JP4915120B2 - Effect monitoring method and injection amount control method for papermaking chemicals - Google Patents

Description

  The present invention relates to a method for monitoring the effect of a papermaking drug and an injection amount control method. In particular, the present invention relates to a method for quickly and surely confirming the effect of a papermaking chemical added to a paper raw material slurry or an inlet in a papermaking process, and a method for accurately controlling the injection amount of the papermaking chemical based on the monitoring result.

  In addition to LBKP, NBKP, TMP, etc., as a raw material for paper, in recent years, the utilization rate of waste paper has been improved, the blending ratio of broke pulp has been improved, and the system has been closed, and used paper, DIP, coat broke, etc. Yes. These raw materials contain many anionic impurities, so-called anionic trash, and not only pitch and defects are generated by the anionic trash, but also a decrease in productivity such as paper breakage and production speed reduction.

  With respect to these problems, a method of adding cationic starch and colloidal silica (USP4388150), a method of adding bentonite in the next step after adding a synthetic cationic polymer (EP235893, JP-A-62-1191598), molecular weight The anionic trash is fixed to the pulp fiber and removed out of the system by adding various chemical agents as disclosed in a method of adding a cationic polymer having a low molecular weight and then adding an anionic polymer (Japanese Patent Publication No. 5-29719). To be done.

Conventionally, the effect of adding these agents is intermittently managed by the following indirect method.
(1) Evaluation of quality and defects of finished paper and management of production speed
(2) Measurement of particle surface charge (cation requirement) of raw slurry and slurry in inlet
(3) Turbidity measurement by transmitted light of filtrate obtained by filtering raw material slurry and slurry in inlet

However, the conventional methods have the following problems.
(1) Evaluation of finished paper quality and defects and management of production speed:
Although the influence of the drug effect can be confirmed directly, it is management after the production has already started or after the paper has been completed, and there is a problem that the response to trouble solving is significantly delayed.

(2) Measurement of particle surface charge (cation requirement) of raw slurry and slurry in inlet:
The surface charge is merely an indirect evaluation, and the change in the surface charge and the defect caused by anion trash may not always be correlated.

(3) Turbidity measurement of filtrate obtained by filtering raw material slurry and slurry in inlet:
It is a direct measure of turbidity due to anionic trash components, and it is highly reliable, but it requires a filtration process, so it is prone to clogging troubles in the filtration device, frequent maintenance, and equipped with a cleaning mechanism. As a result, there are many problems such as an expensive apparatus.

  In order to solve the above-mentioned problems, the applicant of the present application has proposed in Japanese Patent Application No. 2005-370143 a method for monitoring the chemical effect of the paper making process and controlling the chemical injection by using a laser light scattering sensor. This makes it possible to monitor drug effects with high accuracy and prevent paper product abnormalities and troubles during production. However, depending on the case, the quality of the paper-making process water to be measured changes, Since there are cases where complete monitoring and control are difficult only with absolute values, there is a need for improvement.

The reasons for fluctuations in the water quality of the papermaking process are as follows.
That is, as described above, the raw materials for paper include LBKP, NBKP, TMP, etc. In addition, in recent years, the utilization rate of waste paper, the blending ratio of broke pulp have been improved, and the system has been closed, and waste paper, DIP, coat broke Recovered raw materials such as these are also frequently used. Particularly, it is very difficult to keep the quality and properties of the recovered raw material having a great influence on the property fluctuation of the papermaking process water. In other words, not only the solid content concentration, but also the pulp fiber length, its distribution, the amount and type of ash, the color, etc., there are many variable factors and it must be said that it is basically difficult to control these. Because.
USP4388150 EP235893 JP 62-191598 A Japanese Patent Publication No. 5-29719 Japanese Patent Application No. 2005-370143

  The present invention solves the above-described conventional problems, and makes paper such as a yield improver, a drainage improver, a coagulant, and a pitch control agent that are added to papermaking process water such as a paper raw slurry and an inlet slurry in the papermaking process. Method for monitoring the effect of a papermaking drug capable of quickly and reliably confirming the effect of the drug for papermaking, and a method for controlling the injection amount of a papermaking drug that accurately controls the injection amount of the papermaking drug based on such monitoring results The purpose is to provide.

The method for monitoring the effect of the papermaking chemical of the present invention is a method for monitoring the effect of the papermaking chemical added to the papermaking process water, wherein the papermaking process water or its diluted water is used as the fluid to be measured, and the fluid to be measured is predetermined. A first step of irradiating a laser beam amplitude-modulated (AM) at a frequency (hereinafter referred to as a “modulation frequency”), and scattered light scattered by particles in the fluid to be measured is received by a photoelectric conversion circuit. A second step of obtaining scattered light intensity data, and a third step of obtaining particle size information and / or turbidity information of particles in the fluid to be measured based on the scattered light intensity data , the photoelectric conversion circuit comprising: It consists of a photo detector, a band pass filter and an amplifier. The optical signal of the scattered light is converted into an electric signal by the photo detector, and the modulation frequency component of the modulation signal is separated from the natural signal by the band pass filter. The signal is taken out and amplified by the amplifier, then AM detection is performed by the detection circuit, and the signal after detection is output to the minimum value detection circuit. The minimum value detection circuit receives the minimum value from the input signal after AM detection. A method for monitoring the effect of a papermaking chemical to obtain the scattered light intensity data by detecting the signal intensity of the paper, wherein the papermaking process water before the addition of the chemical is used as the papermaking process water, Particle size information obtained through the steps, and / or turbidity information, and using the papermaking process water after the addition of the drug as the papermaking process water, the particle size information obtained through the first to third steps and And / or a fourth step of obtaining comparison data before and after the addition of the drug by comparing with turbidity information.

