustment. Therefore, if the difference between the measured values of both freeness meters 10a and 10b is divided by the disk gap size, the work amount per adjustment amount of the disk can be calculated. The deficiency will be required, but as mentioned above, the relationship between the disk gap and the work amount is not necessarily in a linear proportional relationship, so the calculation becomes complicated when divided by the disk gap dimension. So
In the present invention, when the disk gap is changed, the electric load value of the electric motor 4 changes significantly, and the amount of change has a linear proportional relationship that is suitable for a linear function, so handling is convenient. Instead, the total work amount is divided by the electric load value of the electric motor 4 to obtain the work amount per unit electric load value (delta freeness).

For the electric load value of the electric motor 4, a conventionally known load measuring device 6 can be used, and the power supply circuit 7 and the electric motor 4 can be used.
The load measuring device 6 is provided in the middle of the continuous conductors, and the measured value is sent to the control panel 30.

Further, according to the present invention, the difference (current freeness deviation) between the separately set target freeness value and the measured value of the secondary side freeness meter 10a is calculated. It is needless to say that the target is that the measured value of the secondary side freeness meter 10a matches the target freeness value, but in reality, there is a difference between the two. This difference occurs due to the excess or deficiency of the work amount of the referrer device 1, and the present freeness deviation is the excess or deficiency with respect to the target value.

Therefore, the refiner disk gap is controlled by the control value obtained by the product of the delta freeness and the current freeness deviation. That is, the product of the delta freeness and the current freeness deviation indicates how much the disc gap is excessive or insufficient. Therefore, if the adjusting device 5 is operated with this control value to adjust the disc gap, the freeness becomes the target value. It can be matched.

Of course, the above control value is also calculated by the arithmetic circuit of the control panel 30, but only this control value may be used for actual adjustment by the adjusting device 5 (therefore, in the present application, " Although it is called a "control value" to distinguish it from other correction signals, it is needless to say that it is the same as a kind of correction signal depending on the usage.) However, in this embodiment, based on the load control, It is used as a correction signal for this load control. That is, when the electric load of the electric motor 4 is maintained at the set electric load value, the control value is added to the set electric load value for control.

Further, in this embodiment, the flow rate, temperature, concentration, pressure, etc. of the raw material are detected by the sensors and input to the control panel 30, and these detection signals can also be used for correction. The switching device is provided so that the signal of (1) does not need to be used, and when it is not used, the value set by key input is always input. Further, when these various sensor signals show unacceptable values in comparison with the control value, the measured values may be ignored. Also, when using a raw material whose freeness value can be assumed on the primary side, the freeness meter 1
Even if 0b is omitted, the assumed place can be key-inputted, which is the same as in practice.

[0029]

As described above, the present invention is based on the work amount in which the refiner 1 actually changes the freeness, so that a reliable freeness control method can be provided.

Further, since the present invention uses the work amount (delta freeness) of the refiner device per electric load value unit, it can be easily combined with the conventional load control method and can be realized by using the conventional device. It is possible to provide a freeness control method capable of achieving the above.

It should be noted that the remarkable effect of the present invention is that the work amount of which the refiner device 1 actually changes the freeness is a measurement in consideration of all conditions, and therefore an external factor is added to the measurement result. The reliability can be significantly improved without the need to measure the freeness, and the freeness is measured on the primary side as compared to the conventional case where the freeness was measured only on the secondary side. It is possible to provide a stable freeness control method that is capable of quick response even in intermittent measurement and that is easy to deal with condition changes.

[Brief description of drawings]

FIG. 1 is a front view of an example of an apparatus for carrying out the method of the present invention.

FIG. 2 is a vertical sectional view of an example of a freeness meter used in the present invention.

[Explanation of symbols]

 1 refiner device 4 electric motor 5 adjusting device 6 load measuring device 10a freeness meter 10b freeness meter 30 control panel

Claims (1)

[Claims] 1. A freeness meter is provided on each of the primary side and the secondary side of the refiner device, and the difference between the measured values of the both freeness meters is divided by the electric load value of the electric motor of the refiner device,
The amount of work (delta freeness) of the refiner device per unit of electric load value is calculated, and the difference between the target freeness value set separately and the measured value of the secondary side freeness meter (current freeness deviation) is calculated, A freeness control method in which a refiner disk gap is controlled by a control value obtained by a product of a delta freeness and a current freeness deviation.