Green liquor treatment method

Abstract

To provide a technique for more precisely and more easily conducting an operation control of a green liquid treatment.SOLUTION: The invention relates to a green liquid treatment method of controlling a medicament injection rate to a coarse green liquid from a color tone of a clear green liquid by monitoring a color tone and a temperature of the clear green liquid and managing a temperature of the clear green liquid on a color tone measurement in a certain range, or, by measuring a temperature of the clear green liquid and managing a color tone change of the clear green liquid while conducting temperature correction based on a measurement result.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a green liquor treatment method, a green liquor treatment management system, a method for improving causticizing productivity, and the like. [Background technology]

[0002] Pulp is produced by adding cooking water containing sodium hydroxide (hereinafter also referred to as "caustic soda") to wood chips and cooking them, using white liquor as the cooking water. In the cooking process, the chips are cooked with alkali (white liquor) to obtain pulp, and cooking chemicals and heat energy are recovered from the pulp waste liquor (black liquor). In the pulp production process, chemicals are recovered from the cooking process, pulp washing process, black liquor concentration process, black liquor combustion process, green liquor treatment process, white liquor treatment process, slaking process, causticization process, lime burning process, etc., and the recovered chemicals are reused.

[0003] The smelt produced by burning black liquor contains insoluble impurities (dregs) such as unburned carbon, calcium carbonate, aluminum hydroxide, iron oxide, silicon dioxide, etc. Furthermore, wood chips are rich in calcium salts, barium salts, phosphates, cellulose, lignin, and other substances that are the source of these insoluble impurities, making them prone to producing insoluble impurities. These insoluble impurities, known as dregs, adversely affect the quality of calcium carbonate in the white liquor treatment process. Calcium oxide is produced from calcium carbonate, and white liquor is produced using this calcium oxide in the slaking and causticizing processes. Therefore, calcium carbonate of higher quality is required. Therefore, in the green liquor treatment process, it is important to remove as much dregs as possible from crude green liquor to produce better clarified green liquor.

[0004] For example, Patent Document 1 proposes a method for clarifying green liquor, which is characterized in that quicklime is added to unclarified green liquor during stirring in an amount of 0.5 to 10%, preferably 1 to 5%, of the amount of quicklime required to completely causticize the green liquor, and then solid particles are removed from the green liquor. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication Hei 1-502207 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventionally, in green liquor treatment, the treatment status of green liquor in green liquor clarification equipment such as green liquor clarifiers has been assessed by measuring the SS (suspended solids) value and turbidity contained in the clarified green liquor as indicators of clarification.

[0007] However, the clarified green liquor collected to measure the SS value or turbidity is hot (around 90°C) and has a strong alkaline pH of around 13, so it must be handled with care. The SS value is calculated by collecting clarified green liquor, filtering it, and then drying it to determine the dry weight. As such, measuring the SS value requires careful handling of the clarified green liquor, involves many work steps, and is done exclusively by hand, making it difficult to measure the SS value quickly, with the number of SS value measurements being limited to, for example, three times per day. Because the SS value does not provide quick results and the number of measurements is limited, it is not possible to immediately grasp the current status of green liquor treatment, and there has been a tendency for abnormalities such as an increase in impurities in the clarified green liquor to be discovered late.

[0008] The turbidity is obtained by measuring the degree of turbidity caused by fine particles dispersed in the solution by photometric measurement. The inventors have found that since the turbidity value varies depending on the color of the clarified green liquor, it may not be possible to accurately determine the clarification failure in the green liquor treatment process. Furthermore, the present inventors have found that when impurities increase in a pulp production system, particularly when there is an increase in metal impurities due to corrosion of piping after a long-term scheduled repair or an increase in impurities due to the type of wood, the color of the clarified green liquor is likely to change. The present inventors have also found that a change in the color of the clarified green liquor cannot be fully detected by turbidity, and therefore a defect in the clarification of the clarified green liquor cannot be accurately grasped, which often has a negative impact on the quality of the white liquor and the quality of calcium carbonate, which are the downstream processes in the green liquor treatment system.

[0009] As described above, with conventional measurement methods that obtain SS values ​​and turbidity, it is difficult to speed up the measurement of clarified green liquor, it is difficult to accurately grasp the current state of green liquor clarification treatment, and it is difficult to determine the appropriate amount of chemicals to be injected into crude green liquor. For this reason, it has been difficult to easily manage the operation of green liquor treatment using conventional measurement methods.

[0010] As a result of extensive research, the inventors came up with an idea for enabling more rapid feedback control of the appropriate amount of chemicals to be injected into the crude green liquor based on changes in the color of the clarified green liquor. As a preferred embodiment, they developed a method or system for determining the operational status of the green liquor clarification apparatus from the color obtained by continuously monitoring the clarified green liquor after the green liquor clarifier using a color monitor. However, the inventors discovered a new problem with this method or system: when the temperature of the clarified green liquor fluctuates, the color of the clarified green liquor also changes, and this difference in color changes results in an error in the amount of chemicals to be injected into the crude green liquor. Therefore, the inventors believed that by reducing this error and improving measurement accuracy, operational management of green liquor treatment could be performed more accurately and easily.

[0011] Therefore, a main object of the present invention is to provide a technology that enables more accurate and easier operation management of green liquor treatment. [Means for solving the problem]

[0012] As a result of extensive research, the present inventors have found that by monitoring the color tone and temperature of the clarified green liquor and determining the color tone of the clarified green liquor under controlled conditions that reduce color tone errors due to temperature changes, it is possible to more accurately and easily control the appropriate amount of chemicals to be injected into the crude green liquor, and have completed the present invention as described below in [1] to [4].

[0013] [1] Monitor the color and temperature of the clarified green liquor; By controlling the temperature of the clarified green liquor within a certain range during color measurement, or by measuring the temperature of the clarified green liquor and correcting the change in color of the clarified green liquor based on the measurement results, A method for treating green liquor in which the amount of chemicals injected into crude green liquor is controlled based on the color tone of the clarified green liquor. [2] The method for treating green liquor according to [1], wherein the temperature of the clarified green liquor during the color measurement is controlled within a certain range, thereby reducing errors in color tone due to temperature changes and controlling the amount of chemicals injected into the crude green liquor. [3] The green liquor treatment method according to [1], wherein the amount of chemicals injected into the crude green liquor is controlled based on the color tone of the clarified green liquor after temperature correction, by measuring the temperature of the clarified green liquor and then correcting the change in color tone of the clarified green liquor based on the measured temperature value of the clarified green liquor. [4] Determining whether the temperature measurement value of the clarified green liquor is within a certain range in order to manage the change in color tone of the clarified green liquor after temperature correction; and If the color is within the predetermined range, the amount of chemicals injected into the crude green liquor is controlled based on the color measurement value of the clarified green liquor at this time; or If the color of the clarified green liquor is not within the certain range, the color of the clarified green liquor is measured, and the measured color value of the clarified green liquor is corrected based on the measured temperature at that time, and the amount of chemicals injected into the crude green liquor is controlled. [Effects of the Invention]

[0014] According to the present invention, a technology can be provided that allows for more accurate and easier operation management of green liquor treatment. Note that the effects are not necessarily limited to those described herein, and may be any of the effects described in this specification. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram of a pulp production system equipped with a green liquor production system according to one embodiment of the present invention, but the present invention is not limited thereto. [Figure 2] Fig. 2A is a schematic diagram of a first embodiment of the present invention in which a color tone monitoring unit and a temperature monitoring unit are installed in a clarified green liquor flow path. Fig. 2B is a schematic diagram of a first embodiment of the present invention in which a color tone monitoring unit and a temperature monitoring unit are installed in a bypass of the clarified green liquor flow path. The present invention is not limited to these. [Figure 3] 1 is a flowchart showing an example of a green liquor treatment method (step S1) according to a first embodiment of the present invention. [Figure 4] 4 is a flowchart showing an example of a green liquor treatment method (step S2) according to the first embodiment of the present invention. [Figure 5] 4 is a flowchart showing an example of a green liquor treatment method (step S3) according to the first embodiment of the present invention. [Figure 6] 4 is a flowchart showing an example of a green liquor treatment method (step S4) according to the first embodiment of the present invention. [Figure 7] 10 is a flowchart showing an example of a green liquor treatment method (step S5) according to a second embodiment of the present invention. [Figure 8] 10 is a flowchart showing an example of a green liquor treatment method (step S6) according to a second embodiment of the present invention. [Figure 9] 10 is a flowchart showing an example of a green liquor treatment method (step S7) according to a second embodiment of the present invention. [Figure 10] 10 is a flowchart showing an example of a green liquor treatment method (step S8) according to a second embodiment of the present invention. [Figure 11]10 is a flowchart showing an example of a green liquor treatment method (step S9) according to a second embodiment of the present invention. [Figure 12] In Test Example 2, Sample 2-1 (total Fe 2.1 ppm) and Sample 2-2 (total Fe 3.1 ppm), which were clear green liquors to which soluble iron had been added, were measured using a color measurement device (RGB color analyzer), and the graph shows the effect of temperature on the a* value (vertical axis: a* value, horizontal axis: temperature (°C)). DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments for carrying out the present invention will be described. Note that the embodiment described below shows one example of a typical embodiment of the present invention, and is not to be construed as limiting the scope of the present invention. Note that the upper and lower limit values ​​(to) in the numerical values ​​can be arbitrarily combined as desired.

[0017] An example of one embodiment of green liquor treatment according to the present invention will be described with reference to Figs. 1 to 11, but the present invention is not limited thereto.

[0018] 1. Green liquor treatment method according to the present invention

[0019] The present invention can provide a green liquor treatment method including a control step of monitoring the color tone of clarified green liquor and performing feedback control of the amount of chemicals to be injected into crude green liquor based on the color tone. The green liquor treatment method according to the present invention can be applied to a green liquor treatment system in a pulp manufacturing system (see, for example, FIG. 1).

[0020] <1-1. Green liquor treatment system according to this embodiment> An outline of a green liquor treatment system to which the green liquor treatment method according to the present invention is applied will be briefly explained below, but the present invention is not limited to this and can be applied to various green liquor treatment systems. For example, referring to FIG. 1, the green liquor processing system may include, in order from the upstream side, various locations or parts such as a dissolving tank, a crude green liquor tank (not shown), a green liquor clarification device (preferably a green liquor clarifier), a clarified green liquor tank, and various lines (e.g., flow paths, piping, etc.) connecting the respective parts. Examples of green liquor clarification devices include, but are not limited to, gravity settling type devices and forced filtration type devices. A typical gravity settling type green liquor clarifier is preferred. Examples of green liquor clarifiers include, but are not limited to, multi-stage clarifiers, unit clarifiers, storage tank combined type clarifiers, and sedimentation concentration type clarifiers. Among these, storage tank combined type clarifiers are preferred.

[0021] In the dissolving tank, the smelt transferred from the black liquor treatment system is stirred and dissolved or dispersed in water. This produces green liquor (hereinafter also referred to as "crude green liquor") that is rich in sodium carbonate in addition to caustic soda. The dissolving tank is equipped with a liquor transfer pump (not shown), and the crude green liquor is sucked into this liquor transfer pump and transferred via a line to the green liquor clarification device.

[0022] A green liquor treatment agent (hereinafter also referred to as "agent") is added to the crude green liquor in the green liquor clarification device or upstream thereof. The crude green liquor and the green liquor treatment agent are then mixed in the green liquor clarification device and subjected to solid-liquid separation, thereby performing a clarification process to remove impurities, such as undissolved components, from the crude green liquor. After this clarification process, a clarified green liquor from which impurities have been removed is obtained. During this process, a slurry containing impurities (green liquor mud) is generated and accumulated in the green liquor clarification device. Therefore, to remove the accumulated sludge from the green liquor clarification device at a certain rate (at regular intervals or when a certain amount is reached), a withdrawal pump is used to appropriately withdraw the sludge. The sludge concentration (mass %) per 1 L of the withdrawn sludge is measured in a sludge concentration measurement unit. The sludge concentration can be determined based on JIS K 0067-1992, "Test Method for Weight Loss and Residue of Chemical Products." The sludge is dried by heating at 105±2°C in a dryer, and the weight is determined after drying. After the clarification treatment, the clarified green liquor is transferred from the green liquor clarification device to a clarified green liquor tank via a clarified green liquor transfer line, where it is stored. The clarified green liquor is then transferred from the clarified green liquor tank to a causticizing system via a line.

[0023] <1-2. Green liquor treatment method in this embodiment> In the green liquor treatment method according to an embodiment of the present invention, it is preferable to monitor the color tone of the clarified green liquor and feedback-control the amount of chemicals to be injected based on that color tone. Furthermore, in this embodiment, it is preferable to also monitor the temperature of the clarified green liquor and more accurately control the amount of chemicals to be injected based on the color tone, which is adjusted and managed to reduce color tone errors due to temperature changes (also referred to as "color tone error adjustment management due to temperature changes").

[0024] In this embodiment, the system is configured to monitor the color and temperature of the clarified green liquor, and the amount of chemicals injected into the crude green liquor can be controlled based on the color of the clarified green liquor. For example, FIG. 1 shows a schematic diagram of a green liquor processing system 1, which includes a color monitoring unit 102 equipped with a color measurement device 103, a temperature monitoring unit 104 equipped with a temperature sensor 105, chemical injection units (34, 35) that control the amount of chemicals injected into the crude green liquor in the green liquor clarification device 32, and a control unit 101 that controls these units. The temperature monitoring unit 104 may also include a heating / cooling unit. The color monitoring unit 102 may also include a temperature sensor 105.

[0025] 2A shows that the color of the clarified green liquor flowing in the main flow path from 32 to 40, which connects the outlet of the green liquor clarification device (green liquor clarifier) ​​32 to the slaking / causticizing system 40, is measured in a color monitor 102 using a color measuring device (color sensor) 103 installed above the clarified green liquor surface at a distance from the surface. Also, in FIG. 2B, unlike FIG. 2A, a secondary bypass flow path is provided on the main flow path, and the color monitor 102 is installed on that secondary flow path, rather than on the main flow path.

[0026] By including at least the color tone monitoring unit 102 and the temperature sensor 105, a control unit or an operator, etc. can control heating and cooling (not shown) based on the temperature measurement to manage the temperature of the clear green liquor within a certain range during color tone measurement, or the control unit or an operator, etc. can manage changes in the color tone of the clear green liquor after temperature correction based on the temperature measurement value of the clear green liquor obtained by measuring the temperature of the clear green liquor. Furthermore, changes in color tone may be managed after temperature correction while controlling the heating and cooling temperature to fall within a specific temperature range.

[0027] By measuring and controlling the temperature of the clarified green liquor during color measurement in this way, it is possible to reduce errors in color due to temperature changes. Furthermore, by adopting such a configuration, there is an advantage that errors in color due to temperature changes can be reduced even if the color monitor unit is installed in a desired location within the green liquor processing system.

[0028] Furthermore, the color tone of the clarified green liquor is preferably color tone data of the clarified green liquor obtained by measuring the color tone of the clarified green liquor. In addition, it is preferable that the color tone error adjustment and management due to temperature changes be performed by controlling the temperature of the clear green liquor during color tone measurement within a certain range, and / or by measuring the temperature of the clear green liquor and correcting the change in color tone of the clear green liquor based on the measurement results.

[0029] Here, the present inventors have clarified, as will be shown in the Examples below, the relationship between the color tone of the clarified green liquor and the clarification of the clarified green liquor; more specifically, if the amount of chemical agent injected is insufficient relative to the crude green liquor, the color tone of the clarified green liquor turns reddish, and by further adding the chemical agent, the color tone of the clarified green liquor changes to greenish, making it possible to obtain a more favorably clarified clarified green liquor.

[0030] That is, in this embodiment, by monitoring the color tone of the clarified green liquor, the current treatment status of the green liquor due to chemical injection can be quickly and accurately grasped. The current green liquor treatment status includes the current state of clarification of clarified green liquor (specifically, the presence of impurities that have not flocculated and settled) and the current amount of chemicals injected into crude green liquor (specifically, whether it is in excess, insufficient, or appropriate). The reasons why impurities cannot be coagulated and settled include: if the amount of chemical (specifically, coagulant) injected is insufficient, the insufficient impurities cannot be coagulated and settled; if the amount of chemical (specifically, coagulant) injected is excessive, the flocs become too small, and the coagulation and settling rate decreases; etc. If the amount of chemical injected is too excessive, the coagulation and settling rate decreases, which tends to prevent successful solid-liquid separation and increase the risk of carryover.

[0031] Furthermore, by monitoring the color tone of the clarified green liquor, the degree of clarification of the clarified green liquor can be quickly and accurately grasped. Furthermore, the color tone of the clarified green liquor can be monitored or measured without contacting the clarified green liquor. By monitoring the color tone of the clarified green liquor in this way, the current treatment status of the green liquor after chemical injection can be grasped quickly and safely, compared to the conventional method using SS value and turbidity.

[0032] Furthermore, in this embodiment, as described above, the color tone of the monitored clarified green liquor can be used to quickly and accurately grasp the current treatment status of the green liquor (specifically, the current amount of chemicals injected). Based on the treatment status of the green liquor (specifically, the current amount of chemicals injected), the amount of chemicals to be added to the current crude green liquor (more specifically, whether to increase, decrease, or maintain the same amount) can be determined, and the determined amount of chemicals can be controlled to be added to the crude green liquor. This makes it easier to quickly and accurately clarify the clarified green liquor. This also reduces chemical costs because the amount of chemicals injected is more appropriately adjusted.

[0033] Furthermore, in this embodiment, it is preferable to perform feedback control to increase, maintain, or decrease the amount of chemicals injected based on the color data of the clarified green liquor obtained by measuring the color of the clarified green liquor.Therefore, when obtaining clarified green liquor, the amount of chemicals injected into the crude green liquor can be controlled so that it is appropriate and neither excessive nor insufficient.

[0034] Conventionally, each green liquor treatment site has different treatment scales, required clarification treatment capacity of the green liquor treatment system, and changes in the impurity concentration in crude green liquor over time. For example, in green liquor treatment systems, smelt and other substances flow into the dissolution tank continuously or intermittently, so the impurity concentration in crude green liquor is generally not constant but fluctuates. In addition, conventional methods require the collection of clarified green liquor, which limits the number of measurements and the treatment speed, making it difficult to control the amount of chemicals injected.

[0035] In contrast, by monitoring color and conducting feedback control of the chemical injection amount based on the color tone as described above, this embodiment makes it easy to appropriately adjust the chemical injection amount for each site. Furthermore, as described above, this embodiment allows for instantaneous and repeated monitoring of color tone and feedback control of the chemical injection amount based on the color tone as described above, which makes it possible to appropriately respond to fluctuations in the impurity concentration in the crude green liquor and to add the appropriate chemical injection amount to the current crude green liquor. This allows for rapid and accurate clarification of the green liquor. In this way, by using this embodiment, operational management of the green liquor treatment can be easily performed.

[0036] Furthermore, the inventors confirmed that, when using sensing technology to continuously monitor the operating status of a green liquor clarifier, there is a discrepancy (difference) between the temperature of the clarified green liquor measured downstream of the green liquor clarifier and the temperature of the clarified green liquor immediately after it leaves the green liquor clarifier. The inventors discovered that in a system that monitors operating status, such as optimizing the amount of chemicals injected into crude green liquor, based on the color tone obtained by continuous image analysis of the clarified green liquor using a color measurement device, when the temperature of the object being measured fluctuates (differences) with the temperature of the object at the chemical injection site, a change (difference) in the color tone of the two occurs. This change results in an inappropriate amount of chemicals being injected into the crude green liquor, resulting in a color tone error. Therefore, the inventors' next objective was to further reduce this error and improve measurement accuracy.