The method for controlling the injection amount of a papermaking chemical according to the present invention is a method for controlling the injection amount of a papermaking chemical into papermaking process water. The papermaking process water or its diluted water is used as a fluid to be measured, and a predetermined fluid is measured. A first step of irradiating a laser beam amplitude-modulated (AM) at a frequency (hereinafter referred to as a “modulation frequency”), and scattered light scattered by particles in the fluid to be measured is received by a photoelectric conversion circuit. a second step of obtaining scattered light intensity data, look including a third step of obtaining a particle size information and / or turbidity particle information of the measured fluid based on the scattered light intensity data, the photoelectric conversion circuit , A photodetector, a bandpass filter, and an amplifier. The optical signal of the scattered light is converted into an electrical signal by the photodetector, and the signal of the modulation frequency component is converted from the electrical signal to be distinguished from natural light by the bandpass filter. After taking out and amplifying in the amplifier, AM detection is performed in the detection circuit, and the signal after the detection is output to the lowest value detection circuit. The lowest value detection circuit receives the signal of the lowest value from the input signal after the AM detection. A method for controlling the injection amount of a papermaking chemical to obtain intensity data by detecting the scattered light intensity data , wherein the papermaking process water before the addition of the chemical is used as the papermaking process water, and the first to third processes The particle size information obtained through the first to third steps and / or the turbidity information obtained through the above, and the paper making step water after the addition of the drug as the paper making step water. Alternatively, the method includes a fourth step of obtaining comparison data before and after the addition of the drug by comparing turbidity information, and a fifth step of controlling an injection amount of the papermaking drug based on the comparison data. To do.

  According to the present invention, the effects of papermaking chemicals such as a yield improver, a drainage improver, a coagulant, and a pitch control agent that are added to papermaking process water such as a paper raw slurry and an inlet slurry in the papermaking process. It can be confirmed quickly and reliably, and the injection amount of the papermaking chemical can be accurately controlled based on the monitoring result.

  That is, the reflection of the laser beam is related to the size of the particles that have been irradiated and hit, causing a large reflection when hitting a large particle and a small reflection when hitting a small particle. Therefore, by irradiating the fluid to be measured with laser light and measuring the intensity of the scattered light scattered by the particles in the fluid to be measured, changes in the size of particles such as anion trash in the papermaking process water (particle size Information). In addition, since the minimum value of the scattered light intensity data gives turbidity information indicating gaps between particles, by utilizing this principle, the paper manufacturing chemical added to the paper raw material slurry or the slurry in the inlet is used. The effect can be monitored, and furthermore, this data can be used to accurately control the drug injection of the papermaking drug.

  Moreover, in the present invention, not only the scattered light intensity data is measured for the papermaking process water after the addition of the chemical, but also the scattered light intensity data is measured for the papermaking process water before the chemical addition, and the difference is detected. Stable results can be obtained even if the quality of the process water varies.

  That is, as described above, the properties of the papermaking process water such as the paper raw slurry and the slurry in the inlet are likely to fluctuate. It cannot be determined and management may be difficult. According to the present invention, it is possible to perform stable monitoring and chemical injection control by measuring scattered light intensity data for papermaking process water before and after the addition of a drug and relatively managing them.

  Hereinafter, embodiments of the present invention will be described in detail.

[Monitoring the effects of papermaking chemicals added to papermaking process water]
According to the present invention, in order to monitor the effect of the papermaking chemical added to the papermaking process water, the papermaking process water or its dilution water is used as a fluid to be measured, the fluid to be measured is irradiated with laser light, and the fluid to be measured is measured. Scattered light intensity scattered by the particles therein is received to obtain scattered light intensity data, and changes in the particle size and / or turbidity of the particles in the fluid to be measured are captured based on the scattered light intensity data.

1) Effect monitoring apparatus for papermaking drug First, an effect monitoring apparatus for papermaking drug suitable for the present invention will be described with reference to FIGS.

  FIG. 1 is a block diagram showing a schematic configuration of a papermaking drug effect monitoring apparatus according to a preferred embodiment of the present invention, and FIG. 2 is an enlarged view showing a configuration of a laser beam irradiation unit and a scattered light receiving unit shown in FIG. FIG. In the following, the case where the paper raw slurry is measured as the papermaking process water is shown. However, as will be described later, the fluid to be measured in the present invention is not limited to the paper raw slurry, and the slurry in the inlet, press Various papermaking process waters, such as squeezed water, and its dilution water are mentioned.

