Screening residual quantity calculation method

Abstract

To provide a screening residual quantity calculation device and a screening residual quantity calculation method capable of conducting quality control by screening residual quantity without using a measuring method causing large burdens to measuring persons.SOLUTION: A screening residual quantity calculation device and a screening residual quantity calculation method of the present invention are a screening residual quantity calculation device and a screening residual quantity calculation method for measuring a screening residual quantity from a residual rate and a distribution of a fiber length by using a screening residual quantity measuring device having a storage part for storage of a residual rate per a fiber length of a pulp as a constant and a fiber length measuring mechanism for measuring a distribution of a fiber length of a pulp.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a method for efficiently calculating the sieving residue, which is one item of quality control in the papermaking process. [Background technology]

[0002] In the papermaking industry, the condition of the paper stock fibers, which are the raw material for paper, affects the paper's properties such as tensile strength and tear strength, so understanding the condition of the paper stock fibers is important for quality control.

[0003] Quality control methods for understanding the condition of paper stock fibers include those that use sieving residual volume and fiber length distribution charts.

[0004] The sieving residue is the amount of fibers in the paper stock that are longer than a certain length that are collected and measured, and this determines the amount of fibers in the paper stock that are longer than a certain length.

[0005] The sieving residue is measured using a sieving tester in accordance with the pulp sieving test method specified in JIS P 8207.

[0006] The measurement method is to attach a metal mesh of a specified size to a sieving tank, add the paper stock sample, and then stir and pour water in. At this time, fibers smaller than the mesh of the metal mesh will pass through the mesh, but fibers that do not pass through the mesh will remain in the tank.

[0007] The remaining amount of fiber after sieving is calculated by measuring and calculating the bone dry weight of the fiber remaining in this tank.

[0008] When measuring the amount of sieving residue, there is a problem that the fibers get tangled in the metal mesh or the stirring rod, so it is necessary to check whether there are any fibers remaining inside the sieving tank or on the metal mesh after each measurement. This work is time-consuming and labor-intensive for the workers, making it inefficient and also a cause of measurement errors.

[0009] Furthermore, since it is necessary to change the metal mesh to be attached depending on the type of fiber, this work also places a burden on the workers.

[0010] Furthermore, since it takes more than 10 minutes from measurement to obtaining the results, it is not suitable for measuring processes that require short-term continuous processing.

[0011] On the other hand, a fiber length distribution diagram is a diagram that shows the proportion of each fiber length contained in the paper stock by tallying the fibers contained in the paper stock by fiber length.

[0012] The fiber length distribution diagram is measured using a fiber length measuring device, such as a fiber length measuring device (FS5) manufactured by Valmet.

[0013] The fiber length measuring device takes images of the fibers in the paper stock, and by analyzing and compiling the images, it is possible to understand the condition of the fibers and output a fiber length distribution diagram, etc.

[0014] By using a fiber length measuring device, the measurement can be performed mechanically, which reduces the burden on the person making the measurement and also shortens the time required for measurement.

[0015] On the other hand, when measuring using a fiber length measuring device, although it is possible to measure the fiber length distribution, it is not possible to measure the amount of fiber remaining after sieving.

[0016] Furthermore, there is a technique for measuring fiber length online, as described in Patent Document 1. However, the technique in Patent Document 1 has the problem of requiring the installation of two new flow paths for measurement, resulting in a large-scale device. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] Patent Publication No. 55-151243 Summary of the Invention [Problem to be solved by the invention]

[0018] Quality control based on the amount of sieving remaining is insufficient as a quality control method because the degree of tangled fibers in the stirring section and wire mesh section and the degree to which these tangled fibers are recovered can lead to errors in the measurement results depending on the person making the measurement.In addition, the burden on the person making the measurement is heavy because it requires tasks such as checking the fibers remaining in the tank and metal mesh section and changing the wire mesh depending on the type of fiber.

