Fresh water generator, one of the important machinery on board a ship, is something that cannot be done without. Fresh water produced from fresh water generator is used for drinking, cooking, washing and even running other important machinery which use fresh water as a cooling medium.
Sufficient potable water may be taken on in port to meet crew and passenger requirement. But the quality of this water will be too poor for use in water tube boilers and for filling expansion tanks. It is common practice to take on only a minimum supply of potable water and make up the rest by distillation of sea water. The stowage space that would have been used for fresh water can hence be utilized for fuel or extra space made available for cargo when fresh water generator is installed on a ship. It is statutory requirement to have a distillation plant for emergency use if otherwise ship has carried sufficient potable water. The equipment used on board for the production of freshwater from seawater is known as fresh water generator.
Various types of fresh water generators used on board ships are mainly :
- Submerged tube type fresh water generator.
- Plate type fresh water generator, and
- Reverse osmosis plant
What ever type of plant is used, essential requirement of any fresh water generator is that it should produce fresh water as economically as possible.
Fresh Water Generator Arrangement
The main body of a fresh water generator consists of a large cylindrical body with two compartments. One of the compartments is the condenser and the other is the evaporator. The fresh water generator also consists of an educator which helps in generating the required vacuum. The fresh water pump and ejector pump helps in transfer of water to and from the fresh water generator.