The pulp concentration is between 2 and 3%, and the dewatering capacity of the chopping board and the vacuum board is significantly reduced. The dewatering here must be done with a vacuum suction box with a vacuum ranging from 10 to 33 KPa.

 

When the net passed through the vacuum suction box, it began to remove moisture from the paper, but then the air also passed through the screen, and the air and water were pumped into the vacuum suction box. Where there is much moisture, the light reflects strongly. Like the mirror, the air penetrates the layer, which is called the “waterline” and is sometimes called the “dryer line”.

 

Generally, the water line is about 7% thick. In high-speed new double-layer (multi layer, Nip Wire Machine, etc.) paper machines, the waterline moves forward and is not see on the suction box.

 

The dewatering of the suction box is based on the suction of the vacuum pump, which creates a high pressure difference between the upper and lower sides of the paper, and forcibly dewatering the wet paper. It is hoped that the paper can be transferred to the press section with a high dryness. The vacuum cannot be used to force the dewatering. This accelerates the wear of the fabrics, increases the driving force of the fabrics, improves the tension of the fabrics, and has a long life for the fabrics. Bad effects.

 

The number of vacuum boxes varies according to the type of paper, the model of the paper machine, and the speed of copying. Generally, it is 7~9. In the multi layer,or Nip Wire Machine, the wetness of the wet paper is greatly improved. The number is greatly reduced, usually only 2~5, or even not used. In order to adapt to the change in the wetness of the wet paper, the vacuum of the suction box should be gradually increased.

 

Under the suction of the vacuum pump, the air mixture of water in the suction box is withdrawn from the suction box, enters the vertical pipe connected with the suction box, and the water is separated from the air under the action of gravity, and the white water is lowered to the water sealing groove. The air merges with the manifold and is pumped away by a vacuum pump.

1.Ensure that the surface of the roller is always smooth enough;

2. Release air at both ends of the roller (about 2.5cm from the vacuum area) so that there is no slurry deposit on the roller;

-. Usually, deposits on the rollers are not visible, but can be felt by hand;

3. Check the spray water filter:

– prevent any corroded metal from passing through;

– maintain proper water quality to avoid blockage of nozzle;

4. Check the scraping condition of steering roller and breast roller;

– Deposits on these rollers can cause wrinkling of the forming wire;

5. Before installing the new net, check all rollers for damage.
6. Ensure that all nozzles are tightly fastened;
7. Check the net correction, pendulum and extension devices to ensure that they are in good working condition;
8. Ensure that the high-pressure needle spray is swinging and the water pressure does not exceed 35 kg/cm2 (500 psig/in2);
9. Use a good cleaning procedure:

– Do not wash any debris into the running mesh;

– Do not flush the edge of the net directly with high pressure water;

– Ensure that the flushing hose water source does not contain debris;

Forming fabrics correction failed

1. Check the forming fabrics by hand until a repair is made;
2. If the forming fabrics with manual correction is not stable enough, it needs to stop repairing and correcting;
3. Reduce the degree of vacuum to prevent the forming fabrics from catching or blocking on the vacuum suction box;

Reduced net life

1. The components of the Fourdrinier paper machine network must be accurately lined up and in good mechanical condition;

– All filter elements must be fastened and at the same height;

– Check that the tension roller and automatic tensioning device cannot bounce;

2. Poor cleaning of the case and poor routine maintenance are one of the main reasons for the shortened network life.

(a) Ensure that no fibrous aggregate forming slugs fall inside the forming fabrics;

(b) Keep the scraper in good condition;

– Prevent the slurry from accumulating on the guide roller and the breast roller;

– The first outer roller is essential to prevent the net from being damaged by the slug;

– Squeegee angle (about 25~30 degrees) is very important for ensuring proper wipe without scratching sound;

– The scraper load must be tested repeatedly, but overload must be avoided;

– Swing is a good warning for any and all squeegees;

– The breast roller scraper should always be inspected so as not to cause net marks or too much water on the breast roller;

(c) Check the water tray holes, rusted bolts or spray valves;

