JP2005062116A - Monitoring method and its device of foreign substance level in pulp slurry - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a monitoring method and a device of a foreign substance level in pulp slurry independently of the pulp slurry concentration in a main flow tube, capable of not only perceiving early an abnormality in a process but also acquiring accuracy equal to or higher than that in grasping of an accurate trend by a person, namely, gathering or manual combing of ingredient pulp or in visual determination of the number or the size of the foreign substances. <P>SOLUTION: This monitoring method of the foreign substance level in the pulp slurry is characterized by comprising a process for separating pulp fibers in the pulp slurry from the foreign substance, a process for concentrating and recovering separated foreign substance suspension, and a process for circulating the recovered foreign substance suspension and measuring the foreign substance automatically. This device therefor is also provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a method and apparatus for monitoring the level of foreign matter in pulp slurry, and more specifically to detect abnormalities in the process at an early stage, as well as grasping accurate trends by humans, that is, raw material pulp The method and apparatus for monitoring the level of foreign matter in pulp slurry that is equal to or better than the visual judgment of sampling, hand-working, the number and size of foreign matters, and independent of the pulp slurry concentration in the mainstream pipe Is.

  Conventionally, as an example of this type of inspection apparatus and inspection method, there is a pulp slurry inspection apparatus and inspection method (see, for example, Patent Document 1).

  In this inspection apparatus and inspection method, a light is projected to an inspection part in which a cross section of a middle portion of a pulp slurry flow path is formed in a flat shape and a side wall surface is transparent, and the CCD slurry is passed through the CCD slurry camera. Is configured to detect foreign matters having a predetermined size or more in the pulp slurry at a constant flow rate.

  In particular, in this apparatus, since the inspection section has a smaller cross-sectional area than the main flow pipe portion, the pulp slurry flows at a higher flow rate than before the inspection section inflow, so the inspection section is always kept clean and permeated by the purification action by the high-speed flow. It is characterized in that a foreign object is photographed stably with a small measurement error without impairing the light transmittance.

  In addition, as a method of introducing the pulp slurry to the detector, a tank is connected to the middle part of the main pipe and / or a branch pipe branched from the main pipe, and the measurement accuracy is improved by diluting or coloring the pulp slurry. It is a feature.

  However, since the conventional inspection apparatus and the inspection method monitor foreign matter existing in the pulp slurry, the foreign matter is behind the aggregate of pulp fibers, or the concentration of signals and pulp fibers that detect foreign matter is detected. Due to low discrimination between noise caused by unevenness and low S / N ratio, abnormalities in the process can be detected at an early stage, but trend management during normal operation cannot be performed. Could not omit the conventional work of collecting and hand-pulling raw pulp and visually determining the number and size of foreign matters.

  In addition, as a method for introducing the pulp slurry to the detector, a tank is connected to a branch pipe branched from the main flow pipe, and the pulp slurry is diluted and adjusted to an appropriate concentration for measurement to improve measurement accuracy. When the slurry concentration is extremely reduced, for example, when the operation is started and when the bleaching process is changed, the pulp slurry concentration is changed, which causes a measurement error.

As a similar technique, a technique for observing a wet pulp sheet on a wire with a CCD camera or the like is known. However, this technique is insufficient for the same reason as described above.
Japanese Patent Publication No. 7-92438

  The present invention was made paying attention to the problems listed above, not only to detect abnormalities in the process at an early stage, but also to grasp the correct trend by humans, that is, the collection of raw pulp, hand-drawing, An object of the present invention is to provide a method and an apparatus for monitoring the level of foreign matter in a pulp slurry that is not affected by the pulp slurry concentration in the mainstream pipe while obtaining accuracy equal to or higher than the visual judgment of the number and size of foreign matters. Is.

  As a result of intensive studies in view of the above, the present inventor has invented a method and an apparatus for monitoring the level of foreign matter in the pulp slurry of the present invention.

  That is, the foreign matter level monitoring method in the pulp slurry of the present invention is a step of separating the pulp fibers and foreign matter in the pulp slurry, a step of concentrating and recovering the separated foreign matter suspension, and circulating the recovered foreign matter concentrate. It consists of the process of measuring a foreign material automatically.