[0037] The present inventors have found that poor green liquor treatment results in the clear green liquor taking on a reddish hue, and have therefore found that the reddish hue (a *We have found that the chromaticity index (RII) can be an indicator of the clarity of the clarified green liquor, and further discovered that changes in the color tone of the clarified green liquor can be continuously monitored by image processing. The inventors presume that the red color of the clarified green liquor is due to the increase in iron sulfate II, which is oxidized to iron sulfate III, giving the clarified green liquor a reddish color. They believe that the red color can be reduced by reducing the total amount (concentration) of iron. However, in the present invention, the color tone is monitored not for the purpose of reducing the amount (concentration) of iron in the clarified green liquor, but for the purpose of determining the status of the chemical injection amount, so the objectives are significantly different. Furthermore, the inventors have found that the clarified green liquor immediately after discharge from the green liquor clarifier may be as high as 85 to 95°C and strongly alkaline with a pH of 12 to 14. While the temperature is usually around 75 to 85°C, it may drop to around 65 to 75°C after long-term periodic inspections, repairs, seasonal factors, etc., and the oxidation and reduction states may change, resulting in a change in color tone.

[0038] Based on these findings, the inventors have discovered that it is possible to provide a green liquor processing method that monitors the color tone and temperature of the clarified green liquor and controls the operational status based on the color tone of the clarified green liquor under control conditions that minimize color tone errors due to temperature changes. According to the present invention, a method or system that continuously analyzes images of the clarified green liquor after a green liquor clarifier and determines the operational status based on the color tone can be used to minimize color tone errors due to temperature changes. A preferred embodiment of the control that minimizes color tone errors due to temperature changes is to control the temperature of the clarified green liquor within a certain range during color tone measurement, and / or to measure the temperature of the clarified green liquor and correct the color tone change of the clarified green liquor based on the measurement results. This allows for improved accuracy in color tone measurement in the present invention. Furthermore, the present invention allows for more accurate and easier operational control of green liquor processing. Furthermore, in the present invention, by using management that reduces color tone errors due to temperature changes (hereinafter also referred to as "color tone error adjustment management due to temperature changes") and based on color tone changes in the clarified green liquor, it is possible to control a more appropriate amount of chemicals to be injected into the crude green liquor, and it is also possible to more quickly feedback-control the more appropriate amount of chemicals to be injected into the crude green liquor.

[0039] By reducing the error in the color tone of the clarified green liquor and increasing the accuracy of measuring this color tone in this way, it is possible to more accurately and easily manage the operation of green liquor treatment, for example, by more appropriately injecting the amount of chemicals into the crude green liquor (for example, the timing and amount of addition).

[0040] <1-2-1. Adjustment and management of color tone errors due to temperature changes> In the green liquor treatment method of the present embodiment, it is preferable to perform color tone error adjustment management due to temperature change. Examples of the color tone error adjustment management due to temperature change include, for example, a first color tone error adjustment management in which the temperature of the clear green liquor during color tone measurement is adjusted to be within a certain range, and / or a second color tone error adjustment management in which the temperature of the clear green liquor is measured and, based on the measurement results, the change in color tone of the clear green liquor is corrected for temperature and then adjusted. These are preferred.

[0041] In the green liquor treatment method of the present embodiment, it is preferable to be able to monitor the temperature of the clarified green liquor, and further it is preferable to monitor the color tone of the clarified green liquor, which will be described later, as well as the temperature of the clarified green liquor. The present embodiment provides a green liquor treatment method that monitors the color tone and temperature of a clarified green liquor, and more accurately controls the amount of chemicals injected into a crude green liquor based on the color tone of the clarified green liquor under color tone error adjustment control due to temperature changes, and a green liquor treatment device or green liquor treatment system that includes a control unit configured to execute the method. The color tone error adjustment control unit that can execute the color tone error adjustment control due to temperature changes may be provided in the control unit, or may be provided externally on a server, cloud, or the like.

[0042] Furthermore, in this embodiment, it is more preferable to monitor the temperature of the clarified green liquor, which is involved in the color tone, by controlling the temperature of the clarified green liquor, which is involved in the color tone, and examples of such temperature control include, but are not limited to, temperature measurement and / or temperature control (e.g., heating / cooling, etc.). By controlling the temperature of the clarified green liquor, which is involved in the color tone, it becomes easier to grasp the temperature of the clarified green liquor when measuring the color tone of the clarified green liquor.

[0043] Furthermore, in this embodiment, it is preferable to monitor the temperature of the clarified green liquor and to manage the temperature when measuring the color tone of the clarified green liquor, which allows the treatment status of the green liquor due to chemical injection to be quickly and accurately grasped, as described above.

[0044] <First color tone error adjustment management> In the first color tone error adjustment management of this embodiment, by keeping the temperature of the clarified green liquor constant during color tone measurement, color tone changes due to temperature changes of the measurement object can be suppressed, thereby reducing color tone errors due to temperature changes during color tone measurement and further improving the accuracy of color tone measurement. As a result, when obtaining a clarified green liquor, the amount of chemical agent injected into the crude green liquor can be controlled more accurately and easily so as to be appropriate, without being excessive or insufficient.

[0045] That is, in the first embodiment, a green liquor treatment method can be provided in which the color tone and temperature of the clarified green liquor are monitored, and the temperature of the clarified green liquor during color tone measurement is controlled within a certain range, thereby controlling the amount of chemicals to be injected into the crude green liquor based on the color tone of the clarified green liquor.

[0046] In the first embodiment, a preferred first color tone error adjustment management method involves measuring the temperature of the clear green liquor and heating or cooling the liquor so that the temperature falls within a certain range based on the temperature measurement result. The location where the heating or cooling is performed is preferably the same location where the color tone of the clear green liquor is measured. This allows the temperature of the clear green liquor during color tone measurement to be controlled within a certain range. By controlling the temperature of the clear green liquor during color tone measurement within a certain range in this way, errors due to temperature changes in color tone can be reduced, and reducing the errors allows the amount of chemical agent injected into the crude green liquor to be appropriately controlled.

[0047] <Second tone error adjustment management> In the second color tone error adjustment management of this embodiment, when a change occurs in the temperature of the color tone of the monitored clear green liquid in the temperature management of the clear green liquid, the color tone is corrected by temperature and managed after the temperature correction, thereby reducing color tone errors due to temperature changes during color tone measurement and improving measurement accuracy.

[0048] That is, in the second embodiment, a green liquor treatment method can be provided in which the color tone and temperature of the clarified green liquor are monitored, the temperature of the clarified green liquor is measured, and the change in the color tone of the clarified green liquor is corrected for temperature based on the measurement results and then managed, thereby controlling the amount of chemicals to be injected into the crude green liquor based on the color tone of the clarified green liquor.

[0049] In the second embodiment, the preferred second color tone error adjustment management method involves measuring the temperature of the clarified green liquor and then correcting the color tone of the clarified green liquor for temperature based on the measured temperature. More preferably, the temperature correction model or formula is used to manage the temperature correction of the color tone of the clarified green liquor. The temperature correction model or formula is preferably a model or formula derived from the correlation between the color tone of the clarified green liquor and temperature. A temperature correction model or formula can be appropriately developed for each site. In this case, the color tone (values, data, etc.) of the clarified green liquor after temperature correction at the set temperature is preferably obtained based on the color tone of the clarified green liquor, the temperature of the clarified green liquor at the time of color tone measurement, and the temperature correction model or formula. By correcting the color tone of the clarified green liquor for temperature and then managing the temperature-corrected color tone in this manner, errors due to temperature changes in color tone can be reduced, and by reducing the errors, the amount of chemical agent injected into the crude green liquor can be appropriately controlled. When the second color tone error adjustment management is performed, a line for transporting the clarified green liquor from the clarified green liquor transport line to a location where it can be heated or cooled to a desired temperature may be provided, and temperature and color measurements may be carried out at the destination location where it can be heated or cooled, thereby enabling temperature correction of the color tone change of the clarified green liquor to be managed.

[0050] <Another embodiment of color tone error adjustment management due to temperature change> Furthermore, as another embodiment of the color tone error adjustment management due to temperature changes, a green liquor treatment method can be provided in which the color tone and temperature of the clarified green liquor are monitored, the temperature of the clarified green liquor is managed within a certain range during color tone measurement, and if the temperature cannot be managed within the certain range, the temperature of the clarified green liquor is measured and the change in color tone of the clarified green liquor is corrected for temperature based on the measurement results before management, thereby controlling the amount of chemicals to be injected into the crude green liquor based on the color tone of the clarified green liquor. This reduces errors due to color tone changes of the clarified green liquor, and makes it possible to more appropriately control the amount of chemicals to be injected into the crude green liquor based on the color tone after temperature correction.

[0051] <1-2-2. Monitoring the color of green liquor> In the green liquor treatment method of this embodiment, the color tone of the clarified green liquor is monitored, which makes it possible to quickly and accurately grasp the treatment status of the green liquor due to the chemical injection, as described above.

[0052] The color tone of the clear green liquid is not particularly limited, but is preferably a color tone of a color system that can digitize color. The color system may be either a mixed color system or a color development system, but it is preferable to use the CIE color system. Examples of the CIE color system include the RGB system, the XYZ color system, and the L * a * b * Color system, L * u * v * Among these, the RGB system, the XYZ color system, and the L * a * b * More preferably, one or more selected from the color system.

[0053] These CIE color systems can be converted to each other as needed. For example, RGB color tones can be converted to XYZ color tones or L * a * b * It is possible to convert from XYZ color system tones to L * a * b *It is also possible to convert to color system tones, and vice versa. Therefore, in this embodiment, the L * a * b * Convert to color system tone, etc., and convert to L * a * b * The amount of drug injected can be feedback-controlled using color system tones, etc. * a * b * The color system tone may be converted to an RGB color system tone, and the amount of drug injection may be feedback-controlled using the converted RGB color system tone.

[0054] The color tone of the green liquor is preferably color tone data of the clear green liquor obtained by measuring the color tone of the clear green liquor. More specifically, when monitoring the color tone of the clear green liquor, the color tone of the clear green liquor can be measured using a color tone measuring device, which will be described in detail later, and the measured value can be obtained as color tone data of the color system. After obtaining the color tone data, the color tone data can be sent to the control unit or stored in an internal or external memory unit. The color tone measuring device can be appropriately set at the color tone monitoring location described below.

[0055] It is preferable to monitor the color tone of the clear green liquor over time, thereby obtaining the color tone of the clear green liquor over time. Obtaining the color tone over time makes it easier to perform feedback control of the amount of chemicals injected more accurately. The color tone of the clear green liquid may be monitored continuously or intermittently (preferably at regular intervals). The "regular intervals" may be, for example, every 1 to 60 minutes or every 5 to 20 minutes. By monitoring at regular intervals, the amount of acquired data can be reduced and the processing speed of the control unit can be improved.

[0056] The clarified green liquor to be monitored may be clarified green liquor from the green liquor clarification apparatus described above in <1-1. Green liquor treatment system according to this embodiment> and any of the subsequent locations or parts. More specifically, the green liquor to be monitored may be one or more types of green liquor selected from parts of the green liquor treatment system, such as the green liquor clarification apparatus, the clarified green liquor tank, and the lines (e.g., flow paths, piping, etc.) connecting them.

[0057] The clarified green liquor whose color is to be monitored is more preferably downstream of a green liquor clarification apparatus, and more specifically, the downstream of the green liquor clarification apparatus is the green liquor clarification apparatus, the line following the apparatus (clarified green liquor transfer line), and the clarified green liquor tank. More preferably, it is the green liquor clarification apparatus and the clarified green liquor transfer line, and even more preferably, it is the clarified green liquor transfer line. Furthermore, within the clarified green liquor transfer line, it is preferable to monitor the color tone of the clarified green liquor after it has flowed from the green liquor clarification device to the clarified green liquor transfer line. From the viewpoint of facilitating feedback control of the amount of chemicals injected, the time after it has flowed is preferably the "outlet" of the green liquor clarification device or "immediately after it has flowed out." The time "immediately after it has flowed out" is more preferably within about 1 to 2 hours after it has flowed out, and even more preferably within about 1 to 2 hours after it has flowed out.

[0058] Each location or portion of the green liquor processing system described above can be used as a location for monitoring the color tone of the clarified green liquor. The number of locations for monitoring the color tone of the clarified green liquor is not particularly limited, and may be 1 or more. By using multiple locations for monitoring the color tone, it becomes easier to grasp the treatment status of the green liquor as a whole of the green liquor treatment system, and therefore it is easier to perform feedback control to ensure a more appropriate amount of chemicals is injected. When monitoring the clarified green liquid over time, the clarified green liquid may be monitored over time at the same location or at different locations, but monitoring the clarified green liquid at the same location over time is preferred because it makes it easier to monitor changes in the color tone of the clarified green liquid.

[0059] When monitoring the clarified green liquor, the clarified green liquor can be monitored from any direction, but it is preferable to monitor the clarified green liquor from above. Furthermore, when monitoring the clarified green liquor, it is preferable to monitor the color tone of the clarified green liquor from a predetermined distance (e.g., from the liquid surface to the measurement surface) from the clarified green liquor. This predetermined distance is, for example, 0 to 1000 mm, more preferably 30 to 500 mm, and even more preferably 50 to 200 mm. Furthermore, when monitoring the clarified green liquor, it is preferable to provide a color tone monitoring line (e.g., a bypass line) at each location or section of the green liquor treatment system to allow the clarified green liquor to flow in and monitor the clarified green liquor. In this case, the clarified green liquor to be introduced is preferably near the liquid surface (e.g., between the liquid surface and about 50 cm from the liquid surface). This makes it easier to monitor the clarified green liquor and adjust the temperature, etc., of the clarified green liquor.

[0060] A color tone measuring device (e.g., a color sensor) or a color tone monitoring unit equipped with such a device can be installed at the location where the color tone of the clarified green liquor is monitored. This allows for easy time-dependent monitoring of the clarified green liquor, which has traditionally been difficult to handle due to its strong alkalinity and high temperature. Furthermore, the color tone measuring device does not need to come into contact with the clarified green liquor, and can be easily installed in the clarified green liquor treatment system.

[0061] The pH of the clarified green liquor whose color tone is monitored is not particularly limited, but the pH (20°C) of the clarified green liquor is preferably not less than 11, and more preferably not less than 12. The temperature of the clarified green liquor whose color tone is monitored is not particularly limited, but is preferably about 50 to 95°C, more preferably 60 to 90°C, and even more preferably 70 to 90°C.

[0062] In this embodiment, the temperature of the clarified green liquor is also monitored, thereby reducing errors in color tone due to temperature changes, which has the advantage of allowing greater freedom in the location where the clarified green liquor color tone is monitored.The location where the clarified green liquor color tone is monitored can be appropriately set taking into consideration the overall layout of the green liquor treatment system or pulp manufacturing system on site, and also has the advantage of allowing for more accurate and easier operation management.

[0063] <1-2-3. Monitoring the temperature of green liquor> In the green liquor treatment method of this embodiment, it is preferable to monitor the temperature of the clear green liquor. By monitoring the color tone and temperature of the clear green liquor, it is possible to reduce errors in the color tone of the clear green liquor due to temperature changes. This makes it possible to quickly and accurately grasp the treatment status of the green liquor due to chemical injection, as described above.

[0064] The temperature of the green liquor is preferably temperature measurement value data (also referred to as temperature data) of the clarified green liquor obtained by measuring the temperature of the clarified green liquor. More specifically, when monitoring the temperature of the clarified green liquor, the temperature of the clarified green liquor can be measured by a temperature measurement device (for example, a temperature sensor) described below, and this measurement value can be obtained as a temperature measurement value or this data. After obtaining the temperature measurement value data, the temperature measurement value data can be sent to a control unit or stored in an internal or external storage unit.

[0065] It is preferable to monitor the temperature of the clarified green liquor over time, thereby obtaining the temperature of the clarified green liquor over time. Obtaining the temperature over time makes it easier to perform feedback control of the amount of chemicals injected more accurately. It is also preferable to monitor the temperature of the clarified green liquid together with the color monitoring or at the same time as the color measurement, thereby reducing errors in color tone due to temperature changes and facilitating more accurate feedback control of the amount of chemicals injected. The temperature of the clarified green liquor may be monitored continuously or intermittently (preferably at regular intervals). The "regular intervals" may be, for example, every 1 to 60 minutes or every 5 to 20 minutes. By monitoring at regular intervals, the amount of acquired data can be reduced and the processing speed of the control unit can be improved.

[0066] In this embodiment, it is preferable to monitor the temperature of the clarified green liquor by controlling the temperature of the clarified green liquor. As the temperature control of the clarified green liquor, it is preferable to measure the temperature of the clarified green liquor and / or to heat and cool the clarified green liquor. Furthermore, in the case of temperature control involving heating and cooling, it is preferable to heat and cool the clarified green liquor at the same or a different location as the location where the color tone of the clarified green liquor is measured so as to adjust it to the desired temperature, and to measure the temperature of the clarified green liquor at the heating and cooling location.

[0067] The clarified green liquor whose temperature is monitored may be the clarified green liquor from the green liquor clarification apparatus described above in <1-1. Green liquor treatment system according to this embodiment> and each subsequent location or each part of these. More specifically, the green liquor whose temperature is monitored may be one or more types of green liquor selected from each part of the green liquor treatment system, such as the green liquor clarification apparatus, the clarified green liquor tank, and each line (e.g., flow path, piping, etc.) connecting them.

[0068] The clarified green liquor whose temperature is monitored is preferably downstream of the green liquor clarification apparatus. More specifically, the downstream of the green liquor clarification apparatus refers to the green liquor clarification apparatus, the outlet of the apparatus for discharging the green liquor from the apparatus into a line, the line following the apparatus (clarified green liquor transfer line), and the clarified green liquor tank. The green liquor clarification apparatus and the clarified green liquor transfer line are more preferred, and the clarified green liquor transfer line is even more preferred. Furthermore, within the clarified green liquor transfer line, it is preferable to monitor the temperature of the clarified green liquor after it has flowed from the green liquor clarification apparatus into the clarified green liquor transfer line. From the viewpoint of facilitating feedback control of the amount of chemicals injected, the temperature after flowing is preferably "at the outlet of the green liquor clarification apparatus" or "immediately after outflow." The "immediately after outflow" refers more preferably within about two hours after outflow, and even more preferably within about one hour after outflow.

[0069] Each location or portion of the green liquor processing system described above can be used as a location for monitoring the temperature of the clarified green liquor. The number of locations where the temperature of the clarified green liquor is monitored is not particularly limited, and may be 1 or more. By using multiple locations for monitoring the temperature, it becomes easier to grasp the treatment status of the green liquor as a whole of the green liquor treatment system, and therefore it is easier to perform feedback control to achieve a more appropriate amount of chemicals to be injected. When monitoring the temperature of the clarified green liquor over time, the temperature of the clarified green liquor may be monitored over time at the same location, or at different locations. However, monitoring the temperature of the clarified green liquor over time at the same location is preferred, as it makes it easier to monitor temperature changes in the clarified green liquor. Furthermore, it is preferable that the temperature monitoring location is the same as the color tone monitoring location described below, from the viewpoint of reducing errors due to temperature changes in color tone.

[0070] <1-2-4. Controlling the amount of chemicals injected into crude green liquor> In this embodiment, the color tone of the clarified green liquor can be used to feedback-control the amount of chemicals injected. More preferably, in this embodiment, the amount of chemicals injected can be controlled from the color tone of the clarified green liquor based on the color tone error adjustment management due to temperature change, and feedback control is also possible. This allows for faster and more accurate feedback control so that the amount of chemicals injected is appropriate for the current crude green liquor.

