Falling Film Wastewater MVR Evaporator System For Crystallization & Chemical Desalination
Engineer-to-order falling film MVR (Mechanical Vapor Recompression) evaporator for wastewater concentration, chemical desalination, and salt crystallization. Thin-film vacuum boiling protects heat-sensitive streams while MVR recycles latent heat, delivering low OPEX, deep TDS reduction, and continuous, stable operation for ZLD schemes.
Key Benefits
- High energy efficiency: Electric-driven vapor recompression minimizes fresh steam after start-up.
- Desalination & crystallization: Drives brine to supersaturation for salt recovery and reduced discharge.
- Low ΔT, high quality: Falling-film duty preserves organics and limits thermal degradation/foaming.
- Scaling mitigation: Optimized ΔT/LMTD and film distributors, antiscalant dosing, CIP-ready design.
- Automated uptime: PLC/HMI recipes, alarms, historian, and remote diagnostics for 24/7 operation.
Process & Thermal Economy
Secondary vapor is mechanically compressed to elevate saturation temperature and reused as the heating medium. Even film distribution over vertical exchangers maintains high heat-transfer coefficients; controlled residence time and pressure/ΔT setpoints enable predictable desalination and crystallization with low specific energy.
Materials & Cleanability
Wetted parts in SS316L/duplex (Ti/Hastelloy optional). Drainable layouts, large access for inspection, validated CIP, and elastomer/material selections per chemistry (chlorides, solvents, acids/alkalis).
Process Overview — Wastewater Desalination to Crystals
- Feed conditioning: screening/filtration, softening or pH trim, antiscalant to control Ca/Mg/Si scaling.
- MVR falling film (vacuum): VFD compressor controls ΔT; shell vacuum defines boiling point.
- Crystallization: seeded growth (DTB/OSLO/FC) for targeted PSD and purity; mother liquor recycle.
- Condensate polishing: filters/RO/AC to meet reuse or discharge limits (conductivity/TOC guard).
- Solids handling/ZLD: centrifuge → dryer → regulated disposal or resource recovery.
Key Components
- Falling-film evaporator body with film distributors and vapor–liquid separator
- MVR mechanical vapor compressor (turbo/Roots) with VFD for ΔT/capacity control
- Surface condenser, vacuum/NCG handling, preheaters/heat recovery HX
- Crystallizer, centrifuge, dryer; condensate polishing skid
- PLC/HMI/SCADA; instruments (T/P/flow/cond/level); CIP and antiscalant dosing
Performance & Sizing
| Parameter | Typical Range* |
| Operation | Continuous, vacuum |
| Electric use (MVR) | ~15–40 kWh per ton of water evaporated |
| Shell pressure | ~6–25 kPa(abs), duty-dependent |
| Desalination depth | Up to crystallization/solid discharge (feed-dependent) |
| Materials | SS316L / duplex; Ti/Hastelloy on request |
*Actual performance depends on feed salinity/COD, fouling tendency, compression ratio, and crystallizer design.
FAQ
Can it follow membranes to reach ZLD?
Yes—common flowsheets pair RO/NF pre-concentration with falling-film MVR and a crystallizer for final solids discharge.
How do you control scaling on high-TDS streams?
Through pretreatment, optimized film ΔT/velocity, antiscalant dosing, and scheduled CIP with online fouling indicators.
What condensate quality is achievable?
Low conductivity/TOC suitable for reuse after polishing; quality guards ensure compliance with site limits.
Application
