Views: 2 Author: Site Editor Publish Time: 2021-11-24 Origin: Site
The commonly used vacuum rolls on paper machines are single-vacuum chambers, but there are also double-chambers and three-chambers.
The vacuum degree of the vacuum roller can be used in the range of 46-74kPa. When the top roller covered with a soft rubber layer is installed on the vacuum cover roller, the tightness of the wet paper web can be increased. When the vehicle speed is higher than 200m/min, the steel pipe cover rubber should be installed (the hardness is 30-35 degrees Shore) The top roller to improve the vacuum and dehydration capacity of the roller. The linear pressure between the rollers is 981-1960N/m. There should be a spray water device above the entrance side of the up-and-down roller.
When the speed of the paper machine is higher than 400m/min, the dewatering of the bed roller should be further strengthened, so that the dryness of the paper web after the bed roller can reach 20%-22%, so that the paper web can be smoothly guided from the bed roller to the press. For this reason, it is best to increase the vacuum degree of the roll to 60-75kPa.
Increasing the vacuum degree on the single-chamber vacuum roll will cause the power consumption of the vacuum pump required by the roll to increase sharply. Use multi-chamber vacuum rolls instead of single-chamber vacuum rolls, that is, use several narrower vacuum chambers with gradually increasing vacuum to replace a wider high vacuum chamber, which can achieve the same dehydration effect at the same time. Save the power consumption of the vacuum pump.
The structure of the multi-chamber vacuum roll is more complicated and the diameter is also larger, and it is usually used on large paper machines. The first vacuum chamber of the double-chamber vacuum roll has a water absorption width of 150-250mm and a vacuum degree of 50-55kPa; the second chamber has a width of 100-150mm and a vacuum degree of 70-75kPa. The vacuum degree of each chamber on the three-chamber vacuum roll is usually 20-30, 40-50 and 70-80kPa. The suction width of the single-chamber vacuum roll is generally not more than 230mm. The total water absorption width of the multi-chamber type is not more than 400mm.