Monitoring of pulp quality

Abstract

A method for monitoring hydrophobic particles contained in a pulp suspension is disclosed, the method comprising obtaining (601) a sample from the pulp suspension or a filtrate of the pulp suspension. A dye is added (602) to the sample to stain the particles in the sample, wherein the dye is a fluorescent dye. The sample is fractionated (603) to obtain at least a first fraction and a second fraction, wherein the second fraction is a fibre fraction. The method further comprises, for the obtained fractions, measuring (604) the fluorescence emitted by the particles in the fraction, calculating (605) the fluorescence integral measured for the fractions excluding the fibre fraction, and correlating (606) the calculated fluorescence integral to the amount of acetone-soluble material in the pulp suspension, and optionally measuring the light scattering signal of the particles in the at least first and second fractions.

Description

[0001] This application is a divisional application of Chinese patent application filed on July 2, 2018, with application number 201880043933.5 and invention title "Pulp Quality Monitoring". Technical Field

[0002] This invention relates to a method and system for monitoring acetone-soluble materials in pulp suspensions. Background Technology

[0003] For sulfate pulp mills, one of the quality standards for the produced pulp is the amount of acetone-soluble material measured in the pulp. Acetone primarily extracts hydrophobic materials from pulp samples. If the amount of acetone-soluble material in the pulp is high, the material is sticky and may cause sedimentation problems in the pulping or papermaking process. However, the process of extracting pulp and evaporating solvent to determine the amount of acetone-soluble material is time-consuming and labor-intensive. Results cannot be obtained continuously, in addition to the required labor. Therefore, an easy and simple method for evaluating pulp quality is desirable. The amount of hydrophobic particles can be measured by adding dye to the pulp sample and measuring the fluorescence emitted by the sample. Summary of the Invention

[0004] One object of the present invention is to provide a method, system, and use that mitigates the aforementioned disadvantages. This object of the invention is achieved by methods and arrangements characterized in the independent claims. Preferred embodiments are disclosed in the dependent claims.

[0005] According to one aspect, a method and system for monitoring hydrophobic particles contained in a pulp suspension are provided, wherein the method includes obtaining a sample from the pulp suspension or a filtrate of the pulp suspension. A dye is added to the sample to stain the particles in the sample, wherein the dye is a fluorescent dye. The sample is fractionated to obtain at least a first fraction and a second fraction, wherein the second fraction is a fiber fraction. The method further includes, for each obtained fraction, measuring the fluorescence emitted by the particles in the fraction, calculating the fluorescence integral measured for fractions excluding the fiber fraction, and relating the calculated fluorescence integral to the amount of acetone-soluble material in the pulp suspension, and optionally measuring the light scattering signal of the particles in the at least first and second fractions.

[0006] This method and system can be used to monitor, control, and optimize the chemical and process properties in pulping, papermaking, and / or paperboard manufacturing processes. Attached Figure Description

[0007] The invention will now be described in more detail with reference to preferred embodiments and the accompanying drawings, wherein...

[0008] Figure 1This shows the relationship between pulp quality and the proportion of hydrophobic particles in the pulp;

[0009] Figure 2 The variation of light scattering intensity of the measured pulp sample with classifier elution volume is shown.

[0010] Figure 3 The variation of fluorescence intensity of the measured pulp sample with classifier elution volume is shown.

[0011] Figure 4 The relationship between the scattering skew index of the pulp sample and the proportion of hydrophobic particles in the pulp is shown.

[0012] Figure 5 The relationship between the integrated fluorescence of small particles in the pulp sample and the total amount of extract in the pulp was shown;

[0013] Figure 6 This is a flowchart illustrating an exemplary method for monitoring hydrophobic particles contained in a pulp suspension;

[0014] Figure 7 This is a block diagram illustrating an exemplary system for monitoring hydrophobic particles contained in pulp suspensions. Detailed Implementation

[0015] The following embodiments are exemplary. While the specification may refer to "one," "a," or "some" embodiments in several places, this does not necessarily mean that each such reference is the same one or more embodiments, or that the feature applies only to a single embodiment. Individual features of different embodiments may also be combined to provide other embodiments. Furthermore, the terms "comprising," "containing," and "including" should be understood not to limit the described embodiments to consisting only of those features already mentioned, and such embodiments may also contain features / structures not explicitly mentioned.

