Paper making felt are important dewatering equipment in paper mills and are also valuable consumables. They play a role in conveying, dewatering, and cushioning in the press section of paper machines. The permeability of paper making felt mainly includes breathability, water permeability, and moisture content, which are important physical performance indicators for evaluating the quality of paper making felt during production and use. They directly affect the production efficiency, product quality, and production cost of paper mills. In order to understand and grasp the trend of changes in the performance of paper making felts and effectively adjust them during their service life to maintain optimal working conditions, it is necessary to test the permeability and other performance indicators of paper making felts.
Purpose of Air Permeability Testing for Paper Making Felts
1. Helps Prevent Unexpected Shutdowns
Regularly testing the air permeability of the felt in the paper press section is an effective way to detect paper defects early on. Otherwise, it may lead to economic losses such as substandard paper quality, frequent paper breakage, or increased energy consumption. The practical experience of paper mills has shown that regularly detecting and analyzing the usage status of felts can not only further optimize the dryness of wet paper sheets when they enter the dryer section from the press section, making the dryer section operate efficiently, but also greatly reduce the number of unexpected shutdowns.
2. Helps Determine The Working Condition of Press Felt
The testing of felts is not only used for fault diagnosis, but can also be used to determine the working condition of felts under normal operation. Regularly and irregularly testing press felt can not only monitor their trends and tendencies, but also easily detect errors and take appropriate measures in a timely manner. Practice has proven that the more frequently felts are tested and analyzed, the longer the time interval between unexpected shutdowns and quality issues related to the operation of the press section.
3. Helps with Trend Analysis and Optimization of The Press Section
The adjustment of the press felt, the distribution of the pressure zone load, the wear of the press felt, and the degree of blockage of the felt all have important effects on the permeability detection curve. Minimizing the variation of the curve to the greatest extent is directly related to improving the performance of the paper machine. Applying these detection methods to the press section can further improve production yield and quality. By correctly evaluating the testing of chemicals, press rolls, and press felts, the cause of changes can be accurately determined. Comparing the dehydration efficiency of the press section with the curve changes (related to changes in the felt or equipment) can clearly demonstrate the effects of these changes. For example, the benefits of new advanced technologies in squeezing tracks and shoe covers for improving squeezing efficiency can be demonstrated by the dewatering rate and the uniformity of the horizontal curve. These comparisons can be made throughout the entire lifespan of the press felt and during replacement. Trend analysis is also a good method for predicting the effective service life of press felts.
4. Helps Analyze The Source of The Problem
The wet streaks and other frame issues on wet paper pages have always been a headache, and these problems almost always occur in the press section. By using a steamer or adding moisture after the dryer section, the problem of small distribution uniformity can be solved. However, analyzing the problem, identifying the root cause, and eliminating it is always a better way to solve it. Merely testing the moisture distribution or permeability of the felt is not sufficient to explain the operation of the press section. Both methods must be used simultaneously to obtain comprehensive test results. Using a felt moisture content tester to test the current moisture content distribution of the felt can easily obtain a balanced pressure distribution in the compression zone, and the moisture content distribution can indicate the dehydration situation in the compression zone. Using a felt permeability tester to test permeability can reveal the operating condition of the press felt. Air permeability is clearly related to the dewatering performance of the pressing zone and is influenced by the condition of the felt.
5. Quickly Obtain Returns
The practical experience of paper mills has shown that checking the working condition of the press felt correctly can greatly reduce the number of unexpected shutdowns. In fact, under optimal conditions, felts should be replaced during normal downtime.
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