KR101474264B1 - Method for controlling addition amount of internal chemical and method for measuring concentration of suspended substances - Google Patents

Abstract

It is an object of the present invention to provide a method and an apparatus for determining the concentrations of insoluble suspensions (SS) and ash contents and appropriately adjusting the respective yields according to each product trademark, thereby stabilizing the product quality and improving productivity The present invention provides a method for controlling the amount of addition of A method for controlling the addition amount of an internal medicine is characterized by comprising the steps of: collecting white water generated in a wire part (55) of a paper machine under a predetermined operating condition by using a turbidity measurement unit (30) A step of measuring the turbidity of turbid water (M1) at the time of stirring, a step of measuring the turbidity of the collected white water at the time of stopping as the turbidity equivalent turbidity (M2), and the turbidity- And adjusting the amount of the added drug to be added.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method for controlling the addition amount of an internal drug, and a method for measuring the concentration of a suspended substance. BACKGROUND OF THE INVENTION < RTI ID = 0.0 >

The present invention relates to a method for controlling the addition amount of an internal medicine in a papermaking process for producing paper from a pulp slurry and a method for measuring the concentration of a suspended substance .

Generally, in pulp making, paper pulp is finally pulp slurred through processes such as bleaching, beating, mixing, dilution, etc., and then pulverized by a paper machine And is dehydrated by the wire part. When the pulp slurry is dewatered on the wire, the water filtered down the wire is usually called white water. This white water can be recycled as a raw material for recovery (recycled raw material) or diluted water (circulated water) by circulating the papermaking system and the raw material system (raw material system). However, in the white water, Fuels), eluates from pulp, and remnants of chemicals used in the bleaching process.

When the yield of the raw material in the wire part of the paper machine is lowered, the turbidity of the white water in the white water pit which collects the white water passed without being captured by the wire rises. Here, the turbidity of white water depends mainly on the amount of dispersion (amount of dispersion) of insoluble suspension (SS), that is, pulp fiber having a length of 20 μm or more. When the turbidity of the white water rises, the fluidity of the pipeline through which the white water flows causes slime easily to occur. This grows and adheres to white water silo or piping inside, which causes defects such as product defects and stains.

In this regard, in order to make the yield of the insoluble suspension (SS) constant, the concentration of the white water generated in the wire part of the paper machine is detected, and when the concentration of the white water detected is within a predetermined operating condition The concentration of the white water in the stable state is set as the target concentration, and then the yield of the yield water is increased so that the concentration of the detected white water becomes the target concentration (See Patent Document 1).

On the other hand, as the suspended material contained in the pulp slurry, a fine ash (a suspended material having a length of less than 20 m) such as calcium carbonate or talc added as a charge other than an insoluble suspension (SS) Lt; / RTI > When the yield of the ash is excessively increased, a large amount of ash is mixed in the product, and in the dryer part of the next step, the ratio of the ash adhered to the surface of the dryer cylinder rather than the paper surface . As a result, surface contamination of the dryer cylinder occurs in a short time, resulting in contamination of the product and unevenness in the degree of drying. Also, the operation rate may be lowered by stopping (stopping) the paper machine due to the cleaning of the dryer cylinder. Therefore, as to the ash, it is necessary to make the yield constant in the same manner as in the case of insoluble suspensions (SS), but conventionally, it has been difficult to control the ash because there is no method for measuring it.

Patent Document 1: JP-A-10-325092

As described above, as the suspended material contained in the raw material, ash is present in addition to the insoluble suspension (SS), there is a method of adjusting the added amount of the additive such as the yield improving agent according to the concentration of the white water, that is, the concentration of the insoluble suspension There is a problem in that the yield of the ash can not be controlled. In addition, since the paper mill manufactures a plurality of branded products in a short period of time, the yield of optimum batches also varies depending on the product brand, so that the quality control is not easy, there is a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a process for producing a solid product, which is capable of determining the concentration of each insoluble suspension (SS) and ash and appropriately adjusting the yield according to each product trademark, And a method for measuring the concentration of a suspended solid substance.

The present inventors have found that the turbidity of white water at the time of stirring is correlated with the concentration of insoluble suspensions and the turbidity of white water at the time of stop is correlated with the concentration of ash, thereby completing the present invention. Specifically, the present invention provides the following.

(1) A method for controlling the addition amount of an internal medicine in a paper making process for producing paper from a pulp slurry, comprising the steps of: collecting white water generated in the paper making process under predetermined operating conditions; A step of measuring the turbidity of the collected white water at the time of stop with the turbidity equivalent to the ash value measured on the basis of the measured turbidity corresponding to the insoluble suspension and the turbidity corresponding turbidity, And adjusting the amount of addition.

