JPH03238346A - Method for quantifying pitch in manufacturing process of pulp or paper - Google Patents

Abstract

PURPOSE:To measure the quantity of pitch in a raw material and a process by performing colorimetry for the pitch in the manufacturing process by using one or more specified wavelengths within a specified range. CONSTITUTION:Light in the region of near infrared rays in the range of wavelengths 0.8 - 2.6 mu gives absorption spectrums peculiar to compounds. The light can be used for the identification and determination of a compound. The spectrums have overlapped absorption bands. Differentiated spectrums are used for processing the bands. Thus, gentle change due to the difference in surface properties, the difference in colors and the like can be erased from the complicated spectrums. The absorption peculiar to the component of pitch can be extracted. Each peak is proportional to the quantity of the component, and the quantity can be determined accurately. The absorption peculiar to the component of the pitch among the near infrared rays is indicated. The light having the wavelength whose quantity can be determined is selected. The correlation with respect to the absorbances of the spectrums and the peak intensities of the differentiated spectrums and the quantity of the pitch is obtained for one or more lights. This expression of the correlation is used, and the quantity of the pitch is determined based on the intensity of the peak.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for easily predicting pitch (resin) failures, so-called pitch troubles, that occur in pulp or paper manufacturing processes, and preventing pitch troubles based on the prediction. This is an intermediate method for quantifying pitch.

[Conventional technology and issues]

During the pulp or paper manufacturing process, small spherical sticky aggregates of organic material derived from natural resins or gum-like substances or other additives liberated from wood cells, usually called pitch, are generated. . This kind of pitch aggregates and adheres to various parts of the papermaking machinery equipment such as cheeseboards, beaters, and wires in the above manufacturing process, reducing work efficiency, or gets mixed into the product, causing stains on valve seats or paper. Otherwise, it causes various troubles (pitch troubles), such as causing holes.

Conventionally, various methods have been adopted as measures to prevent such pitch troubles.

The most effective and common method is to add, for example, an adsorbent such as fine talc or kaolin, or sulfuric acid, polyphosphate, various surfactants, emulsifiers, etc.

When these are added to process water at appropriate locations in the pulp and paper manufacturing process, pitch precipitates in the liquid, aggregates into particles of a certain size, and adheres to machinery and equipment, and then separates from the paper. This can have the effect of suppressing adhesion to the skin. However, in this method, the inhibitor is only added after encountering a disturbance phenomenon that occurs during the operation of the manufacturing process, or the necessity of adding the inhibitor is understood and used based on the experience of past operations. However, it does not prevent pitch troubles by predicting them in advance based on the characteristics of the process water.

It is generally said that the major cause of pitch trouble is differences in the types of manufacturing raw materials, but differences in manufacturing equipment, processes, or manufacturing conditions also have a subtle effect on the occurrence of pitch trouble. Furthermore, in the multi-step and long-term pulp and paper manufacturing process, the phenomenon of occurrence of this disorder is extremely diverse, for example, the location and amount of pitch deposited on equipment and products are not constant. For this reason, although the methods described above are effective in themselves, it is often difficult to take appropriate suppression measures, and the addition of inhibitors is always based on estimation, so sometimes Even if there were cases where people were consuming a large amount of food unnecessarily, the current situation was that they overlooked it.

In addition to the above, conventional pitch trouble prevention measures include reducing the amount of resin by seasoning the wood, and cleaning the process with fresh water or a caustic aqueous solution after the cooking or bleaching process or during the papermaking process. . At this time, increasing the period, frequency, and/or amount of water, or increasing the amount of blowing of contaminated process water is considered to be an effective preventive measure, and has been partially implemented. Although this method is effective as a measure when encountering obstacles,
Not only is it inferior to the method of adding a pitch suppressant in terms of the need for excess raw material inventory, savings in fresh water and caustic soda, equipment investment, and complexity of work, but it is also impractical because it does not predict failures and deal with them in advance. I can't blame you for being at a disadvantage.

Therefore, it is clear that if pitch troubles can be known in advance, it is possible to take effective and appropriate preventive measures. was proposed. Among these, the most commonly used methods include measuring the amount of extracts in raw materials or process water by Soxhlet extraction;
These include quantifying the amount of pitch deposited in the process, measuring the amount of pitch deposited on copper or stainless steel propellers and shafts, measuring the amount of pitch deposited on papermaking felt, and measuring the number of colloidal pitches in process water. However, the absolute amount of adhesion pitch is extremely small on a test equipment scale, and accuracy is difficult. For this purpose, various improvements have been attempted, but it cannot be said that sufficient results have been achieved.