  The effect monitoring apparatus for the paper-making drug includes a laser oscillator 1, a first optical fiber 2, a laser light irradiation unit 3, a scattered light receiving unit 4, a second optical fiber 5, a photoelectric conversion circuit 6, a detection circuit 7, It consists of a value detection circuit 8. Reference numeral 20 denotes a measuring tank in which the raw slurry 21 is stored. In the raw slurry 21 in the measuring tank 20, a laser disposed at the bottom of a shielding member 22 (hereinafter sometimes referred to as “sensor probe”). A light irradiation unit 3 and a scattered light receiving unit 4 are provided. The shielding member 22 shields natural light from above from reaching the measurement region 23 between the laser light irradiation unit 3 and the scattered light receiving unit 4.

  That is, as shown in FIG. 3, the shielding member 22 is a pentagonal prism having a bottom surface projecting downward and groove portions 24 formed on both projecting side surfaces. The first optical fiber 2 and the second light are formed in the groove portions 24. The fiber 5 is fixed, and the laser beam irradiating unit 3 that is one end of the first optical fiber 2 and the scattered light receiving unit 4 that is one end of the second optical fiber 5 are symmetric (line symmetric) in FIG. It is arranged. Furthermore, it is preferable that the center lines of the laser light irradiation unit 3 of the first optical fiber 2 and the scattered light receiving unit 4 of the second optical fiber 5 intersect each other at 90 degrees.

  In general, the intensity of the laser light oscillated from the laser oscillator 1 is preferably modulated so as to be distinguished from natural light. In order to return the scattered light intensity received by the photoelectric conversion circuit 6 to the original electric signal, 70 is used. A modulation of about ~ 150 kHz is preferred. Therefore, in the configuration of the present embodiment, the laser oscillator 1 includes a function generator 11 and a laser diode 12, and laser diode amplitude-modulated (AM) with a predetermined frequency, for example, 95 kHz electric signal generated from the function generator 11 is laser diode. 12 is emitted to one end of the first optical fiber 2. This laser beam is emitted from the other end of the optical fiber 2 serving as the laser beam irradiation unit 3 into the raw material slurry via the first optical fiber 2. The laser oscillator is not limited to the function generator and the laser diode, and for example, a light emitting diode or the like can be used.

  The anion trash component particles are present in the raw slurry, and the laser light applied to the anion trash component particles from the laser light irradiation unit 3 is scattered to be scattered light, thereby forming the scattered light receiving unit 4. The second optical fiber 5 is incident on the optical fiber 5 from one end thereof. In the present embodiment, the measurement region 23 is a region where the region irradiated with the laser light emitted from the laser light irradiation unit 3 and the region where the scattered light receiving unit 4 can receive the scattered light are overlapped, The light receiving unit 4 receives scattered light scattered by 90 degrees from the measurement region 23 (center line of the second optical fiber 5).

  Note that the configuration of the laser beam irradiation section in the shielding member 22 is not limited to that shown in FIG. 2, and as shown in FIG. 4, a laser diode 12 is provided in the vicinity of the measurement region 23 of the shielding member 22 and the current cable 12A is connected. The laser beam may be emitted directly in the vicinity of the measurement region of the shielding member 22, and in this case, the optical fiber is not used up to the laser beam irradiation part, thereby preventing the optical fiber from being damaged. Can do. 4, the configuration other than the laser irradiation unit is the same as that shown in FIG. 2, and members having the same functions are denoted by the same reference numerals.

  The photoelectric conversion circuit 6 includes a photo detector 61, a band pass filter 62, and an amplifier 63. The photo detector 61 connected to the other end of the second optical fiber 5 converts the optical signal of the scattered light into an electric signal. Then, in order to distinguish it from natural light by the band pass filter 62, a signal of the modulation frequency component is taken out from the electric signal, amplified by the amplifier 63 and outputted to the detection circuit 7. The photoelectric conversion circuit 6 is not limited to the one described above as long as it converts an optical signal into an electric signal. For example, a photodiode may be used instead of a photodetector, or a low-pass filter may be used instead of a bandpass filter. A pass filter may be used.

  The modulation frequency component signal is subjected to AM detection by the detection circuit 7 in order to measure the change in scattered light intensity, and the detected signal is output to the minimum value detection circuit 8. The signal output by the detection circuit 7 is subjected to signal processing equivalent to the signal passing through the low-pass filter. Accordingly, by appropriately selecting the cut-off frequency of the band-pass filter 62, the detection circuit 7 detects the signal as a DC output waveform signal from which the fluctuation of the cut-off frequency has been removed, and outputs it to the minimum value detection circuit 8. be able to. As described above, in the present embodiment, from the optical signal detected by the photodetector 61, the modulation frequency component is extracted by the bandpass filter 62, amplified by the amplifier 63, and then subjected to AM detection, whereby fine particles of anion trash component are obtained. The change in the light intensity accompanying the scattering of can be measured as the change in the signal intensity. However, AM detection is not necessarily required, and a modulation frequency component signal may be directly output to the minimum value detection circuit 8.

