JPS62502759A - Method in the production of mechanical pulp - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Methods in the production of mechanical valves The present invention refines bulk cellulose-containing materials such as wood chips. The present invention relates to a method for controlling the production of mechanical pulp during a refining process. refi Before coating, the chip should be treated with TMP (thermomechanical pulp) or CTMP (chemiser). processed by heat and/or chemicals to produce mechanical valves) obtain. Refining can be done by single disc refiner or double disc refiner This is done in one or several stages depending on the finisher. These finers are related It is equipped with opposing or finer discs that rotate. The disc has bars and It has a disc segment that includes an intermediate groove. Opposing disk segments The material refuses while passing outward through the gap formed between the fined.

The nature of the valve produced depends on a number of system parameters, in addition to the quality of the wood chips. influenced by. As a system parameter, the distance between disk segments is Gap: The load on the motor that drives the refiner disk for one revolution.

The pressure that pushes the refiner discs toward each other, the pressure during chip feeding, the disc the pressure in the housing surrounding the refiner, the dilution water supply, and the amount of material passing through the refiner. Flow (output), and material concentration can be mentioned. With the above parameters are related to each other, and the others are substantially independent.

For example, as the motor load increases, the discs may be moved closer to each other when the gap becomes smaller. The pressure in the direction also increases.

Examining and controlling all the parameters that affect the properties of the valve is practically is impossible. However, some parameters are particularly important, namely the gap control the size, material concentration, and production output (product 1on) It is possible to obtain valves with the desired quality with a fairly high precision by It was discovered.

One major problem is that the measured values of system parameters directly depend on the properties of the valve. It cannot be used as an indicator. Tensile strength, tear resistance, dehydration ability, binding fiber content In order to investigate the characteristics of valves such as abundance and fiber length, it is necessary to Needless to say, it is necessary to analyze the paper. At the factory, such analysis results It usually takes several hours to obtain a only is done. Therefore, the system parameters have not been determined or If there is no simple relationship between system parameters and valve properties, quickly discover and correct changes in valve characteristics based on system parameters. is impossible.

One factor that causes the relationship between measured values of system parameters and valve characteristics to change during operation. is the wear of the refiner disc segments. Therefore, the system parameters Some of the pulp properties may deteriorate even if the measured values remain unchanged. Ru. Therefore, system performance is based on the analysis results of a valve manufactured several hours ago. In fact, it is necessary to adjust the parameter. This is, of course, a big disadvantage. Ru.

Delayed analysis results may be caused by testing various refiner disc segments. There are also substantial disadvantages when making comparisons. Therefore, during the sofaning process If the above system parameters can be measured, pulp properties can be predicted with higher I accuracy than before. Therefore, it is desirable to measure system parameters during couching. ing.

The present invention provides a solution to this problem. The present invention provides refining while sleeping on the sofa. This involves calculating the characteristics of the valve using the vibrations generated in the inner disk. Main departure The features of the invention are as set forth in the appended claims.

The present invention will be described in more detail below with reference to specific examples and test results shown in the attached drawings. Explain in detail. In the drawings, Figure 1 shows the results of frequency analysis of measured vibrations, and Figure 2 shows the results of frequency analysis of measured vibrations. and Figure 3 show the results when vibration of the refiner disk is not used and when it is used. The measured tensile strength value and the calculated tensile strength value should be in agreement for each case. and

One of the important properties of valve quality is tensile strength. This property applies to paper making machines. This is particularly important in the case of mechanical pulps.

Three system parameters are controlled: gap size, material concentration, and yield. By adjusting it, the desired valve quality can be maintained with a fairly high degree of precision. It is Noh. However, from experiments conducted on a factory scale, it has been found that the above-mentioned system parameters When refiner disc wear cannot be predicted by control, valve quality It was found that the quality deteriorated over time due to wear of the refiner discs.

Relative rotation of refiner disks and morphology of disk segments (desi[n ) by measuring the high frequency vibrations generated in the refiner disk. Capable of calculating vibrational energy for refiner disc segments It is. The frequency, which depends on the rotational speed of the disk and the shape of the disk segment, is It can be several thousand p, s. Vibration measurements on the disc, preferably after the segment Uses an accelerometer attached to the side. In single-disc refiners, accelerometers Attach to the fixed disc. To obtain additional information about disc vibration, Install accelerometers on both discs of single or double disc refiners It's okay.