Optical colorimetric determination is rapid, highly accurate, and simple, and attempts have already been made to quantify pitch in process water using ultraviolet and visible light. However, selective quantification is not possible because the absorption light is not unique to pitch. For this reason, other optical methods of determining pitch have long been desired.

However, the present inventors thought that it would be possible to solve the above problem by developing a test method that can selectively and easily quantify pitch. For many years, we collected process water from various pulp and paper manufacturing processes, as well as the pitch generated therein, and as a result of repeated studies using these samples, we developed a method that can continuously and accurately measure the amount of pitch. has selective absorption and is less affected by absorption by other components, i.e. between 0.8μ and 2.6μ (
The inventors have discovered that it is possible to quantify pitch in raw materials or processes by performing colorimetric determination using light of one or more wavelengths in the near-infrared region (generally referred to as near-infrared region), leading to the present invention.

[Means to solve the problem]

That is, in its aspect, the present invention is characterized in that the pitch in the pulp or paper manufacturing process is determined colorimetrically using light of one or more specific wavelengths between 0.8 and 2.6μ. It provides a method for quantifying pitch in pulp or paper manufacturing processes.

Furthermore, in another aspect of the present invention, an absorption spectrum of a pulp or paper sample whose pitch concentration is known in advance is measured using light of one or more specific wavelengths between 0.8 and 2.6μ. , the correlation coefficient is determined by multiple regression analysis using the peak intensity of this differential spectrum.

This provides a method for quantifying pitch.

The present invention will be explained in more detail below.

As the measurement light used in the present invention, one or more wavelength lights in the range of wavelengths from 0.8μ to 26μ are used. - Examples include 1.1-1.2, 1.3-1.5, 1.6-1.
Light of 8,2.1 to 2.4μ has pitch-specific absorption and can therefore be used advantageously. The absorbance in this region has a proportional relationship to the pitch amount, and as the pitch amount increases, the absorbance naturally increases.

When we measure the absorption spectrum of red pine wood, which is the raw material for ground wood pulp, at wavelengths from 0.8 to 2.6 μ, it is 1.2° 1.4, 1.9
In addition to water absorption appearing around 4μ, 1.55, 2.1μ
Absorption of cellulose nearby, 1.67.2.15.2.2
Lignin absorption near 6 μ, 1.1, 1.7, 1.75
．． This was determined in advance by an extraction operation, etc. by determining the difference between the absorbance in the wavelength range of pitch absorption, which shows pitch absorption around 2.28° and 2.36μ, and the absorbance in the wavelength range that is less affected by pitch. By finding the relational expression with the pitch amount, the pitch amount can be measured from the relational expression with the pitch amount previously obtained by an extraction operation or the like.

The wavelength used as the measurement light in the present invention is 0.8 to 2.
Light in the 6μ range is generally called near-infrared light. It is known that light in the near-infrared region gives a unique absorption spectrum to a compound and can be used for identification and quantification of the compound.

However, spectra are complex and generally difficult to analyze.

In near-infrared spectroscopy aimed at non-destructive measurement of mixed components, it is difficult to obtain the sharp absorption seen in general infrared absorption spectra, and the absorption bands are formed by the absorption of various components influencing each other. It becomes a broad thing. As a method for processing absorption spectra with overlapping absorption bands like this.

The concept of differential spectrum is used.

According to one method of the present invention, since the original spectrum is differentiated by wavelength and used, gradual changes due to differences in surface texture or color can be eliminated from a complex spectrum, thereby making it possible to obtain characteristics specific to the pitch component. It is possible to extract the absorption of As with the original spectrum, each peak in the differential spectrum is proportional to the amount of the component, so accurate quantification is possible. Although it is possible to obtain differential spectra from the first order to the nth order, generally a second order differential spectrum is used.

The first-order differential spectrum captures the rate of change of the original absorption spectrum, that is, the change in the difference in OD (optical clarity) (differential absorbance). The second derivative spectrum is the rate of change of the first derivative spectrum,
Although there is an inconvenience that the absorption band and phase of the original spectrum are reversed, the maximum absorption of the original spectrum can also be obtained as a maximum value in the second derivative spectrum.