  The lowest value detection circuit 8 detects the lowest signal intensity from the input DC signal. This detection of the minimum value is to measure the constricted portion of the waveform, as explained by the signal waveform output from the amplifier 63 shown in FIG. The portion other than the constricted portion is when coarse paper raw material and fine anion trash component particles are present in the measurement region 23, and the constricted portion is when the paper raw material has left the measurement region. Accordingly, the minimum value detection circuit 8 detects the minimum value of the signal intensity, thereby measuring the scattered light intensity when only the fine particles of the anion trash component exist, that is, the particle size of the fine particles of the anion trash component. It becomes possible. This decrease in the minimum value indicates that the particle size of the fine particles of the anion trash component in the measurement region has decreased, and the increase in the minimum value has increased the particle size of the fine particles of the anion trash component. Represents that.

Specifically, the measurement principle of the drug effect is as follows. That is, when colloidal minute anion trash component particles (hereinafter referred to as “micro colloidal particles”) flow into and out of the measurement region 23 as the raw slurry 21 in the measurement tank 20 is agitated, fluctuations in scattered light change. Will occur. The period of this fluctuation can be estimated by assuming the measurement region as a particle and assuming the number of collisions with the micro colloidal particle. That is, when the measurement region 23 is approximated by a sphere having a diameter R and a micro colloidal particle is approximated by a sphere having a diameter r, the collision cross-sectional area Q _{0 in} this case is given by Q ₀ = π (R + r) ² . Further, when the density of the microcolloid particles is N and the relative velocity of the particles with respect to the measurement region is v, the number of times the microcolloid flows into the measurement region per unit time is ν = NQ ₀ v. Similarly, since the same fluctuation occurs when the fine colloidal particles exit the measurement region, the period of the value obtained by differentiating the scattered light intensity becomes a value twice this number. Assuming that the scattered light intensity is proportional to the nth power of the particle diameter of the fine colloidal particle, and ignoring multiple scattering, the fluctuation A of the scattered light intensity accompanying the inflow / outflow of one fine colloidal particle is A = A ₀ r ⁿ . A ₀ is a constant depending on the measurement system, and is calibrated using a standard sample.

  Here, since the micro colloidal particles have a small diameter r and a large particle density N, minute fluctuations in scattered light occur in a short cycle. Therefore, by detecting the modulation frequency component in the detection circuit 7, the output waveform is subjected to signal processing equivalent to passing through the low-pass filter as described above, and therefore the cutoff frequency of the filter 62 is appropriately selected. As a result, it can be detected as a DC signal from which this fluctuation has been removed.

  On the other hand, the paper raw material in the raw material slurry has a large fluctuation when flowing into and out of the measurement region, and the average period of the fluctuation becomes long. Therefore, when the product of the density of the paper raw material and the measurement area volume is smaller than 1, the minimum value of the output waveform after detection corresponds to the scattering of the fine colloidal particles. Thereby, in this embodiment, the minimum value detection circuit 8 is connected to the subsequent stage of the detection circuit 7, thereby distinguishing the scattered light from the fine colloidal particles in the raw material slurry, that is, the anion trash component, and the scattered light from the paper raw material, Since it becomes possible to take out only the scattered light by the anion trash component, the effect of reducing the anion trash component by the drug can be properly grasped.

  Further, in the monitoring apparatus of the present embodiment, it is not necessary to provide a special measurement unit separately, and it is possible to measure the scattered light only by putting the laser light irradiation unit and the scattered light receiving unit attached to the shielding member into the measurement tank. Therefore, a monitoring device having a simple device configuration can be provided. Furthermore, the monitoring device of this embodiment can be a throw-in type monitoring device because the device configuration is simple, lightweight, and downsized.

  In the present invention, such a device is prepared, and a structure and a liquid that can be automatically switched by a solenoid valve or the like between the raw material slurry before the addition of the chemical and the raw material slurry after the addition of the chemical. A mechanism may be incorporated or a manual valve may be used for switching. Two such devices may be prepared, and the raw material slurry before and after the addition of the chemical may be measured separately.

2) Minimum value of electric signal and scattered intensity converted from received scattered light In the apparatus of FIG. 1, when considering the scattered light generated in the measurement region 23, the microcolloid particles present in the measurement region 23 are When added, the flocs are slightly flocked, and the scattered light intensity increases with flocking.

  Accordingly, when the intensity of the scattered light in the minute measurement region 23 is measured using the sensor probe having the structure described above (the shielding member 22 shown in FIG. 2), as shown in FIGS. 5 (a) to 5 (c), Even if the number of fine colloid particles decreases and the number of flocs gradually increases, the number of flocs is much smaller than the decrease in suspended solids (microcolloids), so the minute measurement detected by the probe The average intensity of scattered light in the region 23 decreases. For this reason, the floc aggregation state detected by the probe is not the average intensity of the scattered light except when the intensity of the scattered light temporarily increases due to the floc rarely entering the minute measurement region 23. It can be regarded as indicating the number of particles of the aggregated suspended substance (microcolloid), ie, turbidity. In addition, the horizontal axis of Fig.5 (a)-(c) is a time axis, and t shows time.

