How to Avoid the Wear of Press Felt

During the production process of press felt, the paper materials contain fine fibers, fillers, rubber and other substances, and some impurities in the production water are very easy to adhere to the press felt, blocking the holes of the press felt and affecting the absorption and water filtration performance of the press felt. Therefore, washing the press felt is one of the keys to ensure good dehydration of the press section and extend the service life of the press felt.
Especially for needle-punched press felt, the fluff on the surface of the needle-punched press felt is long and dense, and the fiber gaps are small, which are easily blocked by debris. It is difficult to clean after being contaminated and blocked. Most of the press felta are not caused by wear, but by blockage. It can be seen that washing is important for press felt.

There are two ways to wash press felt: washing during production and washing when the machine is stopped.

(1) Use water needle spray cleaning: the water pressure is 1.47~2.45×106 Pa. Its advantage is that less water is used, and the strong impact of the water needle can reduce the use of chemicals. However, the damage to the press felt is somewhat serious. The cleaning surface is the sticker surface of the press felt. The recommended water temperature is around 50 degrees Celsius to enhance the cleaning effect.

(2) On-machine intermittent chemical cleaning: Detergent, hydrochloric acid or alkali solution can be used. They can be prepared with a more appropriate concentration and can be moved to the entire width of the press felt. After the chemical concentrate is used up within the specified time, the chemical remaining in the press felt is washed away with clean water. (Note: When using acid for cleaning, the concentration must not exceed 5% dilute acid, otherwise the nylon will encounter a concentrated acid solution, which will make the wool hard and affect water filtration.)

(3) On-machine continuous cleaning: On-machine continuous cleaning is the best method to keep the press felt in its final state and achieve the highest papermaking efficiency. This method does not aim to remove impurities that cannot cause press felt blockage, but strives to remove them before the debris stains the press felt or just penetrates the press felt. The detergent concentration for continuous washing is 0.01-0.06%. Although continuous washing is more expensive, it can extend the life of the press felt and keep it in the best condition, which helps reduce consumption, reduce breakage losses, and improve paper quality.