[0071] "From the color tone of the clarified green liquor" preferably means "from the color tone value of the clarified green liquor at the current time (e.g., at the time of color measurement)" or "from the color tone value after color tone correction," and it is preferable to determine the amount of chemical to be added to the current crude green liquor based on the color tone value of the current clarified green liquor or the color tone value after color tone correction. For example, it is preferable to compare the color tone value of the current clarified green liquor with the color tone value of a reference clarified green liquor, and the color tone value of the current clarified green liquor and the color tone value of the clarified green liquor after color tone correction. As described above in "1-2-2. Monitoring the color tone of the green liquor," "the color tone of the clarified green liquor" is preferably the color tone data of the clarified green liquor.

[0072] Examples of the reference color value of the clear green liquid (hereinafter also referred to as the "reference color value of the clear green liquid") include, but are not limited to, a color value of the clear green liquid measured in the past (hereinafter also referred to as the "past color value"), a color value of the clear green liquid (hereinafter also referred to as the "appropriate color value"), and a color value (more preferably a color value after temperature correction) based on the above-mentioned "1-2-1. Color Error Adjustment Control Due to Temperature Change" (more preferably the second color error adjustment control). Furthermore, the color value may have a predetermined numerical range. Of these, in this embodiment, the color value based on the color error adjustment control due to temperature change (hereinafter also referred to as the "color value due to temperature change") is preferred.

[0073] The "past color value" may be a color value of the clear green liquor previously measured in the clear green liquor treatment system, and more preferably, the most recently measured color value of the clear green liquor. The most recently measured color value may be a color value measured one or two times before (more preferably, one time before), or a color value of the clear green liquor measured within 60 minutes (more preferably, within 5 to 30 minutes) before the current measurement, or a combination thereof. Furthermore, it is preferable to compare a previous color value of the clear green liquor measured at the same color monitoring location with the current color value of the clear green liquor. More specifically, it is more preferable to compare a nearby previous color value of the clear green liquor with the current color value of the clear green liquor. This allows for faster and more accurate feedback control of the chemical injection amount.

[0074] When the "appropriate color value" is an RGB color system, the color value of the RGB color system is preferably a color value in the RGB color system that represents a light green color. The R value represents red, the G value represents green, and the B value represents blue, and the combination of these three can also be considered. For simplified control, it is preferable to manage using the G value. The G value is preferably (G100-255), more preferably (G125-255), even more preferably (G150-255), and even more preferably (G200-255). The numerical value varies depending on the operation at the site and is not necessarily limited. By keeping the value within the appropriate range for the site, a more well-clarified clarified green liquor can be obtained and the amount of chemical agent injected can be more effectively optimized.

[0075] The "appropriate color value" is L * a * b * If the color system is L * a * b * The color value of the color system is L, which represents a light green color tone. * a * b * It is preferable that the color value be a color value of the color system. * The value is the brightness, a * High values ​​are red, low values ​​are green, b * A high value indicates yellow, a low value indicates blue, and it can be considered as a combination of the three. * It is preferable to control the value. The appropriate value varies depending on the operating conditions at the site, and is not necessarily limited. * a * b * In the color system, a * With the value 0 as the base, it is -60 (towards green), -0 - (towards red), +60. The a *The value is preferably 1.5 or less, more preferably 1.0 or less, more preferably 0 or less, even more preferably -0.5 or less, more preferably -1.0 or less, and even more preferably -1.5 or less. By keeping the value within this range, a more favorably clarified clarified green liquor can be obtained, and the amount of chemicals injected can be more favorably optimized. * The numerical range of the value may be an index for determining whether the clarified green liquor is in a well-clarified state or an index for determining whether the clarified green liquor is green, and may also be set as an appropriate color value.

[0076] Regarding the "color value due to temperature change," when based on the first color error adjustment management, by controlling the temperature of the clarified green liquor during the color measurement within a certain range, errors due to temperature changes in color can be reduced. Therefore, the color value during the color measurement can be used, but the "past color value" and the "appropriate color value" can also be used. Furthermore, when based on the first color error adjustment management, for example, the temperature during measurement of the clarified green liquor can be controlled to the temperature expected during chemical injection to reduce errors due to temperature changes in color. This reduces errors due to temperature changes in color, and based on the color of the clarified green liquor during measurement, the chemical injection amount relative to the crude green liquor can be controlled to be more appropriate, without being excessive or insufficient. Therefore, a more clarified clarified green liquor can be obtained, and the chemical injection amount can be more appropriately adjusted.

[0077] In the case of the "color value due to temperature change," when the second color error adjustment management is used, the change in the color tone of the clear green liquor can be temperature-corrected based on the temperature measurement value of the clear green liquor obtained by measuring the temperature of the clear green liquor, and then managed. This allows the temperature-corrected color value to be obtained. It is more preferable to use a temperature correction model (e.g., a temperature correction formula, etc.) to obtain this temperature-corrected color value. The temperature correction model is not particularly limited, and it is desirable to obtain a temperature correction model or a temperature correction formula tailored to the actual on-site equipment, etc., by statistical processing, etc. The temperature correction model, etc., can be obtained using known statistical processing, such as the regression formula (y = ax + b: y is the color value, x is the temperature (°C), a is the slope, and b is the intercept) shown in the Examples below. The temperature correction model, temperature correction formula, etc. can be obtained and used by appropriately employing simple regression analysis, multiple regression analysis, multivariate analysis, etc. When based on the second color tone error adjustment management, for example, even if the temperature when measuring the clarified green liquor is different from the temperature at the chemical injection site, it is possible to correct the temperature and manage the color tone to a value that allows for better optimization of the chemical injection amount. This reduces errors in color tone due to temperature changes, and based on the color tone after color tone correction, it becomes possible to control the chemical injection amount relative to the crude green liquor so that it is more appropriate, without being excessive or insufficient. Therefore, it is possible to obtain a more well-clarified clarified green liquor and to better optimize the chemical injection amount.

[0078] As an example based on the second color tone error adjustment management, temperature (°C) and color tone (for example, a * In the case of a regression equation obtained based on the correlation between the temperature and the color value (obtain the slope of a), the actual temperature measurement value is x2, the color measurement value is b, the desired temperature-corrected color value is y, and the desired temperature is x1. By substituting this into y = a(x2-x1)+b, the temperature-corrected color value (a * A more specific explanation of substitutions etc. will be omitted as it will be described in detail in the Examples below. This reduces errors in color tone due to temperature changes, making it possible to control the amount of chemical agent injected into the crude green liquor so that it is neither excessive nor insufficient, and is more appropriate. Therefore, a more clarified green liquor can be obtained, and the amount of chemical agent injected can be more appropriately adjusted. For example, even if the temperature at which the clarified green liquor is measured differs from the expected temperature of the green liquor at the chemical injection location, a temperature-corrected color tone can be obtained from the temperature correction model and the expected temperature of the green liquor at the chemical injection location. Based on the temperature-corrected color tone, the amount of chemical agent injected into the crude green liquor can be controlled so that it is neither excessive nor insufficient, and is more appropriate.

[0079] In this embodiment, the location where the chemical agent is added is preferably the green liquor clarification device (suitably a green liquor clarifier) ​​and / or upstream thereof, more preferably a transfer line upstream thereof, and even more preferably a line for transferring crude green liquor from the dissolution tank (hereinafter also referred to as the "crude green liquor transfer line"). Furthermore, a crude green liquor tank for storing crude green liquor may be arranged on the crude green liquor transfer line, and in this case, the location where the chemical agent is added is more preferably the crude green liquor transfer line between the crude green liquor tank and the green liquor clarification device. In this embodiment, after adding the agent to the crude green liquor, the crude green liquor is treated in a green liquor clarification device, thereby removing impurities (e.g., insoluble impurities, metal impurities, etc.) from the crude green liquor and promoting the clarification of the crude green liquor. The number of locations where the drug is added is not particularly limited, and may be either single or multiple, and may be one or more than one.

[0080] The chemical used for chemical injection in this embodiment is not particularly limited as long as it is a chemical (also referred to as a green liquor treatment agent or chemical) that can be used for the purpose of clarifying crude green liquor, and the same or different types of chemicals may be used. Generally, a high molecular weight polymer capable of flocculating dregs and / or insoluble metals in green liquor is used as the green liquor treatment agent. From the viewpoints of cost reduction and stable quality, it is preferable to use a commercially available polymer flocculant as the green liquor treatment agent.

[0081] The high molecular weight polymer may be anionic, cationic, nonionic, or amphoteric. Of these, cationic and / or anionic high molecular weight polymers are preferably used. The high molecular weight polymer may be one obtained by a known production method, or a commercially available product. The high molecular weight polymer may be incorporated into a polymer flocculant and used as a green liquor treatment agent.

[0082] The viscosity average molecular weight of the high molecular weight polymer is not particularly limited, but is preferably about 10,000 to 60,000,000, more preferably about 20,000 to 40,000,000, and even more preferably about 30,000 to 20,000,000. The viscosity average molecular weight of the polymer used in this embodiment is determined in accordance with JIS K 7367-1:2002 "Plastics - Determination of viscosity of polymer dilute solution using capillary viscometer - Part 1" It can be calculated using the intrinsic viscosity of the polymer obtained based on "Part 1: General Rules" (Polymer Flocculants: Precipitation Flocculants Mainly Based on Polymers, Eizo Omori, Polymer Publishing Association, 1973).

[0083] The cationic high molecular weight polymer used as the cationic flocculant is not particularly limited, but examples thereof include polyethyleneimine, ethylenediamine epichlorohydrin polycondensates, polyalkylenepolyamines, and polymers having quaternary ammonium salts of diallyldimethylammonium chloride and dimethylaminoethyl (meth)acrylate as constituent monomers, and one or more selected from these may be used.

[0084] The anionic polymer used as the anionic flocculant is not particularly limited, but examples thereof include poly(meth)acrylic acid, copolymers of (meth)acrylic acid and (meth)acrylamide, (meth)acrylamide-2-(meth)acrylamide-2-methylpropanesulfonic acid copolymers, and alkali metal salts thereof (e.g., sodium, potassium, etc.), acrylamide-based compounds, and copolymers thereof, and one or more selected from these may be used. The viscosity average molecular weight of the anionic high molecular weight polymer is preferably about 50,000 to 30,000,000, and more preferably about 500,000 to 20,000,000. The use of an anionic flocculant in combination with the cationic high molecular weight polymer is advantageous in that the settling properties of the flocculates are further improved.

[0085] In this embodiment, the amount of chemical to be added to the current crude green liquor (e.g., the mass (mg) of chemical per 1 L of crude green liquor) can be determined based on the color tone of the clarified green liquor. By monitoring the color tone and feedback-controlling the determined amount of chemical to be added, it is possible to adjust the amount of chemical to be added to the crude green liquor to be more appropriate. As a result, in this embodiment, the total amount of chemical to be added to the crude green liquor per period (e.g., one year, one month, one week, one day, etc.) can ultimately be reduced from the conventional total amount based on the color tone of the clarified green liquor.

[0086] The upper and lower limits of the amount of chemical agent to be injected in this embodiment can be determined appropriately for each chemical agent and are not particularly limited. For example, the upper and lower limits of the amount of chemical agent to be injected in a typical green liquor treatment system can be used as reference. The amount of chemical agent to be injected in a typical green liquor treatment system is approximately 0.1 to 50 mg per 1 L of crude green liquor. The amount of anionic polymer flocculant to be added is generally preferably 0.1 to 20 mg per 1 L of crude green liquor. The amount of cationic polymer flocculant to be added is generally preferably 0.5 to 40 mg per 1 L of crude green liquor.

[0087] <1-2-5. Example of green liquor treatment according to this embodiment> An example of the control (preferably feedback control) of this embodiment will be described below, but the invention is not limited to this. In addition, these steps may be combined in any manner. In this embodiment, it is preferable to control the amount of chemical agent injected into the crude green liquor based on the color tone of the clear green liquor. In controlling the amount of chemical agent injected into the crude green liquor, it is preferable to increase the amount of chemical agent injected into the crude green liquor when the color tone of the clear green liquor is reddish, and / or decrease the amount of chemical agent injected into the crude green liquor when the color tone of the clear green liquor is greenish, so that the amount of chemical agent injected into the crude green liquor is appropriate.

[0088] In this embodiment, it is more preferable to monitor the temperature of the clarified green liquor in addition to the color tone of the clarified green liquor, and to control the amount of chemicals injected into the crude green liquor based on the color tone and temperature of the clarified green liquor. This makes it possible to control the amount of chemicals injected into the crude green liquor more appropriately. In a more preferred embodiment, temperature monitoring is performed by controlling the temperature of the clarified green liquor during color measurement within a certain range, and / or by measuring the temperature of the clarified green liquor and correcting for temperature changes in the color of the clarified green liquor to control the change in color, thereby reducing errors in color due to temperature changes.The amount of chemical agent injected into the crude green liquor can be easily and accurately feedback-controlled from the current color value of the clarified green liquor, whose temperature is within a certain range, and / or the color value after temperature correction.

[0089] This embodiment includes the steps of monitoring the temperature, monitoring the color tone, and controlling the amount of chemicals injected, thereby reducing errors in color tone due to temperature changes and controlling the amount of chemicals injected into the crude green liquor. The steps of monitoring the temperature and monitoring the color tone can be performed simultaneously or separately.

[0090] In this embodiment, for example, "to do" such as "to acquire temperature measurement data" may be expressed as a "process" or a "step," a "step" may be expressed as "to do" or a "process," or a "process" may be expressed as "to do" or a step. Also, in this embodiment, a "mechanism" may be expressed as a system, an apparatus, or a part, an "apparatus" may be expressed as a system, a mechanism, or a part, and a "part" may be expressed as a part or an apparatus to be provided in a mechanism, apparatus, system, etc.

[0091] According to this embodiment, the cost of using chemicals in the green liquor treatment system can be further reduced, and crude green liquor can be clarified more quickly and accurately, thereby making it possible to more accurately and easily manage the operation of the green liquor treatment.

[0092] In other embodiments, the feedback control may involve comparing the color value of the current clear green liquor with the color value of a reference clear green liquor to determine the amount of chemical to be added to the crude green liquor, and then adding the determined amount of chemical to be added to the crude green liquor. Furthermore, by monitoring the color value of the current clear green liquor and feedback-controlling the amount of chemical added to the crude green liquor over time, the amount of chemical to be added to the crude green liquor may be further optimized.

[0093] As preferred specific examples, the first color tone error adjustment management will be described below with reference to, for example, Figures 3 and 4 to 7, and the second color tone error adjustment management will be described with reference to, for example, Figures 8 to 10. However, the present invention is not limited to these examples. Note that the "controller" may be replaced with an "operator (human)."

[0094] <1-2-5-1. Temperature monitoring step> An example of the temperature monitoring step in the control of this embodiment will be described with reference to FIGS. 3, 8, etc., for the first color tone error adjustment management and the second color tone error adjustment management, but the present invention is not limited to this. As the first color tone error adjustment management, the temperature of the clarified green liquid is measured to obtain the temperature measurement data. The clarified green liquid is heated or cooled so that its temperature falls within a preset range during color tone measurement. This makes it possible to obtain the current color tone value of the clarified green liquid, whose temperature is within the specified range (see Figure 3). Furthermore, as a second color tone error adjustment management, when acquiring the color tone value data of the clear green liquor, the temperature of the clear green liquor is measured to acquire temperature measurement data. Based on the temperature measurement data and color tone data of the clear green liquor at this time, the assumed set temperature (provisional setting) for the color tone of the clear green liquor, and the temperature correction model or temperature correction formula, the color tone value or color tone value data of the clear green liquor after temperature correction at the set temperature is acquired. This makes it possible to obtain the color tone value after temperature correction (see Figure 8, etc.).

[0095] <1-2-5-2. Color Tone Monitoring Step and Chemical Injection Amount Control Step> Examples of the color tone monitoring step and the drug injection amount control step in this embodiment will be described with reference to Figs. 4, 8, etc., but the present invention is not limited to these. When the temperature monitoring step is performed, a color monitoring step and a drug injection amount control step can be performed. The color monitoring step and the drug injection amount control step involve controlling the drug injection amount based on color monitoring, but are not limited to this. The timing of the temperature measurement and the color measurement is not particularly limited, and it is preferable to perform the temperature measurement and the color measurement at the same time. The simultaneous timing may be such that the respective measurements overlap partially or completely, and the start of each measurement may be different. For example, color measurement may be performed first, followed by temperature measurement, or temperature measurement may be performed first, followed by color measurement, or temperature measurement and color measurement may be performed simultaneously.

[0096] Furthermore, it is preferable that the color tone monitoring step and the chemical injection amount control step be based on the color tone of the clear green liquor, and increase the amount of chemical injection to the crude green liquor if the color tone of the clear green liquor is reddish, and / or decrease the amount of chemical injection to the crude green liquor if the color tone of the clear green liquor is greenish, so that the amount of chemical injection to the crude green liquor is appropriate.

[0097] In this embodiment, a suitable feedback control can also be used to add the amount of chemical agent to be injected to the crude green liquor based on the color value of the current clear green liquor (preferably the color value of the clear green liquor at the time of color measurement or the color value after temperature correction), without "comparing with the color value of the reference clear green liquor." Examples of the "current color value of the clear green liquor" include the "color value of the clear green liquor at the time of color measurement" obtained in the first color error adjustment control, or the "color value after temperature correction" obtained in the second color error adjustment control, but are not particularly limited to these.

[0098] In this embodiment, a more suitable feedback control is to compare the color value of the current clear green liquor with the color value of a reference clear green liquor to determine the amount of chemical to be added to the crude green liquor, and then add the determined amount of chemical to be added to the crude green liquor. Furthermore, by monitoring the color value of the current clear green liquor and feedback-controlling the amount of chemical added to the crude green liquor over time, the amount of chemical to be added to the crude green liquor becomes more appropriate, which is suitable. Feedback control through the color monitoring step can further reduce the cost of using chemicals in the green liquor treatment system and can clarify crude green liquor more quickly and accurately, thereby making it easier to manage the green liquor treatment operation.

[0099] The combination of the temperature monitoring step and the color monitoring step in this manner allows for faster, more accurate, and more precise clarification of the crude green liquor than the color monitoring step alone, thereby enabling more accurate and easier operational management of the green liquor treatment.

[0100] As a preferred specific example of the color tone monitoring step, it is preferable to carry out the step "under color tone error adjustment control due to temperature change." For example, as shown in Figures 3 to 7 (first color tone error adjustment control) and Figures 8 to 11 (second color tone error adjustment control), (a) the current clarified green solution is within the range of red color tone values ​​(for example, red; a * If the value is >0, it is determined that the current amount of chemicals injected is insufficient for the current crude green liquor treatment. Based on this determination result, chemicals are added to the crude green liquor so that the amount of chemicals injected into the crude green liquor is increased from the current amount of chemicals injected. (b) If the current clear green liquor is within the range of green color values ​​(e.g., green or darker green; a * Value < 0? to a * If the value is <-20, it is determined that the current amount of chemicals injected is excessive in the current green liquor treatment. Based on this determination result, chemicals are added to the green liquor so that the amount of chemicals injected to the crude green liquor is reduced from the current amount of chemicals injected. (c) If the current clear green liquor is within a predetermined color value range (e.g., light green; e.g., -20 * ​If the value is <0, the current amount of chemicals injected is determined to be appropriate, and the current amount of chemicals injected into the crude green liquor is maintained in the current green liquor treatment. These (a) to (c) can further suppress excess or deficiency, further reduce the cost of using chemicals in the green liquor treatment system, and enable the crude green liquor to be clarified more quickly and accurately, thereby making it easier to manage the operation of the green liquor treatment.