  The minimum value detection circuit 8 described above is based on the above viewpoint, and detects the minimum value from the envelope component of the signal of the amplitude modulation frequency component obtained from the output of the photoelectric conversion circuit 6 according to the intensity of the scattered light. It is possible to detect the number (turbidity) of unaggregated fine colloids in the raw slurry. Further, the aggregation progresses and the fine colloidal particles become slightly flocked, and the intensity of scattered light in the minute measurement region 23 detected by the probe is increased by the flock. Therefore, it is possible to obtain the particle size information of the minute floc by capturing the change in the scattered light intensity until the minute floc is obtained.

  The scattering intensity is handled as the standard deviation of the detection signal measured by the sensor. Displayed as electrical signal mV. Usually, a change in scattering intensity is relatively detected, and a situation in which the particle size is large or small is detected.

3) Papermaking process water In the present invention, the papermaking process water to be measured includes paper raw slurry, slurry in the inlet, white water, and the like. Among these, the paper raw material slurry is a raw material slurry in a normal paper pulp process, and examples of the paper raw material in the raw material slurry include LBKP, NBKP, TMP, waste paper, DIP, and coat broke. A mixture of two or more of them may be used.
4) Fluid to be measured In the present invention, for the papermaking process water described in 3) above, the papermaking process water before the addition of the papermaking chemical described in 5) and the papermaking process water after the addition are used as fluids to be measured, and before the chemical addition. Measurements are made for both water and subsequent papermaking process water. And the effect evaluation of a medicine is performed by comparing the measured value before and behind medicine addition. In this case, if necessary, each papermaking process water may be diluted with the water for dilution in 6) and measured.

5) Papermaking chemicals The papermaking chemicals added to such papermaking process water are not particularly limited, and are cationic synthetic polymers or cationic synthetic polymers and anionic synthetic polymers that are usually used in the paper pulp process. Any combination of these, amphoteric synthetic polymers, etc. can be used. The amount of these papermaking chemicals added is usually appropriately determined according to the setting conditions of the paper pulp process to be treated and the properties of the raw slurry.

6) Dilution Water and Measurement Concentration In the measurement, the papermaking process water such as raw material slurry before and after the addition of the papermaking chemical may be used as it is, or may be diluted with water as necessary for measurement. In other words, when the pulp fiber concentration in the papermaking process water is excessively high, the irradiation light and scattered light from the anion trash component are likely to be disturbed by the pulp fiber present in a high concentration, so that the accuracy corresponding to the anion trash component is increased. Since it may not be possible to reliably obtain a measured value, the papermaking process water is diluted as necessary. The dilution factor is not particularly limited and can be arbitrarily determined. However, the solid content concentration of the papermaking process water used for the measurement is generally preferably in the range of 500 to 60000 mg / L. It is preferable to perform dilution so as to obtain such a concentration.

  There is no restriction | limiting in particular as water for dilution, Tap water, industrial water, middle water, the pressurization flotation of the white water, or the coagulation precipitation treated water etc. can be used.

7) Flow velocity The fluid to be measured at the time of measurement may be in a fluid state in order to prevent sedimentation of turbidity components and form a uniformly dispersed liquid, and may be stirred as necessary. The flow rate of the fluid to be measured is not particularly limited and varies depending on the concentration of the fluid to be measured. However, from the viewpoint of the stability of the measured value, 0.2 to 5.0 m / s, particularly 0.5 to The range is preferably 3.0 m / s.

8) Size of measuring unit The size of the measuring unit is such that the distance from the laser light emitting surface to the wall surface (in FIG. 1, the distance between the tip of the laser light irradiation unit 3 and the inner wall surface of the measuring tank 20) is 1 cm or more away. Preferably it is. If this distance is shorter than 1 cm, reflection of laser light on the wall surface may affect the measurement value, which is not preferable.

9) Location for Collecting Fluid to be Measured In the present invention, papermaking process water such as paper raw material slurry may be extracted from a predetermined location in the paper pulp process, and measurement may be performed with an apparatus as shown in FIG. Alternatively, measurement may be performed by directly putting the shielding member 22 shown in FIG. 4 into a predetermined portion of the paper pulp process. In the case where the measurement is performed by extracting papermaking process water from the paper pulp process, it is preferable that the apparatus shown in FIG.

10) Measurement interval Measurement may be performed continuously or intermittently. The measurement frequency in the case of intermittent measurement may be arbitrarily set as long as the transition of the drug effect can be confirmed, and can be set to, for example, a measurement frequency once every 1 to 2 hours. When the measurement is not performed, for example, water may be supplied to the measurement tank to clean the laser light irradiation unit / light receiving unit described later.

11) Calibration curve Normally, the change in the drug effect is detected by relatively detecting the minimum value of the electrical signal of the scattered light and the change in the scattering intensity. However, the sample solution in which the minimum value of the electrical signal and the scattering intensity are known in advance. The same measurement is performed using the above, a calibration curve showing the relationship with the measurement value is prepared, and the measurement value is applied to this calibration curve to determine the effect of the drug in the papermaking process water and to control the chemical injection. It can be carried out.