[0019] On the other hand, quality control using a fiber length distribution chart using a fiber length measuring device allows stable quality control because the measurement is mechanical, but it is not possible to measure the amount of fiber remaining after sieving.

[0020] Therefore, there was a demand for a method that would enable stable quality control without errors caused by the measurer, while still allowing quality control based on the remaining amount after sieving, as in the past. [Means for solving the problem]

[0021] The present invention is a sieving residue calculation method for calculating the sieving residue amount of a paper stock containing pulp using a sieving residue calculation device having a memory unit that stores the residual rate for each pulp fiber length as a constant, a fiber length measurement mechanism that measures the distribution of pulp fiber lengths, and a calculation unit that calculates the sieving residue amount from the residual rate and the fiber length distribution, and is characterized by the steps of calling up the residual rate for each pulp fiber length from the memory unit, measuring the fiber length distribution of pulp in the paper stock with the fiber length measurement mechanism, and calculating the sieving residue amount from the residual rate and the pulp fiber length distribution. [Effects of the Invention]

[0022] The sieving remaining amount measurement method of the present invention does not require manual fiber collection, and its structure makes fiber tangles and entanglements less likely to occur than with conventional sieving testers, thereby reducing measurement variation and reducing the burden on the person performing the measurement.

[0023] Therefore, quality control based on the amount remaining after sieving can be performed without using the conventional measurement method using a sieving tester, which places a heavy burden on the measurer. [Brief explanation of the drawings]

[0024] [Figure 1] Diagram showing the outline of the fiber length measuring device [Figure 2] Diagram showing the outline of the sieving tester [Figure 3] Flow diagram of a method for calculating the sieving residual amount constant [Figure 4] Diagram showing measurement using a fiber length measuring instrument [Figure 5] Diagram showing measurement using a fiber length measuring instrument [Figure 6] Diagram showing measurement using a fiber length measuring instrument [Figure 7] Diagram showing measurement using a sieving tester [Figure 8] An example of weight distribution for each fiber length distribution [Figure 9] Figure showing an example of fiber length distribution before and after sieving [Figure 10] Diagram showing examples of weight before and after sieving [Figure 11] Figure showing an example of calculating the residual amount for each fiber length [Figure 12] A diagram showing a sieving remaining amount calculation device [Figure 13] A diagram showing an example of calculation of the remaining amount after sieving DETAILED DESCRIPTION OF THE INVENTION

[0025] The following description will discuss embodiments of the present invention with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described below, and various other embodiments are also encompassed within the scope of the technical concept set forth in the claims.

[0026] The present invention uses a sieving residual amount calculation device having a memory unit that stores the residual rate before and after sieving for each pulp as a constant, and measures the sieving residual amount by multiplying the fiber length measurement result by the residual rate, without using a sieving tester.

[0027] Pulp is generally used as a stock in the paper industry, and pulp can be broadly divided into wood pulp and non-wood pulp.

[0028] Wood pulp can be further divided into L-wood (Laubholz) made from hardwood and N-wood (Nadelholz) made from softwood. Examples of L-wood include beech, oak, birch, poplar, and eucalyptus, while examples of N-wood include pine, cedar, and cypress.

[0029] On the other hand, examples of non-wood pulp include straw, bagasse, kenaf, paper mulberry, and mitsumata.

[0030] Each of the above-mentioned pulps has different fiber properties, fiber length distribution, etc. Therefore, it is necessary to predefine a residual rate corresponding to each pulp as a constant and store it in the memory unit of the sieving residual amount calculation device.

[0031] The method for defining the residual rate as a constant is shown below.

[0032] First, a fiber length distribution diagram is created using a fiber length measuring device (1) before and after sieving the paper stock, and the amount of fiber remaining after sieving is measured using a sieving tester.

[0033] Figure 1 shows a typical fiber length measuring instrument (1). The instrument (1) consists of a main body (2), a monitor (3), a rotating table (4), a sample cup (5), and a stirrer (6).

