Freshwater From Seawater-Understanding Marine Water Supply Systems

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When prepping up, ships require a good amount of freshwater which is typically produced by onboard water production plants. Freshwater is used for a number of different purposes—cooling engine components being the most important. A good marine spares supplier can help a lot in providing quality fresh water generator. 

While earlier, many of the ships had evaporators that utilized steam from boilers as a heating source to evaporate seawater, today the process has been made much simpler through osmosis. The systems use a similar heat source but the procedures have been modified for reliable freshwater production.

In this blog post, we discuss the evaporators used today including tube and flash and how reverse osmosis allows ships to produce freshwater from seawater.

Types Of Evaporators

Different types of evaporators are used to produce freshwater from seawater today. The two most common types are:

  • Tube evaporator
  • Multi-stage flash evaporator
Multi-Stage Flash Evaporators

This evaporator uses two different components—the flash drum and seawater heater. These are two separately installed components.

The seawater is heated using steam from the main engine after which it is passed onto the flash drum. The flash drum includes plenty of different sections that have a lower pressure than the heater. The seawater flashes into steam as it proceeds through the drum.

The steam gradually rises up in the flash drum through the demister where it gets into contact with a condenser tube. The water is then pumped to a freshwater storage tank. 

In case the salt level rises excessively, the salinometer alarm goes off and the water is moved to bilges.

Tube Evaporator

A coil or tube evaporator includes a steel container with a layer of heating pipes at the base. The tank uses the heat and steam generated from the main engine as heat source. A condenser present near the top of the container cools down the water. The container is also vacuumed using pressurized seawater or steam.

Seawater is filled in the container just to cover the heating pipes. Once the pipes are heated, along with the vacuumed container environment, the seawater comes to a boil. The steam then continues to rise, passing to a demister through a tube condenser where the temperature is lowered. The water is evaporated and converted into distilled water. The distilled water is later stored in a separate tank.

If you are looking for a marine spares supplier for parts that help you streamline freshwater production onboard, look no further. Get in touch with us to discuss your needs today.


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