How to dehydrate paper press?
June 7, 2023
The high speed improvement of the speed of the paper machine has higher requirements for the dehydration effect of the press. For a normal paper machine, improving the dehydration performance of the paper machine under the condition of high speed operation can greatly improve the working efficiency of the paper machine.
Eight factors affecting pressing and dehydration
1. The influence of the line pressure
2. The influence of the pressing roller
3. The influence of the drawing blanket Angle at the pressure outlet side
4. The vacuum degree of the vacuum roller and the influence of the vacuum Angle
5. The influence of the lower pressure roller water retaining device
6. The influence of the vehicle speed
7. The influence of the slurry characteristics
8. The influence of the blanket quality
1. The influence of the line pressure
The line pressure refers to the pressure on the unit length of the contact surface of the pressure area, and the specific line pressure refers to the ratio of the line pressure to the width of the pressure area. According to research, increasing specific line pressure is conducive to dehydration, and it is not conducive to dehydration. However, in the actual production, due to the wet paper pages of blankets, the specific pressure can not be calculated, but can only be used by line pressure reaction. All modern paper machines tend to use variable line pressure operation.
2. The influence of the pressing roller
1) Impact of roller diameter:The larger the diameter, the wider the width of the pressure area, when the line pressure is the same, increase the roll diameter, the specific pressure drops, the dehydration ability decreases;
2) Effect of adhesive covering hardness:The higher the hardness of the glue cover, the narrower the pressure area, under the same line pressure, than the line pressure is larger, the dehydration ability is strong;
3) Effect of adhesive covering thickness:The thickness of the rubber layer increases, which is equal to the decrease of the hardness of the rubber layer within a certain range, and the width of the pressure area increases approximately straight line. Under the same line pressure, the ratio line pressure is reduced and the dehydration efficiency is reduced.
3. The influence of the drawing blanket Angle at the pressure outlet side
The main result is the problem of wet paper moisture absorption from the blanket. In the exit direction of the vacuum roller or groove roller is slightly larger, and the page is separated from the blanket as soon as possible, which is conducive to reduce the wet return and improve the dehydration efficiency.
4. The vacuum degree of the vacuum roller and the influence of the vacuum Angle
The vacuum degree of the vacuum roller does not have a great effect on the dehydration directly. The main function of the vacuum roller is to press the moisture out of the blanket and wet paper through the holes and discharge. The vacuum can effectively eliminate the formation of air bubbles, even if the blanket is new or old. Sometimes, although the vacuum degree is much, the actual drainage and degassing capacity is very poor. Therefore, regular cleaning or replacement of vacuum rollers should be paid attention to, which is extremely important to stabilize the production process conditions of the press department.
5. The influence of the lower pressure roller water retaining device
It is very important to install a scraper device at the entrance side of the lower pressure roller or the vacuum roller and the groove roller. Part of the water taken out in the pressure area is left in the pore, thrown out or partially attached to the roller surface by the rotating centrifugal force. If it is not removed, it will be brought into the pressure area and wet the blanket, causing the decrease of dehydration ability to decrease.
6. The influence of the vehicle speed
The speed increases, the page residence time in the pressure area is short, the dehydration time decreases, and the pressing outlet water increases, which affects the strength of the wet paper, and may increase the chance of a broken end.
7. The influence of the slurry characteristics
1) Influences of pulp:Pulping height, will not be conducive to dehydration, in the pressing part is the same;
2) Impact of slurry ratio:In the case of the same pulp, the viscosity of machine wood pulp is lower than that of chemical pulp, chemical wood pulp will be lower than that of reed pulp, slurry viscosity is conducive to dehydration, otherwise it is not conducive to dehydration;
3) Effects of crushing the inlet water:The inlet water is large, the dehydration fluid resistance is large.
8. The influence of the blanket quality
The water absorption of the blanket is a very high factor. On the one hand, the material, weaving method and specification of the blanket itself have a great impact on dehydration; on the other hand, the blanket itself will wear and tear after a few days, thin thickness, increase density, narrow pressure area, and increase dehydration ability.After a period of time, the blanket is gradually dirty and dehydrated ability decreases, thus affecting the continuous production of the paper machine.Therefore, the blankets must always be kept in good cleanliness to meet the requirements of normal production.
Which pressing method is recommended to be more efficient?
Boot press
What is a boot press?
Boot press is to change the instantaneous dynamic dehydration of roller press into a long time wide pressure zone dehydration under static pressure, which is a wide pressure zone press. Boot press is mainly composed of boot roller, back press roller, load locking and some auxiliary components.
Three advantages of the boot press over the conventional press
1. Boot press zone is several times of the traditional press zone: at the same speed, the paper stays in the boot press zone for several times of the traditional press zone.
2. Boot press can obtain higher line pressure: it helps to improve the dewatering efficiency of the paper sheet, is more conducive to the curing of the paper sheet, so that the paper sheet before drying to get better strength, so that the press part to get better performance.
3. Reduced water content in the paper, greatly saving steam consumption.
Conclusion
The dehydration of the press part of the paper machine is of great significance for improving the speed of the paper machine and reducing the steam consumption of the dryer. The strength of the paper width increases greatly with the dryness, and the paper width has low dryness and poor strength in the wet part, which makes it difficult to run. The operation performance of the paper width is fundamentally guaranteed by improving the dryness of the wet part.