(2) calculating an insoluble suspension concentration of the collected white water based on the turbidity of the insoluble suspension measured in the collected white water, and The method according to claim 1, further comprising the step of calculating the ash concentration of the collected white water.

(3) The method according to (2), further comprising a step of performing drug infusion control of the insecticide capable of adjusting the insoluble suspension yield and ash yield in the papermaking step on the basis of the calculated insoluble suspension concentration and the ash concentration, ≪ / RTI >

(4) The method as described in (3), further comprising the step of: feedback-controlling the addition amount of the insoluble drug so that the calculated insoluble suspension concentration becomes the target insoluble suspension concentration and the ash concentration becomes the target ash concentration The way it is.

(5) A method for measuring the concentration of a suspended substance in a papermaking process for producing paper from a pulp slurry, comprising the steps of: collecting white water produced in the papermaking step; and stirring the turbidity of the collected white water as turbidity equivalent to an insoluble suspension A step of calculating an insoluble suspension concentration of the collected white water on the basis of the measured turbidity corresponding to the insoluble suspension and a step of measuring the turbidity of the collected white water at a time of stopping with the turbidity equivalent turbidity collected And a step of calculating the ash concentration of the collected white water based on the measured ash turbidity.

According to the present invention, the insoluble suspension (SS) concentration and the ash concentration are respectively determined, and the yields of the insoluble suspensions (SS) and ash are appropriately adjusted according to each product trademark, Can be saved. It is also possible to efficiently use one turbidity unit to measure the turbidity of the collected white water under different conditions at the time of stirring and at the time of stopping. In this case, the insoluble suspension (SS) concentration and the ash concentration are appropriately So that the configuration of the measurement system can be simplified.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an example of a papermaking process to which a method of controlling the amount of added chemicals to be added according to an embodiment of the present invention is applied.
2 is a schematic view showing the outline of a medicine injection system equipped in the paper making process shown in Fig. 1;
3 is a diagram showing a schematic processing procedure of a method of controlling an addition amount of an internal medicine according to an embodiment of the present invention.
4 is a graph showing the relationship between the turbidity at the time of stirring and the concentration of insoluble suspension (SS) using the analytical instrument according to the method of controlling the addition amount of the internal additive according to the embodiment of the present invention.
5 is a graph showing the correlation between the turbidity at rest and the ash concentration using the analyzer according to the method of controlling the addition amount of the internal additive according to the embodiment of the present invention.
6 is a graph showing the correlation between the turbidity of the insoluble suspension (SS) and the yield of the insoluble suspension (SS) and the correlation between the ash turbidity and the ash yield according to the method of controlling the addition amount of the internal additive according to the embodiment of the present invention FIG.
7 is a diagram showing the correlation between ash concentration and ash concentration in each product trademark according to the method of controlling the addition amount of the internal additive according to the embodiment of the present invention.

Embodiments of the present invention will be described below, but the present invention is not limited thereto.

1 is a schematic diagram of a paper making process (paper making process) 10 relating to an example in which the method according to the present invention is carried out. Paper-making process 10 has a material-based (原料系) (40), the composition, second boundary (調成,抄紙系) (50), recovery system (回收系) (60), about the injection system (藥注入系) (20).

The raw material system 40 includes tanks 41, 42, 43 and 44 for storing the paper stock, a mixing chest 47, a machine chest 48, And a seed box (49). The composition and paper making system 50 includes a fan pump 51 for sending out pulp slurry supplied from the raw material system 40, a screen 52, a cleaner An inlet 54, a wire part 55, and a press part 56. The inlet part 54, the wire part 55, The composition and paper making system 50 is provided with a white water silo 58 for storing white water to be described later. The recovery system 60 further includes a sealing pit 61, a recovery device 62, a recovery water tank 63, an understanding water pump 64, , And a concentration-adjusted water pump (65).

The drug infusion system 20 further includes a turbidity measurement unit 30 for measuring the turbidity of the white water, an arithmetic processing unit 21 for controlling the addition amount of the internal medicine to the pulp slurry, An internal medicine tank 22a, 22b, and drug infusion pumps 23a, 23b.

The raw material system 40 is provided with a chemical pulp tank 41, a recycled pulp tank 42, a broke tank 43 and a recovery raw material tank 44 Chemical pulp such as softwood bleached kraft pulp (NBKP; Nadelholze Bleached Kraft Pulp) and hardwood bleached kraft pulp (LBKP; Laubholze Bleached Kraft Pulp), recycled pulp tank 42, A recycled pulp made of a slurry by a waste paper pulper 45 and a waste pulp such as a deinking pulp (DIP) or a corrugated cardboard waste conveyed from a deinking system, Pulp as a slurry by a broke pulper 46 and pulp feed tank 44 are subjected to solid-liquid separation (solid-liquid separation) of white water by a recovery device 62, As shown in Fig.