There are two methods to obtain a differential spectrum: 1) a method of optically obtaining a differential spectrum by shifting two sweep wavelengths using a three-wavelength spectrophotometer, etc.; There is a method of calculating the differential completely mathematically, and the latter method is generally used.

One of the features of the present invention is to select wavelength light that exhibits specific absorption for pitch components and can be quantified.

The absorbance of a spectrum in a certain wavelength range or the peak intensity of a differential spectrum [OD (optical density)
ty)) and the amount of pitch, and using the obtained phase opening equation, the amount of pitch is determined from the absorbance or peak intensity of the unknown sample. The wavelength used for measurement is 0.8~2
．． A specific wavelength of near-infrared light in the 6μ range is used.

The number of wavelengths used is one or more, preferably two or more, and more preferably three or more.

The correlation was determined by multiple regression analysis, a well-known statistical method.
This is done by finding a correlation equation with reference to a previously known ink density.

The correlation equation can generally be expressed as follows.

C+ = to + to α1+ to 2α2...K,, α.

Here, C1 is the ink concentration, K is the coefficient, and C1 is the peak intensity (OD (optical density) of the differential spectrum at wavelength n where the ink component has strong absorption.
ty)). α can also be taken as the ratio of the peak intensity (○D) for the wavelength n1 of strong absorption and the wavelength n2 of weak absorption for the ink component.

The optimal correlation formula differs depending on the raw materials used, and needs to be determined each time.

The peak due to resin in the second derivative spectrum is 1.1
5 1.37 1.4, 1.65.1, 691.78
2.23 2.28 2.32.2.34゜2.38μ
There are many nearby and elsewhere. However, if a large amount of water is present in the sample, it is necessary to select a wavelength that has little effect on water absorption. 1.15, 1.37, 1
．． It is preferable to use a peak around 69,2.28° and 2.34μ.

Using a differential spectrum, a sufficiently high correlation was obtained between the peak intensity and the amount of resin even at one wavelength.

Naturally, an even higher correlation can be obtained by increasing the number of wavelengths used.

According to the method of the present invention, pitch concentration during the paper valve manufacturing process can be measured with a correlation coefficient as high as 0.98 or higher.

Appropriate locations for measuring the amount of pitch include the steps before the pulping process, bleaching process, and papermaking process, where pitch problems often occur in raw wood, valves, or paper manufacturing processes, such as the washing process. These include the later completed bottle inlet and adjustment process.

Or the pitch can be measured at various parts of the process, such as inside piping, wires, etc.
It adheres and accumulates on blankets and the like, and when a certain amount accumulates, it detaches and mixes with paper, causing defects, paper breaks, and other problems. By periodically or continuously measuring the degree of pitch contamination using the above-mentioned measuring method, it can be used as a method for predicting this type of pitch failure.

Further, the number of these measurement locations may be two or more as necessary.

The amount of pitch is then measured and if a risk of pitch trouble is detected, preventive measures are taken. Preventative measures in the valve or paper manufacturing process include the raw material stage, the process where pitch trouble is likely to occur, or the process before that.
Examples include the inlet part of the bleaching process, the outlet part of the finished base after the washing process, the chest in the conditioning process, the piping system, wires, blankets, etc. in the papermaking process.

Preventive measures include seasoning raw wood or chips;
Pitch trouble can be prevented or suppressed by adding agents (for example, talc, kaolin, aluminum sulfate, polyphosphates, various surfactants, emulsifiers, etc.), cleaning the process with fresh water or a caustic aqueous solution, and replacing papermaking equipment. These preventive measures are very commonly adopted and their effectiveness is widely recognized.

Seasoning is usually performed to reduce the resin content of raw wood or chips. effect of seasoning,
In other words, the reduction in the amount of resin in raw wood is largely influenced by climate conditions and the environment, so the optimal seasoning period differs depending on the region and season. Although seasoning reduces the amount of resin, it also increases raw material inventory, increases storage space, and reduces valve quality. As a result of the pitch determination method of the present invention, the amount of resin can be easily and accurately measured, which not only reduces the amount of resin due to seasoning, but also makes it possible to select an appropriate storage period and storage location and maintain valve quality.

When sufficient resin reduction cannot be achieved by seasoning alone, it is preferable to use a pitch control agent or take other measures.