12) Cleaning of measuring unit It is preferable to periodically clean the laser beam irradiation unit and the scattered light receiving unit used for measurement in order to prevent a decrease in measurement accuracy due to adhesion of dirt. This irradiating part / light receiving part can be cleaned with air or water.

  In the case of cleaning with compressed air, it is performed in a gas-liquid mixed state by air diffusion in the raw material slurry that is the liquid to be measured. The cleaning time is not particularly limited, but 3 to 5 seconds is preferable for each of the laser beam irradiation unit / light receiving unit from the viewpoint of measurement stability. Although there is no particular limitation on the cleaning interval, cleaning is preferably performed at intervals of 40 to 120 seconds for each of the laser beam irradiation unit / light receiving unit from the viewpoint of measurement stability. The washing pressure is not particularly limited, but a pressure of 0.01 MPa or more is preferable from the viewpoint of measurement stability, and more preferably 0.05 to 0.5 MPa.

  In the case of washing with water, the sensor tip is washed with high-pressure water, or fresh water is passed through the measurement tank at a flow rate of 0.5 m / second or more to clean the measurement tank and the sensor tip. The washing time is preferably about 3 to 60 seconds per time in the case of high-pressure water, and 130 seconds or more per time in the case of water flow.

13) Maintenance The apparatus of the present invention described above preferably checks the cleanliness of the laser beam irradiation unit / light receiving unit and the brightness of the irradiated laser beam at a frequency of once a month or once a week. The maintenance frequency can be arbitrarily determined according to the situation.

14) Chemical injection control of papermaking chemicals The chemical injection effect information obtained by the paper chemical effect monitoring apparatus and method of the present invention is output as an output signal, and based on this signal, chemical injection pumps and raw materials are output. It is possible to maintain the optimum chemical injection conditions by controlling the slurry feed pump.

  That is, for example, it may be used in combination with the method for increasing or decreasing the dosage from the lowest signal intensity described above, and the dosage may be increased or decreased by the information from the scattered light intensity signal of the present invention, or the scattering according to the present invention. You may control by increasing / decreasing a chemical injection amount only by the information from a light intensity signal.

Specifically, the following chemical injection control can be performed.
Below, the example of application to the slurry in an inlet as papermaking process water is demonstrated.
Start paper production with normal machine operation, and achieve a stable production state with optimal dosage. At this time, the sampling pipe for the slurry in the inlet before the addition of the yield improving agent and the sampling pipe for the slurry in the inlet after the addition of the yield improving agent are branched, and the sensor measuring tank and the flow path in which the sensor probe is mounted. Is connected via a valve that can be switched. That is, piping is performed so that the slurry in the inlet before and after the addition of the yield improver can be alternately measured by switching the valve. The slurry in the inlet after measurement is returned to the white water bit. After confirming that a predetermined flow velocity is secured in the laser emission section in the sensor measurement tank, measurement of the scattering intensity and measurement of the minimum value of the sensor output signal are started. As an example, measurement with a 200 mS intermittent emission laser once every 2 seconds will be described.

(1) Control using particle size information For the slurry in the inlet before addition of the chemical, the scattering intensity every 2 seconds is measured for 5 minutes, and the average value of the scattering intensity is used as the particle size information. Repeat the same operation 5 times and confirm the average of the particle size information of 5 points. Usually, this value is about 30 to 50 mV. Similarly, the average of the particle size information of 5 particle size information obtained by measuring the scattering intensity every 2 seconds for 5 minutes and averaging the slurry in the inlet after the addition of the drug is confirmed. Usually, this value is about 80 to 150 mV. These change widths are changes in the properties of the slurry in the inlet resulting from changes in raw materials and SS concentrations. The sensor measurement alternately measures the particle size information of the slurry in the inlet before and after the addition of the drug at arbitrary intervals. Since the state before and after the addition of the drug is always monitored, measurement can be performed without being affected by fluctuations in the properties of the slurry in the inlet. In addition, the output% of the inverter pump that is injected with the yield-improving agent in an optimal and stable production state is assumed to be the current value.

  As a control method, scattering intensity after drug injection (mV) −scattering intensity before drug injection (mV) = deviation (mV), for example, when 80 <deviation ≦ 100, the output of the inverter pump remains at the current value and 50 <deviation Current value + 20% when ≦ 80, current value + 30% when 30 <deviation ≦ 50, current value + 50% when deviation ≦ 30, current value −20% when 100 <deviation By incorporating a general program in the sensor in advance and outputting a control signal from the sensor to the inverter pump, it is possible to perform chemical injection control according to the particle size information. The output frequency to the inverter pump with respect to the measurement frequency and the deviation at this time can be arbitrarily determined according to the condition variation in actual manufacturing.

