Analysis and detection of the hottest paper diseas

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Analysis and detection of paper defects

paper defect treatment is the daily basic work of paper machine operators, and the definition of paper defects is also very wide. Any defect detrimental to the use of paper can be called a paper defect, but in my opinion, what we call a paper defect actually refers to the appearance

warehouses and storage facilities will also be built to analyze paper diseases. The periodic method: because many paper diseases occur on equipment, most of our own equipment are rotating shafts, and they all have a certain motion cycle. By measuring the interval cycle of paper diseases, we can find the root cause of paper diseases

2, material confirmation method: there are often some similar paper diseases on the paper, but their causes are different

The paper disease prone to occur in the

section is the key part of wet paper forming in the

section, and is also the root of many paper diseases. The common paper defects in the part mainly include the following aspects:

1. The pulp rejection at the part and the edge is one of the main reasons for the paper defects. When it is light, there will be paper holes at the edge of the paper, or edge cracks. When it is heavy, there will be paper breaks. The pulp rejection at the part is generally caused by the unclean edge of the core layer (wide top and bottom of the core surface), The anti fading ability of the core layer is better than that of non-metallic materials. The unclean edge may be due to the poor adjustment of the flushing water, or it may be due to the fluctuation of the liquid level of the white water tank outside the machine and the movement of the forming. Sometimes, the pulp is thrown at the leading out angle of the top and core. That is because there are too many pulp at the edge, so special attention should be paid to when making high quantity paper

2. Water needle: it can be said that the water needle is a key to the paper machine, and its maintenance should be particularly careful. First of all, the pressure of the water needle should be appropriate. If it is too large, it will splash slurry, and if it is too small, there will be a risk of continuous cutting. Pay attention to the change of the pressure of the water needle in the process of the paper, and pull the water needle slowly and steadily to adjust the width

3. Partial high-pressure water: the partial high-pressure water is responsible for cleaning. If the high-pressure water is blocked, the forming may be blocked by fine fibers and resins. And the dehydration of the part is not smooth, resulting in through curtain paper disease (white stripe)

4. Spray starch pipe: starch spots and small bright spots (because the pressure of spray starch is too high) are easily caused by the spray starch pipe. Sometimes the pressure of spray starch is too low, and the starch does not form fog, but drops, which will also cause continuous starch dropping on the paper

5. Adjustment of the partial vacuum: pay attention to the adjustment of the vacuum of the wet absorption box to ensure the return flow of the white water in the lower pool: pay attention to the position change of the water line when adjusting the vacuum; The vacuum degree of the paper web transfer vacuum box shall be ensured, otherwise the glass made of paper stripping polyurethane may reduce the weight of the car by 50%, resulting in pulp strips

There are many factors that cause paper disease in the

section. Rotten pulp and accumulated pulp on the rack, especially after entering the section on the panel of the suction tank, can also cause paper disease

problems easily caused by the flow section if the flow section adopts a fully enclosed system, the following points should be paid attention to:

1. Ensure the normal operation of the pressure screen and the desander. If the desander is blocked, it may cause an increase in dust in the paper

2. Pay attention to the stability of the liquid level in each tank of the flow section (generally due to the valve), otherwise it will cause the fluctuation of the paper quantity

3. In the process of changing the paper type, it may be necessary to adjust the air cushion pressure and the opening of some air valves in the verification process of circulating torque. After the adjustment, pay attention to the pressure fluctuation. At ordinary times, pay attention to the liquid level of the anti drift tank. If the liquid level is insufficient, the use of anti drift will be affected

4. Do not mix the rotten slurry on the rack into the system. During the large-scale cleaning, the rack must be thoroughly cleaned to drain the sewage. During the cleaning of the system, some dead corners of the lower pool at the top of the headbox must also be cleaned

based on the above problems, some common paper defects in the flow department are: rotten pulp, dust and quantitative fluctuation in the system

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