The method of preventive treatment itself may be any method, but
Appropriate measures may be selected depending on the degree to which the pitch disturbance occurs, that is, the magnitude of the pitch measurement amount.

On the other hand, by measuring the amount of pitch, it can be determined that the possibility of pitch trouble occurring is low or absent, and excessive preventive measures can be omitted. This can be said to be a great advantage brought about by the present invention in terms of resource saving and economy.

Next, the present invention will be explained by examples.

Dog [1] Using chips with various amounts of resin, the points 2.18μ and 2.4μ on the absorption spectrum were connected as a baseline, and the absorbance (relative absorbance) at 2.28μ from the baseline was measured. It was found that there is a correlation with the amount of resin with a correlation coefficient of 0.96.

Resin amount (%) = -0,82+60x ((8BS)2
2. -arrogant×[(^BS)z, +a+(^BS)2. , ]
l (8 BS). Absorbance at two wavelengths nμ Furthermore, the number of measurement points was increased, wavelengths 1.65μ and 1.87μ.
When the relationship with the absorbance of 17 μ from the baseline was taken into account, the correlation coefficient was 0597 or more.

Resin amount (%) = -1,3 + 35X ((ΔBS)2.2@
-'MX[(8BS)2. +8+ (8 BS>2 4])
154x((^BS), -Noisy×[(8BS)+
6. + (8 BS),,,, ]1 dog" L-2 From the spectrum obtained in Example 1, a differential spectrum was obtained by computer calculation processing, and the relationship between the peak intensity C0D at a wavelength of 2.28μ and the amount of resin was calculated. When I calculated the correlation, it was -0
, 98 or higher (correlation coefficients generally take negative values in the case of differential spectra).

m Fat amount (%) = 0.175-9.49X (00)
2□1 When the amount of resin in an unknown sample was measured using this relational expression, a correlation coefficient of 0.98 or more was obtained between the estimated value and the actual value.

The near-infrared spectra of a 1% slurry of crushed wood bulbs of the 1st grade Yuakamatsu were measured, and each second-order differential spectrum was determined.

The following correlation equation was obtained between the peak intensity (OD) at a wavelength of 1.38μ and the amount of resin with a correlation of -0.98 or more.

Pitch concentration (%) = -0,01-1,06X (00)
, 3° where (OD) , , , peak intensity at a wavelength of 1.38μ.

When a slurry of unknown pitch concentration was measured using this relational expression, a correlation with a correlation coefficient of 0.98 or more was obtained between the estimated value and the actual value.

1 Wound 1'' Pitch stains on the blanket were measured using reflected light by near-infrared second-order differential spectrum measurement.

By using a wavelength of 2.28μ, the correlation coefficient between the amount of extraction and the peak intensity was 0.97 or more.

This method made it possible to monitor the rate of contamination and the amount of adhesion and dirt. As a result, it has become easier to determine when it is time to clean the process or replace the papermaking equipment.

〔Effect of the invention〕

The method of the present invention has made it possible to quickly and accurately measure raw materials and in-process pitch amounts in pulp or paper production. For this reason, it is possible to predict the occurrence of pitch trouble using extremely simple and reliable measurements such as the pitch amount of raw materials or process water or the adhesion amount of the equipment, and use existing pinch trouble preventive agents or suppressors. Addition of agents or other appropriate measures can be taken accurately without excess or deficiency. This is also from a process management perspective.
This has extremely beneficial effects in terms of resource conservation and cost reduction.

Claims (4)

[Claims] (1) Pitch in the pulp or paper manufacturing process, characterized by colorimetric determination using the absorption peak intensity at one or more specific wavelengths in the optical absorption spectrum at wavelengths between 0.8 and 2.6μ. quantitative method. (2) After calculating the correlation coefficient by multiple regression analysis using the peak intensity of one or more specific wavelengths of the optical absorption spectrum,
It is characterized by quantifying the pitch based on that relationship.
The method for quantifying pitch according to claim (1). (3) The method for quantifying pitch according to claim (1) or (2), characterized in that the peak intensity of one or more specific wavelengths of light in a differential spectrum obtained from a light absorption spectrum is used. (4) The method for quantifying pitch according to any one of claims (1) to (3), which comprises quantifying pitch in water during a pulp or paper manufacturing process.