Do You Know What Is Wet Suction Box?

Paper Machine Wet Suction Box

The wet suction box on the paper machine is a low vacuum dewatering component with a vacuum degree of 0.2-1kPa. The box surface is composed of multiple dehydration board, and there are also perforated panels with an opening rate of over 50%. The material is the same as the dehydration board and has a large dehydration capacity. It can be used to replace or cooperate with the table roll and applied to various parts of the dehydration board. On high-speed paper machines, the wet suction box used at the wet end of the wire instead of the table roll or dehydration board has a wider box surface with tightly arranged narrow gaps. It is generally believed that the opening ratio of the box surface is large, and the gap between narrow gaps is small. When there is a sharp leading edge in the direction facing the pulp, it can increase the amount of dewatering while maintaining the stability of the pulp on the forming fabic, and can create moderate turbulence in the pulp, which is beneficial for the formation of the paper web.

The Working Principle of The Wet Suction Box

It combines the functions of differential pressure dehydration and scraping, making its dehydration capacity much larger than that of the table roll and dehydration board. When using it instead of a dehydration board, the power consumption of the dehydration board will not increase by more than 20%. The dehydration of the wet suction box is stable, with a certain degree of flexibility in operation, and the retention rate of small fibers and fillers is high. When used on low-speed paper machines for making sticky pulp, the length of the wire table can be shortened or the concentration of pulp in the pulp box can be reduced, which is beneficial for improving the uniformity of the paper sheets.

The natural extension of forming table technology is to enclose the dehydration board in a box, seal both ends and vacuum it, forming a so-called vacuum dehydration board group, which can also be classified as a type of wet suction box according to its performance. It has a high dehydration capacity and is often used in pulp mills and paper machines that produce high weight oil proof base paper from viscous pulp. The vacuum degree used in the vacuum dehydration board group is quite low, about 250-500Pa, and the intensity of pulse suction does not increase, while the amount of water removed significantly increases.

Another form is the equal flow vacuum dehydration board device. As shown in the figure below, △ H is the height difference between the surface of the dehydration board strip and the surface of the strip group below the mesh surface; A is the clearance distance between adjacent dehydration board strip; B is the pitch of the dehydration board strips; A is the distance between the dehydration board strip and the first strip in the blade group below the mesh surface; A ', a', and a 'are the surface widths of each strip in the strip group below the mesh surface, respectively. The device has a strip group below the mesh surface after a short distance from the dehydration board strips. The forming fabric is in a pulled down state after contacting the dehydration board strips, and the removed moisture forms a water seal with the lower scraping group, weakening the pressure pulse and drainage, making the pulse effect more gentle.