A device for manufacturing and supplying the paper stock may be provided upstream of the chemical pulp tank 41. That is, upstream of the chemical pulp tank 41, there may be provided a cooking pot for bleaching wood chips, a device for bleaching pulp, a screen for removing foreign substances, and the like. The broke tank 43 is supplied with the broke pulp generated after the press part 56.

Under the pulp pulp 45 and the brook pulper 46, the understood water for understanding the pulp and the break is supplied from the understood water pump 64. The recycled pulp, broke pulp, chemical pulp and recovered raw material, which are understood by the pulpers 45, 46, are merged with the concentration adjusting water (concentration adjusting water) for adjusting the concentration from the concentration adjusting water pump 65 and stored do. As the water of understanding and the concentration adjusting water, filtrate of filtered white water is used in the present embodiment, but untreated filtered white water, clear water, and slurry of the raw material system 40 are dehydrated or squeezed water ), And a surplus water of another process may be used.

The pulp contained in the chemical pulp tank 41, the recycled pulp tank 42, the brook tank 43 and the recovery raw material tank 44 is supplied to the mixing chest 47 at an appropriate ratio according to the trademark to be produced, And mixed in the chest 47. The mixed pulp is conveyed to the seed box 49 after the papermaking chemicals are added in the machine chest 48.

The pulp contained in the seed box 49 is sequentially fed to the screen 52 and the cleaner 53 by the fan pump 51 of the composition / paper-making system 50 together with the filtered white water from the white water silo 58 And is supplied to the inlet 54 after the foreign matter is removed. The inlet 54 feeds pulp to the wire of the wire part 55 at an appropriate concentration, speed and angle. The pulp is fed, the water is dehydrated at the wire part 55, the press part 56, a reel, wine, which are not shown in the figure via the further (reel-winder) is made of paper.

The water dehydrated from the pulp in the wire part 55 and the press part 56 is supplied to the wire part 55 as white water and the white water pit 57 disposed in the lower part (lower part) of the press part 56 . The white water contained in the half pits 57 flows into the white water silo 58 through a conduit (conduit) 59 and is stored there. A part of the white water stored in the white water silo 58 is supplied to the fan pump 51 and the remaining white water is supplied to the sealing pit 61. The white water fed to the fan pump 51 dilutes (dilutes) the pulp slurry in the composition / paper machine 50. The white water supplied to the sealing pit 61 is transferred to the recovery device 62, filtered by the recovery device 62 and solid-liquid separated to recover the filtrate to the recovery water tank 63.

Here, the pulp slurry supplied from the inlet 54 to the wire part 55 is composed of an insoluble suspension (insoluble suspension) (SS) that is a suspended material (suspended material), that is, (Ash) (suspended solids having a length of less than 20 μm) such as calcium carbonate or talc which is added as a raw material. These insoluble suspensions (SS) and ash are captured by the wire part 55, respectively, and the remainder is filtered under the wire and dispersed into the white water. Therefore, white water includes fine ash (suspended solids having a length of less than 20 탆) such as calcium carbonate or talc added as a feed, in addition to insoluble suspension (SS), that is, pulp fiber having a length of 20 탆 or more as a suspension material.

Hereinafter, the drug infusion system 20 will be described.

The internal medicine tank 22a containing the medicines A is disposed in the downstream side of the fan pump 51 via the medicament injection pump 23a and the internal medicine tank 22b containing the medicines B, Are connected to each other through a drug infusion pump 23b. The medicine infusion pumps 23a and 23b are electrically connected to the output side of the arithmetic processing unit 21 constituting the control unit described later and the turbidity measurement unit 30 is electrically connected to the input side of the arithmetic processing unit 21. [

The turbidity measurement unit 30 measures the turbidity of the white water by taking the white water from the conduit 59 connected to the white water pit 57 and transfers the measurement result to the calculation processing unit 21. The calculation processing section 21 operates the medicine infusion pumps 23a and 23b in accordance with the measurement result to calculate the amount of the infusion medicine A in the infusion medicine tank 22a for the pulp slurry and the infusion amount of the medicine A in the infusion medicine tank 22b, The amount of the injected medicines B is controlled.

In the papermaking process, a yield improving agent, a coagulating agent, a paper force agent and the like are used as an internal medicine. When the amount of these added is changed, the yield of the suspended material in the wire part 55 is changed. That is, for example, when the addition amount of the yield improving agent is increased, the yield of the insoluble suspension (SS) is improved, and the yield of the ash is slightly improved. On the other hand, increasing the addition amount of the coagulant improves both the yield of the insoluble suspension (SS) and the yield of the ash (although excessive use of the coagulant exacerbates the overall condition of the product). In addition, increasing the amount of addition of the power agent increases the yield of the insoluble suspension (SS) and the yield of the ash together.