– Non-uniform flow of water around the spray valve may cause the metal to break off and flow through the spray pipe;

3. Eliminate abrasive fillers, such as: calcium sulfate;
4. Check the trajectory, calibration, tension, load and slip of the net;

– Ensure that the horizontal tension of the paper machine is even;

– Do not run the forming fabrics under too loose conditions;

5. Maintain spray water temperature and pH consistent with the slurry;

– Ensure that the spray water pipes on both sides are not blocked;

6. Adopt the low friction coefficient on the upper surface of the vacuum suction box;

– Check whether the upper surface of the vacuum suction box is flat;

7. Reduce the number of vacuum suction boxes, increase the opening;

– reduce the degree of vacuum to prevent the forming fabrics from catching or blocking on the vacuum suction box;

8. Remove grout in the pulp (centrifugal cleaner);

– Check for scratches and burrs on the forming plate, vacuum suction box surface and the cutting board;

9. Use the net life extension agent (net cleaning agent);
10. Adequate traction should be provided to ensure that the net does not slip at the breast roller;
11. Operate at the lowest vacuum level of water absorber in operating procedures;

– ensure free flow of water from the suction box into the water seal tank;

12. Check the installation of the forming plate to ensure that there is sufficient space for even and minimal drainage of the breast rollers;
13. Check the cleaning of the roller steering system;

– check the load of scraper, scraper, spray water, bearing and excessive spray water pressure;

14. Check the wear strip on the side setting device or the cheek plate of the slurry tank to determine whether it is installed too low;

The net is raised/wrinkled

Note: the net bulge often develops into wrinkles, which may gradually form a cord or overlap.

1. In general, oblique uplift due to unalignment;
2. Straight line heave is usually caused by the following reasons:

– slurry deposition between breast roll and lip plate;

– slag forming on dewatering element;

– resin concentration;

– too much water when rotating;

3. Drumming may come from:

– the vibration distance of the network case is too long;

– roll deflection;

– There is a twist zone in the multiple vacuum box unit

– after the paper is on the web, the vacuum pump has shear force;

– the steam box is still running when the net crawls slow or stops running;

4.- the whole net wear may be due to:

– rough surface hairiness of vacuum water absorber;

– roller corrosion;

– surface abrasion or breakage of glass fiber rollers;

Network vibration

Note: In general, when the slurry is connected to the grid, the vibration will have a negative effect on correcting the deficiencies of the slurry, but it can suppress the flocculation during filtration;

1. Observe the opening and stopping of the forming network;

– Adjust the network corrections;

2. Once vibration stops, the web will dry on the forming fabrics;

– To maintain the quality of the sheet, it is necessary to add water;

3. When the speed is lower than 300~400 meters/minute, the vibration is effective;
4. At lower speeds, the web will resist flocculation more effectively if the vibration frequency increases;
5. Increase the frequency of vibration and remove more water from the net;
6. As the frequency of vibration decreases, the filtered water speeds up, and the web of clouds becomes heavier;
7. Vibration efficiency and vibration amplitude are proportional to the square of the frequency, and indirect proportion to the speed;

Network slip or flutter

1. Maintain proper distribution of traction loads;
2. Use snake woven nets;
3. Tighten the forming fabrics;
4. Reduce vacuum:

– If possible, remove the water to reduce the vacuum;

5. If possible, increase the vacuum level of the couch roller;
6. Check the flow of paper on the forming board;
7. Check for turbulence that is 3 to 5 meters beyond the original forming area;
8. Excessive delay in the initial filtration stage can cause turbulence;

Acidity

1. High acidity (free or total) is almost always detrimental to machine performance and product quality;

– check pH controllers, charts, and acid or base addition points;

2. High acidity (low pH) is corrosive to mechanical equipment;

– Fouling and rust can come off the pump and pipes and create dirt, spots or holes in the web;

3. Check the paper pH value;

– The faded paper may produce residual acid;

4. Control the pH of the factory’s incoming water;
5. High acidity has a bad influence on quality:

– Causes hair loss and powder loss;

– Degrades fiber, thus reducing strength and long-lasting properties;

– Most dyes react differently when the pH is changed, thus affecting the color;

– Seminal plasma requires more energy to change fiber shape;

6. The negative impact of paper machine operations:

– In the case of blankets, the jamming trend has increased;

– It takes longer to dry the web;

– Due to the poor absorption of the paper by the paint, it weakens the absorption of the paint and fiber surface;

See the “Changes in pH” section.

