The roller is the last dewatering component of the long net, and it is also an important dewatering component in the net. It relies mainly on vacuum pumping and belongs to high pressure differential dehydration. When the vehicle speed is low, water and air enter the roller and enter the vacuum chamber. In this case, a water vapor separation system must be used to separate the entrained air and water so that the white water does not enter the vacuum generation system.
At higher vehicle speeds, air and water are drawn into the orifice of the couch roll and once the orifice leaves the vacuum zone, it is forced out by centrifugal force. In this case, the white water pan and the water baffle must be installed so that the water that is thrown out does not return to the roller inlet.
The structure of the vacuum roll can be divided into a small chamber type and a honeycomb type.
The honeycomb type is rarely used because of its low precision, large footprint, and inconvenient network changing operation.
The chamber vacuum rolls are divided into single chambers, double chambers and three chambers. Generally, high-speed paper machines use double chambers, and three chambers are mainly used for high-speed tissue machines. The structural principles are basically the same, but each company has its own characteristics.
The vacuum of the vacuum roll is related to the structure of the paper machine, the speed of the machine, the nature of the slurry, the quality requirements of the paper, and the structure of the vacuum roll itself.
The higher the speed of the paper machine or the poor water filtration performance of the paper, the higher the vacuum of the roller, and the vacuum of the roller should not be lower than the vacuum of the vacuum.