  Further, the foreign matter level monitoring device in the pulp slurry of the present invention is a means for separating the pulp fiber and foreign matter in the pulp slurry, a means for concentrating and recovering the separated foreign matter suspension, and circulating the collected foreign matter concentrate. It is characterized by comprising means for automatically measuring foreign matter.

  In the above invention, the means for separating the pulp fibers and the foreign matters in the pulp slurry is a screen.

  In the above-described invention, the foreign substance suspension filtration concentrator is characterized in that the concentration rate of the foreign substance suspension can be calculated from the input amount and concentration of the pulp slurry.

  In the above invention, the means for circulating the collected foreign substance concentrate and automatically measuring the foreign substance is an imaging device provided in the circulation system.

  In the above invention, the imaging device uses a CCD camera.

  Further, in the above invention, the present invention has a function of integrating the amount of foreign matter of the foreign matter concentrate continuously imaged by the imaging device and calculating the amount of foreign matter in the pulp slurry.

  Moreover, in the said invention, when the amount of foreign materials in the calculated pulp slurry exceeds a foreign material level, it has the function to issue an alarm, It is characterized by the above-mentioned.

  Further, in the above invention, a sample inlet for introducing a known foreign substance in order to verify the accuracy of the imaging device is provided in the circulation system in the means for circulating the collected foreign substance concentrate and automatically measuring the foreign substance. Features.

  In the above invention, the collected foreign substance concentrate is circulated, and a discharge port for discharging the foreign substance concentrate after measurement is provided in the circulation system of the means for automatically measuring the foreign substance, and the foreign substance is collected. And

  As is clear from the above description, according to the present invention, not only the abnormalities in the process can be detected at an early stage, but also an accurate grasp of the trend by humans, that is, sampling of raw pulp, hand-pulling, the number of foreign matters It is effective as a method and apparatus for monitoring the level of foreign matter in pulp slurry that is not affected by the pulp slurry concentration in the mainstream pipe while obtaining accuracy equal to or higher than that of visual size determination.

  Hereinafter, the monitoring method and apparatus for the level of foreign matter in the pulp slurry of the present invention will be described in detail.

  In the present invention, as well as detecting abnormalities in the process at an early stage, grasping accurate trends by humans, that is, collecting raw pulp, hand-pulling, the number of foreign matters, equivalent to visual determination of the size, Alternatively, higher accuracy is obtained, and the accuracy is not influenced by the pulp slurry concentration in the main pipe.

  In the present invention, it is desirable that the means for separating fibers and foreign matters in the pulp slurry continuously treat the pulp slurry, and examples thereof include a hermetic screen. Furthermore, when the pulp slurry concentration is high, a large amount of pulp slurry can be processed by adding water. Further, it is desirable that the screen plate has a slit width suitable for the purpose and a structure in which foreign matter is not subdivided as much as possible.

  As a method of operating the screen, a method of continuously removing fibers by continuously operating in a cycle of water filling, pulp slurry reception, water dilution, and foreign matter discharge is desirable. Moreover, the structure which returns the pulp slurry from which the foreign material was removed to a mainstream pipe is good.

  In the present invention, examples of means for concentrating and recovering the separated foreign substance suspension include a filter (filter concentrator) having a filter medium having a network structure as a main element. The filter may have any structure, but the present invention aims to recover the solid content. Therefore, the screen drainage containing foreign matter is received from the lower part of the filter medium, and excess water is discharged from the upper part of the filter medium. A structure in which the foreign matter adhering to the lower part is washed off from the upper part is advantageous in terms of high recovery rate and high foreign matter concentration rate.

  In the filtration concentrator, the concentration rate of the foreign material concentrate is calculated from the input amount and concentration of the pulp slurry supplied when separating the pulp fibers and the foreign material, and the amount of water that washes off the foreign material adhering to the lower part of the filter medium. Can do.

  In the present invention, as a means to circulate the collected foreign substance concentrate and automatically measure the foreign substance, when imaging the foreign substance concentrate, simply image the foreign substance concentrate left on the flat plate while changing the position, Although there is a method of sequentially imaging by flowing a foreign substance concentrate into the imaging field, the present invention provides an imaging cell that provides an imaging field for sequential imaging in that the number of foreign objects for each imaging field is averaged. The object is to provide a circulation system in which a circulation tank of a foreign substance concentrate having a stirring device is connected by piping and circulated using a pump.

  As a means for automatically counting and / or weighing foreign matter by photographing the foreign matter used in the present invention and classifying the foreign matter according to a taught shape or a set classification value, the number of scanning bits of the CCD camera is subdivided. Thus, the foreign matter is detected corresponding to the size of the foreign matter.

  In the present invention, as a means for circulating the collected foreign substance concentrate and automatically measuring the foreign substance, an imaging device is provided in the circulation system, and the foreign substance concentrate flowing in the circulation system is continuously imaged. It measures the amount and shape. The measured data is input to an arithmetic device connected to the imaging device, integrated, and calculated as the amount of foreign matter per pulp slurry.

  In addition, in the circulation system of the means for automatically measuring foreign matter by circulating the collected foreign matter concentrate, a foreign material measurement is provided by providing a sample insertion port for introducing known foreign matter in order to verify the accuracy of the imaging device. The accuracy can be improved. The sample inlet may be provided at any position in the circulation system, but is preferably provided above the circulation tank.

  By providing a sample inlet in the circulation tank of the foreign substance concentrate and introducing a foreign substance sample having a known number and area, the accuracy of the imaging and measurement system can be verified, and the versatility can be improved. In particular, in conjunction with the level of foreign matter, a mechanism that automatically collects when the set abnormal level is exceeded and issues an alarm in some cases is advantageous in that the cause of the abnormality can be solved quickly.

  In addition, the collected foreign matter concentrate can be circulated to collect the foreign matter after measurement by providing an outlet for discharging the foreign matter concentrate after measurement in the circulation system of the means for automatically measuring foreign matter. It can be used for analysis of the composition of foreign matter.

  Hereinafter, it demonstrates concretely using drawing.

  FIG. 1 is an example showing an advantageous aspect of the present invention, and is a schematic diagram showing the whole of a foreign matter level monitoring device in pulp slurry according to the present invention. In FIG. 1, the monitoring device is capable of further circulation by measuring the water with a screen tank 1 that separates pulp fibers and foreign matters in the pulp slurry, a foreign matter concentrator 2 that removes excess water and concentrates foreign matters. The circulation tank 3 includes an imaging device 4 that measures the number of foreign matters for each area, and an arithmetic device 5 that calculates the measured data.

  The screen tank 1 is configured to be continuously operated in a cycle of water filling, pulp slurry reception, water dilution, and foreign matter discharge.

  The foreign matter concentrator 2 includes a wire mesh 6 as a filter medium having a mesh structure at the upper part of the tank, and is configured such that water flows from the lower part of the tank to the upper part and foreign matters are collected by the wire mesh 6. Yes.

  The circulation tank 3 is provided with a liquid level gauge 7 for adjusting the amount of water, and further provided with an agitator 8 so that foreign matter does not settle.

  The imaging device 4 is provided with an inspection part in the middle of the circulation pipe 9 and the foreign matter flowing therethrough is imaged by a CCD camera, and the obtained imaging is sent to the arithmetic device 5 as an input signal for a plurality of times. While integrating the imaging data, the amount of foreign matter per mass of pulp in the pulp slurry can be calculated.

  The operation of the case where the foreign substance level monitoring device in the pulp slurry having the above configuration is connected to the main pipe through which the pulp slurry flows will be described again with reference to FIG.

  The pulp slurry is supplied to the screen tank 1 from the branch pipe 10 branched from the main flow pipe through which the pulp slurry flows, and the supply amount is adjusted by the flow rate control valve 11.

  Pulp slurry is supplied to the screen tank 1 filled with water, the impeller 12 inside the tank is rotated, and the pulp fiber and the foreign matter are separated by the screen 13, the pulp fiber is returned to the mainstream pipe, and the foreign matter is the screen tank 1. Collect in.

  Next, after the water is received in the screen tank 1 and the pulp fibers are completely removed, the valve 14 is opened and the foreign substance suspension is discharged to the foreign substance concentrator 2.

  The foreign substance suspension received from the lower part of the foreign substance concentrator 2 collects the foreign substance into the foreign substance concentrator 2 by the wire mesh 6 provided at the upper part of the foreign substance concentrator 2, and excess water is collected at the upper part of the foreign substance concentrator 2. More discharged outside the system.