(2) Control using turbidity information For the slurry in the inlet before chemical addition, measure the sensor output minimum value every 2 seconds for 5 minutes, and use the average value as turbidity information. Repeat the same operation 5 times and check the average of 5 points of turbidity information. Usually, this value is about 4000 to 5000 mV. Similarly, the average of the turbidity information of 5 points of turbidity information obtained by measuring the scattering intensity every 2 seconds for 5 minutes and averaging the slurry in the inlet after the addition of the chemical is confirmed. Usually, this value is about 2000 to 4000 mV. These change widths are changes in the properties of the slurry in the inlet resulting from changes in raw materials and SS concentrations. The sensor measurement alternately measures the turbidity information of the slurry in the inlet before and after the addition of the drug at arbitrary intervals. Since the state before and after the addition of the drug is always monitored, measurement can be performed without being affected by fluctuations in the properties of the slurry in the inlet. In addition, the output% of the inverter pump that is injected with the yield-improving agent in an optimal and stable production state is assumed to be the current value.

  As a control method, the sensor output minimum value before drug injection (mV) −the sensor output minimum value after drug injection (mV) = deviation (mV). For example, when 2000 <deviation ≦ 3000, the output of the inverter pump remains the current value. When 1500 <deviation ≦ 2000, current value + 20%, when 1000 <deviation ≦ 1500, current value + 30%, when deviation ≦ 1000, current value + 50%, when 3000 <deviation, current value−20%, Such a general program is incorporated in the sensor in advance, and a control signal is output from the sensor to the inverter pump, thereby enabling chemical injection control according to the turbidity information. The output frequency to the inverter pump with respect to the measurement frequency and the deviation at this time can be arbitrarily determined according to the condition variation in actual manufacturing.

  Hereinafter, the present invention will be described more specifically with reference to comparative examples and examples.

In the following comparative examples and examples, the following were used as additive chemicals and papermaking process water.
1) Drug: Cationic synthetic polymer Structure / Composition: Dimethylaminoethyl acrylate methyl chloride quaternized / acrylic
Amide = 25/75 (mol%)
Intrinsic viscosity: 13.5 (dl / g) (solvent = 1N NaCl (30 ° C.))
・ Use concentration: 0.2wt%
Addition rate: 0 to 5.6 mg / l (vs. slurry)
2) Papermaking process water: slurry in the inlet ・ Concentration: 6850 mg / l
・ Appearance: White slurry containing fiber

(Comparative Example 1)
The filtrate amount was measured by the following procedure.
(1) 180 ml of the slurry collected from the inlet was placed in a 500 ml beaker, and a predetermined amount of drug was added.
(2) The mixture was stirred with a stirrer at 500 rpm for 40 seconds.
(3) The above solution (2) was immediately put into a Nutsche funnel covered with a 60 mesh nylon filter cloth, and the amount of filtered water for 10 seconds was measured.
(4) The relationship between the drug addition rate of (1) and the amount of filtrate measured in (3) is shown in FIG.

Example 1
Using the apparatus shown in FIG. 1, the scattered light intensity was measured by the following procedure.
(1) 1800 ml of the slurry collected from the inlet was placed in a 3000 ml beaker, and a predetermined amount of drug was added.
(2) The mixture was stirred with a stirrer at 500 rpm for 40 seconds.
(3) A sensor probe (laser member 22 shown in FIG. 2) of laser scattered light was immersed in the liquid (2), and measurement was performed with a sensor under stirring at 250 rpm (flow rate 1.3 m / s). The measurement items are the difference in the minimum value of the electrical signal of the scattered light measured for the slurry in the inlet before and after the addition of the drug (hereinafter referred to as “turbidity information (mV)”), and the difference in the scattering intensity (hereinafter referred to as “particle size”). In the information method (mV) ”, laser light was emitted at intervals of 2 minutes for 200 milliseconds, and the average value of scattering intensity for 120 seconds was obtained.
(4) In the analysis, the difference between the measured value when no drug was added (0 mg / l) and the measured value when the drug was added was determined, and the relationship with the normal drainage test results shown in the comparative example was arranged.

  FIG. 7 shows the relationship between the drug addition rate and the difference in turbidity information (mV) between the case of drug addition and the case of no drug addition. FIG. 7 shows the drug addition rate and the particle size when the drug is added and when no drug is added. The relationship with the difference in information (mV) is shown in FIG.

Further, FIG. 9 shows the relationship between the filtrate amount of Comparative Example 1 at the same drug addition rate and the difference in turbidity information (mV) between the case of drug addition and the case of no drug addition, and Comparative Example 1 at the same drug addition rate. FIG. 10 shows the relationship between the amount of the filtrate and the difference in particle size information (mV) between when the drug was added and when no drug was added.
These results are summarized in Table 1.

  From these results, a clear correlation was found between the turbidity information and the particle size information obtained from the difference in the electrical signal of the scattered light and the scattering intensity measured for the papermaking process water before and after the addition of the chemical and the amount of filtrate. It was confirmed that the minimum value of the scattered light intensity of the laser light and the electrical signal of the scattered light detected by the sensor detected the size and turbidity of the fine floc of the slurry in the inlet due to the addition of the chemical.