The drug (A) may be suitably selected from drugs capable of adjusting the yield of the insoluble suspension (SS) in the wire part (55) by adjusting the injection amount of the drug (A) and may be a yield improving agent. The additive drug (B) is suitably selected from among drugs capable of adjusting the yield of ash in the wire part (55) by adjusting the injection amount of the drug (B), and may be a coagulant.

It is also shown here that when the additive chemicals A and B are added to the pulp slurry, they are injected into the composition / paper-making system 50 downstream of the fan pump 51. However, (For example, the machine chest 48) may be injected into any part of the composition / papermaking system 50 from the raw material system 40, or may be injected into a plurality of these parts.

Fig. 2 is a schematic view showing the outline of the medicine infusion system 20 equipped in the paper making step 10 shown in Fig.

The turbidity measurement unit 30 is configured to collect white water from the conduit 59 in a predetermined order, store the white water in the measurement vessel 31, and measure the turbidity. Specifically, the turbidity measurement unit 30 includes a supply system (supply system) 37 (sampling system) having a sampling pump 33 for pumping up the white water flowing through the conduit 59 and supplying the white water to the measurement vessel 31 And a circulation system (circulation system) 38 which flows out of the measurement container 31 and returns the same to the conduit 59. The supply system 37 and the circulation system 38 are provided with a supply valve 34 and a circulation valve 35 controlled to be selectively opened and closed by the calculation processing unit 21 respectively and the turbidity measurement unit 30 The opening and closing control of the supply valve 34 and the circulation valve 35 and the operation control of the sampling pump 33 can be performed to collect the white water flowing through the conduit 59 into the measuring container 31.

When the sampling pump 33 is of a positive displacement type, the supply valve 34 is unnecessary, and the measurement vessel 31 is in an open system and overflows the collected liquid The circulation valve 35 is also unnecessary. In this embodiment, the white water is taken from the conduit 59, but the white water may be taken directly from the white water pit 57.

The turbidity measurement unit is preferably one as in the present embodiment from the viewpoint of simplification of the system configuration, but may be plural. Since the turbidity at the time of stirring and the turbidity at the time of stop are measured in separate containers when a plurality of turbidity measurement units are employed, both turbidity can be measured in parallel without waiting for the time to stop .

The measuring container 31 has a depth of about 0.3 to 1.5 m, for example, and has a volume to store about 20 to 1,000 L, preferably about 30 to 50 L, of white water. And a drain valve 36 constituting a drainage system. The turbidity at the upper part of the white water stored in the measurement container 31 is measured at an upper portion (upper portion) of the inner wall surface of the measurement vessel 31, for example, at a position 50 to 200 mm below the water surface And a turbidity sensor 32 for measuring the turbidity is provided. The turbidity sensor 32 may be, for example, an absorbance sensor (absorbance sensor), a reflected light sensor (reflected light sensor), or a transmitted light sensor (transmitted light sensor). A water surface sensor (not shown) for detecting that the water level of the white water reaches the full water level position is installed at the full water level position (full water level position) of the inner wall surface of the measurement vessel 31 .

A water jet nozzle or a wiper (not shown) for cleaning the periphery of the turbidity sensor 32 or its sensor surface is provided in the vicinity of the turbidity sensor 32 A cleaning mechanism (washing mechanism) 39 is provided. The cleaning mechanism 39 measures the turbidity of the white water collected in the measurement container 31 by the turbidity sensor 32 and then drains the white water by opening the drain valve 36, And cleans the sensor surface or the periphery of the sensor 32 to keep the inside of the measurement container 31 clean.

Here, the supply rate of the supply system 37 (and the discharge rate of the circulation system 38) [L / sec] and the capacity [L] of the measurement vessel 31 are set such that the white water in the measurement vessel 31 is supplied to the supply system 37 (Water stream) flowing in from the water tank (not shown).

The arithmetic processing unit 21 calculates the injection amount of the additive chemicals A and B into the pulp slurry on the basis of the turbidity of the white water collected in the measurement vessel 31 and measured by the turbidity sensor 32 as described above . The calculation processing unit 21 optimizes and controls the injection amount of the internal medicine A in the internal medicine tank 22a and the injection amount of the internal medicine B in the internal medicine tank 22b, respectively.

Fig. 3 is a diagram showing a schematic processing procedure of a method for controlling the amount of added chemicals to be added according to the embodiment of the present invention. Hereinafter, the injection amount control (injection amount control) of the injected medicine by the arithmetic processing unit 21 will be described with reference to FIG.