Aluminum sulfate added

1. Aluminum sulfate can be used to control pH value, fixed rosin gum, auxiliary retention and flocculation, and resin sediment control;
2. The change of pH value caused by changing the amount of aluminum sulfate can change the color and influence the adsorption force between wet paper width and press roller;
3. The peeling or “anti-stripping performance” of wet paper amplitude changes with the content of alumina;

– if the pH value is too high, crushing paper may be produced; When the pH value decreases, the paper will disappear.

4. Too much aluminum sulfate in the system will have a negative impact on the strength of paper pages, the filtration water at the screen and the combination of fibers, and may even reduce the efficiency of rosin sizing.
5. Many problems are related to low levels of alum or bauxite ions in the system. Low sizing, foam problem, formation of free rosin deposits, decrease of fiber binding force, deterioration of water filtration and significant trend of resin deposition all testify to this.

See the section “sodium aluminate”.

Wet-end chemistry

1. Many chemicals used in the wet part can improve the water filtration to varying degrees, and improve the internal binding force of fine fiber, the retention rate of fillers and the dry and wet strength.
2. Too little essential chemicals will not achieve the desired effect:

– may lead to poor water filtration, loss of fine materials and fillers, as well as reduction of binding force and strength between fibers;

3. However, excessive use of chemicals may have the opposite effect. For example, overflocculation leads to poor evenness, which in turn has a negative effect on almost all strength properties;
4. It is very important to strictly control the solid content and viscosity when preparing the auxiliary materials;

– temperature is also important for viscosity control;

5. Increasing the amount of water entering the sizing press paper can increase the amount of glue hanging and the retention of surface glue;
6. Reduce the pressure of the sizing press line, increase the amount of glue hanging, and ensure more treatment of the page surface;
7. Reduce the amount of glue applied in the slurry to improve the amount of glue applied on the surface;

 

The main reason for the top pulp of the fabrics is the local wear of the belt. I have checked the worn area with a magnifying glass, and the worn surface is flat after a period of time, and is relatively smooth.

The solution can be considered from the following aspects:

1. Select a mesh made by a large manufacturer with good quality, and it is better to require that warp monofilamens are imported and wear resistant.
2. Use the imported ceramic panels, such as dehydration board and vacuum box panels, have low friction coefficient and less wear to the network;
3. In the production process, the control vacuum degree is appropriate, and the tension degree of the net is appropriate;
4. Select filler with small particle size and large mesh size, and strengthen the cleaning of network;
5. Use good chemicals to improve the retention rate of fillers, reduce the loss of small fibers, and reduce the wear of the mesh belt.

 

1. The development status of mesh belt joints

Polyester mesh belt is extremely versatile. It can be applied in mine transport metallurgy, food, and paper industry. It is also an important piece of equipment for sewage treatment in environmental protection.With the development of the chemical industry, the polyester mesh belt has better performance and is an ideal supporting product for some industrial upgrading. According to the actual needs of the work, mesh belts are generally divided into end connectors and endless connectors. However, endless joints require complex mechanical structures, and it takes a long time to install the online machine, the development trend is mostly end connectors. Therefore, research on the structure of end connector and the use of materials is necessary. It was originally used with the same wire as the mesh (for example, nylon) to make the flat (ellipsoid section) spiral connection ring. The latter is made of stainless steel wire and made of the same form, both of which are woven by hand in the end of the net. When the machine is installed, just take the mesh belt across the drive roller. For a good link, insert the thread into the thread. This eliminates some of the disadvantages of the endless connector mesh belt, which is easy to install and reduce labor intensity. The benefits of efficiency. However, they are prone to early damage, and their short service life (ie, low strength) is the fatal weakness of such joints. Test data show. The tensile strength of such joints is reduced by more than one third compared to mesh belts. and so. A net with thousands of dollars. Some serious problems with connector damage occurred in just over one hour. For spiral processing, high temperature setting surface is required to reduce the strength, what is more noteworthy is the failure of the screw joint observed from the experiment: when a line is broken somewhere, the entire helix is pulled out of the thread. This is also the case in production. The mesh belt immediately loses its ability to work. New network belt. This affects the timely completion of production tasks and damages the reputation and benefits of the manufacturers.