[0016] The amount of hydrophobic particles in pulp can be measured by measuring the fluorescence emitted by the pulp. If all particle fractions (including fibers) are present in the pulp when measuring the amount of acetone-soluble material, the relationship between the amount of acetone-soluble material and pulp quality is invalid, i.e., an erroneous reading is obtained in the measurement due to the presence of fibers. Therefore, one embodiment discloses fractionating the pulp sample before measuring the amount of acetone-soluble material. The fluorescence integral of the pulp sample fraction, but not the fiber fraction, is then correlated with the (absolute or relative) amount of acetone-soluble (acetone-extractable) material in the pulp sample. Optionally, the light scattering intensity of each fraction in the sample can be measured, where the skewness index (i.e., skewness index, skewness) of the measured light scattering signal is an indicator of the general quality of the pulp. A high scattering skewness index is associated with a high amount of acetone-soluble material in the pulp sample, and a low scattering skewness index is associated with a low amount of acetone-soluble material in the pulp sample. Optionally, the light scattering signal of particles in each fraction is measured, the scattering skewness index of the measured signal for that fraction is calculated, and the calculated scattering skewness index is correlated with the amount of acetone-soluble material in the pulp suspension.

[0017] Figure 6 This is a flowchart illustrating an exemplary method for monitoring hydrophobic particles contained in a pulp suspension (or pulp stock). The method includes obtaining a sample 601 from the pulp suspension. A dye is added to the sample 602 to stain the particles in the sample, wherein the dye may be a fluorescent dye. The sample is fractionated 603 into at least two fractions based on the mass and / or particle size of the particles in the sample. The sample may be a pulp sample or pulp filtrate taken from a self-made pulping process or a papermaking system production line, and the fractions typically include at least a colloidal fraction and a fibrous fraction. The method further includes, for at least the colloidal fraction, measuring 604 the change in fluorescence emitted by the particles in the fraction over time, calculating 605 the integral of the fluorescence intensity signal measured for the colloidal fraction, and correlating the calculated integral of the fluorescence signal with the amount of acetone-soluble material in the sample 606. In addition to steps 604-606, the method may include measuring the change in light scattering of particles 604 over time for each fraction in the sample, and calculating the skewness index of the light scattering signal measured in step 605, including each fraction of the sample.

[0018] Based on this relevant 606, the pulp or papermaking process can be automatically or manually optimized 607 by adjusting the amount and / or type of chemicals added to the pulp or pulp filtrate. For example, the size and / or viscosity of hydrophobic particles can be affected by the use of chemicals. Some chemicals (so-called fixatives) can be used to fix hydrophobic particles to fibers. Some chemicals can be used to stabilize and disperse hydrophobic particles, thereby allowing them to be washed away from the pulp. Figure 6The procedure shown can be repeated at predetermined and / or random intervals, or it can be performed when needed (e.g., if poor pulp quality is suspected).

[0019] Figure 7 This is a block diagram illustrating an exemplary system for monitoring pulp quality by monitoring hydrophobic particles contained in a pulp suspension (or pulp stock). The system includes means (sampling device 701) for obtaining a sample from the pulp suspension or pulp filtrate. The pulp suspension may be diluted if necessary. The pulp suspension may also be pulp with a low amount of water, obtained, for example, from a screen washing process in a sulfate pulp mill. The system includes means (dyeing device 702) for adding a dye to the sample to dye the particles in the sample; the dye may be a fluorescent dye. The system includes a flow classifier 703 (e.g., a field flow classifier) ​​to classify the sample into at least two fractions based on its mass and / or size. Typically, the pulp sample contains colloidal fractions and fibrous fractions. The fractions of the pulp sample may include, for example, colloidal fractions, fine fractions, aggregate fractions, and fibrous fractions. The system further includes, for fractions of the graded sample, and for at least colloidal fractions, means (optical measuring device 704) for measuring fluorescence signals emitted by particles in the fractions, means (calculating device 705) for calculating the fluorescence integral measured for the colloidal fractions, and means (calculating device 705) for relating the calculated fluorescence integral to the amount of acetone-soluble material in the sample. In addition to means 704-705, the system may include means (optical measuring device 704) for measuring light scattering from particles in each fraction, and means (calculating device 705) for calculating the skewness of the light scattering signals measured for all fractions.