This processing for controlling the injection amount of the injected medicine is performed in such a manner that the measurement vessel 31, the supply valve 34 and the circulation valve 35 and the drain valve 36 are connected to the " measurement vessel 31: beam, drain valve 36: The supply valve 34 and the circulation valve 35 are in the initial state and the supply valve 34 and the circulation valve 35 are opened (Step S2), and then feeding the white water from the conduit 59 via the supply system 37 to the measurement vessel 31 by operating the sampling pump 33. At the same time, a timer, not shown in the figure, provided in the arithmetic processing unit 21 is activated according to the start of supply of the white water to the measurement vessel 31, and the supply time is measured.

The amount of the white water stored in the measuring container 31 is increased by supplying the white water and the white water exceeding the capacity of the measuring container 31 reaches the circulation system 38 when the white water stored in the measuring container 31 reaches full water. To the conduit (59). In this state, the supply amount of the white water to be supplied to the measurement container 31 becomes equal to the outflow amount of the white water to be discharged from the measurement container 31, and the water surface position of the white water in the measurement container 31 is maintained at the full water position. At this time, the white water stored in the measurement vessel 31 is in a state of being stirred by supplying the white water continuously to the measurement vessel 31.

When the supply time reaches the predetermined time t1, that is, when the white water is supplied over the time t1 and the white water in the measurement vessel 31 becomes full (step S3) (Preferably the absorbance of the white water) of the white water is measured using the infrared sensor 32 (step S4).

As described above, since the white water stored in the measurement vessel 31 at this time is in the stirring state by continuous supply of white water, the turbidity measured is the " turbidity at the time of stirring " ) Equivalent turbidity and has a correlation with the insoluble suspension (SS) concentration of white water.

Here, the predetermined time t1 is a time required for the water surface position of the white water in the measurement container 31 to reach a predetermined full height on the basis of the volume of the measurement container 31 and the supply rate of the white water, Is set. In this case, it is detected that the water level position of the white water reaches the full water level by the elapse of the predetermined time (t1) by starting the timer in addition to the start of the supply of the white water. However, instead of or in combination with the timer, (Not shown) installed at the full water level position of the water level sensor (not shown).

The sampling pump 33 is stopped next (step S5), and the supply valve 34 and the circulation valve 35 are closed with the drain valve 36 closed. When the measurement of the turbidity of " (Step S6), thereby stopping the supply of the white water to the measurement container 31 and the outflow of the white water from the measurement container 31. Then, the white water stored in the measuring container 31 is allowed to stand by the supply of the white water and the stop of the outflow.

The turbidity sensor 32 disposed at the position for measuring the turbidity at the upper part of the white water stored in the measurement vessel 31 as described above is used simultaneously with the start of the white water stored in the measurement vessel 31, Continuous measurement of turbidity (preferably absorbance of white water) is started (step S7). The continuous measurement of the turbidity of the white water may be performed by sampling the measurement value of the turbidity sensor 32 at a predetermined sampling frequency (for example, sampling frequency = 0.1 to 5 Hz).

When a sufficient time has elapsed after the start of the measurement and the continuous measurement value of the turbidity of the white water is stable (for example, when the rate of change of the continuous measurement value is less than or equal to a predetermined value), the end point is determined ), And the stabilized measured value is set as the "turbidity at stop" of the number of millions (step S9). As will be described later, the "suspended turbidity" of the white water has a correlation with the ash concentration of white water as a turbidity equivalent turbidity. The predetermined value of the rate of change defining the stopping time is apt to obtain a turbidity correlated with a higher correlation with the ash concentration, but when the turbidity is measured at the stop while the increase in the correlation is saturated even if the turbidity is too low (Standby time) from the standby state to the standby state is prolonged (prolonged). For this reason, the specific value is appropriately set based on the balance of the accuracy of the required control and the efficiency, but may be set as the end point at which the rate of decrease becomes 1 NTU (Nephelometric Turbidity Unit) / minute or less, for example.

Thereafter, the drain valve 36 is opened and all of the white water stored in the measurement vessel 31 is drained (step S10). Further, the cleaning mechanism 39 is operated so that the sensor surface of the turbidity sensor 32, And the interior of the measurement container 31 is cleaned (step S11), whereby the initial state can be restored.

After that, the steps described above are repeatedly carried out in a batch to control the turbidity of turbidity of turbidity and the turbidity at rest continuously. That is, the drug infusion system 20 can continuously measure in real time the " turbidity at the time of agitation " and the " turbidity at rest " of the white water generated in the wire part 55 and the press part 56.

The calculation processing section 21 obtains the measured value M1 as information for grasping the insoluble suspension (SS) concentration of white water when measuring the turbidity of the white water using the turbidity sensor 32, It is based on the following reasons.