[0034] The main body (2) refers to the main body of the U-shaped fiber length measuring instrument (1) in Figure 1, and is structured so that the stock to be measured is placed in the recess of the U. Inside the main body (2) are installed a measurement camera, a pump for suction and discharge of the stock, an instrument for measuring the concentration of the stock to be measured, software for tallying and analyzing the measured fibers, etc.

[0035] The monitor (3) is a screen that displays the settings and measurement results of the fiber length measuring instrument (1). It is a touch panel, and can be used to give instructions to start measurement and change the settings of the main unit.

[0036] The sample cup (5) is a container into which the paper stock is poured.

[0037] The turntable (4) is a platform on which the sample cup (5) is placed, and multiple sample cups (5) can be placed. The turntable (4) rotates after the measurement is completed, automatically switching from the stock sample (sample cup (5)) for which the measurement has been completed to the stock sample fiber length measuring device (1) for which the measurement has been completed. This allows for automatic and continuous stock measurement.

[0038] The agitators (6) are devices consisting of a stirring rod, a stock suction port, and a discharge port. While the stirring rod stirs the stock, the stock to be measured is sucked in through the suction port, and the sucked stock is measured and analyzed using a camera inside the main body (2). After measurement, the stock is returned to the sample cup (5) through the discharge port.

[0039] A typical sieving tester (7) is shown in Figure 2. The sieving tester (7) consists of a pump (8), a tank (9), a stirring section (10), a wire mesh (11), a discharge port (12), a rubber stopper (13), a stand (14), and a paper stock collection container (15).

[0040] The pump (8) is a pipe for discharging water into the tank (9). It is set to intermittently discharge a predetermined amount of water for a specified period of time.

[0041] The tank (9) is a container for storing the pulp and water discharged from the pump (8). It has two outlets (12) at the bottom and holes on the side for installing wire mesh (11).

[0042] The agitation section (10) is a section for agitating the stock and water in the tank (9) and is set to agitate the stock and water with an agitator rod for a certain period of time.

[0043] The wire mesh (11) is a metal mesh with holes. The size of the holes is determined for each type of paper stock to be sieved, and fibers contained in the paper stock that are shorter than the holes pass through the wire mesh (11) and are discharged from the discharge outlet (12).

[0044] The outlet (12) is a hole in the tank through which the sieved stock is discharged.

[0045] The rubber stopper (13) is a rubber stopper that prevents the stock and water from being discharged from the outlet (12). When measuring the sieving, it is attached to the outlet (12) and removed after the sieving measurement is completed, and the stock remaining in the tank (9) is collected in the stock collection container (15).

[0046] The stand (14) is the legs that support the entire sieve testing machine (7).

[0047] The stock collection container (15) is a container for collecting the stock after the sieving test. The sieved stock is discharged from the discharge port (12) into the stock collection container (15).

[0048] Figure 3 shows a flow diagram for comparing the weight of each fiber length before and after sieving and calculating the constant for the residual fiber amount for each fiber length. In the present invention, the constant for the residual fiber amount for each fiber length of each pulp is called the "residual rate."

[0049] First, in STEP 1, the fiber length distribution of the stock for which the residual rate is to be calculated is measured using a fiber length measuring device (1).

[0050] As shown in Figure 4, first, the stock to be measured is diluted to a concentration that can be measured by the fiber length measuring instrument (1), and the sample cup (5) containing the diluted stock is placed on the turntable (4).

[0051] Next, as shown in FIG. 5, the type of paper stock to be measured is selected from the monitor (3) or the operating PC (16) connected to the fiber length measuring instrument (1), and a measurement start button is pressed.

[0052] When the measurement is completed, the sample cup (5) starts to be washed automatically as shown in Figure 6, and the measurement result of the fiber length is displayed on the monitor (3) or the operating PC (16).

