Method for detecting content of stickies in papermaking system

Abstract

The invention discloses a method for detecting the content of stickies in a papermaking system, and belongs to the technical field of papermaking. The detection method comprises the following steps: attaching a special adhesive tape to a glass slide, fixing the special adhesive tape on a stirring rod of a stirrer, and placing a to-be-detected slurry sample in the stirrer for oscillation stirring; and after enriching for a certain time, taking out the glass slide, scanning an image of the stickies on the adhesive tape, and analyzing the relative content of the stickies by using an image analysis technology. The detection method disclosed by the invention is simple to operate, low in cost and relatively high in accuracy of a detection result.

Description

Technical Field

[0001] The invention belongs to the technical field of papermaking, and more specifically, relates to a method for detecting the content of stickies in a papermaking system. Background Art

[0002] The adhesives produced in the papermaking process are generally viscous substances derived from recycled fibers, most of which are negatively charged. It is generally composed of a mixture of adhesives, hot melt adhesives, labels, book binding glue, tapes, latex, ink adhesives, wet strength resins and other polymers in paper materials. According to the particle size, it can be divided into large adhesives and fine adhesives. Large adhesives can be removed by selection, purification and flotation. Fine adhesives generally refer to adhesives that can pass through a 0.15mm sieve gap. They are mainly substances that exist in a dissolved or colloidal state in the system. With the increasing use of secondary fibers and the increase in the degree of closed circulation of white water, some dissolved substances will aggregate and become larger, and may even generate new secondary adhesives. These secondary adhesives are easy to deposit and block the forming network, felt or dry network, causing paper breaks, and even causing paper machine shutdowns in severe cases. Compared with large adhesives, fine adhesives are more difficult to remove. At present, the effective control methods for fine adhesives are mainly chemical fixatives and bioenzyme methods.

[0003] At present, the method for evaluating the sticky content in papermaking workshops is usually to visually inspect the size of stickies attached to scrapers, dryer nets, drying cylinders and calenders, feel their stickiness and degree of compaction by hand, and regularly extract fixed scrapers each shift to weigh the weight of the stickies attached to measure the sticky content in the production system.

[0004] The laboratory usually uses a sticky material screening instrument to repeatedly wash a certain mass of pulp, and then screen it through a 0.15mm sieve, leaving the stickies attached to the receiving paper below, and flushing away non-sticky impurities with a small amount of clean water. After drying, the paper sample is placed in the supporting scanning software for scanning to evaluate the distribution quantity and area of ​​stickies of different sizes. This method not only has high requirements for equipment, but also is relatively cumbersome to operate, requiring a large number of pulp samples and a large amount of flushing water, which is time-consuming and not convenient for rapid judgment of the sticky situation in the papermaking system.

[0005] For example, the Chinese patent application No. 201210174816.7 discloses a method for detecting obstructive fine adhesives in papermaking white water. The application adopts the "Pulmac Master Screen screening method for large adhesives" and image analysis method to detect the adhesive content of the white water after pretreatment and the adhesive content of the untreated white water under normal temperature and pressure conditions. The two test results are subtracted to obtain the harmful fine adhesive content in the white water. However, it is to use an adhesive screening instrument to repeatedly wash and screen the pulp, and the overall operation is relatively complicated. Summary of the invention

[0006] The purpose of the present invention is to provide a method for detecting the content of stickies in a papermaking system, thereby effectively solving the problem that the existing methods for detecting stickies in papermaking systems are relatively complicated to operate. The detection method of the present invention is simple to operate and has a high accuracy rate in the detection results.

[0007] In order to achieve the above object, the technical solution provided by the present invention is:

[0008] The present invention provides a method for detecting the content of stickies in a papermaking system, comprising:

[0009] Attach the special tape to the glass slide and fix it to the stirring rod of the stirrer, and place the slurry sample to be tested in the stirrer for shaking and stirring;

[0010] After a certain period of enrichment, the slide was taken out, the image of the stickies on the tape was scanned, and the relative content of the stickies was analyzed using image analysis technology.

[0011] In view of the problems that the prior art usually has complicated operation and large water consumption when detecting stickies generated in the papermaking system, the present invention fixes a special tape on the stirring rod of the stirrer, and places the pulp sample to be tested in the stirrer for oscillation and stirring, so that the stickies are oscillated and adsorbed on the tape, and then the stickies image on the tape is scanned, and the relative content of the stickies can be analyzed using image analysis technology. The method is not only simple to operate and easy to implement, but also can effectively guarantee the detection results, so it is convenient for laboratory and industrial promotion and application.