[0101] As a more preferred example, it is preferable to carry out "under the control of color tone error adjustment due to temperature change." For example, as shown in FIG. 7, (a1) in (a), the current clear green liquid is within the range of reddish color tone values ​​(for example, a * If the result is YES, and the concentration of the extracted sludge, which is the sludge discharged from the green liquor clarifier, is within a predetermined value (more preferably 1 to 15% by mass) (YES), it is determined that solid-liquid separation by coagulation in the current green liquor clarifier is being achieved, and the amount of chemicals injected to promote the removal of impurities is increased. Based on this determination result, the amount of chemicals injected into the crude green liquor is increased. On the other hand, if the sludge concentration is outside the predetermined value (more preferably not within the range of 1 to 15% by mass) (NO), it is determined that solid-liquid separation by coagulation in the current green liquor clarifier is not being achieved. In this case, the amount of chemicals injected to promote the removal of impurities, which may have a positive or negative effect on coagulation, is maintained.

[0102] More preferably, it is preferable to carry out the process "under the control of adjusting color tone errors due to temperature changes." (b1) In the above (b), the current green solution is within the range of color tone values ​​of green (for example, *If the value is <-20% (YES), and the concentration of the extracted sludge, which is the sludge discharged from the green liquor clarifier, is not within a predetermined value (more preferably 1 to 15% by mass) (NO), it is determined that solid-liquid separation by coagulation in the current green liquor clarifier is not being achieved. In this case, the amount of chemicals injected that promote the removal of impurities that may have a positive or negative effect on coagulation is maintained. On the other hand, if the sludge concentration is within a predetermined value (more preferably 1 to 15% by mass) (YES), it is determined that solid-liquid separation by coagulation in the current green liquor clarifier is being achieved. In this case, the amount of chemicals injected that promote the removal of impurities that may have a positive or negative effect on coagulation is reduced. The amount of chemicals injected into the crude green liquor is reduced according to the result of this determination.

[0103] More preferably, it is preferable to carry out the process "under the control of adjusting color tone errors due to temperature changes," and (c1) in (a), the current clear green liquid is within the range of reddish color tone values ​​(for example, a * If the answer is NO, and if the current clear green liquor is within the range of green color tone values ​​in (b) above (e.g., a * If the value is not <-20 (NO), the current amount of chemical injected is determined to be appropriate, and the current amount of chemical injected is maintained. In accordance with this determination result, the amount of chemical injected into the crude green solution is maintained. In addition, when maintaining the amount of chemical injected, the color value is preferably in the light green range, and as the light green, for example, -20 * Examples of suitable upper limit values ​​include a value <0, and examples of suitable lower limit values ​​include -30, -20, and -10.

[0104] These (a1) to (c1) can further prevent excess or shortage of chemical injection, further reduce the cost of chemical use in the green liquor treatment system, and enable the crude green liquor to be clarified more quickly and accurately, thereby making it easier to manage the operation of the green liquor treatment. The dregs concentrations in (a1) to (c1) above may be input by the operator via the input unit and transmitted to the control unit, or the dregs concentrations pre-stored in the memory unit may be transmitted to the control unit. ​

[0105] In this embodiment, it is preferable to link and manage the "color value of the reference clear green liquor" and the "amount of chemical to be injected into the crude green liquor" (for example, the type of chemical and a suitable amount to be injected). This makes it possible to obtain a suitable "amount of chemical to be injected into the crude green liquor" from the "color value of the reference clear green liquor" and use this in green liquor treatment.

[0106] In a further preferred embodiment, in order to manage the change in the color tone of the clarified green liquor after correcting for temperature, it is determined whether the measured temperature value of the clarified green liquor is within a certain range. If the measured temperature value is within the certain range, the amount of chemical agent injected into the crude green liquor is controlled based on the measured color tone value of the clarified green liquor at that time. Alternatively, if the measured temperature value is not within the certain range, the color tone of the clarified green liquor is measured, and the measured color tone value of the clarified green liquor obtained based on the measured temperature at that time is corrected, and the amount of chemical agent injected into the crude green liquor is controlled. For example, if the constant set temperature is set to 80±3°C, when the actual measured temperature of the clear green liquor during color measurement is 70 to 77°C, the control unit temperature-corrects the color data using a temperature correction model so that the set temperature becomes 80°C, and determines the amount of chemical to be injected into the crude green liquor based on the temperature-corrected color (set to 80°C).

[0107] <1-3. Example of green liquor treatment method in this embodiment> In describing the example of the green liquor treatment method in this embodiment, descriptions of the components and treatment methods of the crude green liquor, clarified green liquor, the temperature of the clarified green liquor, the temperature monitoring location, the temperature measurement value, color tone error adjustment management due to temperature change, the color tone of the clarified green liquor, the color tone monitoring location, the color tone value, chemicals, feedback control, etc., which overlap with those in "1-1.", "1-2.", etc., will be omitted as appropriate, but the descriptions in "1-1." and "1-2.", etc., also apply to this embodiment and can be adopted as appropriate. Furthermore, in describing the example of the green liquor treatment method in this embodiment, the descriptions in "2." to "5.", etc., which will be described later, can also be applied to this embodiment and can be adopted as appropriate.

[0108] The green liquor treatment method in this embodiment preferably includes at least a control step of feedback-controlling the amount of chemicals injected into the crude green liquor based on the color tone of the clarified green liquor. More preferably, the method further comprises a temperature monitoring step of monitoring and / or measuring the temperature of the clarified green liquor. In the temperature monitoring step, more preferably, the temperature of the clarified green liquor is measured to control the temperature of the clarified green liquor during the color measurement within a certain range, and / or a change in the color of the clarified green liquor is controlled after temperature correction based on the color measurement value and the temperature measurement value of the clarified green liquor during the color measurement. More preferably, the method further comprises a color tone monitoring step of monitoring and / or measuring the color tone of the clarified green liquor. In the color tone monitoring step, more preferably, the color tone of the clarified green liquor is measured to obtain color tone data.

[0109] In the control step of this embodiment, the control unit can control or feedback-control the amount of chemical agent injected into the crude green liquor based on the color tone of the clarified green liquor or based on the color tone and temperature of the clarified green liquor.

[0110] The control unit can manage the temperature and color tone of the clarified green liquor based on the temperature data of the clarified green liquor from the temperature monitoring unit, and can instruct the temperature monitoring unit to measure the temperature of the clarified green liquor as necessary. Based on the temperature data of the clarified green liquid, the control unit can instruct the temperature monitoring unit to control the temperature of the clarified green liquid during color measurement within a certain range as a first color tone error adjustment control, and / or can perform temperature correction control of the color tone of the clarified green liquid based on the temperature of the clarified green liquid as a second color tone error adjustment control, and these can be set as the color tone data of the clarified green liquid obtained under color tone error adjustment control. The control unit or the temperature monitoring unit can instruct the heating / cooling unit to maintain the temperature within a certain range as the first color tone error adjustment management. As a second color tone error adjustment management, the control unit or the temperature monitoring unit can use a temperature correction model stored in the memory unit or externally to obtain a temperature-corrected color tone value from the color tone measurement value, the temperature measurement value at the time of the color tone measurement, and the temperature of the color tone after temperature correction that is desired to be obtained.

[0111] The control unit can monitor the color tone of the clarified green liquor based on the color tone data of the clarified green liquor from the color tone monitoring unit, and can instruct the color tone monitoring unit to measure the color tone of the clarified green liquor as necessary. The control unit can instruct the chemical dosing unit on a predetermined amount of chemical to be added to the crude green liquor based on the color data of the clear green liquor obtained under the color error adjustment management. The control unit can instruct the chemical dosing unit on a predetermined amount of chemical to be added to the crude green liquor based on the color data of the clear green liquor as well as sludge concentration data from the sludge concentration measurement unit. Furthermore, the color monitoring unit can measure the treatment status of the green liquor after adding the predetermined amount of chemical to the crude green liquor as the color of the clear green liquor (color data), and transmit the color of the clear green liquor (color data) to the control unit. The control unit can monitor the color and perform feedback control of the chemical dosing of the determined amount, preferably over time.

[0112] As described above, the control unit can feedback-control the amount of chemicals injected into the crude green liquor based on the color tone of the clear green liquor. Furthermore, the control unit can feedback-control the adjustment of the amount of chemicals injected to the chemical injection unit continuously or intermittently (at regular intervals) based on the color tone of the clear green liquor, thereby ensuring an appropriate amount of chemicals injected into the crude green liquor. In this way, the control unit can further reduce the over- or under-injection of chemicals, thereby reducing the cost of chemicals used in the green liquor treatment system and enabling the crude green liquor to be clarified more quickly and accurately, thereby making it easier to manage the green liquor treatment operation.

[0113] This embodiment can also provide a green liquor treatment method that includes a control step of monitoring the color tone and temperature of the clarified green liquor, and feedback-controlling the amount of chemicals to be injected into the crude green liquor based on the color tone of the clarified green liquor under control of adjusting color tone errors due to temperature changes. In this embodiment, it is preferable that the control step includes a step of controlling color tone errors due to temperature changes, which involves controlling the temperature of the clear green liquor during color tone measurement within a certain range, and / or a step of controlling changes in the color tone of the clear green liquor after correcting for temperature based on the measurement results of the temperature of the clear green liquor. The present embodiment preferably provides a green liquor treatment method that further includes, in addition to the control step, a color tone monitoring step of measuring the color tone of the clarified green liquor, and / or an agent injection step of injecting an agent into the crude green liquor. In a more preferred embodiment of the present invention, Performing color error adjustment management due to temperature changes (color error adjustment management process due to temperature changes); Monitoring and / or measuring the color of the clarified green liquor (color monitoring step); Injecting a chemical into the crude green liquor (chemical injection step); and The method includes monitoring and / or measuring the color tone of the clarified green liquor, feeding back the amount of chemicals to be injected into the crude green liquor based on the color tone, and controlling the injection of chemicals into the crude green liquor (control step).

[0114] Furthermore, a more preferred embodiment of the present invention provides a method for treating green liquor, further comprising the step of measuring the concentration of sludge withdrawn from the green liquor clarification device. In a more preferred embodiment of the present invention, Controlling color tone errors due to temperature changes (temperature change color tone error control step), monitoring and / or measuring the color tone of the clarified green liquid (color tone monitoring step), Measuring the concentration of sludge extracted from the green liquor clarification device (sludge concentration measurement step); Injecting a chemical into the crude green liquor (chemical injection step); and The method includes monitoring and / or measuring the color tone of the clarified green liquor, monitoring and / or measuring the concentration of the extracted sludge, and feeding back the amount of chemical agent to be injected into the crude green liquor based on the color tone of the clarified green liquor and the sludge concentration, thereby controlling the injection of the chemical agent into the crude green liquor (control step).

[0115] <1-4. Example of green liquor treatment in this embodiment> The green liquor treatment procedure in this embodiment will be described in more detail with reference to Figures 3 to 11, but the green liquor treatment method in this embodiment is not limited to these. These procedures in Figures 3 to 11 may be freely combined. The explanation of the green liquor treatment procedure can also be used to explain the operation of the green liquor treatment method, green liquor treatment management device, and green liquor treatment system of this embodiment. <1-4-1. Example 1 of green liquor treatment in this embodiment> Example 1 of green liquor treatment in this embodiment includes a temperature monitoring step (first color tone error adjustment management step), followed by a color tone monitoring step and a chemical injection step (see FIGS. 3 and 4).

[0116] <1-4-1-1. Temperature monitoring step> The flow for controlling the temperature of the clarified green liquor within a certain range during color measurement in the temperature monitoring step will be described with reference to Figure 3. This temperature monitoring step can be performed simultaneously with the color monitoring step and the chemical injection step or at separate times, but performing them simultaneously is preferable because it allows temperature control in real time and reduces color errors due to temperature changes. In step 101, the control unit starts color tone error adjustment management in order to manage changes in the color tone of the clarified green liquid. In step 102, the control unit instructs the temperature sensor unit to measure the temperature of the clarified green liquor. The temperature sensor unit may transmit the measured temperature data of the clarified green liquor to the control unit, or may transmit the measured temperature data to the control unit via the temperature monitoring unit or the memory unit. In this way, the control unit acquires the measured temperature data of the clarified green liquor. The control unit may instruct the temperature monitoring unit (temperature sensor unit) to monitor and / or measure the temperature of the clarified green liquor. The temperature monitoring unit preferably monitors and / or measures the clarified green liquor with a contact or non-contact temperature sensor, and the clarified green liquor may be clarified green liquor that has flowed into the measurement container from the clarified green liquor transfer line. After measuring the temperature of the clarified green liquor, the temperature monitoring unit may transmit the measured temperature data to the control unit, or may store the measured temperature data in a memory unit and transmit it from the memory unit to the control unit.

[0117] In step 103, the control unit adjusts the temperature of the clear green liquor based on the first color tone error adjustment so as to reduce the error in the color tone of the clear green liquor. Based on a preset temperature range, it instructs the heating and cooling unit to keep the temperature within that range. The control unit uses the heating and cooling unit to adjust the temperature of the clear green liquor to stay within that range. When presetting a temperature within the preset range, the control unit can obtain data on the set temperature and ±°C by an operator entering it through the input means, or by transmitting the set temperature and ±°C that are previously stored in the memory unit. The set temperature and ±°C can be appropriately determined from the description (e.g., within a certain range) of <2-1-3-2. Heating and Cooling Device (Heating and Cooling Unit)> described below. The control unit may also instruct a temperature sensor capable of measuring the temperature of the green liquor inside the green liquor clarification device or at the outlet of the device to measure the temperature and send the measurement result to the control unit as a signal or data, thereby obtaining the measured temperature and setting it as a set temperature (a temperature within a predetermined range).

[0118] In step 104, the control instructs the temperature monitoring unit (temperature sensor unit) whether to continue or end the temperature measurement. If it is to continue (YES), the process returns to step 102, and if it is to end (NO), the temperature measurement ends.

[0119] 3 can be applied as a second color tone error adjustment management step, which can be a step including steps 101 and 102. Steps 101 and 102 can be performed in the same manner as steps 101 and 102 in <1-4-1-1. Temperature monitoring step> above, and detailed explanations will be omitted, but for example, in step 101, the control unit starts color tone error adjustment management in order to manage changes in the color tone of the clear green liquid, and in step 102, the control unit instructs the temperature sensor unit to measure the temperature of the clear green liquid, and can obtain measured temperature data of the clear green liquid.

[0120] 3 (the above-mentioned <Another embodiment of color tone error adjustment management due to temperature change>), a step of determining whether the measured temperature value of the clarified green liquor is within a certain range, and if it is within the certain range, a step of controlling the amount of chemical agent injected into the crude green liquor based on the measured color tone value of the clarified green liquor at that time, or a step of measuring the color tone of the clarified green liquor, correcting the measured color tone value of the clarified green liquor based on the measured temperature at that time, and controlling the amount of chemical agent injected into the crude green liquor can also be performed (not shown). This makes it possible to better manage changes in the color tone of the clarified green liquor after correcting for temperature.

[0121] In the other embodiment, the control unit preferably performs steps 102 and 102 described above as steps 1001 and 1002, determines whether the measured temperature of the clarified green liquor is within a certain range in step 1003, and then performs step 1004 if the measured temperature is within the certain range and step 1005 if the measured temperature is not within the certain range. The control unit preferably uses the above-mentioned "set temperature and ±°C data" to determine whether the measured temperature is within the certain range. The control unit preferably performs a first color error adjustment management step in step 1004 and a second color error adjustment management step in step 1005. If the measured temperature is not within the certain range, the control unit may perform temperature adjustment by heating or cooling in the first color error adjustment management step.

[0122] In the case of the other embodiment, by reducing the error in the color tone of the clarified green liquor and increasing the accuracy of measuring this color tone, it is possible to more accurately and easily manage the operation of green liquor treatment, such as by more appropriately injecting the amount of chemicals into the crude green liquor (for example, the timing of addition, the amount of addition, etc.).

[0123] <1-4-1-2. Color monitoring step and chemical injection step> The color tone monitoring step and the drug injection step will be described with reference to FIG. The color tone monitoring step and the chemical injection step can be performed at the same time as the temperature monitoring step (first color tone error adjustment management step) or at different times. In step 201, feedback control of drug infusion is initiated. In step 202, the control unit acquires color data of the clear green liquor from the color monitoring unit or the memory unit. At this time, the color monitoring unit transmits color data of the clear green liquor at the time of measurement, measured by the color measurement unit, to the control unit. The control unit may instruct the color tone monitoring unit to monitor and / or measure the color tone of the clarified green liquor. The color tone monitoring unit preferably monitors and / or measures the clarified green liquor that has flowed into the measurement container from the clarified green liquor transfer line from above in a non-contact manner. The color tone monitoring unit may store the measured color tone data in a memory unit, and in this case, the measured color tone data may be transmitted from the memory unit to the control unit.

[0124] In step 203, the control unit adjusts the amount of chemical agent to be injected into the crude green liquor to be more appropriate based on the color data of the clear green liquor at the time of measurement. More specifically, the control unit compares the color data of the clear green liquor with the color value data of the reference clear green liquor (reference value of the clear green liquor color) to determine a more appropriate amount of chemical agent to be injected. The reference value of the clear green liquor color may be stored in the memory unit in advance and transmitted from the memory unit to the control unit. Based on this determination, the control unit instructs the chemical injection unit on the amount of chemical to be injected into the crude green liquor. The chemical injection unit then uses a chemical pump to add chemicals from the chemical tank to the crude green liquor in the green liquor treatment system (preferably the crude green liquor transfer line). The chemical injection unit then adjusts the operation of the chemical pump to increase or decrease the amount of chemical injected per liter of crude green liquor compared to the amount injected during measurement, or to maintain the amount injected during measurement.

[0125] In step 204, after adjusting the amount of chemicals injected into the crude green liquor, the control unit instructs whether or not to measure the color tone of the adjusted clear green liquor. If measurement is to be performed, the process returns to step 202, and feedback control continues. If measurement is not to be performed, the feedback control process ends. It is preferable that the operator set "measure" in advance to "continue feedback control." If "measure" is set in advance, the operator may also set "end" as appropriate, or may set the end time in advance.

[0126] <1-4-2. Example 2 of green liquor treatment in this embodiment> Example 2 of green liquor treatment in this embodiment includes a temperature monitoring step (first color tone error adjustment management step), followed by a color tone monitoring step and a chemical injection step (see FIGS. 3 and 5). The temperature monitoring step can be performed in the same manner as in <1-4-1-1. Temperature monitoring step>. Example 2 of this embodiment will be described with reference to Figures 3 and 5. Portions that overlap with Example 1 of green liquor treatment of this embodiment will be omitted as appropriate. In step 301, feedback control is initiated. In step 302, the control unit acquires color data of the clarified green liquor from the color monitoring unit or the memory unit. In step 302, the explanation of the control unit and color monitoring unit that overlap with step 202 will be omitted.

[0127] In step 303, the control unit compares the color tone of the clear green liquor at the time of measurement with the color tone of the clear green liquor in the past based on the color tone data of the clear green liquor at the time of measurement, and determines whether or not the color tone has become reddish (YES or NO). If the color has become reddish (YES), the process proceeds to step 304; if the color has not become reddish (NO), the process proceeds to step 306.

[0128] In step 304, based on the determination of red (YES), the control unit instructs the chemical injection unit to increase the chemical injection amount for the crude green solution compared to the chemical injection amount during measurement. This causes the chemical injection unit to adjust the operation of the chemical pump to increase the chemical injection amount per 1 L of crude green solution compared to the chemical injection amount during measurement.