[0053] This procedure allows the creation of a fiber length distribution diagram for the paper stock before sieving.

[0054] In STEP 2, the weight of the stock to be measured for the sieving tester (7) is calculated based on the stock consistency and the stock amount.

[0055] For example, if the bone dry weight of the paper material to be used for measurement is 5 g and the concentration of the measured paper material is 3%, the weight of the required measured paper material can be calculated by "bone dry weight of measured paper material / concentration of measured paper material", which in this embodiment is shown in Equation 1 below. (Formula 1) 5g ÷ 3% = 166.7g

[0056] In STEP 3, the amount of sieving residue is measured using a sieving tester (7). The detailed measurement method is shown in Figure 7.

[0057] In STEP 3-1, a predetermined amount of paper stock is put into the sieving tester (7) filled with water, and stirring is started.

[0058] In STEP 3-2, after the stirring is completed, the rubber stopper (13) is removed and the stock remaining in the tank is collected in a stock collection container (15).

[0059] In STEP 3-3, a general hand-made papermaking machine (17) or similar is used to separate the paper material from the water and dry it.

[0060] In STEP 3-4, the weight of the dried stock is compared with the weight of the specified amount of stock before sieving to calculate how much stock remains.

[0061] In STEP 4, the paper stock recovered in STEP 3-2 is measured with a fiber length measuring device (1), and a fiber length distribution diagram after sieving can be created.

[0062] In STEP 5, the weight of the remaining paper stock after sieving calculated in STEP 3-4 can be measured.

[0063] In STEP 6, the weight of each fiber length is calculated from the fiber length distribution diagram and the weight measurement results of the stock before and after sieving. An example is shown in Figure 8.

[0064] An example of the fiber length distribution before and after sieving is shown in Figure 9. The solid line shows the measurement results before sieving, and the dotted line shows the measurement results after sieving.

[0065] An example of the weight before and after sieving is shown in Figure 10. In Figure 10, if the weight of the measured pulp before sieving is 5 g and the weight after sieving is 3 g, the residual weight of the measured pulp after sieving can be calculated by "weight after sieving / weight before sieving", which in this embodiment is given by the following formula 2. (Formula 2) 3g / 5g×100=60% This becomes:

[0066] By calculating the weight of each fiber length before and after sieving and comparing these, the residual amount of each fiber length can be calculated. An example is shown in Figure 11.

[0067] In Figure 11, 1 to 3 mm indicates the fiber length. Also, the percentages next to the fiber length in Figure 11(a) indicate the proportion in the stock. This can be calculated from the fiber length distribution diagram in Figure 9. The values ​​in parentheses next to the percentages indicate the weight of each fiber length in the stock. This can be calculated from the weight before and after sieving and the fiber length distribution diagram before and after sieving.

[0068] Regarding the weight of each fiber length before sieving, to find the total weight of fibers with a fiber length of 1 mm, multiply the pre-sieve weight of 5 g by 30%, which is the proportion of 1 mm fiber length in the paper stock, to get 1.5 g. Applying this to each fiber length, the weight of each fiber length before sieving can be calculated. The weight of each fiber length after sieving can also be calculated using the same calculation.

[0069] An example of the weight change for each fiber length is shown in Figure 8. The solid line shows the weight for each fiber length before sieving, and the dotted line shows the weight for each fiber length after sieving.

[0070] In FIG. 11(b), the residual rate can be determined by calculating the change in weight for each fiber length before and after sieving.

[0071] The above steps are carried out for each pulp, the residual rate of each pulp is defined, and the defined residual rates are stored as a database in a storage unit, which will be described later.

[0072] Next, the sieving residual amount calculating device and the sieving residual amount calculating method of the present invention will be described.

[0073] 12 shows a sieving residual amount calculating device (100) used in the present invention. The sieving residual amount calculating device (100) includes a fiber length measuring mechanism (101), a memory unit (102), and a calculation unit (not shown).