[0020] The system may include a control device (706) for optimizing the pulp and / or papermaking process based on the relevant parameters by automatically or manually adjusting the amount and / or type of chemicals added to the pulp or pulp filtrate. Chemical treatment, for example, can affect the size and / or viscosity of the hydrophobic particles. Chemicals (so-called fixatives) can be used to fix the hydrophobic particles to the fibers. Chemicals can be used to stabilize and disperse the hydrophobic particles, thereby allowing them to be washed away from the pulp if necessary. The system may be configured to repeat the procedure described in any of steps 601-607 above at predetermined and / or random intervals, or it may be configured to perform the procedure when necessary (e.g., if it is suspected that the pulp does not meet the specifications set by the paper mill using the pulp, for example, the pulp may have poor quality).

[0021] The computing device may include at least one processor and at least one memory (which includes computer program code), wherein the at least one memory and the computer program code, together with the at least one processor, are configured to enable the system to perform the program of the computing device described above.

[0022] The fluorescence integral can contain more than two fractions of fluorescence, but the fluorescence of the fiber is not used for correlation, that is, the fluorescence of the fiber is not used when the fluorescence is correlated with the amount of acetone-soluble material in the sample.

[0023] One embodiment provides an online method and system for monitoring and controlling the amount of acetone-soluble material in pulp or pulp filtrate during a pulp or papermaking process. The method includes adding a fluorescent dye, such as Nile Red, to a sample that reacts with hydrophobic materials contained in the sample; fractionating the sample into two or more fractions before or after the addition of the dye; and measuring the fluorescence of at least one fraction (which is not a fiber fraction). Optionally, light scattering of all fractions is also measured. The dye, such as Nile Red, also reacts with fibers and can result in higher fluorescence, attributed to hydrophobic substances such as residual lignin contained in the fibers. Therefore, it is preferable not to measure the fluorescence signal (fluorescence intensity) of the fiber fraction, or at least preferably not to consider it when integrating the fluorescence signal of the fraction with the amount of acetone-soluble material.

[0024] The method includes the steps of: sampling from the pulp process, adding a fluorescent dye such as a Nile Red solution to the sample, classifying the sample into at least two fractions to obtain, for example, the following fractions: colloids and fibers (typically in samples of ready-made pulp obtained from a pulp mill, before the wire box of a wire dryer), measuring the fluorescence intensity signal and, optionally, the light scattering signal from the effluent stream of the classifier, calculating the fluorescence signal integral of the fraction, correlating the fluorescence of the fraction (except for the fiber fraction) with the amount of acetone-soluble material in the pulp suspension, and using information about the relative or absolute amount of acetone-soluble material and / or the skewness of the light scattering signal to enhance the pulp process and / or deposition control at the paper machine / paper system.

[0025] The sample can be obtained from sampling points in the pulp or papermaking process, such as the wire box in the pulp drying process, or the pulp suspension or filtrate entering the papermaking system.

[0026] The dye is added to the sample such that it has sufficient time to interact with the particles in the pulp suspension before fluorescence / light scattering measurements. The dye can be mixed with a solvent before being added to the pulp suspension. Those skilled in the art can determine sufficient time for mixing the pulp and dye without excessive experimentation. The dye can be added before or after grading.

[0027] The pulp suspension may include sulfate pulp, chemical pulp, thermomechanical pulp, chemi-thermomechanical pulp, birch pulp, and / or any other type of cellulose or wood-based pulp. Additionally, the pulp may include or consist of recycled fibers.

[0028] This method is preferably an online method. However, sampling and measurement can also be performed manually using portable devices. In the online method, the sampling (and subsequent grading and measurement) can be based on a predetermined schedule, on intermittent intervals, and / or on a continuous process.

[0029] One or more chemicals that alter the size and / or surface properties of one or more hydrophobic particles can be used. Information obtained regarding the amount of hydrophobic particles in the fluid can be used to form a control loop for the addition of one or more chemicals (dosage and / or type of the chemicals), which can be used to control the amount of hydrophobic particles. The one or more chemicals may include at least one of the following: fixatives, viscosity reducers, dispersants, surfactants, and retention aids. The chemical can be added to dry or wet pulp. The chemical can be added, for example, before the wire feed box in the pulping process or at the wet end of the papermaking process.

