Introduction to the wet suction box of Fourdrinier paper machine

The wet suction box on the paper machine is a low vacuum dewatering element with a vacuum degree of 0.2-1kPa. The box surface is composed of multiple chopping boards, and there are also open-hole panels. The opening rate is more than 50%. The material is the same as the chopping board. It has a large dehydration capacity. It can be used to replace or cooperate with the chopping roll (chopping board). On all parts of the net case.

On a high-speed paper machine, the wet suction box used at the wet end of the screen instead of the table roll or chopping board has a wider box surface and tightly arranged narrow slits. It is generally believed that: the opening ratio of the box surface is large, the gap between the narrow slits is small, and when there is a sharp leading edge in the direction facing the pulp, it can increase the amount of dehydration while maintaining the stability of the pulp on the net. Moderate turbulence is caused in the pulp, which is conducive to the formation of the paper web.

The working principle of the wet suction box. It combines the two functions of pressure difference dehydration and wiping, so that its dehydration capacity is much larger than that of the counter roll and the chopping board. When it is used to replace the cutting board, the power consumption of the net case will not increase by more than 20%. The dehydration of the wet suction box is stable, the operation has a certain degree of flexibility, and the retention rate of small fibers and fillers is high. When used on a low-speed paper machine for making viscous pulp, it can shorten the length of the screen or reduce the consistency of the pulp in the headbox, which is beneficial to improve the uniformity of the paper.

The natural extension of chopping board technology is to enclose chopping boards in a box, seal both ends and vacuum to form a so-called vacuum chopping board group, which can also belong to a type of wet suction box according to its performance. Its dewatering capacity is very large, and it is often used in pulp-board machines and paper machines that use viscous pulp to make high-quantity oil-repellent base paper. The vacuum degree used by the vacuum chopping board group is quite low, about 250-500Pa, the intensity of pulse suction does not increase, but the dehydration volume increases significantly.

There is another form of iso-flow type vacuum cutting board device. The device has a blade group below the mesh surface after a short distance of the cutting board blades. The forming net is in a state of being pulled down after contacting the cutting board blades, and a water seal is formed between the removed water and the lower scraper group, which weakens the pressure pulse and drainage, and makes the pulse effect more relaxed.

The above is the brief introduction of the wet suction box of the Fourdrinier paper machine.