The Fresh Water generator

How do ships produce fresh water out of sea water?

Have you ever wonder how ships seem to have limitless supply of fresh water onboard, despite sailing for days or weeks at sea?

By the name itself, the Fresh Water Generator is the answer to all those questions.

We all know that fresh water is one of the basic needs of life. Onboard the ships water is used for shower, washing, cooking flushing toilets and for cooling various machineries including the Main Engine of the vessel. So it is very important to produce enough fresh water for the continuous operation of the vessel.


How does it work?

The working principle of the fresh water generator is quite simple – Distillation. But the heating medium here is hot water through heat exchangers. It is just boiling the sea water to produce vapor (evaporation) and cool it down (condensation) to produce the fresh water or basically known as distilled water.

The combined brine (sea water)/air ejector driven by the ejector pump creates a vacuum in the system in order to lower the evaporation temperature of the feed water (sea water).

In a normal atmospheric condition the boiling temperature of water is 100°C. But because of the vacuum in the system, the water can boil even at 80°C.

The feed water (sea water) is introduced into the evaporator section through a spring loaded valve orifice and distributed into every second plate channel ( evaporation channels).

The hot water( jacket cooling water) approx. 80 to 90°C is distributed into the remaining channels, thus tranferring its heat to the feed water in the evaporation channels.

Upon reaching the boiling temperature, which is lower than 100°C ( atmospheric pressure) the feed water undergoes a partial evaporation and the mixture of generated vapour and sea water enters the separator vessel where the brine is separated from the vapour and extracted by the brine/ air ejector.

Passing through a demister the vapour enters every second plate channel on the top of the condenser section.

The sea cooling water supplied to the condenser distributes itself into the remaining condenser channels, thus absorbing the heat being transferred from the condensing vapour.

The produced fresh water (distilled) is extracted by the fresh water pump and delivers to the fresh water tank.

A salinometer is fitted on the fresh water pump delivery side to continuously check the actual salinity of the produced fresh water.


#freshwatergenerator #marineengrsdailybycegarylano #engineersatsea #lifeatsea #chiefengineers

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