Why Does the Pressure Screen Get Blocked
The pressure screen is the core paper mill machine that cleans and screens pulp in a paper mill. Understanding why the pressure screen gets blocked is important for every operator. The pressure screen can get blocked for three main reasons: plugging, mechanical problems, and process issues. Plugging is the most common problem. When the pressure screen gets blocked, you will see a sudden increase in pressure difference, higher motor current, and less good pulp output. The pressure screen has a drum with holes or slots. Pulp passes through these openings while impurities are caught and removed. But when too much pulp or too many impurities enter, the pressure screen gets blocked. Two main types of plugging occur: drum plugging and slot/hole plugging. Both can stop production and damage the pulp and paper machinery if not fixed quickly.
Main Causes and Solutions for Pressure Screen Blockage
| Problem Type | Cause | Solution |
|---|---|---|
| Drum Blockage | High feed consistency, too many impurities (stickies, plastics), no rinsing after shutdown, too fast feed increase | Reduce feed flow immediately, backflush with dilution water and reject valve, control feed consistency properly, rinse with clean water after shutdown |
| Slot/Hole Blockage | Too much feed flow from upstream, high pressure loss across screen plate, rotor cannot create enough self-cleaning suction | Check and adjust upstream feed flow, inspect rotor condition |
Why does the pressure screen get blocked so often? The pressure screen gets blocked when the feed consistency is too high. This causes pulp to build up on the drum surface too quickly. The pressure screen also gets blocked when there are too many impurities like stickies and plastic pieces in the pulp. These materials stick to the screen surface. The pressure screen gets blocked when operators do not rinse it after shutdown, letting leftover pulp dry and harden. The pressure screen gets blocked when feed flow and consistency increase too fast, overwhelming the equipment. Another reason why the pressure screen gets blocked is too much flow from upstream, which creates high pressure loss across the screen plate. When this happens, the rotor cannot create enough negative pressure to self-clean the slots. This is why the pressure screen gets blocked even when the pulp itself is clean.
To prevent the pressure screen from getting blocked, operators should control feed consistency properly, remove impurities before the pulp reaches the screen, rinse the screen after every shutdown, and check the rotor regularly to ensure it can self-clean. When the pressure screen gets blocked during operation, reduce feed flow immediately. For a quick fix, close the accept valve and open the dilution water and reject valves to backflush. For a long-term solution, always maintain proper feed consistency and rinse with clean water after each shutdown. If the slots or holes are blocked, check and adjust the upstream feed flow. Regular maintenance and proper operation can greatly reduce how often the pressure screen gets blocked, saving time and money on repairs.
As a leading manufacturer of paper industry machinery, Zhengzhou Leizhan Technology provides high-quality paper manufacturing machine and paper making machine solutions. We offer reliable paper production equipment and paper mill machinery for mills around the world. Our industrial paper machine and paper forming machine products are built for stability and efficiency. Whether you need a single paper processing line component or a complete paper production line, we can help. We also provide paper making line and complete paper mill line solutions. For turnkey paper production line projects, Leizhan offers design, manufacturing, installation, and commissioning services. If you have any questions about pressure screens or other paper mill plant machinery, please contact us at leizhanworld@gmail.com.