[0129] In step 305, based on the red-based determination (NO), the control unit instructs the chemical injection unit to reduce the chemical injection amount for the crude green solution compared to the amount injected during measurement. This causes the chemical injection unit to adjust the operation of the chemical pump to reduce the chemical injection amount per 1 L of crude green solution compared to the amount injected during measurement. Although not shown in the figure, the control unit can instruct the drug injection unit to maintain the drug injection amount at the time of measurement if the color tone does not become reddish and is at the ``appropriate color tone value.''

[0130] In step 306, after adjusting the amount of chemicals injected, the control unit instructs whether or not to measure the color tone of the adjusted clear green solution. If measurement is to be performed, the process returns to step 302, and feedback control continues. If measurement is not to be performed, the feedback control process ends. It is preferable that the operator set "measure" in advance to "continue feedback control." If "measure" is set in advance, the operator may also set "end" as appropriate, or may set an end time in advance.

[0131] <1-4-3. Example 3 of green liquor treatment in this embodiment> Example 3 of green liquor treatment in this embodiment includes a temperature monitoring step (first color tone error adjustment management step), followed by a color tone monitoring step and a chemical injection step (see FIGS. 3 and 6). The temperature monitoring step can be performed in the same manner as in <1-4-1-1. Temperature monitoring step>. Example 3 of this embodiment will be described with reference to Figures 3 and 6. Portions that overlap with Examples 1 and 2 of the feedback green liquor treatment of this embodiment will be omitted as appropriate. In step 401, feedback control is initiated. In step 402, the control unit acquires color data of the clarified green liquor from the color monitoring unit or the memory unit. In step 402, the explanation of the control unit and color monitoring unit that overlap with step 202 will be omitted.

[0132] In step 403, the control unit compares the color tone of the clear green liquor at the time of measurement with the color tone of the clear green liquor in the past based on the color tone data of the clear green liquor, and determines whether or not the color tone has become greenish (YES or NO). If the color has become greenish (YES), the process proceeds to step 404; if the color has not become greenish (NO), the process proceeds to step 406.

[0133] In step 404, based on the determination of green (YES), the control unit instructs the chemical injection unit to reduce the chemical injection amount for the crude green liquor from the chemical injection amount during measurement. This causes the chemical injection unit to adjust the operation of the chemical pump to reduce the chemical injection amount per 1 L of crude green liquor from the chemical injection amount during measurement.

[0134] In step 405, based on the determination of green (NO), the control unit instructs the chemical injection unit to increase the chemical injection amount for the crude green liquor from the chemical injection amount at the time of measurement. As a result, the chemical injection unit adjusts the operation of the chemical pump to increase the chemical injection amount per 1 L of crude green liquor from the chemical injection amount at the time of measurement. Although not shown in the figure, the control unit can instruct the drug injection unit to maintain the drug injection amount at the time of measurement when the color tone becomes greenish and the color tone is at the ``appropriate color tone value.''

[0135] In step 406, after adjusting the amount of chemical injection, the control unit instructs whether or not to measure the color tone of the adjusted clear green solution. If measurement is to be performed, the process returns to step 402, and feedback control continues. If measurement is not to be performed, the feedback control process ends. It is preferable that the operator set "measure" in advance to "continue feedback control." If "measure" is set in advance, the operator may also set "end" as appropriate, or may set the end time in advance.

[0136] <1-4-4. Example 4 of green liquor treatment in this embodiment> Example 4 of green liquor treatment in this embodiment includes a temperature monitoring step (first color tone error adjustment management step), followed by a color tone monitoring step and a chemical injection step (see FIGS. 3 and 7). The temperature monitoring step can be performed in the same manner as in <1-4-1-1. Temperature monitoring step>. Example 4 of this embodiment will be described with reference to Figures 3 and 7. Portions that overlap with Examples 1 to 3 of the green liquor treatment of this embodiment described above will be omitted as appropriate. In step 501, feedback control is initiated. In step 502, the control unit acquires RGB color system color data of the clear green liquid from the color tone monitoring unit. At this time, the color tone monitoring unit transmits the color tone data (RGB color system) of the clear green liquid at the time of measurement, measured by the color tone measuring unit, to the control unit. In step 502, descriptions of the control unit and color tone monitoring unit that overlap with step 202 will be omitted.

[0137] In step 503, the control unit converts the acquired RGB color system color data of the clear green liquid into L * a * b * Convert to colorimetric data. The color tone monitoring unit calculates the RGB color system color tone data of the clear green liquid by L * a * b * In this case, the control unit skips step 502 and receives the L * a * b * Color system color tone data may also be acquired.

[0138] In step 504, the control unit * a * b * Based on colorimetric data, a * If the value is equal to or greater than the predetermined value (preferably >0) (YES), the process proceeds to step 505. Alternatively, the control unit may omit or skip step 505 and proceed to step 506. * If the value is not greater than or equal to the predetermined value (preferably > 0) (NO), the process proceeds to step 507 .

[0139] In step 505, if the sludge concentration is within a predetermined value (preferably 1 to 15% by mass) (YES), the control unit determines that solid-liquid separation by coagulation in the current green liquor clarifier is successful, and further increases the injection amount of chemicals that promote the removal of impurities. According to this determination result, the injection amount of chemicals to the crude green liquor is increased. The process proceeds to step 506. On the other hand, if the sludge concentration is not within the predetermined value (preferably 1 to 15% by mass) (NO), the control unit determines that solid-liquid separation by coagulation in the current green liquor clarifier is not successful. In this case, the injection amount of chemicals that promote the removal of impurities, which may have a positive or negative effect on coagulation, is maintained, and the process proceeds to step 510. The control unit may acquire data on the sludge concentration from the sludge concentration measurement unit or a memory unit that stores measured values ​​of the sludge concentration. The sludge concentration measurement unit may measure the sludge concentration at a fixed rate and store the measured sludge concentration as data in the memory unit.

[0140] In step 506, the control unit instructs the chemical injection unit to increase the chemical injection amount for the crude green solution compared to the amount injected during color measurement, based on the determination results of steps 504 and 505. This causes the chemical injection unit to adjust the operation of the chemical pump to increase the chemical injection amount per 1 L of crude green solution compared to the amount injected during color measurement. Then, the process proceeds to step 510.

[0141] In step 507, the control unit * a * b * Based on colorimetric data, a * If the value is equal to or less than the predetermined value (preferably <-20) (YES), the process proceeds to step 508. Alternatively, the control unit may omit or skip step 508 and proceed to step 509. * If the value is not equal to or less than the predetermined value (preferably <-20) (NO), the amount of medicine injected during color measurement is determined to be appropriate, the amount of medicine injected during color measurement is maintained, and the process proceeds to step 510.

[0142] In step 508, if the control unit determines that the sludge concentration is within a predetermined value (preferably 1 to 15% by mass) (YES), the control unit proceeds to step 509. On the other hand, if the sludge concentration is not within the predetermined value (preferably 1 to 15% by mass) (NO), the control unit determines that solid-liquid separation through coagulation in the current green liquor clarifier is not being achieved. In this case, the control unit maintains the amount of chemical agent injected at the time of color measurement, which promotes the removal of impurities that may have a positive or negative effect on coagulation, and proceeds to step 510.

[0143] In step 509, the control unit instructs the chemical injection unit to reduce the amount of chemical injected into the crude green solution compared to the amount injected during color measurement, based on the results of the determinations in steps 507 and 508. This causes the chemical injection unit to adjust the operation of the chemical pump to reduce the amount of chemical injected per 1 L of crude green solution compared to the amount injected during color measurement. Then, the process proceeds to step 510.

[0144] In step 510, after adjusting the amount of chemicals injected, the control unit instructs whether or not to measure the color tone of the adjusted clear green solution. If measurement is to be performed, the process returns to step 502, and feedback control continues. If measurement is not to be performed, the feedback control process ends. It is preferable that the operator set "measure" in advance to "continue feedback control." If "measure" is set in advance, the operator may also set "end" as appropriate, or may set an end time in advance.

[0145] <1-4-5. Example 5 of green liquor treatment in this embodiment> Example 5 of the green liquor treatment in this embodiment includes a temperature monitoring step (second color error adjustment management step), followed by a color monitoring step and a chemical injection step (see Figures 3 and 8, etc.). Example 5 of green liquor treatment according to this embodiment will be described with reference to Figures 3 and 8. Portions that overlap with Examples 1 to 4 of green liquor treatment according to this embodiment will be omitted as appropriate. In step 601, feedback control of drug infusion is initiated. In step 602, color data and temperature data of the clarified green liquor are obtained. It should be noted that the "acquisition of color tone data of green liquor" in step 602 can be performed in the same manner as step 202 in Example 2 of green liquor processing of this embodiment, and a detailed description thereof will be omitted. Furthermore, "acquire temperature data" in step 602 is a second color tone error adjustment management step that includes steps 101 and 102 in Fig. 3. Steps 101 and 102 can be performed in the same manner as steps 101 and 102 in <1-4-1-1. Temperature monitoring step> above, and detailed explanations will be omitted, but for example, in step 101, the control unit starts color tone error adjustment management in order to manage changes in the color tone of the clear green liquor, and in step 102, the control unit instructs the temperature sensor unit to measure the temperature of the clear green liquor, and the measured temperature value data of the clear green liquor can be acquired.

[0146] In step 603, "a * "Temperature correction of value" is a second color tone error adjustment management step including step 103 in FIG. 3. The control unit applies the color tone data (a) of the clarified green liquid at the time of measurement to a temperature correction model (temperature correction formula) prepared in the control unit for correcting color tone with temperature. * The temperature data (℃) and temperature data (℃) of the clarified green liquid are used to obtain the "temperature-corrected color tone" used for feedback control. The temperature-corrected color tone (a * Here, the temperature is °C and the color is a * However, these units may be converted into other mutually convertible units to obtain the temperature-corrected color tone. The temperature correction model may be created in advance and transmitted to the control unit by accessing a storage unit or the like. The control unit may create the temperature correction model from each feature quantity using statistical processing, such as AI learning, and the feature quantities include, but are not limited to, the color tone of the clarified green liquor and the temperature of the clarified green liquor. Steps 604 and 605 after step 604 in Example 5 of green liquor treatment of this embodiment can be performed in the same manner as steps 203 and 204 (see FIG. 4) in the color tone monitoring step and chemical injection step in Example 1 of green liquor treatment of this embodiment, except for the “color tone after temperature correction” acquired in step 603, and therefore detailed explanations will be omitted. In step 604, the control unit adjusts the amount of chemical agent injected into the crude green solution based on the "temperature-corrected color data." In step 605, after adjusting the amount of chemicals injected into the crude green liquor, the control unit instructs whether or not to measure the color tone of the adjusted clear green liquor. If measurement is to be performed, the process returns to step 202, and feedback control continues. If measurement is not to be performed, the feedback control process ends.

[0147] <1-4-6. Example 6 of green liquor treatment in this embodiment> Example 6 of the green liquor treatment in this embodiment includes a temperature monitoring step (second color error adjustment management step), followed by a color monitoring step and a chemical injection step (see Figures 3 and 9). Example 6 of green liquor treatment according to this embodiment will be described with reference to Figures 3 and 9. Portions that overlap with Examples 1 to 5 of green liquor treatment according to this embodiment will be omitted as appropriate. In step 701, feedback control of drug infusion is initiated. In step 702, color data and temperature data of the clarified green liquor are acquired. In step 703, the color data of the clarified green liquid at the time of measurement (a * The temperature data (℃) and temperature data (℃) of the clarified green liquid are used to obtain the "temperature-corrected color tone" used for feedback control. The temperature-corrected color tone (a * Get the value. Steps 704, 705, 706, and 707 following step 704 in Example 6 of green liquor treatment of this embodiment can be performed in the same manner as steps 303, 304, 305, and 306 (see FIG. 5 ) in the color tone monitoring step and chemical injection step in Example 2 of green liquor treatment of this embodiment, except for the “color tone after temperature correction” acquired in step 703, and detailed explanations thereof will be omitted. In step 704, the control unit adjusts the amount of chemical agent injected into the crude green liquor based on the "temperature-corrected color data." In step 705, the control unit compares the color tone data after temperature correction with the color tone of the clear green liquid, which serves as the judgment standard, and determines whether the color tone has become reddish (YES or NO). If the color tone has become reddish (YES), the process proceeds to step 705; if the color tone has not become reddish (NO), the process proceeds to step 706. In step 705, based on the determination of red (YES), the control unit instructs the chemical injection unit to increase the chemical injection amount for the crude green solution compared to the chemical injection amount during measurement. In step 706, based on the determination of red (NO), the control unit instructs the chemical injection unit to decrease the chemical injection amount for the crude green solution compared to the chemical injection amount during measurement. In step 707, after adjusting the amount of chemicals injected, the control unit instructs whether or not to measure the color tone of the adjusted clear green solution. If measurement is to be performed, the process returns to step 702, and feedback control continues. If measurement is not to be performed, the feedback control process ends.

[0148] <1-4-7. Example 7 of green liquor treatment in this embodiment> Example 7 of the green liquor treatment in this embodiment includes a temperature monitoring step (second color error adjustment management step), followed by a color monitoring step and a chemical injection step (see Figures 3 and 10). Example 7 of green liquor treatment according to this embodiment will be described with reference to Figures 3 and 10. Portions that overlap with Examples 1 to 6 of green liquor treatment according to this embodiment will be omitted as appropriate. In step 801, feedback control of drug infusion is initiated. In step 802, color data and temperature data of the clarified green liquor are acquired. In step 803, the color data of the clarified green liquid at the time of measurement (a * The temperature data (℃) and temperature data (℃) of the clarified green liquid are used to obtain the "temperature-corrected color tone" used for feedback control. The temperature-corrected color tone (a * Get the value. Steps 804, 805, 806, and 807 following step 804 in Example 7 of green liquor treatment of this embodiment can be performed in the same manner as steps 403, 404, 405, and 406 (see FIG. 6 ) in the color tone monitoring step and chemical injection step in Example 3 of green liquor treatment of this embodiment, except for the “color tone after temperature correction” acquired in step 803, and detailed explanations thereof will be omitted. In step 804, the control unit adjusts the amount of chemical agent injected into the crude green liquor based on the "temperature-corrected color data." In step 804, the control unit compares the color tone of the clear green liquor at the time of measurement with the color tone of the clear green liquor that serves as the judgment standard based on the color tone data of the clear green liquor, and determines whether or not it has become greenish (YES or NO). If it has become greenish (YES), the process proceeds to step 805, and if it has not become greenish (NO), the process proceeds to step 806.

[0149] In step 805, based on the determination of green (YES), the control unit instructs the chemical injection unit to decrease the chemical injection amount for the crude green solution compared to the chemical injection amount during measurement. In step 806, based on the determination of green (NO), the control unit instructs the chemical injection unit to increase the chemical injection amount for the crude green solution compared to the chemical injection amount during measurement. In step 807, the control unit instructs whether or not to measure the color tone of the adjusted clear green solution after adjusting the amount of chemicals injected. If measurement is to be performed, the process returns to step 802 and continues feedback control. If measurement is not to be performed, the feedback control process ends.

[0150] <1-4-8. Example 8 of green liquor treatment in this embodiment> Example 8 of the green liquor treatment in this embodiment includes a temperature monitoring step (second color error adjustment management step), followed by a color monitoring step and a chemical injection step (see Figures 3 and 11). Example 7 of green liquor treatment according to this embodiment will be described with reference to Figures 3 and 11. Portions that overlap with Examples 1 to 7 of green liquor treatment according to this embodiment will be omitted as appropriate. In step 901, feedback control of drug infusion is initiated. In step 902, color data and temperature data of the clarified green liquor are acquired. In step 903, the color data of the clarified green liquid at the time of measurement (a * The temperature data (℃) and temperature data (℃) of the clarified green liquid are used to obtain the "temperature-corrected color tone" used for feedback control. The temperature-corrected color tone (a * Get the value. Each of the steps from step 905 onwards, ie, steps 905 to 911, in Example 8 of green liquor treatment of this embodiment can be performed in the same manner as each of steps 504 to 510 (see FIG. 6) in the color tone monitoring step and chemical injection step in Example 4 of green liquor treatment of this embodiment, except for the “color tone after temperature correction” acquired in step 903, and detailed explanations thereof will be omitted. In step 904, the control unit adjusts the amount of chemical agent injected into the crude green solution based on the "temperature-corrected color data."

[0151] In step 905, the control unit * a * b * Based on colorimetric data, a *If the value is equal to or greater than the predetermined value (preferably >0) (YES), the process proceeds to step 906. Alternatively, the control unit may omit or skip step 906 and proceed to step 907. * If the value is not greater than or equal to the predetermined value (preferably > 0) (NO), the process proceeds to step 908 .

[0152] In step 906, if the sludge concentration is within a predetermined value (preferably 1 to 15% by mass) (YES), the control unit determines that solid-liquid separation by coagulation in the current green liquor clarifier is successful, and further increases the injection amount of chemicals that promote the removal of impurities. According to this determination result, the injection amount of chemicals to the crude green liquor is increased. The process proceeds to step 907. On the other hand, if the sludge concentration is not within the predetermined value (preferably 1 to 15% by mass) (NO), the control unit determines that solid-liquid separation by coagulation in the current green liquor clarifier is not successful. In this case, the injection amount of chemicals that promote the removal of impurities, which may have a positive or negative effect on coagulation, is maintained, and the process proceeds to step 911.

[0153] In step 907, the control unit instructs the chemical injection unit to increase the chemical injection amount for the crude green solution compared to the amount injected during color measurement, based on the results of the determinations in steps 905 and 906. This causes the chemical injection unit to adjust the operation of the chemical pump to increase the chemical injection amount per 1 L of crude green solution compared to the amount injected during color measurement. Then, the process proceeds to step 911.

[0154] In step 908, the control unit * a * b * Based on colorimetric data, a * If the value is equal to or less than the predetermined value (preferably <-20) (YES), the process proceeds to step 909. Alternatively, the control unit may omit or skip step 909 and proceed to step 910. * If the value is not equal to or less than the predetermined value (preferably <-20) (NO), the amount of medicine injected during color measurement is determined to be appropriate, the amount of medicine injected during color measurement is maintained, and the process proceeds to step 911.

[0155] In step 909, if the control unit determines that the sludge concentration is within a predetermined value (preferably 1 to 15% by mass) (YES), the control unit proceeds to step 910. On the other hand, if the sludge concentration is not within the predetermined value (preferably 1 to 15% by mass) (NO), the control unit determines that solid-liquid separation through coagulation in the current green liquor clarifier is not being achieved. In this case, the control unit maintains the amount of chemical agent injected at the time of color measurement, which promotes the removal of impurities that may have a positive or negative effect on coagulation, and proceeds to step 911.

[0156] In step 910, the control unit instructs the chemical injection unit to decrease the chemical injection amount for the crude green solution compared to the chemical injection amount during color measurement, based on the determination results of steps 908 and 909. Then, the process proceeds to step 911.

[0157] In step 911, after adjusting the amount of chemicals injected, the control unit instructs whether or not to measure the color tone of the adjusted clear green solution. If measurement is to be performed, the process returns to step 903, and feedback control continues. If measurement is not to be performed, the feedback control process ends.

[0158] 2. Green liquor treatment management device according to this embodiment, and green liquor treatment management system and green liquor treatment system equipped with the green liquor treatment management device

[0159] In the description of the green liquor treatment management device, the green liquor treatment management system including the green liquor treatment management device, and the green liquor treatment system in this embodiment, the description of each configuration, each processing method, each device, etc., such as the temperature of the crude green liquor, the clarified green liquor, the clarified green liquor, the temperature monitoring location, the temperature measurement value, the color tone error adjustment management due to temperature change, the color tone of the clarified green liquor, the color tone monitoring location, the color tone value, the chemicals, the feedback control, etc., which overlaps with the above-mentioned "1." etc., will be omitted as appropriate, but the description of "1." etc. also applies to this embodiment and can be adopted as appropriate. Furthermore, in the description of the example of the green liquor treatment method in this embodiment, the description of "3." to "5." etc., which will be described later, can also apply to this embodiment and can be adopted as appropriate.