[0030] In this relevant step, the integrated fluorescence intensity obtained from the sample (excluding the fiber fraction) is compared with a predetermined calibration curve of the analytical system, which indicates the correlation between the amount of acetone-soluble material (mg / g, for example, predicted by HP-SEC analysis) and the integrated fluorescence intensity.

[0031] Additionally, this correlation can optionally represent a comparison of the skew index obtained from all fractions, including the fiber fraction (i.e., the entire sample), with a predetermined calibration curve for the analytical system. This calibration curve indicates the correlation between the weight percentage of hydrophobic particles in the pulp suspension and the skew index. The skew index can be used to monitor the shape of the particle size distribution curve (the degree of skewness, or distortion, from a symmetrical particle size distribution). For example, this particle size distribution can be displayed using particle counts on the y-axis and particle size on the x-axis, where the retention time (fractionation time, elution time) of the fraction is obtained using field-flow fractionation technology (longer fractionation time corresponds to larger particle size).

[0032] In one embodiment, the integrated fluorescence intensity and optional light scattering skewness are compared with corresponding predetermined fluorescence values ​​and optional predetermined light scattering skewnesses predefined by the system. The difference between the measured value and the predetermined value is preferably used for manual or automated control of the amount and / or type of chemicals in the pulp / paper / paperboard production process.

[0033] Therefore, the amount of acetone-soluble material in pulp can be quantified. The amount of acetone-soluble material in pulp can be correlated with pulp quality, for example, regarding its runnability on a paper machine. Acetone-soluble materials, for example, reduce pulp quality by making it more viscous.

[0034] This method and system enable online monitoring of the amount of acetone-soluble materials in cellulose pulp. The pulping process monitors the amount of acetone-soluble materials in the pulp suspension or filtrate online, obtaining online values ​​for the amount of acetone-soluble materials in the pulping process.

[0035] This online analysis system can be used to monitor hydrophobic particles in pulp or papermaking processes. It can analyze the particle size and hydrophobicity distribution of samples. The system can determine, for example, the effect of one or more chemicals, such as fixatives, on the distribution of hydrophobic particles.

[0036] The method includes measuring at least one of the particle groups by optical measurement to generate at least one measurement signal representing the amount and / or properties of the particles, processing the measurement signal to extract the fluorescence integral of each particle group and optionally the skewness of light scattering across the entire sample, wherein processing the measurement signal includes filtering, averaging, and baseline correction of the signal.

[0037] The skewness of this light scattering signal is an indicator of pulp quality. A high scattering skewness index indicates that there are more small particles (colloidal particles) than large particles (e.g., fibers), i.e., a high amount of hydrophobic particles, which means poor pulp quality. Colloidal particles are small particles, typically in the size range of 0.1µm-2µm.

[0038] Before grading, the pre-diluted consistency of the pulp is less than 4%, preferably 0.5%-1%.

[0039] In one implementation, techniques for grading and / or analyzing pulp samples and / or controlling pulp / paper / paperboard processes discussed in WO2013 / 175077 and / or WO2015 / 075319A1 may be utilized.

[0040] One implementation is based on the fluorescence of particles in the sample being measured. Fluorescence is measured (and the fluorescence integral is calculated), and the results of the fluorescence measurement can optionally be used to control the addition of chemicals. The fluorescence integral is an indication of the absolute or relative amount of acetone-soluble / hydrophobic materials in the pulp suspension.

[0041] Optionally, light scattering was also measured. The results of the light scattering measurements provide general information such as the size of the hydrophobic particles and the particle size of the extract that is attached to or bound to it.

[0042] The skewness of light scattering values ​​is an indicator of the acetone-soluble material (wt%) in the pulp suspension. Skewness can be confirmed by measuring fluorescence and by calculating the fluorescence integral.

[0043] This correlation can, for example, mean comparing the calculated value with a specific correction curve or correlation curve.

[0044] In one embodiment, the calculated fluorescence intensity can be correlated with the amount of acetone-soluble material (e.g., based on a specific correlation curve).

[0045] Fluorescence can provide precise indications of the relative and / or absolute amounts of acetone-soluble materials in pulp suspensions.

[0046] Skewness can be used to indicate the level of acetone-soluble material in pulp suspension.

