Preventing scaling in Three-effect Forced Circulation Crystallization Evaporator needs a mix of process optimization, equipment upgrades, and chemical interventions. Here are the key practical measures:

1. Optimize Process Operations

Control supersaturation and concentration. Don’t let solution concentration get too high—this avoids crystal deposition. Monitor supersaturation in real time and use gradient evaporation to prevent sudden crystallization.

Adjust temperature and pressure. Operate at low temperature and negative pressure (e.g., triple-effect temperature ≤80℃) to lower scaling risks from high heat. Keep the temperature difference between effects within 5℃ to avoid local boiling point rise.

Boost flow rate to prevent deposition. Use forced circulation pumps to push material flow to 2–5 m/s, creating turbulent flow to scour pipe walls. Add heat tracing to easy-clog sections (elbows, valves) to stop low-temperature crystallization.

2. Upgrade Equipment and Structure

Anti-scaling design. Heating tubes use smooth, corrosion-resistant materials (e.g., PTFE, Hastelloy) to reduce adhesion. Use a conical bottom (cone angle >60°) for separators plus mechanical scrapers to prevent wall caking.

Improve pipeline layout. Avoid right-angle elbows—use 45° bevels or arc transitions to reduce blockages. Install quick-release flanges on easy-clog sections for easy maintenance.

Add on-line anti-clog systems. Equip mother liquor circulation devices (circulation ratio 30–50%) to dilute high-concentration solutions. Use hydrocyclones to separate large crystal particles.

3. Chemical and Maintenance Methods

Use scale inhibitors. Add organic phosphonates (e.g., HEDP) to inhibit calcium and magnesium scaling (concentration 5–20 ppm). For sulfate systems, use polycarboxylate-based scale inhibitors.

Regular cleaning. Physical cleaning: Use high-pressure water guns to wash hard scale off pipe walls.Chemical cleaning: Soak in acidic agents (for inorganic scale) or alkaline agents (for organic scale) to soften deposits. For severe scaling, combine physical and chemical cleaning.

Pre-treat feed water. Filter suspended solids (SS ≤50 mg/L). Adjust pH to 6–9 and use Fenton oxidation to break down organic matter.

Conclusion

Stopping scaling requires three steps: controlling the source, optimizing operations, and strengthening maintenance. Forced circulation technology is the core anti-scaling method. Combining scale inhibitors with intelligent monitoring can extend the cleaning cycle to three times that of traditional equipment.

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