50 T/Day Marine Seawater Desalination System

A commercial cargo vessel operating in tropical regions required a reliable freshwater supply for crew consumption, equipment cooling, and onboard services. With limited access to port facilities and high freshwater costs in remote areas, the shipowner sought a compact, energy-efficient seawater desalination system capable of producing 50 tons of freshwater per day.

Facing the following challenges 

1. Space limitations: The installation space for vessel’s engine room is limited. 

2. High salinity and high temperature: Operating in seawater with a salinity as high as 45,000 ppm and a temperature up to 35°C. 

3. Energy Efficiency: Minimize power consumption to be in line with the capacity of the ship's diesel generator. 

4. Durability: Resistant to corrosion, vibration and fluctuating working conditions.

VOCEE Solution
A reverse osmosis (RO) desalination system was designed and installed, optimized for marine environments. 

Key features included:

1.Compact Modular Design: Pre-engineered skid-mounted components for easy integration into tight spaces.

2.High-Efficiency RO Membranes: Dow Filmtec™ SW30HRLE-400 elements to handle high salinity and temperature.

3.Energy Recovery Device (ERD): Reduced energy consumption by 35% by recycling hydraulic energy from the brine stream.

4.Automated Control System: PLC-based interface for real-time monitoring of pressure, salinity, and flow rates, with automatic flushing and shutdown protocols.

Main Technical Specifications

1)Capacity: 50 m³/day (12,500 gallons/day) at 40% recovery rate.

2)Power Consumption: 3.8–4.2 kWh/m³ (including pretreatment and pumps).

3)Output Water Quality: < 700 ppm TDS, compliant with WHO drinking standards.

4)Pretreatment: Multi-media filtration, security filters (5 μm), and antiscalant dosing to prevent membrane fouling.

5)Materials:High-pressure pump made of duplex steel 2507, FRP membrane housings, and corrosion-resistant piping.

Results

1)Reliable Supply: Achieved consistent 50 T/day output, meeting 100% of the vessel’s freshwater demand.

2)Cost Savings: Reduced freshwater procurement costs by $12,000/month.

3)Energy Efficiency: Energy consumption lowered to 3.9 kWh/m³, compatible with the vessel’s 440V/60Hz power system.

4)Low Maintenance: Automated CIP (clean-in-place) cycles extended membrane life to 3+ years.