[0047] During monitoring, the acquired measurement data can be transmitted in real time to a data collection system, thereby enabling real-time monitoring of the method and the measured / calculated / related values, for example, via a web-based system such as a web portal. This system can be configured to monitor the amount of acetone-soluble material. This value is compared to a preset value. An alarm is generated if the monitored value exceeds (is higher than) the preset value. The measured / calculated / related values ​​can be directly transmitted to a control device to automatically control, for example, the amount of process chemicals fed into the process, such as chemicals capable of altering the size and / or surface properties of the acetone-soluble material in the pulp suspension.

[0048] Therefore, in one embodiment, fluorescence is measured, fluorescence integral is calculated, and the data / calculated values ​​are sent to a data collection system. This enables monitoring of the amount of acetone-soluble material in the pulp suspension.

[0049] Optionally, light scattering and skewness can also be measured, and the data and / or calculated values ​​can be sent to a data collection system. Light scattering and / or skewness can also be used to monitor the amount of acetone-soluble material in pulp suspensions. Controlling the feed of chemicals to affect the amount, size, and / or properties of acetone-soluble material in pulp suspensions can be based on fluorescence, skewness, or both.

[0050] In one embodiment, the monitored values ​​can be used to control the feed of chemicals by monitoring only the fluorescence integral and thus for control, or by monitoring both the fluorescence integral and light scattering skewness, and either or both of these are used to control the system.

[0051] In one embodiment, measurements and / or calculations can be performed based on one or more samples. One embodiment enables simple and accurate classification of samples. Another embodiment also enables the acquisition of the particle size distribution of the samples.

[0052] The calculated fluorescence integral is correlated with the amount of acetone-soluble material in the pulp suspension. Monitoring is based on these results.

[0053] One implementation includes providing, instructing, sending, and / or transmitting the relevant results to a control device and / or to a user.

[0054] The relevant results can be displayed to the user through output devices such as a monitor.

[0055] One embodiment includes, for a given fraction, measuring the fluorescence emitted by particles in the fraction, calculating the fluorescence integral measured for the fraction excluding the fiber fraction, relating the calculated fluorescence integral to the amount of acetone-soluble material in the pulp suspension, and providing the correlated result to a control device.

[0056] One implementation has the advantage of providing an online analytical system for monitoring acetone-soluble materials in pulp or papermaking processes. This system can be based on the particle size distribution of the analyzed sample.

[0057] One advantage of the sampling technique used is that sampling and measurement can also be performed using portable devices.

[0058] In one implementation, sampling, monitoring, and correlation can be performed automatically.

[0059] Fluorescence and, optionally, the scattering index can be measured.

[0060] Figure 1 This shows the relationship between pulp quality and the proportion of hydrophobic particles in the pulp.

[0061] Figure 2 The invention illustrates the variation of light scattering intensity of a pulp sample with the elution volume of the classifier. Figure 3 The invention illustrates the variation of fluorescence intensity measured in pulp samples with classifier elution volume, according to the present invention.

[0062] Figure 4 The relationship between the scattering skew index of the pulp sample and the proportion of hydrophobic particles in the pulp is shown. Figure 5 The relationship between the integrated fluorescence of small particles in the pulp sample and the total amount of extract in the pulp is shown.

[0063] Figure 1 , 4 Figures 5 and 6 show examples of calibration curves that can be compared with fluorescence intensity / skewness index obtained by an online measurement system to quantify acetone-soluble materials in pulp suspensions.

[0064] Example 1

[0065] The laboratory analytical system was used to study the amounts of hydrophobic and hydrophilic particles in front-of-wire box samples from various sulfate pulp mill dryers. Based on knowledge of high, medium, or low quality sulfate pulp production in sulfate pulp mills (regarding paper machine runnability), the proportion of hydrophobic particles in all analyzed particles showed a significant correlation with pulp runnability behavior.

[0066] exist Figure 1 In the figure, the percentage of the analyzed hydrophobic particles is plotted relative to the general perception of the quality of sulfate pulp from a given pulp mill (without considering daily variations). Figure 1 The pulp quality is shown as a plot relative to the percentage of hydrophobic particles in the wet pulp before drying (showing a point slightly off the scale). Figure 1 The study showed that a low percentage of hydrophobic particles was associated with higher pulp quality, while a high percentage of hydrophobic particles was associated with lower pulp quality.