  Based on this result, by using a laser light scattering method sensor, the scattered light intensity and the minimum value of the electrical signal of the scattered light are measured for the paper making process water before and after the addition of the drug according to the present invention, thereby adding the steps added to the paper making process water. It can be seen that the effect of a drug such as a retention aid can be continuously monitored.

It is a block diagram which shows schematic structure of the effect monitoring apparatus of the papermaking chemical | medical agent which concerns on embodiment. It is an enlarged view which shows the structure of the laser beam irradiation part and scattered light light-receiving part which were shown in FIG. It is a perspective view of the shielding member 22 shown in FIG. It is an enlarged view which shows the other structural example of a laser beam irradiation part and a scattered light light-receiving part. It is a schematic diagram which shows the mode of the change of the scattered light intensity in a micro measurement area | region accompanying aggregation of a micro colloid particle. 6 is a graph showing a relationship between a drug addition rate and a filtrate amount in Comparative Example 1. It is a graph which shows the relationship between the chemical | medical agent addition rate in Example 1, and the difference of the turbidity information (mV) in the case of chemical | medical agent addition and the case of no chemical | medical agent addition. It is a graph which shows the relationship between the chemical | medical agent addition rate in Example 1, and the difference of the particle size information (mV) in the case of chemical | medical agent addition and the case of no chemical | medical agent addition. It is a graph which shows the relationship between the amount of filtrate of the comparative example 1 in the same chemical | medical agent addition rate, and the difference of the turbidity information (mV) in the case of the chemical | medical agent addition in Example 1, and the chemical | medical agent non-addition. It is a graph which shows the relationship between the amount of filtrate of the comparative example 1 in the same chemical | medical agent addition rate, and the difference of the particle size information (mV) in the case of chemical | medical agent addition in Example 1, and the case of no chemical | medical agent addition.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 1st optical fiber 3 Laser irradiation part 4 Scattered light light-receiving part 5 2nd optical fiber 6 Photoelectric conversion circuit 7 Detection circuit 8 Minimum value detection circuit 11 Function generator 12 Laser diode 20 Measurement tank 22 Shielding member 23 Measurement Region 24 Groove 61 Photodetector 62 Bandpass filter 63 Amplifier

Claims (2)

In the method of monitoring the effect of the papermaking chemicals added to the papermaking process water,
A first step of irradiating the fluid to be measured with amplitude-modulated (AM) laser light having a predetermined frequency (hereinafter referred to as “modulation frequency”), using papermaking process water or diluted water thereof as a fluid to be measured;
A second step of receiving scattered light scattered by particles in the fluid to be measured by a photoelectric conversion circuit to obtain scattered light intensity data;
Based on said scattered light intensity data observed including a third step of obtaining a particle size information and / or turbidity information of particles in the fluid to be measured,
The photoelectric conversion circuit includes a photo detector, a band pass filter, and an amplifier, converts the optical signal of the scattered light into an electric signal by the photo detector, and distinguishes it from natural light by the band pass filter. After being amplified by the amplifier, AM detection is performed by the detection circuit, and the detected signal is output to the minimum value detection circuit. The minimum value detection circuit receives the minimum signal from the input signal after AM detection. A method for monitoring the effect of a papermaking drug to obtain the scattered light intensity data by detecting a signal intensity of a value ,
Using the papermaking process water before the addition of the drug as the papermaking process water, particle size information and / or turbidity information obtained through the first to third processes,
By using the papermaking process water after the addition of the drug as the papermaking process water, comparing the particle size information and / or turbidity information obtained through the first to third processes, before and after the drug addition And a fourth step of obtaining the comparison data. In the method of controlling the amount of papermaking chemicals injected into the papermaking process water,
A first step of irradiating the fluid to be measured with amplitude-modulated (AM) laser light having a predetermined frequency (hereinafter referred to as “modulation frequency”), using papermaking process water or diluted water thereof as a fluid to be measured;
A second step of receiving scattered light scattered by particles in the fluid to be measured by a photoelectric conversion circuit to obtain scattered light intensity data;
Based on said scattered light intensity data observed including a third step of obtaining a particle size information and / or turbidity information of particles in the fluid to be measured,
The photoelectric conversion circuit includes a photo detector, a band pass filter, and an amplifier, converts the optical signal of the scattered light into an electric signal by the photo detector, and distinguishes it from natural light by the band pass filter. After being amplified by the amplifier, AM detection is performed by the detection circuit, and the detected signal is output to the minimum value detection circuit. The minimum value detection circuit receives the minimum signal from the input signal after AM detection. A method for controlling the amount of injection of a papermaking drug to obtain the scattered light intensity data by detecting a signal intensity of a value ,
Using the papermaking process water before the addition of the drug as the papermaking process water, particle size information and / or turbidity information obtained through the first to third processes,
By using the papermaking process water after the addition of the drug as the papermaking process water, comparing the particle size information and / or turbidity information obtained through the first to third processes, before and after the drug addition A fourth step of obtaining comparison data of
And a fifth step of controlling the injection amount of the papermaking drug based on the comparison data.

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