2. Development of new connector.

With the rapid development of China’s economic construction and the increasingly prominent environmental protection of the city, the crucial link of mesh belt joints should be able to be reformed and improved in strength. This has become an urgent practical problem to be solved. In view of the above-mentioned joint damage characteristics and the reasons for the strength reduction, a comprehensive analysis should be carried out to consider the joint structure shape, manufacturing process and dimensions, etc., to develop a high-strength joint. In the investigation and study of various types of mesh belt joint structure and materials used at home and abroad, trial and trial trials were repeated to design a new type of more ideal net with terminal joint structure. Stainless steel wire was used to make the steel buckle without heating. The performance of raw materials, each steel buckle is independently bound at the end of the mesh belt. Even if individual steel buckles are damaged – they can continue to work. This shows their advantages: the shape and size change, the steel buckles on each side are different from each other, and are set on 3 to 5 wefts in a positive and negative manner, so that the steel buckles The force is absorbed by the two cross-sections of the mesh belt to improve the stress state; the strands are coated to achieve a smooth transition of the mesh belt ends and the positioning of the steel buckles, which enhances the firm connection between the mesh belt and the steel buckle. These process effective measures. All contribute to the improvement of joint strength.

3. Steel buckle production and binding

The steel buckles are made by the designed machine. Because of the different mechanical properties of different grades of materials, their molds should be different. The mold requires high strength, good abrasion resistance material processing, and requires heat treatment to increase the hardness, not easy to wear. The precision of the core groove of the binding tool is very high. In the binding process of the steel buckle, the direction of component force of deformation is not allowed to be zero, so as to ensure that the steel buckle is set along the desired direction. The steel buckle of different specifications should be Corresponding to the core slot. In order to further improve the binding quality of the joints, there are many advantages to grinding the tip of the steel buckle into a wedge shape: the steel buckle is easily bound, the mesh belt is less damaged, the mesh belt joint strength is further improved, the bound end of the mesh belt is relatively smooth, and the transmission is more stable. Small mutual wear, is conducive to extend the life of the mesh belt, but the specific test data should also be identified.

“Looking at the world, we face a major change that has not been seen in a century.” said by President Xi Jinping when he received all envoys who returned to China to participate in the 2017 Diplomatic Mission job meeting recently.

The international community generally believes that the reform of the global governance system is at a historical turning point. The trend of multipolarization in the world has become even more obvious.The current international system originated in the west and is based on the westphalian system, and the west has always been dominant. Now, with the rise of the emerging countries, developing countries as a whole have contributed more and more to the world in terms of political and economic culture. At present, the global manufacturing landscape is undergoing a dramatic reshaping, intelligentization, and the Internet has changed the traditional manufacturing industry. The original production system based on Western industrial standards is undergoing a revolutionary transformation in the emerging economies.Henan Benost Textile Technology Co., Ltd., as a pioneering star in the field of Chinese industrial textiles, has gradually updated old parameters, developed new ideas, and developed revolutionary new works from the design of raw materials, the transformation of weaving processes, and the development of cutting-edge applications. Benost has continuously launched new materials technology products such as papermaking forming fabrics and dryer fabrics. The nano-grade self-lubricating forming fabric adopts a special weaving process, which has excellent dewatering performance, and the fiber retention rate is significantly improved, which improves the paper quality while achieving higher production speed for the papermaking production line.