[0067] The proportion of hydrophobic particles (both hydrophilic and hydrophobic) in samples from several different sulfate pulp mills producing birch pulp was analyzed. The results showed a significant correlation with pulp quality and paper machine runnability.

[0068] Example 3

[0069] The same sample was also analyzed according to the present invention. The pulp, including fibers, was graded and analyzed using an online system. Figure 2 Light scattering profiles of two sulfate pulp samples, including colloidal and fibrous fractions, are shown. Large variations exist in the light scattering of the fibrous fraction of the sample (shown as a change with elution volume), indicating differences in fiber morphology and the possible amounts of fine fiber particles and / or fibrils. Figure 2 The light scattering curves (light scattering as a function of fractionation and elution volume) of two sulfate pulp samples from different pulp mills are shown. Clearly, the light scattering curves (main peaks) of the fiber fractions in these samples are different. The skewness index can be used to describe this difference. A high skewness index indicates the presence of more small particles compared to the amount of large particles. A low skewness index indicates the presence of fewer small particles compared to the amount of large particles.

[0070] Example 4

[0071] Figure 3 Fluorescence curves obtained from sulfate pulp from three different pulp mills are shown. Figure 3 The typical fluorescence intensity signal (hydrophobicity) of the sulfate pulp samples is shown. Significant differences exist between samples, particularly regarding the fluorescence response of small particles (colloidal fraction), indicating variations in the amount of hydrophobic material present in the samples. Large variations can be observed between samples, especially regarding the amount of small particles.

[0072] Example 5

[0073] The scattering skew index was compared with the measured percentage of hydrophobic particles (which is significantly correlated with perceived pulp quality). This also indicates that good pulp runnability is indicated by a high percentage of small hydrophilic particles in the pulp. Furthermore, the total number of particles is not important for pulp runnability.

[0074] Figure 4 This shows the proportional percentage of hydrophobic particles in the pulp sample as measured by a laboratory system (where proportionality is the cube of the percentage, i.e., percentage). 3 The scattering skewness index of the sample was also considered. A high skewness index indicates the presence of more small particles compared to large particles in sulfate pulp, and vice versa. This result indicates... Figure 4 There is a correlation between the measured skewness index and the percentage of hydrophobic particles. Figure 4 The results showed that a high percentage of hydrophobic particles was associated with a higher skewness index, and a low percentage of hydrophobic particles was associated with a lower skewness index.

[0075] Example 6

[0076] According to the present invention, fluorescence is a measure of the hydrophobic material in a sample. Sulfate pulp contains two different types of extracts: so-called free extracts such as fatty acids and sterols, and polymeric extracts, the formation mechanism of which remains unclear. Free extracts can be identified and quantified by gas chromatography (GC). However, polymeric extracts are intended to be quantified using HP-SEC analysis and are not observed by GC. Typically, approximately 20% by weight of sulfate pulp extracts are in the form of so-called free extracts, but nearly 100% by weight of all extracts can be quantified by HP-SEC.

[0077] Figure 5 The amount of acetone-soluble extract (measured by HP-SEC analysis) is shown, and its correlation with the integrated fluorescence of small particles as measured by fluorescence analysis is shown. Figure 5 The total amount of hydrophobic extracts analyzed by HP-SEC and the integrated fluorescence of dispersed and colloidal materials measured by a fluorescence measurement system are shown. This result (the correlation between the detected HP-SEC measurements and fluorescence measurements) strongly indicates that the fluorescence measurement system can be used for online monitoring of the amount of acetone-soluble materials in pulp. The amount of acetone-soluble materials in pulp provides a measure of the content of wood extracts (often referred to as resins). These acetone-soluble materials may include, for example, fatty acids, resin acids, fatty alcohols, sterols, diglycerides, triglycerides, sterols, and / or waxes. Additionally, acetone extracts of mechanical pulp may also contain phenolic compounds such as lignans.

[0078] The amount of hydrophobic material in pulp is related to the quality of pulp in terms of runnability on paper machines and sedimentation tendency.

[0079] This online measurement system can be installed in a sulfate pulp mill to enable the analysis of pre-wire box pulp samples (including colloids, aggregates, and / or fibers). The fluorescence intensity and scattering skew index obtained through the online measurement system and method can be correlated (compared) with calibration values ​​(calibration curves) to determine the amount of acetone-soluble materials in the pulp. Calibration curves can be, for example, as described above regarding... Figure 1 , 4 It is obtained as described in Examples 1, 2, 5 and 6.

