The pulping process is the core pre-production stage of papermaking, and pulp pumps serve as critical fluid-handling equipment that directly dictates production continuity and efficiency. Pulp pump seals, as the key protective components of pulp pumps, are responsible for preventing the leakage of fiber-containing media and blocking impurities from entering the seal chamber. Pulping conditions are characterized by media with high fiber content, corrosive components such as black liquor, and a high tendency for crystallization and deposition. Improper selection or irregular maintenance of pulp pump seals can easily lead to failures like clogging, wear, and leakage, resulting in equipment downtime and disrupting the entire production line. Therefore, mastering the scientific selection and anti-clogging maintenance techniques for pulp pump seals is crucial for paper mills to reduce costs, enhance efficiency, and ensure stable production.

I. Core Selection Principles for Pulp Pump Seals (Adapting to Special Pulping Conditions)

The selection of pulp pump seals must be precisely tailored to the characteristics of pulping conditions, focusing on two core dimensions: media compatibility and working condition parameter matching, to avoid inherent failure risks caused by improper selection.

In terms of media compatibility, for pulp media containing fibers and suspended solids, the rotating and stationary rings of pulp pump seals should prioritize high-strength, wear-resistant materials—silicon carbide-silicon carbide combinations are recommended. With high hardness and low friction coefficients, this material effectively resists scouring and wear from fibrous impurities. Sealing rings should adopt corrosion-resistant, anti-aging fluororubber to adapt to corrosive media such as black liquor, preventing seal aging and damage that could cause leakage.

For working condition parameter matching, selection must be based on the operating speed and seal chamber pressure of the pulp pump. Pulp pump speeds typically range from 1450 to 3000 r/min; for high-speed operations, pulp pump seals with elastic compensation structures should be selected to balance end face specific pressure and reduce wear from high-speed friction. Seal chamber pressure generally stays ≤1.6 MPa, and the rated pressure resistance of pulp pump seals must be at least 1.2 times the actual working pressure to prevent seal face deformation and failure due to high pressure. Meanwhile, flushing-type seals should be avoided in all selections. Integrated structures with built-in anti-impurity designs are preferred to fundamentally reduce clogging risks.II. Practical Anti-Clogging Maintenance Techniques for Pulp Pump Seals (Suitable for Frontline Operations)

Clogging of pulp pump seals is mostly caused by fiber impurity deposition and media crystallization. Standard daily maintenance and targeted protection are required to achieve anti-clogging and anti-leakage goals. Based on frontline operational experience, the core practical techniques are summarized in three points:

1. Optimize Flushing and Protection System Configuration: Adopt a combined "internal flushing + pre-filtration" solution. Use clean soft water as the flushing medium, with flushing pressure controlled at 0.1–0.2 MPa. Continuous gentle flushing removes fibrous and crystalline impurities adhering to the inner wall of the seal chamber in a timely manner. The pre-filter screen should have a mesh size of ≥80 to intercept large fibrous particles, preventing them from entering the seal chamber and contacting the pulp pump seal faces, which would otherwise cause clogging and wear.

2. Standardize Daily Inspection Frequency and Standards: Establish a twice-daily inspection routine, focusing on checking the seal chamber pressure of pulp pump seals and the smoothness of flushing pipelines. If reduced flushing flow or abnormally high seal chamber temperature (exceeding 80°C) is detected, shut down the equipment immediately for troubleshooting, clear fiber blockages in the pipelines. Weekly, regularly disassemble the protective end caps of pulp pump seals, clean accumulated impurities on the inner wall of the seal chamber, and inspect seal face wear to ensure no scratches or impurity adhesion.

3. Strengthen Daily Protection of Seal Faces: Before starting the equipment, confirm that the pulp pump seal faces are fully lubricated—apply a small amount of high-temperature resistant grease to avoid dry friction, which could damage seal faces and make them prone to impurity adhesion. After equipment shutdown, promptly flush the seal chamber with clean water to remove residual pulp media, preventing media crystallization and drying on the seal faces, which would cause clogging and jamming during subsequent startups.

III. Emergency Handling of Common Failures of Pulp Pump Seals (Quick Troubleshooting Guide)

In pulping production, pulp pump seals are prone to two common failures: "leakage caused by fiber jamming" and "seal failure due to crystallization". Mastering quick emergency handling methods is essential to minimize downtime. The core troubleshooting steps are summarized in the table below:

Common   Failure Types	Quick   Troubleshooting Points	Emergency   Handling Measures
Leakage from fiber jamming	1. Observe pulp seepage at the seal end; 2.   Check if flushing pipelines are unobstructed; 3. Feel if seal chamber   temperature is abnormal	1. Shut down immediately and close inlet/outlet   valves; 2. Disassemble the protective cover of thepulp   pump seal and clean fiber impurities from the seal   chamber and faces; 3. Inspect seal face wear—reinstall if no severe damage,   or replace with the same model pulp pump seal if damaged
Seal failure from crystallization	1.   Difficult equipment startup with abnormal noise at the seal end; 2.   Abnormally high seal chamber pressure; 3. No obvious leakage but increased   pump vibration	1.   After shutdown, flush the seal chamber with warm water to dissolve   crystalline impurities; 2. Disassemble the pulp pump seal and wipe off crystals from the seal faces; 3. Check seal ring   elasticity—replace if aged, then test operation after reinstallation

Emergency Handling Notes: Handle pulp pump seals with care during disassembly and installation to avoid impact damage to the seal faces. When replacing seals, use pulp pump seals of the original model to ensure dimensional and material compatibility with working conditions. Mixing different specifications is prohibited.

IV. Conclusion

The stable operation of pulp pump seals is a key guarantee for uninterrupted production in the pulping stage of papermaking, with the core lying in "scientific selection + standardized maintenance + quick troubleshooting". By selecting wear-resistant and corrosion-resistant seals adapted to pulping conditions, and implementing regular anti-clogging maintenance, the failure rate of pulp pump seals can be effectively reduced, minimizing equipment downtime losses. Paper mills should strengthen the professional skills of frontline maintenance personnel and implement daily protection and inspection systems for pulp pump seals, providing solid support for safe and efficient production.