Washing, maintenance and precautions for press felt

press felt is a consumable product on paper machine, which has a very important impact on the quality of paper. In the production process, impurities such as fine fibers, fillers and rubber materials in paper are easy to adhere to the press felt, clog the holes of the press felt, and affect the absorption and water filtration of the press felt. Therefore, the washing of the press felt is very important, which can ensure the good dehydration performance of the press and extend the service life of the press felt. It is especially important for needled press felt, which have long and thick fluff on the surface and small empty fiber gap, which is easy to be blocked, resulting in subsequent cleaning difficulties. As opposed to wear, 90% of the press felt drop is caused by clogging. The importance of press felt washing can be seen.

There are two ways to wash press felt: continuous washing in normal production and shutdown washing

(1) Water needle spray cleaning: the water pressure is 1.47~2.45×106 pa.

Advantages: less water, the use of water needle forced impact effect can use less chemical cleaning agent.

Disadvantages: Greater damage to the press felt.

The cleaning surface is the press felt sticker page, and the washing water temperature is recommended to use about 50℃ to strengthen the dirt removal effect of the method, which can be determined according to the actual production situation.

(2) Intermittent chemical cleaning on the machine: intermittent cleaning can use detergent, hydrochloric acid or lye, prepare them in a more appropriate concentration, can be moved to the full press felt, in the prescribed time after the use of chemical concentrated liquid, with water will remain in the press felt chemical washed away. When cleaning with acid, the concentration shall not exceed 5% of dilute acid, otherwise the nylon will encounter stronger acid, which will harden the hair and affect the filter water.

(3) on-board continuous cleaning: The press felt can always be maintained in the final state to achieve the highest manufacturing efficiency, on-board continuous cleaning is the best method.

Continuous cleaning agent concentration is generally 0.01~0.06%, continuous cleaning on the machine is not to remove the dirt that can not cause the press felt clogging, but to try to remove it before the dirt stains the press felt or just penetrate the press felt.

Matters needing attention:

When removing the press felt, you also need to pay attention to the following points:

(1) The needled wet press felt is smooth and thick, which is not easy to break. After the new press felt is put on the machine, do not tensify it too tightly. First, drive a slow car and spray water to moisten the press felt evenly and make it shrink naturally; And need to run empty for 6 to 10 minutes, make it hydrophilic, and remove a small amount of floating hair.

Tighten the press felt properly before pulping and making paper. Generally keep loose use, which will not affect the operation. If it is too tight, it will cause the horizontal shrinkage of the press felt, and the holes of the substrate will be deformed, which is not easy to filter water.

(2) When the paper machine is shut down, the press felt must be relaxed to avoid tension after drying and the press felt will be stretched. If the downtime is long, the press felt should be washed with water and then relaxed.

When starting, should drive slow, and spray water to wet the press felt, after the press felt wet, then pressurize and drive fast.

(3) If the press felt is too wide, pull the edge, pay attention to the neat incision, and be careful when pulling. Some heavy, best cut with scissors.