[0080] It will be apparent to those skilled in the art that the concept of this invention can be implemented in various ways as technology advances. The invention and its embodiments are not limited to the above-described embodiments, but can be varied within the scope of the claims.

[0081] In particular, the present invention also relates to the following items.

[0082] Project 1. A method for monitoring hydrophobic particles contained in pulp suspension, the method comprising:

[0083] Samples are obtained from pulp suspension or filtrate of pulp suspension;

[0084] A dye is added to the sample to stain the particles in the sample, wherein the dye is a fluorescent dye;

[0085] The sample is graded to obtain at least a first grade and a second grade, wherein the second grade is a fiber grade.

[0086] The method further includes

[0087] - For the obtained fraction, the fluorescence emitted by the particles in the fraction is measured, the fluorescence integral measured for the fraction excluding the fiber fraction is calculated, and the calculated fluorescence integral is correlated with the amount of acetone-soluble material in the pulp suspension.

[0088] - Optionally, the light scattering signal of the particles in the at least first and second fractions is measured.

[0089] Project 2. According to the method of Project 1, wherein the method includes calculating the scattering skew index of the measured light scattering signal and relating the calculated scattering skew index to the amount of acetone-soluble material in the pulp suspension.

[0090] Project 3. Based on the method of Project 1 or 2, wherein the method includes:

[0091] The calculated fluorescence integral is correlated with the amount of acetone-soluble material in the pulp suspension by comparison with a predetermined correction value.

[0092] Optionally, the calculated scattering skew index is correlated with the amount of acetone-soluble material in the pulp suspension by comparing it with a predetermined correction value.

[0093] Project 4. Based on the method of Project 1, 2, or 3, wherein the method includes:

[0094] Monitoring process performance in pulping, papermaking, tissue papermaking, or paperboard manufacturing processes, wherein the method includes: based on the correlation, controlling the amount of at least one chemical added to the process, wherein the chemical is capable of altering the size and / or surface properties of the acetone-soluble material in the pulp suspension.

[0095] Project 5. The method according to any of the preceding projects, wherein the sample is classified into one or more of colloidal fractions, fibrous fractions, and optionally fine-particle fractions and aggregate fractions by means of a filter or field flow classifier.

[0096] Project 6. The method according to any one of the preceding projects, wherein the method includes dividing the sample into particle groups according to the size and / or mass of the sample.

[0097] Project 7. The method according to any one of the preceding projects, wherein the dye is a hydrophobic dye.

[0098] Project 8. The method of any of the preceding projects, wherein the scattering skewness index of the sample is measured by measuring the light scattering of particles in the sample.

[0099] Project 9. The method of any of the preceding projects, wherein the hydrophobicity of the particles in the sample is measured by measuring the fluorescence emitted by the particles in the sample.

[0100] Project 10. The method according to any of the preceding projects, wherein the method is an online method or includes manual measurement using a portable device.

[0101] Project 11. A system for monitoring hydrophobic particles contained in pulp suspension, the system comprising:

[0102] Apparatus for obtaining a sample from the pulp suspension or the filtrate of the pulp suspension;

[0103] Apparatus for adding a dye to a sample to stain particles in the sample, wherein the dye is a fluorescent dye;

[0104] A classifier, which is arranged to classify the sample into at least a first fraction and a second fraction, wherein the second fraction is a fiber fraction;

[0105] The system further includes

[0106] - An optical measuring device for measuring the fluorescence emitted by particles in the fraction with respect to that fraction; a computing device for calculating the fluorescence integral measured for fractions excluding the fiber fraction; and a correlation device for relating the calculated fluorescence integral to the amount of acetone-soluble material in the pulp suspension.

[0107] - An optional optical measuring device for measuring the light scattering of particles in the at least first and second fractions.

[0108] Project 12. The system according to Project 11 includes a computing device for calculating a scattering skew index of a measured light scattering signal; and an associated device for relating the calculated scattering skew index to the amount of acetone-soluble material in the pulp suspension.

[0109] Project 13. A system based on Project 11 or 12, which includes a processing unit adapted to automatically perform sampling, grading, and data collection.