[0074] The fiber length measuring mechanism (101) is a mechanism for measuring the distribution of fiber lengths in a sample, and the above-mentioned fiber length measuring device (1) can be used.

[0075] The storage unit (102) stores the above-mentioned residual rate of each pulp in the form of a database.

[0076] The storage unit (102) may be provided in a PC connected to the fiber length measuring mechanism (101) as shown in FIG. 12, or may be built into the fiber length measuring mechanism (101).

[0077] The calculation unit calculates the sieving residue using the residual rate of each pulp stored in the storage unit (102) and the fiber length distribution measured by the fiber length measurement mechanism (101).

[0078] In this embodiment, the calculation unit is configured to be provided in the PC, but it may also be built into the fiber length measuring mechanism (101) like the storage unit (102).

[0079] The fiber length measuring mechanism (101) also has a touch panel monitor, from which an instruction to start fiber length measurement and the selection of each pulp residual rate to be read from the memory unit (102) can be given.

[0080] It is also possible to use a monitor on a PC instead of providing the fiber length measuring mechanism (101) to instruct the start of fiber length measurement and select the residual rate of each pulp from the PC.

[0081] Next, a method for calculating the remaining amount after sieving using the above-mentioned remaining amount after sieving calculation device (100) will be described.

[0082] In STEP 1, the stock for which the sieving residue is to be calculated is fed into the fiber length measuring mechanism (101).

[0083] In STEP 2, the pulp in the stock to be measured is selected from the monitor of the fiber length measuring mechanism (101), and the residual rate of the corresponding pulp, which is registered in advance in the database, is read from the memory unit (102).

[0084] In STEP 3, the fiber length of the stock is measured using the fiber length measuring mechanism (101).

[0085] In STEP 4, the residual amount after sieving is calculated using the residual rate read from the memory unit for the fiber length distribution of the measurement results.

[0086] An example of this calculation is shown in Figure 13. Here, the results of measuring 5g of stock using the fiber length measurement mechanism (101) are shown on the left, and the result was that the stock contained 50% (2.5g) of fibers with a fiber length of 1mm, 30% (1.5g) of fibers with a fiber length of 2mm, and 20% (1.0g) of fibers with a fiber length of 3mm. This result is multiplied by the residual rate constants of 40% for fibers with a fiber length of 1mm, 45% for fibers with a fiber length of 2mm, and 100% for fibers with a fiber length of 3mm to calculate the amount of remaining fiber. These are then added together to calculate the remaining amount after sieving.

[0087] In STEP 5, the calculation results are displayed on the monitor.

[0088] As described above, the sieving residual amount calculation method of the present invention makes it possible to calculate the sieving residual amount without performing sieving. [Explanation of symbols]

[0089] 1 Fiber length measuring instrument 2 Main body 3 monitors 4 Turntable 5 Sample cups 6 Stirring machines 7. Sieving tester 8. Pump 9 tanks 10 Stirring section 11 Wire Mesh 12 Outlet 13 Rubber stopper 14 Mounting stand 15 Paper collection container 16 Operation PC 17 Handmade paper machine 100 Sifting residual amount calculation device 101 Fiber length measurement mechanism 102 Storage section

Claims

[Claim 1] A sieving residue calculation method for calculating a sieving residue amount of a stock containing pulp using a sieving residue calculation device having a memory unit that stores a residual rate for each fiber length of the pulp as a constant, a fiber length measurement mechanism that measures the fiber length distribution of the pulp, and a calculation unit that calculates the sieving residue amount from the residual rate and the fiber length distribution, calling up the residual ratio for each fiber length of the pulp from the storage unit; measuring the fiber length distribution of the pulp in the stock with the fiber length measuring mechanism; A method for calculating a sieving residue, comprising calculating the sieving residue from the residual rate and the fiber length distribution of the pulp.

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