JPS5949055B2 - Pump drive device for controlling raw material blending - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to raw material blend control in a paper manufacturing process,
This article relates to a raw material pump drive device that achieves power and labor savings.

The paper manufacturing process is broadly divided into raw material blending, adjustment process, and paper making process.

The raw material blending and adjustment process involves beating the raw material pulp sent from the raw material CHEST using a refiner, and adding filler (
The process involves adding certain amounts of clay, dyes, and other chemicals, diluting the paper with a large amount of water, and finally passing it through a machine chest as a raw material for paper and sending it to the papermaking process. FIG. 1 shows a system diagram of the raw material blending and adjustment process for blending four types of pulp raw materials.

Pulp raw material is sent out from a raw material chest 1 by a pump 3 driven by an electric motor 4, passes through a refiner 12 that beats the raw material, and is stored in a blending chest 13. A sensor 6 for detecting the pulp raw material concentration and a sensor 8 for detecting the pulp raw material flow rate are installed in the pipeline between the raw material chest 1 and the refiner 12. The output of the sensor 6 is input to a concentration controller 5, and the amount of dilution water from the dilution water supply device 2 is adjusted by a valve 7 to control the pulp raw material concentration to a set value. Each pulp raw material flow rate controller 9 controls a valve 11 installed in the pipeline to adjust the pulp flow rate to a set value. In addition to the above-mentioned pulp raw materials, the blending chest 13 receives filler (clay), dye,
Additives such as chemicals are sent and mixed with pulp raw materials,
Equalized.

Next, the paper stock homogenized in the blending chest 13 is sent to a machine chest by a pump 3a driven by an electric motor 4a, and further transferred to a paper making process. There are various types of paper manufactured in the papermaking process, such as high-quality paper, medium-quality paper, kraft paper, newspaper, and tissue paper.

Even within the same type, there are many brands that differ in factors that determine the characteristics of the paper, such as basis weight (weight per lm of paper), moisture content (percentage of water contained in paper), and paper quality. When a certain brand is determined from such a large number of brands, the blending ratio of each pulp raw material in the raw material blending and adjustment process is uniquely determined. Conventionally, once the brand has been determined, the machine operator 7 adjusts the setting values of each pulp flow rate controller 9 so that the blending ratio of each pulp raw material in the raw material blending and adjustment process becomes the determined value. The opening degree of the valve 11 was controlled to control the flow rate of each pulp raw material to the set value.

For this reason, there were a large number of operating and monitoring points for the machine operator, and the machine operator operated based on his experience and intuition, resulting in low operational efficiency.

Further, in this device, the flow rate of each pulp raw material is controlled by each pulp flow rate controller 9, and the concentration of each pulp raw material is controlled by each pulp concentration controller 5. Therefore, since the flow rate and concentration are controlled independently and separately, it is not possible to correct the flow rate when the concentration fluctuates, and the blending ratio of each pulp raw material fluctuates, which is undesirable from a quality standpoint. Furthermore, each pulp raw material is pumped by a pump 3 driven by a squirrel cage induction motor 4 at a constant speed.
Since the flow rate of each pulp is regulated by a valve 11 installed in the pipeline, there is a drawback that power loss is large.

In view of the above, an object of the present invention is to realize blending control that does not have the above-mentioned drawbacks by driving a pulp feed pump in the blending and adjustment process with a variable speed electric motor.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a system diagram of the device according to the invention. This device uses a variable speed motor as the drive motor 4 of the raw material feed pump 3. A pulse transmitter 18 is directly connected to the shaft of the drive motor 4 for speed detection, and the motor drive control device 2 ]. Further, the motor drive control device 21 is connected to a blending control device 31, and a signal from the concentration signal detector 15, a signal from the blending ratio setter 16, and a signal from the blending total amount setting device 17 are input to the blending control device 31. Ru.

This apparatus differs from the apparatus shown in FIG. 1 in that the sensor 8 for detecting the pulp flow rate, the pulp flow rate controller 9, and the valve 11 are omitted. The operation of this device will be explained in detail below, but since all four systems have the same configuration, only one system will be explained.

FIG. 3 is a block diagram of the blending control device 3. The mixing ratio setting device 16 sets the mixing ratio (α%) of the raw materials, and the total mixing amount setting device 174 sets the mixing total amount (α%) of the pulp raw materials.
Total amount of pulp raw material solid content of 4 systems GCTON/DAY]
When set, the outputs of these setting devices are
4 is input. The blending amount calculation unit 34 calculates the blending amount G1 [TON/DAY] of the pulp raw material.

is determined by the following equation (1).The output G1 of the blended amount calculator 34 and the output signal C% of the concentration signal detector 15 are input to the blended flow rate calculator 35, and the following (
2) The blended flow rate FsCms/HOUR is determined by the formula.

Here, ρ is the density [g/Af] of the pulp raw material.

The output Fs of the mixing flow rate calculator 35 becomes an input to the speed (frequency) calculation circuit 36 of the drive motor 4 of the raw material feed pump 3.

Set speed (set frequency) ν8 [R. P. M] is determined by the following equation (3), assuming that the number of revolutions of the raw material feed pump 3 (the number of revolutions of the drive electric motor 4) is proportional to the pulp flow rate. The output signal ν of the speed (frequency) calculation circuit 36 is input to the speed setting circuit 25 of the motor drive control device 21, and the speed of the drive machine 4 is controlled so as to reach the set speed ν8, and the pulp raw material is kept at the initially set blending ratio. (α%).

If controlled as described above, each pulp raw material will be strictly controlled to have a predetermined blending ratio, and the quality of the paper will be significantly improved.

FIG. 4 is a block diagram of the motor drive control device 21. Since all four systems are the same, only one system will be explained.

Although a variable speed motor is used as the drive motor 4 of the raw material feed pump 3, a squirrel cage induction motor using an inverter power supply is generally used from the viewpoint of installation environment and maintainability. Three-phase AC power source 22 is input to converter section 23 and rectified.

This DC voltage is applied to the speed setting circuit 25 in the inverter section 24.
It is converted into an alternating current with a frequency proportional to the speed setting signal set by the controller, and is supplied to the drive motor 4. Further, the voltage/frequency control section 27 generates a pulse with a frequency proportional to the speed setting signal, and sends the pulse to the inverter section 24 so that the voltage/frequency ratio is constant. The pulse transmitter 18 is directly connected to the 597s plane 11 station Yamada W latitude A'-1↓2 Y-Haiyama country L, and the feedback signal is negatively fed back to the control unit 27 via the speed control circuit 26. The drive electric motor 4 is strictly controlled to a set speed ν5.

By controlling as described above, the flow rate of each pulp is controlled with high precision so that it becomes a predetermined blending ratio, and the sensor 8 that detects the pulp flow rate, the pulp flow rate controller 9, and the valve 11
This eliminates the need for a high-precision blending control system.

Furthermore, since a variable speed motor is used as the drive motor 4, significant power savings can be achieved for the following reasons. FIG. 5 shows the relationship between the flow rate Q and the discharge pressure (head) H of a typical pump.

The solid lines H(n1) and H(N2) are the pump rotational speeds Nl and n
2, and the dashed lines R(1), R
(11) is a pipe resistance curve determined by the resistance of the pipe through which fluid flows and the water level difference between the water intake port and the discharge port. Now, in the case of a conventional system using a constant speed squirrel cage induction motor 4 to drive the pump 3, the pump flow rate QA is
The intersection point A of R(1) and H(n1) is set by adjusting the opening degree in step 1 (the rotational speed of the pump is n1 at this time) and becomes the operating point.

If the blending ratio of pulp raw materials is changed and the pulp flow rate is reduced from QA to QB, the opening degree of valve 11 will be narrowed down and the pipe resistance curve will become R(11), and R(11) and H(n1)
The intersection is the driving point. At this time, the discharge pressure increases from HA to HB, which consumes extra power. Next, in the case of the present invention in which the variable speed electric motor 4 is used to drive the pump 3, the pulp flow rate QA is uniquely determined if the pump rotation speed is n1, and when the pulp flow rate is decreased from QA to QB, This becomes possible by reducing the rotation speed of the pump (that is, the rotation speed of the variable speed electric machine 4) from n1 to N2.

At this time, the pump characteristic curve changes from H(n1) to H(N2), and the pipe resistance curve remains unchanged at R(1), so point C becomes the operating point. At this time, the discharge pressure decreases from HA to Hc, and the electric power can be reduced accordingly. From the above explanation, when reducing the pulp flow rate from QA to QB, when the opening degree of the valve 11 is throttled, the discharge pressure increases by Hv (HB-Hc) compared to when changing the rotation speed of the drive motor 4. This is necessary and consumes a lot of power.

Note that although the above explanation has been made for only one system, the same applies to the remaining three systems, and the overall power saving is extremely large.

As described above, according to the present invention, each pulp flow rate in the raw material blending and adjustment process is adjusted to a predetermined blending ratio without using a sensor for detecting the pulp flow rate, a pulp flow rate controller, or a flow rate control valve. It becomes possible to perform highly accurate control so that the

Furthermore, the power required to drive the pump can be significantly reduced. Therefore, a skilled operator as in the past is not required, and it is possible to provide an effective pump drive device with significantly improved performance, which not only automates operation and saves labor, but also saves power in the drive equipment.

[Brief explanation of drawings]

Fig. 1 is a system diagram of the raw material blending and adjustment process, Fig. 2 is a system diagram showing an embodiment of the present invention, Fig. 3 is a block diagram of the blending control device, and Fig. 4 is a block diagram of the motor drive control device. , FIG. 5 is a flow rate-discharge pressure characteristic diagram of the pump. 1... Raw material chiest, 2... Dilution water supply device, 3, 3a... Pump, 4, 4a...
...Electric motor, 5...Concentration controller, 6...
...Concentration detector, 7...Valve, 8...Flow rate detector, 9...Flow rate controller, 11...
・Flow control valve, 12...Refiner 1, 13.
...Blend Chest, 14...Additive delivery device, 15...Concentration signal detector, 16...
...Blending ratio setting device,]7......Blending total amount setting device, 18...Pulse transmitter, 21...Motor drive control device, 22... 3-phase AC power/source,
23...Converter section, 24...Inverter section, 25...Speed setting circuit, 26...
... Speed control circuit, 27 ... Voltage/frequency control section, 31 ... Mixture control device, 34 ...
・Blend amount calculator, 35...Blend flow rate calculator, 3
6... Speed calculation circuit.

Claims (1)

[Claims] 1. A variable speed electric motor that individually drives a pump installed in each liquid raw material delivery pipe in order to mix a plurality of liquid raw materials at a fixed ratio, and a concentration detector that detects the concentration of the liquid raw material delivered from the pump. Then, the pump rotation speed required to obtain the flow rate of the raw material to be delivered from the pump is calculated based on the preset blending ratio and total blended amount of each raw material and the raw material concentration detected by the concentration detector. A raw material blending control device comprising a blending control device that performs calculations and a motor drive control device that controls the speed of the variable speed motor so that the pump rotation speed calculated by the blending control device is achieved. pump drive device.