[0160] <2-1. Green liquor treatment management equipment and green liquor treatment management system> This embodiment can provide a green liquor treatment management device or a green liquor treatment management system equipped with such a device, which includes a control unit that monitors the color tone and / or temperature of the clarified green liquor and controls the amount of chemical agent to be injected into the crude green liquor based on the color tone obtained by the monitoring. This embodiment can also provide a green liquor treatment management device or a green liquor treatment management system equipped with such a device, which includes a control unit that monitors the color tone of the clarified green liquor and controls the amount of chemical agent to be injected into the crude green liquor based on the color tone. More preferably, the control unit is configured to monitor the color tone and temperature of the clarified green liquor and control the amount of chemical agent to be injected into the crude green liquor based on the color tone based on the color tone error adjustment management caused by temperature changes. Even more preferably, the control unit is configured to control the amount of chemical agent to be injected into the crude green liquor based on the color tone of the clarified green liquor by monitoring the color tone and temperature of the clarified green liquor and controlling the temperature of the clarified green liquor within a certain range during color tone measurement, or by measuring the temperature of the clarified green liquor and controlling the change in color tone of the clarified green liquor based on the measurement results after temperature correction.

[0161] The green liquor treatment management device in this embodiment preferably includes at least a control unit configured to monitor the color and temperature of the clarified green liquor and perform feedback control of the amount of chemicals injected into the crude green liquor based on the color. This allows for faster and more accurate management of the green liquor treatment status in the green liquor treatment system. By using this embodiment, operational management of the green liquor treatment can be more easily performed. The green liquor treatment management device may further include a communication unit, which is preferably configured to enable wireless and / or radio communication between the control unit and other units and / or devices. By providing such a communication unit, a green liquor treatment management system using a network may be constructed.

[0162] The green liquor treatment management device may include the control unit and a color tone measuring device (also referred to as a "color tone measuring unit") for monitoring and / or measuring the color tone of the clarified green liquor. The color tone measuring device may be included in the color tone monitoring unit, or the green liquor treatment management device may include the control unit and a color tone monitoring unit that includes the color tone measuring device. The green liquor treatment management device may include the control unit and a temperature measuring device (also referred to as a "temperature measuring unit") for monitoring and / or measuring the temperature of the clarified green liquor. The temperature measuring device may be provided in the temperature measuring unit and / or the color tone measuring unit, and the green liquor treatment management device may include the control unit and a temperature monitoring unit including the temperature measuring unit. A more preferable green liquor treatment management device comprises the control unit, the color tone monitoring unit, and the temperature monitoring unit. Furthermore, the green liquor treatment management device may be appropriately equipped with one or more components selected from an input unit, an output unit, a storage unit, and a communication unit, which will be described later.

[0163] <2-1-1. Control Unit in the Present Embodiment> The control unit in this embodiment is configured to monitor the color tone and / or temperature of the clarified green liquor, and perform feedback control of the amount of chemical agent to be injected into the crude green liquor based on the color tone of the clarified green liquor, which is based on color tone error adjustment management due to temperature changes. The control unit in this embodiment can also be configured to monitor the color tone of the clarified green liquor, and perform feedback control of the amount of chemical agent to be injected into the crude green liquor based on the color tone. It is also preferable that the control unit be capable of controlling at least a color tone monitoring unit for monitoring the state of green liquor treatment and measuring the color tone of the clarified green liquor, and / or a temperature monitoring unit for measuring the temperature of the clarified green liquor. It is more preferable that the control unit be capable of controlling a chemical tank that stores a chemical to be added to the green liquor clarification apparatus, a chemical injection pump that injects the chemical from the chemical tank into the crude green liquor, a color monitoring unit that monitors the state of green liquor treatment and measures the color of the clarified green liquor, and a temperature monitoring unit that measures the temperature of the clarified green liquor.It is more preferable that the temperature monitoring unit is a temperature monitoring unit that measures the temperature of the clarified green liquor and controls heating and cooling.The control unit may control the chemical injection unit that includes the chemical tank and the chemical injection pump to adjust the amount of chemical injected into the crude green liquor. Furthermore, the control unit can control an extraction pump that extracts slurry from the green liquor clarification device and a sludge concentration measuring unit that measures the concentration of the extracted sludge.

[0164] Furthermore, the control unit and each of the units such as the chemical tank, chemical injection pump, color tone monitoring unit, temperature monitoring unit, extraction pump, and sludge concentration measuring unit may each be provided with a communication unit configured to be able to send and receive wirelessly and / or wired, thereby enabling a network-based system to be constructed and the control unit to control each unit via the network. The control unit can perform green liquor treatment or green liquor treatment management in accordance with the method of this embodiment, such as "1." (preferably, <1-2. Green liquor treatment method in this embodiment>, <1-3. Example of green liquor treatment method in this embodiment>, <1-4. Example of green liquor treatment in this embodiment>).

[0165] <2-1-2.Color tone monitoring section> The color tone monitoring unit preferably includes at least a color tone measuring device (also referred to as a "color tone measuring unit") capable of measuring the color tone of the clarified green liquor. The color tone monitoring unit may further include a communication unit configured to be able to transmit and receive data to and from at least the control unit wirelessly and / or via a wire. The location where the color tone measuring device is installed in the green liquor processing system can be the above-mentioned color tone monitoring location, and for example, preferably the clarified green liquor transfer line.

[0166] The color tone monitoring unit may further include a measurement container and / or a color tone monitoring line in addition to the color tone measuring device. In such a case, a clear green liquid may be introduced into the measurement container and / or the color tone monitoring line, and the color tone of the introduced clear green liquid may be measured by the color tone measuring device.

[0167] <2-1-2-1. Color tone measurement device (color tone measurement section)> The color tone measuring device may include, but is not limited to, measuring instruments such as a colorimeter, a spectrophotometer, and a color difference meter. Examples of the color tone measuring device include a device that uses a direct stimulus value reading method (e.g., a color sensor device) that directly measures the three stimulus values ​​that form the basis of color; and a spectrophotometer that measures spectral reflectance (transmittance) and then calculates tristimulus values ​​such as X, Y, Z, and L*a*b*, or other indexes.

[0168] Examples of the color tone measuring device include, but are not limited to, a color sensor device, an image sensor device, a colorimeter, a spectrophotometer, etc. The color tone measuring device used in the present invention may be a commonly used color tone measuring device.

[0169] The color tone of the clear green liquid expressed by the color tone measuring device is not particularly limited, but is preferably one or more selected from the RGB color system, the XYZ color system, and the L*a*b* color system. These color systems are mutually convertible, so it is possible to convert a color system measured by, for example, a color sensor device, an image sensor device, a colorimeter, or a spectrophotometer into the required color system. More specifically, it is possible to convert from the L*a*b* color system measured by a colorimeter into the XYZ color system. It is also possible to convert from the RGB color system measured by a color sensor device into the L*a*b* color system.

[0170] The color tone of the clarified green liquor obtained as described above is preferably in the RGB color system and / or the XYZ color system, more preferably in the XYZ color system. By using a color sensor device or an image sensor device, the combination of the obtained values ​​of the three colors (red, green, and blue) can be used as an indicator of the clarification of the green liquor treatment. By using the combination of these three colors as an indicator of increasing or decreasing the amount of chemicals injected into the crude green liquor, it is possible to provide feedback on a more appropriate amount of chemicals injected, thereby enabling better clarification of the crude green liquor.

[0171] The color sensor device is a type of optical sensor device that irradiates a detection object (clear green liquid) with light from a light projecting unit and detects light reflected by the detection object (clear green liquid) with a light receiving unit. The color sensor device (especially the RGB color sensor device) can detect and calculate the amount of light received by each of red, green, and blue and the ratio of the amount of light received, and can determine the color of the object to be detected (for example, light receiving ratio = red:green:blue = 4:4:1, etc.).

[0172] In addition, the color sensor device can display the color tone results of the clear green liquid in the XYZ color system and the RGB color system, but can also convert from the XYZ color system to the L*a*b* color system for display. The color sensor device may capture and analyze an image of the object to be detected, calculate the amount of received light and the ratio of the amount of received light, or determine the color of the object to be detected.

[0173] The color sensor device includes at least a light-projecting unit and a light-receiving unit, and the light-projecting unit and the light-receiving unit are arranged as a detection unit, and the light-projecting surface of the light-projecting unit and the light-receiving surface of the light-receiving unit may be the same surface (light-projecting / light-receiving surface). Furthermore, it is preferable that the light-projecting surface and / or the light-receiving surface be arranged above the surface of the object to be detected and approximately parallel to the surface of the object to be detected. The light projecting unit includes a light source such as a white LED (light emitting diode) or a white fluorescent lamp, with a white LED being preferred. The light receiving section includes a light receiving element such as a CCD (Charge Coupled Device) or a photodiode (for example, a 3ch (RGB) Si photodiode).

[0174] The measurement distance is the distance between the object to be detected and the light-emitting surface and / or the light-receiving surface. This measurement distance is not particularly limited, but may be, for example, 30 to 500 mm, and is preferably about 200 to 500 mm (more preferably 250 to 400 mm) from the liquid surface of the clear green liquid when it is placed in a measurement container for measuring the color tone of the clear green liquid. In this case, the diameter of the variable spot is preferably about 9 to 18 mm. The temperature of the detection object (clarified green liquor) during measurement is not particularly limited, but a green liquor temperature of 50 to 95°C in a typical green liquor processing system is preferred, and when the clarified green liquor is taken into a measurement container for measuring the color tone, 60 to 90°C is more preferred, and 70 to 90°C is even more preferred. The ambient illuminance during measurement is preferably 10,000 lux or less in the case of artificial light such as an incandescent lamp, and 20,000 lux or less in the case of natural light such as sunlight. The ambient temperature and humidity during measurement are not particularly limited, but may be, for example, about -20 to +50°C and 35 to 85% RH, and measurements can be performed within normal climatic temperatures or room temperatures (4 to 30°C).

[0175] Furthermore, the color sensor device may be equipped with a communication unit for transmitting data to the outside, an input unit for inputting conditions, etc., an output unit for displaying alerts and measurement results, etc. on a display, etc., and a memory unit for storing measurement conditions, measurement results, etc., as necessary.

[0176] An example of a color sensor device is the LR-W500 amplifier-integrated white spot photoelectric sensor (manufactured by Keyence Corporation), but is not limited to this.

[0177] The image sensor device can employ the same configuration as a color sensor device (e.g., a light-emitting unit, a light-receiving unit, etc.) as the color sensor device. By analyzing an image obtained from an object to be detected, the image sensor device can detect and calculate the amount of red, green, and blue light received and the ratio of the received light amounts, and can determine the color of the object to be detected, just like a color sensor device.

[0178] <2-1-2-2. Measurement container> The measurement container is a container for measuring the color tone of the clarified green liquid, and preferably has a structure or material that allows the projected and reflected light of the color tone measuring device to pass through or be transmitted therethrough. Examples of such materials include glass, quartz, and plastic resin, with alkali-resistant materials being more preferred. The measurement container may have an opening (such as a hole) through which the projected and reflected light can pass, and is preferably open upward.

[0179] <2-1-2-3. Color Tone Monitoring Line> The color monitoring line can be appropriately installed at a color monitoring location in the green liquor treatment system, and the clarified green liquor to be monitored and / or measured can be flowed through this line. Furthermore, the color monitoring line can be a bypass line that returns the flowing clarified green liquor to the green liquor treatment system (e.g., to the same location). A color measuring device can be installed on the color monitoring line to monitor the clarified green liquor. Furthermore, the measurement container can be placed on the color monitoring line, and the clarified green liquor can be flowed into the measurement container to monitor the clarified green liquor in the measurement container. By providing the color tone monitoring line, the clarified green liquor, its amount, its speed, etc. can be appropriately adjusted, making it easy to monitor and / or measure the clarified green liquor.

[0180] <2-1-3.Temperature monitoring section> The temperature monitoring unit preferably includes at least a temperature measuring device (also referred to as a "temperature measuring unit") that can measure the temperature of the clarified green liquor. In a preferred embodiment, the temperature monitoring unit preferably comprises a temperature management unit configured to control temperature measurement and / or temperature adjustment of the clarified green liquor, including a temperature measurement unit (temperature sensor, thermometer, etc.) and a temperature adjustment unit (temperature controller, etc.), and a heating / cooling unit configured to heat and cool the clarified green liquor in response to instructions from the temperature management unit. The temperature monitoring unit can control temperature-related operations of the clarified green liquor, such as temperature measurement, temperature adjustment, and heating / cooling, by receiving signals or data from the temperature measurement unit, temperature management unit, and heating / cooling unit, or by sending signals or data to instruct them. The temperature management unit and the heating / cooling unit may be configured to transmit and receive signals or data to and from each other. The heating / cooling unit may be provided with a temperature measurement unit. Furthermore, a temperature control unit capable of performing temperature control such as temperature measurement of the clarified green liquor which is involved in the color tone and / or temperature control such as heating and cooling of the clarified green liquor which is involved in the color tone may be provided within the system, either in the control unit or outside the control unit, or may be provided externally, such as on a server or in the cloud.

[0181] The temperature control device may also be appropriately set at the temperature monitoring location. Furthermore, the temperature control device (preferably a temperature sensor) may be installed at a location other than the cooling location or the color monitoring location, and is preferably placed, for example, at the chemical agent injection location and / or a location nearby, more preferably in the green liquor clarification device (green liquor clarifier) ​​or at a location immediately after discharge from the device (green liquor clarifier) ​​(for example, at the outlet of the device), from the viewpoint of reducing errors due to color changes by taking into account the temperature of the chemical agent injection location. The location where the temperature measurement unit is installed in the green liquor treatment system can be the temperature monitoring location and / or color tone monitoring location described above, and for example, it is preferably the clarified green liquor transfer line, and it is more preferable to install it at the color tone monitoring location (more preferably the color tone measurement location) from the viewpoint of reducing errors in color tone due to temperature changes. The temperature monitoring unit or the like may further include a communication unit configured to be able to transmit and receive data to and from at least the control unit wirelessly and / or via a wire.

[0182] <2-1-3-1.Temperature measurement device (temperature measurement part)> The temperature measuring device may include, but is not limited to, measuring devices such as a temperature sensor and a temperature regulator (temperature controller). Preferably, the temperature measuring device includes at least a temperature sensor. By using the temperature measuring device, the temperature of the clarified green liquor during color measurement can be obtained, and the color of the clarified green liquor can be more accurately and easily managed based on the temperature measurement data. The temperature sensor may be either a contact type or a non-contact type. Examples of contact type temperature sensors include a thermistor, a thermocouple, and a resistance temperature detector, while examples of non-contact type temperature sensors include a radiation temperature sensor and a color temperature sensor. One or more of these may be selected. Furthermore, in addition to the location where the color tone of the clarified green liquor is monitored, it is also preferable to install a temperature sensor at a location where a chemical agent is added to and mixed with the crude green liquor to process it into a clarified green liquor, or downstream of that location (for example, at the outlet of the processing location), in order to monitor the temperature of the clarified green liquor, since this allows for feedback control to be performed so that the amount of chemical agent injected into the crude green liquor is appropriate.More specifically, this is desirable because it allows the color tone after temperature correction to be obtained using an appropriate temperature correction model.

[0183] <2-1-3-2.Heating and cooling device (heating and cooling section)> The heating and cooling device is not particularly limited as long as it is configured to be capable of heating and cooling. Examples of heating and cooling mechanisms include a heat exchanger using a fluid (liquid or gas), a heater, and a cooling mechanism (refrigerant piping, cooling water piping, etc.). The heating and cooling device preferably includes a heating and / or cooling device, a temperature sensor, a temperature adjustment mechanism, etc. The temperature control device may be configured to enable feedback temperature control. Known operation control may be used for the temperature control, and suitable examples include ON / OFF operation control, P operation (proportional operation) control, and PID operation control.

[0184] In this embodiment, when the temperature of the clarified green liquor during color measurement is controlled within a certain range, the certain range is not particularly limited, and the set temperature can be set as appropriate. For example, the certain range can be set to a set temperature ±°C, and the temperature can be controlled within the certain range. The ±°C is preferably ±8°C, more preferably ±5°C, and even more preferably ±3°C, ±2°C, or ±1°C. The set temperature may be the temperature inside or at the outlet of the green liquor clarification device (green liquor clarifier), or the normal temperature of the clarified green liquor (75 to 85°C), or the temperature of any single point may be set. For example, 80°C may be selected from 80, 81, 82, 83, 84, and 85°C, and 80°C ±3°C may be set as the certain range.

[0185] <2-2. Green liquor treatment management system in this embodiment> The green liquor processing management system according to this embodiment is preferably provided with a green liquor processing management device that includes at least the control unit described above. The green liquor processing management system of this embodiment may further include a communication unit that allows wireless and / or wired communication between the control unit or the green liquor processing management device that includes the control unit and other units or other devices.

[0186] The method according to this embodiment can also be realized by a device or control unit including a CPU in a device for managing the green liquor treatment status (for example, a computer, PLC, server, cloud service, etc.). The method according to this embodiment can also be stored as a program in hardware resources including a recording medium (non-volatile memory (such as a USB memory), HDD, CD, DVD, Blu-ray, etc.) and realized by a control unit. It is also possible to provide a device including the control unit or the system, such as a green liquor treatment status management system that controls the addition of a predetermined amount of chemicals to crude green liquor by the control unit. The management device may also include an input unit such as a keyboard, a communication unit such as a network, a display unit such as a display, etc.

[0187] An apparatus for managing the status of green liquor processing or a management system for green liquor processing can include an input unit such as a keyboard, a communication unit such as a network, an output unit such as a display, a storage unit such as a HDD, the color measurement unit described above, etc. The apparatus or system preferably includes an input unit, an output unit, and a storage unit, and preferably further includes a communication unit and / or a measurement unit. The input unit can accept user operations by an operator performing the method of the present embodiment. The input unit can include, for example, a mouse and / or a keyboard. Alternatively, the display surface of the display device may be configured as an input unit that accepts touch operations. The output unit can output the green liquor processing status and related information (e.g., tables, diagrams, explanatory text, etc.) Examples of the output unit include, but are not limited to, a display device that displays images, a speaker that outputs sound, and a printer that prints on a print medium such as paper. The storage unit can store data input by an operator and data set for viewing the green liquor processing status. The storage unit may include, for example, a recording medium. The green sap treatment management system according to this embodiment can be implemented by using a program and hardware. One embodiment of a computer 1 according to one embodiment of the present invention (not shown) includes, but is not limited to, at least a CPU as its components, and can further include one or two components selected from RAM, a memory unit, an output unit, an input unit, a communication unit, a ROM, and a measurement unit. Of these, it is preferable for the computer 1 to include RAM, a memory unit, an output unit, and an input unit, and it is also preferable for it to include at least one of a communication unit, a measurement unit, a ROM, etc. The components are preferably connected by a bus, for example, as a data transmission path.

[0188] <2-3. Green liquor treatment system> In the description of the green liquor treatment management device and the green liquor treatment management system including the green liquor treatment management device in this embodiment, the description of each configuration, each processing method, each device, etc., which overlaps with the above-mentioned "1." <2-1.><2-2.>, such as the temperature of the crude green liquor, the clarified green liquor, the temperature monitoring location, the temperature measurement value, the color tone error adjustment management due to temperature change, the color tone of the clarified green liquor, the color tone monitoring location, the color tone value, the chemicals, the feedback control, etc., will be omitted as appropriate, but the description of "1." <2-1.><2-2.> etc. also applies to this embodiment and can be adopted as appropriate. Furthermore, in the description of the example of the green liquor treatment method in this embodiment, the description of "3." to "5." etc. described below can also apply to this embodiment and can be adopted as appropriate.