That is, when the white water is sufficiently stirred in the measurement vessel 31, the insoluble suspension (SS) and the ash are dispersed in the white water without sedimentation. Since the particle size (particle size) of the insoluble suspension (SS) is larger than the particle size of the ash, when the turbidity of the white water is measured in the stirred state, the turbidity of the insoluble suspension (SS) The influence is dominant and the influence of the ash content (concentration) is small. Therefore, since the "turbidity at the time of stirring" has a correlation with the insoluble suspension (SS) concentration of the white water, the measurement value M1 of the "turbidity at the time of stirring" of the white water measured using the turbidity sensor 32 is referred to as " (SS) equivalent turbidity ", it can be obtained as information for grasping the insoluble suspension (SS) concentration of white water.

Here, the "turbidity at stirring" [NTU] of white water has a positive correlation with the insoluble suspension (SS) concentration [mg / L] of white water as described later. Therefore, in the calculation processing section 21, in the memory not shown in the drawing in the arithmetic processing section 21 based on the measurement value M1 [NTU] of the "turbidity at the time of agitation" of the white water measured using the turbidity sensor 32 The corresponding insoluble suspension (SS) concentration D1 (mg / L) is calculated along the stored calibration curve. (SS) concentration (D1) [mg / L] according to the calculated insoluble suspension (SS) concentration target value (T1) [mg / (Step S12), by adjusting the injection amount of the insoluble suspension (SS) to adjust the yield of the insoluble suspension (SS). Here, the predetermined insoluble suspension (SS) concentration target value T1 (NTU) is a predetermined value, but may be a predetermined numerical range. Then, the medicine infusion pump 23a is controlled in accordance with the optimum infusion amount to adjust the infusion amount of the infusion medicine A to be injected into the pulp slurry (step S13).

On the other hand, the arithmetic processing unit 21 obtains the measured value M2 as information for grasping the ash concentration of the white water when measuring the turbidity of the white water using the turbidity sensor 32, .

That is, when the white water is settled, the insoluble suspension (SS) having a relatively large particle size dispersed in the white water rapidly precipitates, while the ash with a relatively small particle size hardly precipitates, and the white water is gradually separated into solid and liquid. As described above, when the turbidity of the white water (supernatant liquid portion) is continuously measured by the turbidity sensor 32 while the white water stored in the measurement container 31 is being continuously measured, the turbidity of the insoluble suspension SS The turbidity measurement is reduced. When the measured value of the turbidity is stable after a sufficient time has elapsed since the start of the measurement (for example, when the rate of change of the continuous measurement value is less than a predetermined value) as the end point, the stable measurement value is set to "turbidity at rest" . Therefore, the "suspended turbidity" of the white water has a correlation with the ash concentration without being affected by the insoluble suspension (SS) concentration. Therefore, the "suspended turbidity" of the white water measured using the turbidity sensor 32 Can be obtained as information for grasping the ash concentration of the white water as the " ash-dependent turbidity ".

Here, the "turbidity at rest" [NTU] of white water has a positive correlation with the ash concentration [mg / L] of white water as described later. Therefore, in the calculation processing unit 21, the calculation processing unit 21 calculates the turbidity of the turbidity measured by the turbidity sensor 32 based on the measurement value M2 [NTU] of turbidity at the turbidity measured by the turbidity sensor 32 And calculates the corresponding ash concentration D2 [mg / L] along the stored calibration curve. The injection amount is adjusted so that the ash concentration D2 [mg / L] becomes the predetermined ash concentration target value T2 [NTU] according to the calculated ash concentration D2 [mg / L] The optimum injection amount of the injected drug B is obtained in a feedback manner (step S14). Here, the predetermined batch concentration target value T2 [NTU] is set to a predetermined value, but it may be a predetermined numerical value range. Then, the medicine infusion pump 23b is controlled according to the optimum infusion amount to adjust the infusion amount of the infusion medicine B to be injected into the pulp slurry (step S15).

However, as described above, it is desired to maintain the quality of the paper produced at a desired value by controlling the yield of the raw material to be constant in the wire part 55. The yield rate R (%) of the raw material in the wire part 55 is approximated by the following equation.

R = [1 - (whitish concentration / inlet raw material concentration)] x 100

From this equation, it is assumed that the concentration of the inlet raw material in the inlet 54 is controlled to be constant, the insoluble suspension (SS) concentration of the white water and the ash concentration are adjusted respectively, The yield ratio R1 (%) of the water (SS) and the yield ratio R2 (%) of the ash can be controlled to be constant. That is, by stabilizing the concentration of the insoluble suspension (SS) in the white water and the fluctuation range of the ash concentration, the pulp and the ash that can float on the wire are kept at a constant amount, And the deviation of the quality of the paper to be produced can be expected to be small.

Therefore, the insoluble suspension (SS) concentration target value T1 (NTU) and the ash concentration target value T2 (NTU) satisfy the yield ratio R1 (%) of the insoluble suspension SS in the wire part 55 Is preferably set on the basis of an appropriate value of the yield ratio R2 (%) of the ash. The optimum value of the yield ratio R1 (%) of the insoluble suspension (SS) and the yield ratio R2 (%) of the ash in the wire part 55 according to the operating condition including the product trademark to be manufactured It is desirable to suitably modify the insoluble suspension (SS) concentration target value T1 (NTU) and the ash concentration target value T2 (NTU) according to the change of the operating condition including the product trademark to be manufactured.

On the other hand, when the inlet material concentration or the flow rate fluctuates in the inlet 54, it is possible to change the insoluble suspension (SS) concentration target value T1 [NTU] according to the variation of the concentration or the flow rate, The condition of the operation control of the medicine infusion pump 23a based on the calculated insoluble suspension (SS) concentration D1 (mg / L) may be corrected by multiplying the coefficient by the coefficient (correction coefficient).

Similarly, by calculating the calculated ash concentration D2 [NTU] by changing the ash concentration target value T2 [NTU] or multiplying the required optimum injection amount by the correction coefficient in accordance with variation of the inlet raw material concentration or the flow rate in the inlet 54, the condition of the operation control of the drug infusion pump 23b based on the concentration of the drug (mg / L) may be corrected.

It is preferable to set the upper limit value to the injection amount of the injected drug A, for example, because the effect may be saturated even if the injected drug A is excessively injected. In the same way, the effect may be saturated even when the drug B is excessively injected. Therefore, it is preferable to set the upper limit of the injection amount of the drug B2, for example.

[Example]

Hereinafter, the present invention will be described in more detail by way of examples.

≪ Example 1 >

Using the turbidity measurement unit 30 according to the present embodiment, the white water concentration was continuously measured in a batch to measure the turbidity at the time of stirring and the turbidity at the time of stopping. At the same time, the analytical instrument was used to measure the insoluble suspended solids (SS) concentration and ash concentration of the white water.

4 is a graph showing the correlation between the "turbidity at the time of stirring" and the insoluble suspension (SS) concentration using the analytical instrument according to the method of controlling the addition amount of the internal additive according to the embodiment of the present invention.

Based on this result, it was confirmed that "turbidity at the time of stirring", which was measured in the stirred state of white water, had a positive correlation with the actual insoluble suspension (SS) concentration, in accordance with the embodiment of the present invention. It was also confirmed that the insoluble suspension (SS) concentration can be calculated based on the " turbidity at the time of stirring " by using the linear line shown in Fig. 4 as a calibration curve. Therefore, if this calibration curve is converted into data and stored in a memory not shown in the drawing in the calculation processing unit 21, the insoluble suspension (SS) is calculated from the measured value (M1) of the "turbidity at the time of stirring" ) Concentration (D1) [mg / L] can be calculated.

5 is a graph showing the correlation between the "turbidity at rest" and the ash concentration using the analyzer according to the method of controlling the addition amount of the internal additive according to the embodiment of the present invention. The term " turbidity at the time of stopping " is a turbidity measurement value when the rate of decrease of the turbidity measurement value continuously measured with the white water set at 1 NTU / minute or less.

Based on this result, it was confirmed that the "suspended turbidity" measured after the white water was allowed to stand for a sufficient time in accordance with the embodiment of the present invention has a positive correlation with the actual ash concentration. It was also confirmed that the ash concentration can be calculated based on the " turbidity at rest " by using the linear form shown in Fig. 5 as a calibration curve. Therefore, if the calibration curve is converted into data and stored in a memory not shown in the figure in the calculation processing unit 21, the concentration of the ash concentration (D2) is calculated from the measured value (M2) [NTU] of the "turbidity at rest" [mg / L] can be calculated.

Fig. 6 shows the relationship between the turbidity at the time of stirring, that is, the turbidity corresponding to the insoluble suspension (SS) and the yield rate of the insoluble suspension (SS) prepared on the assumption that the inlet concentration is constantly controlled And " turbidity at rest ", i.e., turbidity-corresponding turbidity and ash yield rate.

When the inlet concentration is constantly controlled in accordance with this result, the turbidity at the time of stirring, that is, the turbidity equivalent to the insoluble suspension (SS) is determined by the yield of the insoluble suspension (SS) and the turbidity at rest And the ash yield ratios, respectively. Therefore, the yield of insoluble suspension (SS) can be adjusted by adjusting the "turbidity at the time of stirring" (insoluble suspension (SS) concentration), and the turbidity yield can be adjusted by adjusting the "turbidity at rest" .

≪ Example 2 >

Using the turbidity measurement unit 30 according to the present embodiment, the white water concentration was continuously measured at once and the turbidity of the white water was measured. At the same time, the batch concentration of white water was measured using analytical instruments.

