Multi-Effect MVR Falling Film Vacuum Evaporator — Sodium Chloride Salt Line
Engineer-to-order multi-effect falling film evaporator integrated with MVR (Mechanical Vapor Recompression) for sodium chloride (NaCl) refining lines. Operating under vacuum, the hybrid MEE+MVR train achieves high thermal efficiency, precise supersaturation control, and continuous crystal quality for edible and industrial salt production.
Key Benefits
- Energy efficiency: MVR recycles latent heat; multi-effect staging lowers specific energy use and fresh steam demand.
- Crystal quality: Controlled nucleation/growth delivers narrow size distribution for table, fine, or coarse grades.
- Stable vacuum duty: Falling film with low ΔT preserves heat-transfer coefficients and limits fouling.
- Food-grade compliance: 316L/duplex materials, drainability, CIP-ready design supporting HACCP/ISO.
- Line integration: Seamless tie-in with brine purification, centrifugation, drying, sizing, iodization, and packing.
Process & Thermal Economy
Secondary vapor is mechanically recompressed and reused as the primary heating medium, while upstream/downstream multi-effect falling film effects cascade energy. Tight control of ΔT/LMTD, residence time, and recirculation stabilizes supersaturation for repeatable NaCl crystallization and low OPEX.
Materials & Hygiene
Wetted parts in SS316L/duplex (Ti/Hastelloy on request), sanitary finishes, sloped/drainable piping, validated CIP, and material traceability for food-contact applications.
Process Overview — Refined NaCl Line
- Brine make-up & purification: dissolving, softening (Ca/Mg removal), clarification/filtration, polishing.
- Multi-effect + MVR evaporation (vacuum): staged effects with recompressed vapor to drive heat duty.
- Crystallization control: supersaturation setpoints for target grain bands (fine/table/coarse).
- Solid–liquid separation: peeler/pusher centrifuge; mother liquor recycle.
- Drying & sizing: fluid-bed/vibratory drying; sieving/polishing to spec; optional iodization & anti-caking.
- Packing: retail (1 kg) to bulk (25–50 kg) with weight checks and metal detection.
Key Components
- Multi-effect falling film evaporator bodies with preheaters/condensers
- MVR compressor (turbo/Roots) with VFD for ΔT/capacity control
- Vapor–liquid separator, main heater, vacuum/NCG handling system
- Brine purification skid (dissolver, softening, clarification, filtration)
- Peeler or pusher centrifuge; fluid-bed/vibratory dryer; sieving/polisher
- PLC/HMI/SCADA, instrumentation (T/P/flow/cond/level), historian & remote access
- CIP skid; iodization and anti-caking dosing modules
Performance & Sizing
| Parameter | Typical Target / Range* |
| NaCl purity (dry) | ≥ 99.2% (up to 99.7% with enhanced purification) |
| Moisture (final) | ≤ 0.2% (grade-dependent) |
| Crystal sizes | Fine 0.2–0.5 mm; Table 0.5–1.2 mm; Coarse 1.2–2.5 mm |
| Line capacity | 5–500 t/day (modular trains) |
| Electric use (MVR) | ~15–40 kWh per ton H₂O evaporated |
| Fresh steam demand | Very low after start-up (backup/ancillary only) |
| Campaign length | ≥ 10–20 days between CIP (feed-dependent) |
*Performance depends on feed composition, scaling tendency, compression ratio, and heat-exchange area.
FAQ
Why combine multi-effect with MVR?
The hybrid layout merges the low utility demand of MVR with the thermal economy of MEE, balancing CAPEX and OPEX.
Can you supply food-grade documentation?
Yes—material traceability, surface finish records, and CIP validation support HACCP/ISO 22000 programs.
What product grades are supported?
Fine, table, and coarse salt with optional iodization and anti-caking, plus industrial grades on request.
Application