[0012] Furthermore, the special tape is a black non-reflective tape, and its viscosity is ≥486N / m, which is conducive to further ensuring the adsorption effect of adhesives and thus ensuring the detection accuracy.

[0013] Furthermore, the slurry sample to be tested is placed in a stirrer for oscillating stirring at a stirring speed of 500-1000 RPM. By optimizing and controlling the stirring speed of the oscillating stirring, it is beneficial to further ensure that the adhesives can be fully adsorbed and avoid the sticky substances falling off due to excessive stirring speed.

[0014] Furthermore, the method for preparing the slurry sample to be tested comprises:

[0015] Sampling of pulp in papermaking systems;

[0016] The obtained slurry is sampled and dehydrated;

[0017] Warm water is added to the dehydrated absolute dry pulp to prepare a pulp sample with a certain mass concentration, which is then placed on a standard deflaking machine for deflaking.

[0018] Furthermore, warm water is added to the dehydrated bone-dry pulp, and the temperature of the warm water is 20±0.5°C.

[0019] Furthermore, the slurry sample is placed on a standard deflaking machine for deflaking, the deflaking revolution number is 10,000-30,000 revolutions, the rotation speed is 3000±50RPM, and the mass concentration of the slurry sample to be deflaked is 1-2%. The slurry sample is pre-deflaked before the oscillation stirring adsorption, and the specific process parameters of the deflaking are optimized and designed, so as to ensure that the slurry is fully dispersed to prevent adhesion and affect the subsequent oscillation adsorption of adhesives.

[0020] Furthermore, the pulp in the papermaking system is sampled, and the sampling locations include but are not limited to the pulper outlet, the heat dispersion outlet, the pulp tower, the paper machine mixing pulp tank, the pre-papering tank and the pulp on the screen.

[0021] Furthermore, the obtained slurry is sampled for dehydration treatment, specifically, the obtained slurry is sampled for suction filtration or centrifugal drying, and then the moisture content is detected after drying.

[0022] In summary, the technical solution provided by the present invention has the following beneficial effects compared with the prior art:

[0023] (1) The present invention can effectively adsorb the stickies in the papermaking pulp through the vibration stirring adsorption effect, so it is easy to detect the content of the stickies through image analysis technology. The overall operation of the process is simple, the cost is low, and it is easy to promote and apply.

[0024] (2) The present invention further optimizes the process parameters of the oscillating stirring adsorption, including the selection of the adhesive tape, the rotation speed of the oscillating stirring, and the debonding treatment of the slurry before the oscillating stirring, so as to selectively respond to those stickies that will cause deposition and affect the operation rate of the paper machine and the product quality, and ensure their full adsorption; at the same time, the technology can also establish a close relationship with data such as on-site production efficiency, and can not only be used to diagnose system sticky problems, but also to verify the actual effect of the sticky control products used on-site. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the fixing structure of the glass slide on the stirring rod of the stirrer in the present invention.

[0026] In the figure: 1. stirring rod; 2. slide glass; 3. stirring blade. DETAILED DESCRIPTION

[0027] In order to further understand the content of the present invention, the present invention is now described in detail in conjunction with specific embodiments.

[0028] Example

[0029] An embodiment of the present invention provides a method for detecting the content of stickies in a papermaking system, comprising:

[0030] 1. Preparation and pretreatment of slurry samples:

[0031] 1) Take about 300-500 ml of pulp sample to be tested. The sampling locations include pulper outlet, heat dispersion outlet, pulp tower, paper machine mixing pulp tank, pre-paper tank, pulp on the screen, etc.;

[0032] 2) Take out two slurry samples of 100-150 ml each, filter or centrifuge (centrifugal dryer), dry and test the moisture content - test the slurry concentration;

[0033] 3) Take 5 g of absolute dry pulp, add warm water (20±0.5℃) to prepare 500 ml pulp sample with a mass concentration of 1%, and deflagrate it in a standard deflagrator at 10,000-30,000 revolutions (specifically 30,000 revolutions in this embodiment) and a rotation speed of 3000±50RPM to fully disperse the pulp and prevent it from sticking together.

[0034] 2. Pulp Sample Testing

[0035] 1) Use special tape (viscosity: ≥486N / m, black, non-reflective) to stick it vertically on the slide 2, and then fix it on the stirring rod 1 of the stirrer (such as Figure 1 As shown), a stirring blade 3 is provided at the bottom of the stirring rod 1;

[0036] 2) The slurry after the decomposition treatment is placed in an oscillator, and after vibrating and stirring for a certain period of time, the tape is taken out to scan the image of the stickies therein, and then the relative content of the stickies on the adsorption specimen is analyzed by image analysis technology. The stirring speed of the vibrating stirring is 500-1000RPM, and specifically 800RPM in this embodiment.