[0110] Item 14. According to Item 11, 12 or 13, the system includes means for performing any method steps of the items 2-10.

[0111] Item 15. Use of the methods of any one of Items 1-10 or the systems of any one of Items 11-14 for the monitoring, control and optimization of chemical and process properties in pulping, papermaking and / or paperboard manufacturing processes.

Claims

1. A method for monitoring the amount of acetone-soluble material contained in a pulp suspension, the method comprising: Samples are obtained from pulp suspension or filtrate of pulp suspension; A dye is added to the sample to stain the particles in the sample, wherein the dye is a fluorescent dye; The sample is graded to obtain at least a first fraction and a second fraction, wherein the first fraction is a colloidal fraction and the second fraction is a fibrous fraction; The method further includes - For the at least first fraction, measure the fluorescence emitted by the particles in the at least first fraction, calculate the fluorescence integral measured for the at least first fraction, and correlate the calculated fluorescence integral of the at least first fraction, excluding the fiber fraction, with the amount of acetone-soluble material in the pulp suspension, and - Optionally, the light scattering signal of particles in at least the first and second fractions is measured.

2. The method of claim 1, wherein the method comprises calculating a scattering skew index of the measured light scattering signal and relating the calculated scattering skew index to the amount of acetone-soluble material in the pulp suspension.

3. The method according to claim 1 or 2, wherein the method comprises: The calculated fluorescence integral is correlated with the amount of acetone-soluble material in the pulp suspension by comparison with a predetermined correction value. Optionally, the calculated scattering skew index is correlated with the amount of acetone-soluble material in the pulp suspension by comparing it with a predetermined correction value.

4. The method of claim 1 or 2, wherein the method comprises: Monitoring process performance in a pulping process, papermaking process, tissue paper manufacturing process, or paperboard manufacturing process, wherein the method includes: based on the correlation, controlling the amount of at least one chemical added to the process, wherein the chemical is capable of altering the size and / or surface properties of the acetone-soluble material in the pulp suspension.

5. The method according to claim 1 or 2, wherein the sample is fractionated into one or more of fine-particle fractions and aggregate fractions, as well as colloidal fractions and fibrous fractions.

6. The method of claim 1 or 2, wherein the sample is classified into fractions by means of a filter or a field flow classifier.

7. The method of claim 1 or 2, wherein the method comprises dividing the sample into particle groups according to the size and / or mass of the sample.

8. The method according to claim 1 or 2, wherein the dye is a hydrophobic dye.

9. The method of claim 1 or 2, wherein the scattering skewness index of the sample is measured by measuring the light scattering of particles in the sample, and / or The hydrophobicity of the particles in the sample is measured by measuring the fluorescence emitted by the particles in the sample.

10. The method of claim 1 or 2, wherein the method is an online method, or includes manual measurement using a portable device.

11. A system for monitoring the amount of acetone-soluble material contained in a pulp suspension, the system comprising: Apparatus for obtaining a sample from the pulp suspension or the filtrate of the pulp suspension; Apparatus for adding a dye to a sample to stain particles in the sample, wherein the dye is a fluorescent dye; A classifier is arranged to classify the sample into at least a first fraction and a second fraction, wherein the first fraction is a colloidal fraction and the second fraction is a fibrous fraction. The system further includes - An optical measuring device for measuring fluorescence emitted by particles in the at least first fraction; a computing device for calculating the fluorescence integral measured in the at least first fraction; and related apparatus for relating the fluorescence integral measured at least in the first fraction, excluding the fiber fraction, to the amount of acetone-soluble material in the pulp suspension, and - An optional optical measuring device for measuring the light scattering of particles in the at least first and second fractions.

12. The system of claim 11, further comprising a computing device for calculating a scattering skew index of the measured light scattering signal; and a correlation device for relating the calculated scattering skew index to the amount of acetone-soluble material in the pulp suspension.

13. The system of claim 11 or 12, wherein the system includes a processing unit adapted to automatically perform sampling, grading and data collection.

14. The system of claim 11 or 12, wherein the system is configured to perform any method step of any of claims 2-10.

15. The method of any one of claims 1-10 or the system of any one of claims 11-14 is used for monitoring, controlling and optimizing the chemical and process properties in pulping, papermaking and / or paperboard manufacturing processes.

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