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Horizontal inner Tube Evaporator

The Wärtsilä Horizontal inner Tube Evaporator (HiTE) is a multi-stage evaporator specifically designed for producing small to medium capacities of 30 to 120 tons of distillate per day. It guarantees freshwater for human consumption or clean process water for technical applications. It serves in a wide range of operational areas where alternative technologies like reverse osmosis or plate technology reach their limits. Shallow waters with poor seawater quality is an example of this. 

The HiTE operates smoothly even at partial load, for example during dynamic positioning (DP) operations. The unit’s control system is fully automated, and its smart processes adapt automatically to the amount of energy available. The HiTE is able to utilise waste heat, which is very convenient for vessels with varying engine profiles. The 4-stage HiTE offers up to 75% energy savings with a specific heat consumption of 180 kWh/t compared to single stage designs (700 kWh/t). For a 3-stage HiTE this is 240 kWh/t.  

The HiTE is able to utilise waste heat. This is very convenient for vessels with varying engine profiles.


    • Efficient & reliable multi-stage distilling process
    • Low operational cost
    • Lowest energy consumption in its range
    • Most efficient solutions when utilising engine waste heat
    • Designed for easy maintenance and long service intervals
    • Flexible adaptation to demand and/or supply (down to 50%) thanks to exceptional part-load capability
    • High quality distillate ≤ 5 ppm
    • Flexible use of heat sources: engine jacket water, steam or combination
    • Fully automatic system
    • Also suited for land-based applications  


    • Seawater inlet temperature: 0 – 35°C
    • Capacity 30 – 120 tons/day
    • Footprint: 1.8 – 5.4 m2
    • Weight empty: 2,156 – 5,200 kg
    • Heating water inlet temperature from 70 – 90°C
    • Thermal power consumption: 180 - 240 kWh/t
    • Electrical power consumption: 3 kWh/t 


    Evaporation in the HiTE takes place inside horizontally placed tubes. Seawater is fed into the tubes and heated from the outside with hot water or steam. Heating continues until reaching boiling temperature. Due to both the rise in temperature as well as a decrease in pressure during upstream flow, vapour is continually released. This vapour is finally condensed to the desired high-quality distillate.  

    The design uses multiple stages in which seawater is evaporated. The follow-up stage uses the heat from the previous stage to heat up the seawater. This way the energy is recovered, further increasing the total capacity of freshwater production and the overall efficiency.  
    Process flow from Horizontal inner Tube Evaporator


    System Capacity (tons/day) Thermal power (kWh/t) Electrical power (kWh/t) Dry weight (kg) Footprint (m3) Water quality (ppm)
    HiTE 30-3 30 to/d 240 3 2156 6,64 5 ppm
    HiTE 50-3 50 to/d 240 3 3600 14,47 5 ppm
    HiTE 80-3 80 to/d 240 3 5200 11,94 5 ppm


    Delivered as standard  

    • Tube evaporator with condenser 
    • Distillate pump 
    • Ejector pump Seawater pump
    • Chemical dosing tank with dosing instruments
    • Solenoid valve for draining lower quality distillate
    • Siemens S7 control panel 


    • Mineralization filter for adjusting distillate pH-value 
    • UV steriliser for disinfecting the distillate 
    • Booster heater 
    • Distillate cooler 
    • Control panel mirroring 


    The Wärtsilä Horizontal inner Tube Evaporator is suited for a wide variety of vessel types, including special vessels, chemical tankers and small cruise ships. Also offshore and land-based applications can be equipped with HiTE’s. 

    Also land-based industry
    orders HiTE units

    Wärtsilä has strong roots in the maritime industry and has been supplying freshwater generation systems...

    Read more »


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