Fig. 7 is a diagram showing the correlation between ash turbidity and ash concentration in each product trademark by the method of controlling the addition amount of the internal additive according to the embodiment of the present invention. Fig.

Based on this result, the "turbidity at rest" measured after standing the white water for a sufficient time in accordance with the embodiment of the present invention, ie turbidity-corresponding turbidity, has a positive correlation with the actual ash concentration in each product trademark I could confirm. It was also confirmed that the ash concentration in each product trademark can be calculated based on the " turbidity at rest " using linearity of each product trademark shown in Fig. 7 as a calibration curve. Therefore, if the calibration curves of these product trademarks are converted into data and stored in a memory not shown in the drawing in the calculation processing unit 21, a measurement value of the "turbidity at rest" measured using the corresponding calibration curve for each product trademark (D2) [mg / L] can be calculated from the equation (M2) [NTU].

As described above, according to the medicine injection system 20 according to the present embodiment, the insoluble suspension (SS) concentration is obtained from "turbidity at the time of stirring" in which white water is collected and the white water is measured in a stirred state, The optimal injection amount of the internal medicine (A) capable of adjusting the yield of the insoluble suspension (SS) is obtained in a feedback manner by adjusting the injection amount. Also, the optimum injection amount of the additive (B) capable of adjusting the yield of ash by adjusting the injection amount based on the measured concentration after the white water has been allowed to stand for a sufficient time and measuring the "ash turbidity" . Therefore, it is possible to optimize the injected amounts of these injected medicines, respectively, and to minimize the cost of the required medicament.

In addition, since the optimal injection amounts of the internal medicine A and the internal medicine B are obtained respectively, it is easy to follow the fluctuation of the inlet raw material concentration and the flow rate in the inlet 54, and the time lag of the feedback is It is possible to realize control for optimally injecting an insoluble drug without any (less) drug. It is possible to construct an internal medicine injection control system suitable for controlling the optimum injection amount of the internal medicine in a situation where both the insoluble suspension (SS) concentration and the ash concentration are greatly fluctuated, particularly when the product brand is manufactured.

Further, the turbidity sensor (32) assembled in the measurement vessel (31) is efficiently used to determine the insoluble suspension (SS) concentration from the " turbidity at the time of stirring " The turbidity concentration is obtained from the measured "turbidity at rest" measured after standing for a sufficient number of hours, so that it is possible to simplify the structure of the apparatus and simplify the physical structure. In addition, there is an advantage such that the maintenance and management work of the measuring equipment is reduced, and the operation is simplified and efficient.

10; Paper Processing
30; Turbidity measuring unit
55; Wire Parts
M1; Turbidity (turbidity corresponding to insoluble suspension)
M2; Turbidity at rest (turbidity equivalent turbidity)
D1; Insoluble suspension concentration
D2; Ash concentration

Claims (5)

As a method for controlling the addition amount of an internal medicine in a paper making process for producing paper from a pulp slurry,
(White water) generated in the paper making process in a predetermined operating condition (operating condition)
Measuring the turbidity of the collected white water at the time of stirring (stirring) as turbidity corresponding to the insoluble suspension (insoluble suspension relative turbidity)
Measuring the turbidity of the collected white water at a standstill as a turbine equivalent turbidity (ash turbidity equivalent turbidity)
Adjusting the amount of the additive to be added based on the measured turbidity corresponding to the insoluble suspension and the turbidity equivalent to the ash,
Methods of inclusion.
The method according to claim 1,
Calculating an insoluble suspension concentration of the collected white water based on the measured insoluble suspension-corresponding turbidity in the collected white water;
And calculating the ash concentration of the collected white water based on the measured ash turbidity corresponding to the collected white water.
3. The method of claim 2,
Further comprising a step of performing drug infusion control of the insecticide capable of adjusting the insoluble suspension yield and ash yield in the papermaking step based on the calculated insoluble suspension concentration and the ash concentration .
The method of claim 3,
Further comprising the step of feedback-controlling the addition amount of the additive agent so that the insoluble suspension concentration is a target insoluble suspension concentration and the ash concentration is a target ash concentration.
A method for measuring the concentration of a suspended material in a papermaking process for producing paper from a pulp slurry,
Collecting white water generated in the papermaking process;
Measuring the turbidity of the collected white water as turbidity corresponding to an insoluble suspension at the time of stirring;
Calculating an insoluble suspension concentration of the collected white water based on the measured turbidity corresponding to the insoluble suspension;
Measuring the turbidity of the collected white water as the ash-dependent turbidity at the time of stop,
Calculating the ash concentration of the collected white water based on the measured turbidity-corresponding turbidity
A method for measuring the concentration of a suspending substance contained therein.

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