[0189] The green liquor treatment system of this embodiment can use a green liquor treatment method in which the color tone of the above-mentioned clarified green liquor is monitored and the amount of chemicals injected into the crude green liquor is feedback-controlled based on the color tone. The green liquor treatment system of this embodiment may include a green liquor treatment management device or a green liquor treatment management system that includes at least a control unit configured to monitor the color tone of the above-mentioned clarified green liquor and perform feedback control of the amount of chemicals to be injected into the crude green liquor based on the color tone. The green liquor treatment system of this embodiment can be applied to a pulp production system.

[0190] 1 , a control unit 101 included in a green liquor treatment management apparatus 100 can cause a color measurement device (not shown) included in a color monitoring unit 102 to monitor and / or measure the color of the current clarified green liquor and acquire color data of the current clarified green liquor from the color monitoring unit 102. Furthermore, the control unit 101 can cause a temperature monitoring unit 104 to monitor and / or measure the temperature of the current clarified green liquor and acquire measured temperature data of the current clarified green liquor from the temperature monitoring unit 104. The control unit 101 can instruct a chemical injection unit, including a chemical 34 and a chemical injection pump 35, to adjust the amount of chemical injection to an appropriate amount for the crude green liquor based on changes in the acquired color data of the clarified green liquor using the method according to this embodiment. After the chemical is added to the chemical transfer line from the chemical injection unit, the green liquor is treated in the green liquor clarifier 32. The green liquor treatment status is monitored by the color monitoring unit 102, which transmits color data of the green liquor after the chemical addition to the control unit 101, which then acquires the color data of the clarified green liquor after the chemical addition. The green liquor treatment status is further monitored by the temperature monitoring unit 104, which transmits measured temperature data of the green liquor after the chemical addition to the control unit 101, which then acquires the measured temperature data of the clarified green liquor after the chemical addition. The control unit 101 then repeatedly monitors the color and / or temperature and injects a determined amount of chemical, as shown in FIGS. 2 to 11 , thereby performing feedback control to ensure that the chemical injection amount is appropriate for the crude green liquor. This allows for an appropriate amount of chemicals to be injected into the crude green liquor in the green liquor treatment system. In this way, the amount of chemicals injected into the crude green liquor can be feedback-controlled based on the color tone of the clarified green liquor measured by the instrument, and this control allows for adjustment to an appropriate amount of chemicals to be injected into the crude green liquor. This facilitates operational management of the green liquor treatment.

[0191] The control unit 101 can also instruct the extraction pump 36 to extract sludge containing dregs from the green liquor clarifier at a constant rate. The control unit 101 can also obtain the measured value of the extracted sludge concentration from the sludge concentration measurement unit 37, or from a memory unit that has stored the data transmitted from the measurement unit 37. The control unit 101 can then adjust the amount of chemicals injected into the crude green liquor to an appropriate amount based on the color data of the clarified green liquor and the sludge concentration data. Based on the change in the obtained color data of the clarified green liquor, the control unit 101 can instruct the chemical injection unit, which includes the chemical 34 and the chemical injection pump 35, to inject an appropriate amount of chemicals into the crude green liquor. After the chemical is added to the chemical transfer line from the chemical injection unit, the green liquor is treated in the green liquor clarifier 32. The status of the green liquor treatment is monitored by the color tone monitoring unit 102 and / or the temperature monitoring unit 104, and the color tone data and / or temperature measurement data of the clear green liquor to which the chemical has been added is transmitted from the color tone monitoring unit 102 and / or the temperature monitoring unit 104 to the control unit 101, which then acquires the color tone data and / or temperature measurement data of the clear green liquor after the chemical has been added. The control unit 101 then repeatedly monitors the color tone and injects a determined amount of chemical, thereby performing feedback control to ensure that the chemical injection amount is appropriate for the crude green liquor (e.g., FIGS. 2 to 5). This allows the appropriate amount of chemicals to be injected into the crude green liquor in the green liquor treatment system, making it easier to manage the operation of the green liquor treatment.

[0192] 3. Overview of pulp production system using green liquor treatment method in this embodiment

[0193] An outline of a pulp production system using the green liquor treatment method according to the present invention will be described below, but the pulp production system described here is just one example, and the present embodiment is not particularly limited to this pulp production system. In the description of the pulp production system using the green liquor treatment method of this embodiment, the description of each configuration, each method, each device, etc. of the crude green liquor, clarified green liquor, the temperature of the clarified green liquor, the temperature monitoring location, the temperature measurement value, the color error adjustment management due to temperature change, the color of the clarified green liquor, the color monitoring location, the color value, the agent, feedback control, etc., which overlaps with "1." and "2." above, will be omitted as appropriate, but the description of "1." and "2." also applies to this embodiment and can be adopted as appropriate. Furthermore, in the description of an example of the green liquor treatment method of this embodiment, the description of "3." to "5." described later can be applied to this embodiment and can be adopted as appropriate.

[0194] 1 is a schematic diagram of a pulp production system 1 that uses a green liquor treatment method according to the present invention, but the present invention is not limited to this. The pulp production system in this embodiment may be a general pulp production system that incorporates the green liquor treatment management device or green liquor treatment management system of this embodiment.

[0195] The pulp production system 1 according to this embodiment may include a cooking system 10, a black liquor treatment system 20, a green liquor treatment system 30, and a slaking / causticizing system 40. These systems may be connected to each other by pipes shown by solid lines in Fig. 1, and may form a circulation path as a whole. Each system is described in more detail below.

[0196] <3-1. Cooking system> The cooking system 10 includes a digester 11, and a pulp refining section may be provided downstream of the digester 11. Wood chips, which are raw materials for pulp, and white liquor containing caustic soda are fed into the digester 11, and the wood chips are cooked. The resulting pulp is transferred to a pulp screening system where it undergoes screening and washing processes, followed by bleaching and papermaking processes to produce paper. Meanwhile, the waste black liquor is transferred to an evaporator 21, which will be described later, for the recovery of caustic soda, etc.

[0197] <3-2. Black liquor treatment system> The black liquor treatment system 20 may include, in order from upstream, an evaporator 21 and a boiler 22. After being concentrated in the evaporator 21 (black liquor concentration step), the black liquor is transferred to the boiler 22 and combusted in the boiler 22 (black liquor combustion step). This melts the inorganic sodium salts contained in the black liquor, and the smelt is discharged from the bottom of the boiler 22 as smelt. The discharged smelt is transferred to a dissolving tank 31.

[0198] A heat recovery system for recovering thermal energy may be provided in the boiler 22. As such a heat recovery system, a conventionally known system can be used (see, for example, Japanese Patent Application Laid-Open No. 6-212586).

[0199] <3-3. Green liquor treatment system> In the explanation of the green liquor treatment system 30 in this embodiment, explanations of the components and treatment methods that overlap with those in "1." and "2." above will be omitted as appropriate, but the explanations in "1." and "2." also apply to this embodiment and can be adopted as appropriate.

[0200] At least a control unit 101 capable of monitoring the color tone of the clarified green liquor and capable of more quickly performing feedback control to determine a more appropriate amount of chemical to be injected into the crude green liquor, or a green liquor treatment management device 100 equipped with the control unit 101, is provided. Furthermore, the green liquor treatment system 30 is preferably provided with a color tone monitoring unit 102 capable of monitoring the color tone of the clarified green liquor and measuring the color tone of the clarified green liquor.

[0201] Furthermore, the green liquor treatment system 30 is preferably provided with an agent tank 34 and an agent injection pump 35 that can add a green liquor treatment agent to the crude green liquor. The number of agent tanks is not particularly limited and may be one, two, or three or more, and an agent tank may be provided for each type of agent used. The number of agent injection pumps is also not particularly limited and may be one, two, or three or more, and an agent injection pump may be provided for each type of agent used.

[0202] The control unit 101 can manage the chemical status (e.g., remaining amount, concentration, type) in the chemical tank 34 and can control the chemical status. The control unit 101 can control the pump operation of the chemical injection pump 35, thereby adjusting the chemical injection amount of the green liquor treatment agent to be added to the crude green liquor. Meanwhile, the chemical tank 34 and the chemical injection pump 35 can transmit the status of the chemical status and the chemical injection amount to the control unit 101.

[0203] <3-4. Slaking and causticizing systems> The slaking / causticizing system 40 may include a causticizing system 41, a white liquor clarifier 42, and a white liquor tank 43. The slaking / causticizing system 40 may further include a lime mud washer 46, a lime mud filter 45, and a kiln 44 located downstream of the white liquor clarifier 42. The causticizing system 41, the white liquor clarifier 42, and the white liquor tank 43 are interconnected and collectively form a circulation path.

[0204] The clarified green liquor transferred to the causticizing system 41 is mixed with calcium oxide supplied from the kiln 44 in the causticizing system 41. This mixing will be described in more detail below.

[0205] The causticizing system 41 may have a slaker 411 and a plurality of causticizing reaction tanks 412 located downstream of the slaker 411. The clarified green liquor (usually 90-100°C, pH 13-14) transferred to the slaker 411 is mixed with calcium oxide also supplied to the slaker 411. As a result, the calcium oxide is slaked with water to produce calcium hydroxide (slaked reaction step). Thereafter, when the green liquor is transferred to the causticizing reaction tank 412, the sodium carbonate in the green liquor reacts with the calcium hydroxide to produce caustic soda and calcium carbonate (causticizing reaction step).

[0206] The white liquor obtained in this manner is transferred to a white liquor clarifier 42. In this white liquor clarifier 42, the insoluble calcium carbonate is precipitated and separated, and then the white liquor is stored in a white liquor tank 43 and eventually circulated to the digester 11 for reuse. Meanwhile, the separated calcium carbonate is recovered in a kiln 44, where it is roasted to return to calcium oxide (lime calcination step), and reused in the causticizing system 41.

[0207] More specifically, in the causticizing system 41, calcium oxide (CaO) obtained in the kiln 44 is added to the clarified green liquor in the slaker 411, causing a slaked reaction: CaO + water → Ca(OH)2 + water, which then reacts with the Na2CO3 in the clarified green liquor in the slaker 411 to form Ca(OH)2 + Na2CO3 + water → CaCO3 (↓) + 2NaOH + water, and the aqueous solution containing NaOH from which CaCO3 has been recovered is used as white liquor. In this way, caustic soda and calcium carbonate are repeatedly used as recycled resources in the recovery cycle during the causticizing process.

[0208] 4. Causticizing productivity improvement method and productivity improvement management system according to this embodiment

[0209] In the description of the causticizing productivity improvement method and productivity improvement management system of this embodiment, the description of each configuration, each processing method, each device, etc., which overlaps with the above-mentioned "1." to "3.", such as the crude green liquor, clarified green liquor, temperature of the clarified green liquor, temperature monitoring location, temperature measurement value, color tone error adjustment management due to temperature change, color tone of the clarified green liquor, color tone monitoring location, color tone value, chemicals, feedback control, etc., will be omitted as appropriate, but the description of "1." to "3." also applies to this embodiment and can be adopted as appropriate. Furthermore, in the description of an example of the green liquor processing method of this embodiment, the description of "5." described below can be applied to this embodiment and can be adopted as appropriate.

[0210] This embodiment can provide a method for improving causticizing productivity using clarified green liquor that has been clarified by the green liquor treatment method or green liquor treatment system. With the conventional method, green liquor clarification was poor, and the presence of impurities led to a lower causticization rate, resulting in poor white liquor quality, as well as poor lime quality. Furthermore, white liquor with a low causticization rate would not perform well even if returned to the cooking process. Furthermore, poor lime quality would also result in a lower effective lime content, which is converted into quicklime when burned in the kiln, meaning that the amount of newly purchased lime would increase.

[0211] In contrast, as described above, the clarified green liquor clarified by the green liquor treatment method or green liquor treatment system of this embodiment is more satisfactorily clarified because the green liquor is treated with a more appropriate amount of chemicals. Furthermore, the clarified green liquor can be clarified in accordance with fluctuations in the impurity concentration in the crude green liquor, resulting in more satisfactory clarification.

[0212] Therefore, by using green liquor clarified according to this embodiment, the causticization rate is improved, the quality of white liquor is improved, and the quality of lime is also improved. Furthermore, white liquor with an improved causticization rate works better when returned to the cooking process. Furthermore, because the quality of the lime is improved, the effective lime content that becomes quicklime when burned in a kiln is also higher, making it possible to reduce the amount of newly purchased lime. Generally, the causticization rate is expressed as (NaOH / (NaOH+Na2CO3) x 100(%) (as Na2O)), and the calcination rate is expressed as (CaO / (CaO+CaCO3) x 100(%)).

[0213] As described above, by using the clarified green liquor clarified according to the present embodiment, it is possible to improve the productivity of causticizing, to better control the causticizing process, and to better control the effective lime content, and therefore the present embodiment relating to the above-mentioned "1." to "3." can be applied to a slaking / causticizing system, a method or apparatus used in the system, etc. The present embodiment may be, for example, a method for managing slaking / causticizing treatment, a slaking / causticizing treatment management system, or a management apparatus for slaking / causticizing treatment, etc. Therefore, the present embodiment can provide a method for improving the productivity of causticizing, controlling the slaking and causticizing process, and controlling the effective lime content, or a management system for these, using clarified green liquor clarified by the green liquor treatment method.

[0214] The improvement in productivity of causticization means an improvement in productivity of caustic soda and / or calcium carbonate. More specifically, it includes improvements in the causticization rate, calcium carbonate recovery rate, caustic soda quality, calcium oxide quality, kiln firing rate, etc., and an improvement in the recovery cycle of caustic soda and calcium carbonate (calcium oxide).

[0215] This embodiment provides a method or system for improving causticizing productivity using clarified green liquor that has been clarified by a green liquor treatment method that monitors the color of the clarified green liquor and feedback-controls the amount of chemicals injected into the crude green liquor based on the color. Furthermore, it is preferable to monitor the temperature of the clarified green liquor. This embodiment provides a method or system for controlling the slaking and causticizing process using clarified green liquor that has been clarified by a green liquor treatment method that monitors the color of the clarified green liquor and feedback-controls the amount of chemicals injected into the crude green liquor based on the color. Furthermore, it is preferable to monitor the temperature of the clarified green liquor. This embodiment provides a method or system for controlling effective lime content using clarified green liquor that has been clarified by a green liquor treatment method that monitors the color of the clarified green liquor and feedback-controls the amount of chemicals injected into the crude green liquor based on the color. Furthermore, it is preferable to monitor the temperature of the clarified green liquor. The above-described method or system can be used to produce, for example, white liquor for use in a cooking system, calcium carbonate for calcination in a kiln, or caustic soda and / or calcium carbonate for reuse in pulp production, but is not limited to these effects.

[0216] 5. Method and system for recovering chemicals in pulp production according to the present invention

[0217] In the description of the chemical recovery method and recovery management system in pulp production in this embodiment, the description of each configuration, processing method, etc., which overlaps with the above-mentioned "1." to "4.", such as "crude green liquor, clarified green liquor, temperature of clarified green liquor, temperature monitoring location, temperature measurement value, color error adjustment management due to temperature change, color of clarified green liquor, color monitoring location, color value, chemicals, feedback control, etc." will be omitted as appropriate, but the descriptions of "1." to "4." also apply to this embodiment, and can be adopted as appropriate.

[0218] In this embodiment, (a) a green liquor treatment step using the green liquor treatment method, or (b) A recycling system for chemicals in pulp production can also be provided, which includes a green liquor treatment step using the green liquor treatment method and a slaking / causticizing step using the clarified green liquor clarified in the green liquor treatment step. The green liquor treatment method can appropriately adopt each of the configurations and methods described in "1." above.

[0219] In this embodiment, by applying the chemical recovery process related to the present invention to a general pulp manufacturing process, it is possible to provide a pulp manufacturing method or pulp manufacturing system including a chemical recovery process, a chemical recovery method in pulp manufacturing, a method for improving the chemical quality or recovery rate, a recovery management system, etc.

[0220] The pulp production method or pulp production management system is not particularly limited, and a general pulp production method or management system can be adopted. Typical pulp manufacturing processes include, for example, a raw material chipping process in which wood is chipped, a cooking process in which processing water (specifically, white liquor) containing caustic soda is added to the wood chips and boiled at high temperature and pressure to dissolve the resin (lignin) and extract the fiber (pulp), a screening and washing process in which foreign matter in the pulp is removed by passing it through a screen and a washing device and washed, an enzymatic delignification process in which the resin remaining in the cooking process is decomposed with oxygen, and a bleaching process in which the pulp is bleached with chemicals, and pulp is usually manufactured in this order. Pulp is usually used in paper manufacturing, which includes a papermaking process.

[0221] In the chemical recovery method or recovery management system of this embodiment, it is preferable to treat crude green liquor produced from a black liquor treatment system that treats black liquor produced in the cooking step. In addition, in the chemical recovery method or recovery management system of this embodiment, it is preferable to transfer the white liquor obtained in the slaking / causticizing system of this embodiment to the cooking step, and more specifically, it is more preferable to add it to the digester. This makes it possible to carry out the cooking step in which chips are cooked using white liquor with improved causticizing productivity. According to the chemical recovery method or recovery management system of this embodiment, the quality and / or recovery rate of caustic soda and / or calcium carbonate can be improved. This can improve the productivity of causticization. Therefore, the present invention is an excellent technology as a recovery method or recovery management system, or a recycling method or recycling management system for chemicals such as caustic soda and / or calcium carbonate.

[0222] The present technology may also employ the following configuration. [1] A green liquor treatment method that monitors the color tone of a clarified green liquor and performs feedback control of the amount of chemical agent to be injected into a crude green liquor based on the color tone. The clarified green liquor monitored is preferably clarified green liquor downstream of a green liquor clarification device. The feedback control is preferably performed based on a comparison between the current color tone value and a reference color tone value of the clarified green liquor (e.g., a past color tone value, an appropriate color tone value). The location where the chemical agent is added is preferably the green liquor clarification device and / or upstream thereof. The chemical agent is preferably a chemical agent (green liquor treatment agent) that can be used for the purpose of clarifying the green liquor. Furthermore, it is preferable to monitor the temperature of the clarified green liquor, and it is preferable to perform color tone error adjustment management due to temperature changes. Furthermore, it is preferable to monitor the color tone using a color measurement device that is positioned above the clarified green liquor surface at a distance from the surface.

[0223] [2] The method for treating green liquor according to [1], wherein the amount of chemicals to be injected into the crude green liquor is controlled based on the color of the clarified green liquor by monitoring the color and temperature of the clarified green liquor and controlling the temperature of the clarified green liquor within a certain range during color measurement, or by measuring the temperature of the clarified green liquor and controlling changes in the color of the clarified green liquor after correcting for temperature based on the measurement results. [3] The method for treating green liquor according to [1] or [2], wherein the temperature of the clarified green liquor during the color measurement is controlled within a certain range, thereby reducing errors in color tone due to temperature changes and controlling the amount of chemicals injected into the crude green liquor. [4] The method for treating green liquor according to [1] or [2], wherein the amount of chemicals injected into the crude green liquor is controlled based on the color tone of the clarified green liquor after temperature correction, by measuring the temperature of the clarified green liquor and then managing the change in color tone of the clarified green liquor based on the measured temperature value of the clarified green liquor. [5] determining whether the measured temperature value of the clarified green liquor is within a certain range in order to manage the change in color tone of the clarified green liquor after correcting for temperature; and If the color of the clarified green liquor is within the specified range, the amount of chemicals injected into the crude green liquor is controlled based on the color measurement value of the clarified green liquor at that time; or if the color of the clarified green liquor is not within the specified range, the color of the clarified green liquor is measured, the color measurement value of the clarified green liquor obtained based on the measured temperature at that time is corrected, and the amount of chemicals injected into the crude green liquor is controlled.