  The foreign substance suspension remaining in the foreign substance concentrator 2 flows into the circulation tank 3 by opening the valve 15. On the other hand, the foreign matter adhering to the wire mesh 6 is washed out to the circulation tank 3 with the shower water 16 provided on the upper part of the wire mesh 6, and the amount of water in the circulation tank 3 is adjusted using this shower water 16 to concentrate the foreign matter. Use liquid.

  After rotating the agitator 8 provided in the circulation tank 3 whose water amount has been adjusted, the valve 17 is opened, and the foreign matter concentrate is caused to flow through the circulation pipe 9 by the circulation pump 18 for circulation.

  After circulating for several minutes, the image pickup device 4 is operated, the number of foreign matters for each area that entered the image pickup 1 screen is measured, input as an input signal to the arithmetic device 5, repeated, integrated, and accumulated in the pulp slurry. The amount of foreign matter per mass of pulp is calculated. Thereafter, the foreign substance concentrate after the completion of imaging is discharged out of the system by opening the valve 19 in a circulating state and closing the valve 20.

  At this time, the measurement accuracy can be improved by adjusting the amount of water in the circulation tank 3 and further increasing the number of times of imaging so that the foreign matters entering the imaging 1 screen do not overlap each other.

  The amount of foreign matter per pulp mass can be calculated from the results obtained above and the amount of pulp slurry and the concentration of pulp slurry received in the screen tank 1.

  FIG. 2 is a schematic view showing the whole of a foreign matter level monitoring device in a pulp slurry provided with a recovery tank in the present invention. In FIG. 2, the collection tank 21 collects the entire amount of water containing foreign matter after the imaging by the imaging device 4 and includes a Buchner funnel 22 at the bottom of the collection tank 21 so that the foreign matter can be collected on the filter paper. ing.

  The operation of the case where the collected foreign substance concentrate is recovered in the recovery tank 21 having the above configuration will be described again with reference to FIG.

  The foreign substance concentrate after the completion of imaging is supplied to the recovery tank 21 by opening the valve 19 in a circulating state and closing the valve 20.

  The foreign material concentrate received in the recovery tank 21 recovers the foreign material to the filter paper by the Buchner funnel 22 provided at the lower part of the recovery tank 21. The amount of water flowing to the Buchner funnel 22 at this time may be adjusted in advance by the valve 23.

  The foreign matter collected on the filter paper can be visually confirmed with respect to the content of the foreign matter, which is effective in identifying the location where the foreign matter is abnormal.

  FIG. 3 is a schematic view showing the whole of the foreign material level monitoring device in the pulp slurry having a sample inlet at the upper part of the circulation tank in the present invention. In FIG. 3, a filter funnel-shaped sample inlet 24 is provided in the upper part of the circulation tank 3 so that foreign substances can be introduced.

  The operation of the case where foreign matter is introduced from the sample inlet at the upper part of the circulation tank having the above configuration will be described again with reference to FIG.

  A sample inlet 24 is provided in the upper part of the circulation tank 3, and a foreign material sample having a known number and area is supplied from the sample inlet 24.

  The amount of water in the circulation tank 3 is adjusted with the shower water 16, the agitator 8 provided in the circulation tank 3 is rotated, the valve 17 is opened, and the circulation pump 18 circulates the foreign substance concentrate in the circulation pipe 9. Let

  After the circulation for several minutes, the imaging device 4 is operated to measure the number of foreign matters for each area entered in the imaging 1 screen, and the foreign matter concentrate after completion of the photography is circulated to open the valve 19 and close the valve 20. To discharge out of the system.

  By performing the above operation, the imaging device 4 can be calibrated, the reliability of the imaging device 4 can be ensured, and the application can be expanded.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples at all. In addition, all the mixture ratios are mass%.

(Example 1 and Comparative Example 1)
Table 1 below shows the results of comparing the measurement accuracy of Example 1 and Comparative Example 1 with respect to visual judgment by a person. In Example 1 and Comparative Example 1, the measurement results obtained by sampling at the same time from the same branch pipe branched from the main flow pipe where the pulp slurry passed through the dust removal process flows after the bleaching process, and the visual judgment by humans are carried out. It is the measurement result obtained by extract | collecting the final product which followed Example 1 and Comparative Example 1.