[0037] It should be noted that the above image analysis technology is an existing technology, that is, the size information of adhesive particles on the tape surface is collected by scanning, and then the total area occupied by the statistical adhesive particles is divided by the total tape scanning area, which is the adhesive particle content, unit: mm 2 / m 2 ) and quantity (When scanning and collecting the sticky particle size information on the black tape surface, the number of sticky particles is obtained at the same time, that is, the number of particles. The total number of sticky particles counted is divided by the total filter paper scanning area, which is the number of sticky particles. The unit is: pieces / m 2 ).

[0038] The final analysis result in this embodiment is expressed as "stickies index (ppm)". The higher the index is, the higher the content of harmful stickies in the slurry is; and vice versa.

[0039] 3. Test data verification:

[0040] The following Table 1 shows comparative data of the detection results of the detection method of the embodiment of the present invention and the detection method of the existing stickies screening instrument. It can be seen from the table that the detection method of the present invention has a detection accuracy that is substantially the same as that of the stickies screening instrument, and the detection accuracy can meet the detection requirements, but the overall process operation is simple and the cost is low, and there is no need to use a more expensive stickies screening instrument for screening.

[0041] Table 1 Comparison results between the test data of the present invention and the test data of the stickies sieving instrument

[0042]

[0043] Comparative Example 1

[0044] The operation of this comparative example is basically the same as that of the above embodiment, with the main difference being that before the stickies are subjected to vibration stirring adsorption, the slurry sample is deflated in a standard deflagrator at 5000 revolutions, and the defragmented stickies are sticky, thus significantly affecting the effect of subsequent vibration stirring adsorption, resulting in incomplete adsorption.

[0045] Comparative Example 2

[0046] The operation of this comparative example is basically the same as that of Example 1, with the main difference being that the stirring speed of the oscillating stirring in this comparative example is 1500RPM, and stirring too fast causes excessive collision with water, and the shear force of the water is relatively large, which is not conducive to the adhesive tape adhering to the adhesive.

Claims

1. A method for detecting the content of stickies in a papermaking system, characterized in that: include: Attach the special tape to the glass slide and fix it to the stirring rod of the stirrer, and place the slurry sample to be tested in the stirrer for shaking and stirring; After a certain period of enrichment, the slide was taken out, the image of the stickies on the tape was scanned, and the relative content of the stickies was analyzed using image analysis technology.

2. The method for detecting the stickies content in the papermaking system according to claim 1, characterized in that: The special tape is a black non-reflective tape, and its viscosity is ≥486N / m.

3. The method for detecting the stickies content in the papermaking system according to claim 2, characterized in that: The slurry sample to be tested is placed in a stirrer for oscillation stirring at a stirring speed of 500-1000 RPM.

4. The method for detecting the stickies content in a papermaking system according to any one of claims 1 to 3, characterized in that: The method for preparing the slurry sample to be tested comprises: Sampling of pulp in papermaking systems; The obtained slurry is sampled and dehydrated; Warm water is added to the dehydrated absolute dry pulp to prepare a pulp sample with a certain mass concentration, which is then placed on a standard deflaking machine for deflaking.

5. The method for detecting the stickies content in the papermaking system according to claim 4, characterized in that: The warm water is added to the dehydrated absolutely dry pulp, and the temperature of the warm water is 20±0.5°C.

6. The method for detecting the stickies content in the papermaking system according to claim 5, characterized in that: The pulp sample is placed on a standard deflaking machine for deflaking, the deflaking revolution number is 10,000-30,000 revolutions, the rotation speed is 3000±50RPM, and the mass concentration of the pulp sample to be deflaked is 1-2%.

7. The method for detecting the stickies content in a papermaking system according to claim 4, characterized in that: The pulp in the papermaking system is sampled, and the sampling locations include but are not limited to the pulper outlet, the heat dispersion outlet, the pulp tower, the paper machine mixing pulp tank, the pre-papering tank and the pulp on the screen.

8. The method for detecting the stickies content in a papermaking system according to claim 4, characterized in that: The dehydration treatment of the obtained slurry is carried out by sampling the obtained slurry, specifically, the obtained slurry is sampled for suction filtration or centrifugal drying, and then the moisture content is detected by drying.

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