H2 / Hydrogen production from ultra clean water; High quality distillate for P2X
Ultra clean water for H2 production
Lowest conductivity distillate in the industry

Multi Stage Flash Evaporator

Wärtsilä's Multi-Stage Flash (MSF) evaporator produces high-quality distillate from sea, well or industrial water. The conductivity of this 'ultra clean water' is extremely low: less than 1.5 μS/cm. This makes the MSF one of the most useful enabling technologies for Hydrogen / H2 production, serving many P2X applications.

A specific advantage of the multi-stage flash technology is that the heat consumption - or thermal efficiency - can continuously be  adjusted to the set requirements of an application. The MSF is able to produce up to 1500 tons of distillate per day. The distillate's quality and quantity are not impacted by the uptaken water temperature.

The MSF ultra clean water generator proves to be one of the most reliable low-maintenance seawater desalination plants in the world. It is the only evaporator technology that strictly separates heat transfer and evaporation, minimizing the risk of scaling and greatly reducing maintenance costs



    • Conductivity distilled water < 1.5 μS/cm.
    • Proven technology, manufactured for decades and installed on hundreds of ship & offshore installations worldwide.
    • Evaporates sea or well water from electrolyser’s waste heat. Most sustainable distillate process available.
    • No scaling thanks to patented design.
    • Solution with lowest sensitivity to malfunction & lowest lifecycle costs.
    • Full-automatic process control.
    • Operational flexibility – best load range utilisation.
    • Flexible dimensions allow for best utilisation of space.
    • Operating frequency converter for pumps saves energy.


    • Capacity up to 1500 ton/day. 
    • Steady production of distilled water from seawater at temperatures between 0 - 32°C. 
    • Either steam, engine jacket water or combination can be used for heating 
    • Full-automatic or semi-automatic operation
    • Can be operated in part load

    Materials used

    • Condenser tube material: CuNi, CuZn  
    • Pipes in contact with seawater: CuNi 
    • Pipes in contact with steam, motor-water, condensate: Steel 
    • Distillate: CuNi  
    • Shell: CuNi 


    After leaving the first stage condenser (3), the seawater flows through the brine heater (1), where the heat input to the plant (steam or engine jacket water) causes a further temperature increase.

    The seawater leaves the brine heater (1) and enters the first flash chamber (2), reaching a brine top temperature of approx. 80°C.

    At this point the pressure of the incoming seawater is suddenly reduced, by means of an orifice, below its equilibrium vapour pressure resulting in explosive boiling or evaporation (flashing). The pure vapour produced is then condensed, giving up its latent heat to preheat the incoming seawater (3).

    If this process is repeated over a large number of effects, at successively lower pressures and temperatures, large distillate production rates at reasonable performance ratios can be achieved. 

    Internal process flow Multi Stage Evaporator - generating low conductivity distilled water for P2X / hydrogen production


    System Capacity (ton/day) Power (kW) Dry weight (kg) Wet weight (kg) Footprint
    (L x W x H, mm)
    MSF 115-5 115 915 18000 21000 5700 x 2900 x 3000
    MSF 300-6 300 2388 27000 32000 7300 x 2900 x 3300
    MSF 650-6 650 5146 37000 45000 9200 x 3500 x 3900
    MSF 775-8 775 4812 42000 52000 10500 x 3600 x 3900
    MSF 850-8 850 4780 43000 53000 11700 x 4200 x 3900
    MSF 950-8 950 6395 45000 55000 12000 x 3700 x 3900

    Capacity up to 1500 ton/day.
    Steady production of freshwater at seawater temperatures 0 - 32ºC.
    Water conductivity of distillate for all models: < 1.5 μS/cm.


    Delivered as standard

    • Flash vessel with condenser and condenser tubes 
    • Base frame 
    • Pumps, including e-motors 
    • Air ejectors 
    • Feed water heater 
    • Distillate cooler 
    • Complete internal pipework 
    • Control equipment and instrumentation 
    • Optional steam booster 


    • Steam booster  
    • Distillate cooler 
    • Frequency converters for pumps 
    • Cleaning stations 

    MSF's contribution to the H2 production chain

    process flow - how the MSF helps hydrogen / H2 production

    Contact us

    Wärtsilä Water & Waste
    Freshwater Generators

    • Leif Abildgaard, Sales Director, +45 2910 3777
    • Jan Patrick Reich, Sales Manager, +49 172 455 9691
    • waw.sales@wartsila.com

    Pankower Str. 16-18
    21502 Geesthacht

    © 2022 Wärtsilä