The vibrational energy measured in this way is taken into account to calculate the pulp properties. that these properties can be predicted with much greater accuracy by is a surprising finding. In particular, predicting the strength properties (tensile strength) of pulp Can be done. In this way, the tensile strength caused by the wear of the disc segments It was found that it is possible to predict the decline in

This also means that vibrational energy is used to determine the condition of the treated surface of the segment. This means that it can also be used to Vibrational energy can be generated by various types of discs. can be used to compare the efficiency of segment segments.

In a single-disc refiner, the accelerometer is mounted on a fixed disc disc set. It was installed in a hole drilled on the back side of the component. The segments are bars of different sizes. It was designed with three bands including a groove.

Refining was performed on preheated chips for the production of TMP. 2 The system parameters and pulp properties in the trial run were as follows: Test I Test 11 Production yield (absolute dry weight of pulp/ton/24 hours) 7080 Material concentration (%) 48 48 Gap size (mm) 0.46 0.38 Tensile index (N m/g) 3 3 33CF S (ml) 184 150 Tear index (+nN m”/g) 8.5 7.5 Specific energy (kW h/pa Simultaneously measure and separate signals from 2150 and 2075 accelerometers analyzed. The frequency range of interest was 5-25 kc/sec. Figure 1 shows the frequency of this signal. The wavenumber analysis results are shown. The signal is distributed in three different areas corresponding to the three bands of the segment. Can be divided. In the inner band containing the coarsest lines, frequencies 5.6 to 11. 2kc/sec was recorded. 11.2-17' in the central band, 6kc/s, and the highest In the outer band containing the denser lines, 17.6-25 kc/sec was recorded. vibration energy The energy is represented in FIG. 1 by the area under the frequency curve.

After 800 operating hours, the system parameters and pulp properties were measured again. Most of the measured pulp properties are based on measured system parameters and previous tests. The results were found to be in close agreement with the pulp properties calculated by f.

One exception was the tensile strength, whose measured value was lower than the calculated value. Figure 2 shows the pull The measured value of the tension index is calculated from the measured values of production output, gap size, and material la. It is shown as a function of the calculated tensile index. Significant systematic errors are observed. . Solid lines indicate perfect agreement, dotted lines indicate acceptable error range.

Consider vibration energy obtained from accelerometer signals when calculating valve characteristics As a result, all measured valve properties could be predicted with high accuracy. Figure 3 The measured tensile index is determined by the adjusted yield, gap size and material concentration. as a function of the tensile index calculated using vibrational energy. ing. Here, the white eyebrows match within the error range. It can be said that there is no systematic error. .

The deterioration of the tensile strength of the pulp can be explained by the jl of the disc segment.

Finding a controllable relationship between tensile strength and segment wear has not been previously achieved. did not come.

In contrast, the present invention provides such control possibilities. Therefore, the present invention Therefore, the condition of the disk segment can be investigated by measuring the vibration energy. You can also determine when a segment should be replaced. Book The invention can also be used to compare different segment patterns and materials.

The invention is, of course, not limited to the concrete examples described, but may be modified within the scope of the inventive concept. obtain.

Claims (5)

[Claims] 1. Measured by an accelerometer attached to the disc and converted to vibration energy The vibration of at least one refiner disk is controlled by one or more process changes. It is used to control the refiner process and the properties of the pulp produced. Two opposing sheets of bulk cellulose-containing material that rotate relative to each other, characterized by While passing through the gap between the refiner discs A method for controlling the production of mechanical pulp in an inner process. 2. Vibration is measured on a disc segment placed on the fixed disc of the refiner The refiner process is a single disc refiner. The method according to claim 1, which is carried out. 3. Control vibration energy combined with yield, gap size and material concentration The method according to claim 1 or 2, characterized in that the method is based on -. 4. Vibration energy can also be used to examine the condition of the beaten surface of the disc segment. 4. The method according to any one of claims 1 to 3, characterized in that the method is used. 5. Vibration energy is used to evaluate and compare different disk segment configurations. 5. The method according to any one of claims 1 to 4, characterized in that: