Mechanical Vapor Recompression (MVR) System
MVR reuses the evaporator’s secondary vapor as the heat source. A high-efficiency steam compressor raises the vapor’s pressure and temperature, then routes it back to the evaporator for heating. This heat-pump loop recovers latent heat, slashing utility demand—no live (fresh) steam is required once running.
How it works
- Pretreatment: Filter seawater or brine and adjust concentration for evaporation.
- Evaporation: Low-pressure boiling generates secondary vapor and concentrate.
- Mechanical recompression: The secondary vapor is compressed and returned as the heating medium.
- Crystallization & separation: Salt crystals form as brine concentrates; recover via filtration or centrifugation.
- Drying & packaging: Dry crystals and pack for storage or sale.
Advantages
- Ultra-low energy use: typically 15–50 kWh per ton of water evaporated (design-dependent).
- Gentle heating: small ΔT operation reduces product degradation.
- Compact footprint: ~50% less floor area than traditional multi-effect units.
- Clean utilities: no live steam consumption; low cooling-water demand; no boiler flue gas plume.
- Flexible turndown: stable at low load; long service life.
- Low-temperature capability: evaporation possible below 40 °C—ideal for heat-sensitive products.
Typical electric consumption by evaporator type
Evaporator |
Electric use (kWh/ton H₂O evaporated) |
Climbing film |
15–40 |
Falling film |
20–45 |
Forced circulation |
30–60 |
Note: Ranges vary with feed composition, fouling tendency, compression ratio, and heat-exchange area.
Applications
- Vacuum salt & brine concentration
- Environmental protection / ZLD & wastewater minimization
- Chemicals
- Food & ingredients
- Other thermal-separation duties