[0224] [6] The method for treating a green liquor according to any one of [1] to [5], wherein the color tone of the clear green liquor is color tone data of the clear green liquor obtained by measuring the color tone of the clear green liquor. The color system of the color tone can be an RGB system, an XYZ color system, or an L * a * b * It is preferable to use one or more types selected from the color system. [7] A green liquor treatment method according to any one of [1] to [6], wherein, based on the color tone of the clarified green liquor, the amount of chemicals injected into the crude green liquor is increased if the color tone of the clarified green liquor is reddish, and / or the amount of chemicals injected into the crude green liquor is decreased if the color tone of the clarified green liquor is greenish, thereby performing feedback control to ensure that the amount of chemicals injected into the crude green liquor is appropriate. [8] a from the color tone of the clarified green liquor * Based on the value, the color of the clarified green liquid is a * If the value is >0, the amount of chemicals injected into the crude green liquor should be increased, and / or the color of the clarified green liquor should be adjusted to a * The method for treating green liquor according to any one of [1] to [7] above, wherein when the value is not > 0, the amount of chemicals injected into the crude green liquor is reduced, and feedback control is performed so that the amount of chemicals injected into the crude green liquor becomes appropriate. * If the value is <0, preferably a lower limit of -30, more preferably -20 or -10, it is preferable to maintain the amount of chemical injected into the crude green liquor, and if the green color is darker than this upper limit, it is preferable to reduce the amount of chemical injected into the crude green liquor. [9] Furthermore, by adding sludge concentration data, a from the color tone of the clarified green liquor * The method for treating green liquor according to any one of [1] to [8] above, wherein the amount of chemicals injected into the crude green liquor is feedback-controlled based on the data of the value and the sludge concentration data. .

[0225]

[10] A green liquor treatment method including a control step of monitoring the color tone of a clear green liquor and performing feedback control of the amount of chemicals injected into the crude green liquor based on the color tone. The control step preferably further includes a color tone monitoring step of measuring the color tone of the clear green liquor and / or a chemical injection step of injecting a chemical into the crude green liquor, and more preferably further includes a color tone error adjustment management step.

[11] Monitoring and / or measuring the color of the clarified green liquor (color monitoring step); Injecting a chemical into the crude green liquor (chemical injection step); and ​A green liquor treatment method comprising: monitoring and / or measuring the color tone of the clarified green liquor, and controlling the amount of chemicals to be injected into the crude green liquor based on the color tone (control step).

[0226]

[12] A green liquor treatment management device comprising a control unit that monitors the color tone of clarified green liquor and performs feedback control of the amount of chemicals to be injected into crude green liquor based on the color tone. The control unit is preferably configured to perform the green liquor treatment method according to any one of [1] to

[11] above.

[13] A green liquor treatment management system including a green liquor treatment management device, the green liquor treatment management system including a control unit that monitors the color tone of clarified green liquor and performs feedback control of the amount of chemicals injected into crude green liquor based on the color tone. The control unit is preferably configured to perform the green liquor treatment method according to any one of [1] to

[11] above. 14 A method for improving causticizing productivity using clarified green liquor that has been clarified by a green liquor treatment method in which the color of the clarified green liquor is monitored and the amount of chemicals injected into the crude green liquor is feedback-controlled based on the color. 15 A method for improving causticizing productivity, using clarified green liquor that has been clarified by the green liquor treatment method according to any one of [1] to

[11] above. 16. A green liquor treatment process using a green liquor treatment method in which the color of the clarified green liquor is monitored and the amount of chemicals injected into the crude green liquor is feedback-controlled based on the color. A system for recycling caustic soda and / or calcium carbonate in pulp production. 17 The method includes a green liquor treatment process using a green liquor treatment method that monitors the color tone of clarified green liquor and feedback controls the amount of chemicals injected into crude green liquor based on the color tone, and a slaking and causticizing process that uses the green liquor clarified in the green liquor treatment process. A system for recycling caustic soda and / or calcium carbonate in pulp production. 18 (a) a green liquor treatment step using the green liquor treatment method according to any one of [1] to

[11] above, or (b) A green liquor treatment process using the green liquor treatment method according to any one of [1] to

[11] above, and a slaking and causticizing process using the green liquor clarified in the green liquor treatment process, A system for recycling caustic soda and / or calcium carbonate in pulp production. [Example]

[0227] The following test examples and the like are used to explain the embodiments of the present invention, but the scope of the present invention is not limited to these test examples and the like.

[0228] <Test Example 1> As shown below, we continuously measured the clarified green liquor using a green liquor color measurement device and considered adjusting the amount of chemicals added to the green liquor clarification device.We extracted the color of the clarified green liquor as RGB data, determined the range of each number, and considered controlling it so that when it deviated from that range, we increased or decreased the amount of cationic flocculant (coagulant) or anionic flocculant added.

[0229] <Configuration of green liquor measuring device> The green liquid measuring device includes an RGB color sensor, a multi-sensor controller, a programmable controller, and a network communication unit as a color sensor device. The principle of clear green liquor measurement is that white LED light projected from the color sensor hits the object to be measured (liquid surface), the color reflected by the object is detected by the light receiving part of the color sensor, the data is calculated and output as RGB color components, and this RGB value data is output to the outside from the communication unit. This RGB value data is output to a computer including the control part of the green liquor processing, and the RGB value at this time is displayed on the computer screen.

[0230] The RGB color sensor used was an amplifier-integrated white spot photoelectric sensor LR-W500 (manufactured by Keyence Corporation). The multi-sensor controller used was the multi-sensor controller MU-N12 (manufactured by Keyence Corporation). The programmable controller (PLC) used was the KV-NC32T2 (manufactured by Keyence Corporation) with 16 inputs and 16 outputs. As a network communication unit, communication unit EtherNet / IP TM The corresponding NU-EP1 (manufactured by Keyence Corporation) was used.

[0231] <White Spot Photoelectric Sensor LR-W500> Detection distance: 30 to 500 mm (from the light projection surface to the liquid surface of the sample) Minimum Spot Size: Variable Spot: Approx. o3.5 at 100mm / Approx. o9 at 250mm / Approx. o18mm at 500mm Response time: 200μs / 1ms / 10ms / 100ms / 500ms selectable Light source White LED Ambient illumination: Incandescent lamp: 10,000 lux or less, sunlight: 20,000 lux or less; Ambient temperature: -20 to +50°C (no freezing) Ambient humidity during use: 35 to 85% RH (no condensation)

[0232] 1. Experimental data for measuring the color tone of liquids in this invention <Experimental conditions> The following four types of sample solutions were measured using the above green liquor measuring device. (1) N / 1000 iodine solution (2) Clarified green liquor from a major paper company (clarified green liquor collected from the on-site green liquor treatment system after clarification treatment) (3) The supernatant liquid (simulated clarified green liquor) obtained by solid-liquid separation of crude green liquor from a major paper company using a high-molecular-weight polymer flocculant for green liquor treatment (the crude green liquor stored in the crude green liquor tank when the clarified green liquor in (2) above was collected). (4) Iodine-starch reaction solution (starch 100 mg / L)

[0233] The pH of crude green liquor (without flocculant added) from a major paper manufacturer was above 13. The crude green liquor was also measured using the color sensor of the green liquor measuring device described above, but no color data could be obtained. The polymer (acrylamide-sodium acrylate copolymer, viscosity average molecular weight 16 million) used as the acrylamide flocculant in (3) above. As shown in Table 1 below, the G value of the clarified green liquor is (G228), a * The G value of the supernatant of the crude green liquor precipitate (clarified green liquor) was (G241), a * The value was (-1.5). The sludge concentration when extracted from the green liquor treatment system where these samples were obtained was 8%, and this sludge concentration was measured according to the above-mentioned "JIS K 102 14.1 "Factory wastewater test method" (suspended solids).

[0234] <Measurement conditions> 200 mL of each of the sample solutions (1) to (4) above was placed in a 200 mL glass beaker, preparing glass beakers 1 to 4 containing the sample solutions. The liquid temperature of the sample solutions was adjusted to room temperature (18°C). The pH (20°C) of the sample solutions of the clear green liquids (2) and (3) above was 13 or higher. The color sensor of the green liquor measuring device was placed above the liquid surface of the glass beaker. At this time, the light projection surface of the color sensor and the liquid surface of the beaker were approximately parallel. The distance between the light projection surface of the color sensor and the liquid surface of the beaker was set as the measurement distance below. The color tone of the sample solution in each of the glass beakers 1 to 4 was measured from above using a color sensor provided in the green liquor measuring device. Measurement container: 200 mL glass beaker (height 90 mm, diameter 67 mm) Measurement distance: 30 cm from the sensor's light-emitting and light-receiving surfaces (distance from the sensor's measurement surface to the beaker's liquid surface) Measurement temperature Room temperature (18℃)

[0235] [Table 1]

[0236] <Considerations of Test Example 1> The inventors discovered that poor green liquor treatment results in a reddish color in the clarified green liquor, and discovered that the color change can be continuously monitored using image processing. The red color is presumably due to an increase in iron sulfate II, which is oxidized to iron sulfate III, giving it a reddish color. Although the purpose is not to reduce the amount of iron in the crude green liquor, they discovered that adding a flocculant to the crude green liquor changes the color to light green, and as a result, the color can serve as an indicator of the clarity of the clarified green liquor. Furthermore, taking into consideration the results of the above tests, the clarified green liquor after the green liquor clarification device is placed in a container, and an image of the clarified green liquor surface is captured from above the clarified green liquor using a green liquor measuring device capable of detecting the color tone of the clarified green liquor, and the color tone of the clarified green liquor can be analyzed. Based on the results of this analysis, the amount of chemicals added to the green liquor clarification device can be adjusted so that the color tone of the clarified green liquor falls within a desired range. For example, if the color tone of the clear green liquor is reddish, the amount of chemical agent can be increased relative to the crude green liquor, and if the color tone of the clear green liquor is greenish, the amount of chemical agent can be decreased relative to the crude green liquor. In this way, feedback control can be performed to ensure the appropriate amount of chemical agent is injected.

[0237] <Test Example 2> As shown in the <Configuration of the Green Liquor Measuring Device> below, a color detector or the like is used to continuously measure the clarified green liquor, and the amount of chemicals added to the green liquor clarifier is adjusted. The explanations for (1) to (4) in <Test Example 2: Configuration of the Green Liquor Measuring Device> manufactured by Keyence Corporation are adopted from the explanations in <Test Example 1>, <Green Liquor Measuring Device>. (5) Thermocouple thermometer is a device that can measure the temperature (°C) of the green liquor using a temperature sensor, and a commercially available product was used. <Test Example 2: Configuration of green liquor measuring device> The green liquor measuring device has the following configuration: (1) Color sensor: Keyence Corporation LR-W500 (2) Controller: Keyence Corporation MU-N12 (3) PLC Keyence Corporation KV-NC32T (4) Communication unit: NU-EP1 manufactured by Keyence Corporation (5) Thermocouple thermometer

[0238] <Experimental conditions> Using the measuring device configured as described above in <Test Example 2: Configuration of green liquor measuring device>, the following samples 2-1 and 2-2 were heated and measured at predetermined temperatures (70°C, 80°C, 90°C). The iron (Fe) concentration can be measured using ICP atomic emission spectroscopy according to JIS-K-102.57.4. In this experiment, the amount of Fe in the clarified green liquor (clarified green liquor A from a major paper manufacturer) was measured using this ICP atomic emission spectroscopy. Furthermore, in this experiment, a standard solution with a known concentration of Fe (soluble iron) was added externally to the clarified green liquor A from the major paper manufacturer, and Samples 2-1 and 2-2 were prepared. The total Fe concentration (ppm) in Samples 2-1 and 2-2 was calculated from the results of the ICP atomic emission spectroscopy and the concentration of the standard solution. <Sample of Test Example 2> Sample 2-1: Major paper company's clarified green liquor A + soluble iron 1 ppm Sample 2-2: Major paper company's clarified green liquor A+ soluble iron 2 ppm <Measurement conditions for Test Example 2> Measurement container: 100 mL glass beaker Measurement distance: 30cm from the sensor Measurement temperature 70℃, 80℃, 90℃

[0239] <Results and Discussion of Test Example 2> Sample 2-1 (a solution in which 1 ppm of soluble iron was added to clear green liquid A, resulting in a total of 2.1 ppm of Fe in the soluble iron-added clear green liquid) was heated, and the color tone in the peaker was measured with an RGB color sensor at 70°C, 80°C, and 90°C. Sample 2-2 (a solution in which 2 ppm of soluble iron was added to clear green liquid A, resulting in a total of 3.1 ppm of Fe in the soluble iron-added clear green liquid) was heated, and the color tone in the peaker was measured with an RGB color sensor at 70°C, 80°C, and 90°C. The lower dashed lines in Figure 12 represent the a of Sample 2-1 at 70°C, 80°C, and 90°C. *The upper dashed lines in Fig. 12 show the a values ​​and slopes of sample 2-2 at 70°C, 80°C, and 90°C. * The value and slope are 0.13 and b-12.7.

[0240] In this way, Fe is used to control the color of the clarified green liquor (preferably a * The relationship between the color (a value) and temperature (℃) can be clarified by statistical processing (in this case, a simple regression line (y=ax+b: a is the slope, b is the intercept)). * It was confirmed that the color of the clear green liquid (preferably a * The relationship between the temperature (°C) and the saturation temperature (°C) can be determined by statistical processing. If necessary, soluble iron can be added externally to the clarified green liquor or the Fe concentration can be changed, and a temperature correction formula or temperature correction model can be created by statistical processing. When determining this relationship, the iron measurement method used can be ICP atomic emission spectroscopy as specified in JIS-K-102.57.4.

[0241] In <Test Example 2>, although the ultimate purpose was not to reduce the amount of iron contained in the clarified green liquor or to improve the measurement accuracy of the Fe amount, the inventors discovered that the amount of Fe in the clarified green liquor can serve as an indicator of the clarity of the clarified green liquor. From the results of <Test Example 2>, the inventors were able to demonstrate that the measurement accuracy of the Fe amount, an impurity, can be improved by maintaining a constant temperature of the clarified green liquor, which is the measurement target of the color measurement device. Furthermore, the inventors were able to correct for deviations in the temperature change of the color tone of the clarified green liquor by measuring the temperature of the clarified green liquor, thereby improving the measurement accuracy of the Fe amount, an impurity.

[0242] The present inventors have derived the following <measurement principle>. <Measurement principle> The white LED light emitted from the color sensor hits the object to be measured, The light receiving unit detects the color reflected by the object and calculates and outputs the color coordinates as desired, such as RGB or L*a*b*. Temperature compensation is performed.

[0243] The inventors then derived the following temperature correction model or temperature correction formula: However, this embodiment is not limited to these temperature correction models, and it is also possible to construct a temperature correction model that is suited to the actual equipment or site using, for example, statistical processing.

[0244] Here is an example of how to control the change in color tone of the clarified green liquor by correcting for temperature based on the temperature measurement value of the clarified green liquor obtained by measuring the temperature of the clarified green liquor. First, since the color tone of the clarified green liquor varies with temperature (temperature change), the color tone a at a temperature of 75°C is corrected. * If the temperature is 80℃ (set temperature), what color tone a * In other words, even if the measurement temperature of the clarified green liquid is different, find out what color measurement value will be at a temperature of 80°C, and determine the color tone after temperature correction. Then, the color tone after temperature correction [a * The amount of chemicals injected into the crude green liquor is controlled based on the temperature (80°C).

[0245] for example 1) The actual measurement value of the clear green liquid is a temperature measurement value of 70°C, and the color measurement value is a * If the value is -3.0, then "a * Value (80℃) = 0.13 × (80-70) + a * Value (70℃) = 0.13 × 10-3.0 = -2.7. 2) The actual measurement value of the clarified green liquid is a temperature measurement value of 70°C and a color measurement value of a * If the value is 0.0, then "a * Value (80℃) = 0.13 × (80-70) + a * The value (70℃) = 0.13 × 10 + 0.0 = 1.3. 3) The actual measurement value of the clarified green liquid is a temperature measurement value of 85°C and a color measurement value of a * If the value is 0.0, then "a * Value (80℃) = 0.13 × (80-85) + a * The value (85℃) = 0.13 × (-5) + 0.0 = -0.65. 4) The actual measured value of the clarified green liquid is a temperature measurement of 87°C and a color measurement of a * A value of 1.0 means "a * Value (80℃) = 0.13 × (80-87) + a * The value (85℃) = 0.13 × (-7) + 1.0 = -0.09.

[0246] [Table 2]

[0247] Based on this, the inventors have provided a green liquor treatment method or system that includes, for example, introducing a portion of the clarified green liquor after the green liquor clarifier into a container via a flow path, measuring the temperature of the container that has introduced the clarified green liquor, and capturing and analyzing an image of the clarified green liquor from above (above) the container using a color measurement device (color detection device) to determine a temperature correction value, and adjusting the amount of chemicals to be added to the crude green liquor in the green liquor clarifier based on the color of the clarified green liquor after temperature correction. This reduces errors in color tone due to temperature changes, improves the accuracy of measuring the color of the clarified green liquor, and adjusts the amount of chemicals to be added to the crude green liquor in the green liquor clarifier. Furthermore, by monitoring the measurement target (clarified green liquor, slurry-like clarified green liquor, etc.) using monitoring, optical sensors, temperature sensors, or temperature control in the causticizing process of pulp production, the green liquor clarifier can be operated more easily and stably. [Explanation of symbols]

[0248] 1 Pulp manufacturing system; 10 Cooking system; 11 Digester; 20 Black liquor treatment system; 21 Evaporator; 22 Boiler; 30 Green liquor treatment (crude green liquor treatment) system; 31 Dissolving tank (dispersion); 32 Green liquor clarifier (clarification); 33 Clarified green liquor tank; 36 Withdrawal pump; 37 Sludge concentration measurement section; 34 Chemical tank; 35 Chemical injection pump; 40 Slaking and causticizing system; 41 Causticizing system; 42 White liquor clarifier; 43 White liquor tank; 44 Kiln; 411 Slaker; 412 Causticizing reaction tank; 45 Lime mud filter; 46 Lime mud washer; 100 Green liquor treatment control device; 101 Control section; 102 Color monitoring section; 103 Color sensor; 104 temperature monitoring unit; 105 temperature sensor

Claims

1. Monitor the color and temperature of the clarified green liquor; A green liquor treatment method in which the amount of chemicals to be injected into the crude green liquor is controlled based on the color tone after temperature correction, by measuring the temperature of the clarified green liquor and then correcting the change in color tone of the clarified green liquor based on the measured temperature value of the clarified green liquor.

2. A green liquor processing method as described in claim 1, wherein the temperature of the clarified green liquor is controlled within a certain range, thereby reducing errors due to temperature changes in color tone.

3. Monitor the color and temperature of the clarified green liquor; Determining whether the temperature measurement value of the clarified green liquor is within a certain range in order to manage the change in color tone of the clarified green liquor after temperature correction; and If the color is within the predetermined range, the amount of chemicals injected into the crude green liquor is controlled based on the color measurement value of the clarified green liquor at this time; or If the color of the clarified green liquor is not within the specified range, the color of the clarified green liquor is measured, the measured color value of the clarified green liquor is corrected based on the measured temperature at that time, and the amount of chemicals injected into the crude green liquor is controlled.

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