<Measurement method>
Visual judgment: The result of collecting the final product, hand-drawing, and visually measuring the number of foreign matters.
Example 1: Method for monitoring the level of foreign matter in pulp slurry.
Comparative Example 1: PV value of an electrical signal obtained by the method described in Japanese Patent Publication No. 7-92438.

  As is apparent from the results in Table 1, in Example 1, the correlation coefficient is higher than that of Comparative Example 1, and the measurement accuracy is excellent. Furthermore, it can be seen that the method in Example 1 detects a larger number of foreign objects with respect to the visual determination, and measurement accuracy exceeding the visual determination can be obtained.

  Table 2 below shows the results of comparing the measurement accuracy of Example 1 with respect to visual judgment by a person.

<Measurement method>
Visual judgment: The result of collecting the final product, hand-drawing, and visually measuring the area of the foreign matter.
Example 1: Method for monitoring the level of foreign matter in pulp slurry.

  As apparent from the results in Table 2, in Example 1, it is possible to obtain a measurement accuracy that exceeds the visual determination with respect to the visual determination, and also to measure the area of the foreign matter.

  The present invention can be applied to a method and apparatus for monitoring the level of foreign matter in pulp slurry.

It is the schematic which shows the whole monitoring apparatus of the foreign material level in the pulp slurry in this invention. It is the schematic which shows the whole foreign material level monitoring apparatus in the pulp slurry provided with the collection tank in this invention. It is the schematic which shows the whole the monitoring apparatus of the foreign material level in the pulp slurry which provided the sample insertion opening in the circulation tank upper part in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Screen tank 2 Foreign material concentrator 3 Circulation tank 4 Imaging device 5 Arithmetic device 6 Wire mesh 7 Liquid level gauge 8 Agitator 9 Circulation piping 10 Branch pipe 11 Flow control valve 12 Impeller 13 Screen 14, 15, 17, 19, 20, 23 Valve 16 Shower water 18 Circulation pump 21 Recovery tank 22 Buchner funnel 24 Sample inlet

Claims (10)

  A pulp comprising a step of separating the pulp fibers and foreign matter in the pulp slurry, a step of concentrating and recovering the separated foreign matter suspension, and a step of automatically measuring the foreign matter by circulating the collected foreign matter concentrate. A method for monitoring the level of foreign matter in a slurry. A pulp characterized by comprising means for separating the pulp fibers and foreign matter in the pulp slurry, means for concentrating and collecting the separated foreign matter suspension, and means for automatically measuring the foreign matter by circulating the collected foreign matter concentrate. Monitoring device for foreign matter level in slurry.   3. The apparatus for monitoring the level of foreign matter in pulp slurry according to claim 2, wherein the means for separating the pulp fibers and foreign matter in the pulp slurry is a screen.   4. The apparatus for monitoring the level of foreign matter in pulp slurry according to claim 2, wherein the means for concentrating and collecting the separated foreign matter suspension is a filtration and concentrator for foreign matter suspension.   The pulp slurry according to any one of claims 2 to 4, wherein the means for circulating the collected foreign substance concentrate and automatically measuring foreign substances is an imaging device provided in the circulation system. Foreign matter level monitoring device.   6. The apparatus according to claim 5, wherein the imaging device uses a CCD camera.   7. The device according to claim 2, further comprising a function of integrating the amount of foreign matter of the foreign matter concentrate continuously imaged by the imaging device and calculating the amount of foreign matter in the pulp slurry. Monitoring device for foreign matter level in pulp slurry.   The apparatus for monitoring a foreign matter level in pulp slurry according to claim 7, further comprising a function of issuing an alarm when the calculated amount of foreign matter in the pulp slurry exceeds the foreign matter level.   3. A sample insertion port for introducing a known foreign substance for verifying the accuracy of the imaging device is provided in the circulation system of the means for circulating the collected foreign substance concentrate and automatically measuring the foreign substance. The monitoring apparatus of the foreign material level in the pulp slurry of any one of -8.   The collected foreign substance concentrate is circulated, and a discharge port for discharging the foreign substance concentrate after measurement is provided in the circulation system in the means for automatically measuring the foreign substance, and the foreign substance is collected. The monitoring device for the level of foreign matter in the pulp slurry according to claim 9.

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