A fresh water generator is a device that converts seawater into freshwater on a ship. Freshwater is essential for various purposes on board, such as drinking, cooking, washing, and cooling. However, storing enough freshwater on a ship can be costly and impractical, especially for long voyages. Therefore, many ships use a fresh water generator to produce their own freshwater from seawater.
There are different types of fresh water generators on ships, but the most common one is based on the principle of vacuum distillation. This method uses heat and low pressure to evaporate seawater and then condense it into freshwater. The heat source can be taken from the waste heat of the main engine or other machinery, which makes this process energy-efficient and environmentally friendly.
The main components fresh water generator are:
– An evaporator, where seawater is heated and evaporated under low pressure.
– A condenser, where the evaporated seawater is cooled and condensed into freshwater.
– An ejector, which creates the vacuum inside the evaporator and condenser by pumping out air and non-condensable gases.
– A seawater pump, which circulates seawater through the evaporator and condenser.
– A freshwater pump, which transfers the freshwater to a storage tank.
Reasons Why FWG producing Less Water
A fresh water generator can produce up to 60 m3 of freshwater per day, depending on the capacity, temperature, and salinity of the seawater. However, there are some factors that can affect the performance and efficiency of a fresh water generator, such as:
– Fouling: The accumulation of dirt, scale, or biological growth on the heat exchangers can reduce the heat transfer and increase the pressure drop, resulting in lower evaporation rate and higher power consumption.
– Air leakage: The presence of air or non-condensable gases in the system can reduce the vacuum level and increase the boiling point of seawater, resulting in lower evaporation rate and higher power consumption.
– Corrosion: The exposure of metal parts to seawater or brine can cause corrosion and deterioration, resulting in leaks or failures.
-Temperature: Some setups have automatic valve which control how much HT water to bypass, but mostly it is manual, and you have to keep correct by little bit of practice. Also, sea water temperature plays great role in such scenarios. The best setting is to keep around 48-50 degrees, shell temperature. This way production and efficiency will be the highest.
Therefore, it is important to maintain and service a freshwater generator regularly to ensure its optimal performance and reliability. Some of the maintenance tasks include:
– Cleaning: The heat exchangers should be cleaned periodically using chemical or mechanical methods to remove any fouling or deposits.
– Flushing: The system should be flushed with freshwater or chemicals to remove any salt or impurities that may have accumulated in the pipes or valves.
– Lubricating: The moving parts such as pumps or ejectors should be lubricated according to the manufacturer’s instructions to prevent wear and tear.
– Inspecting: The system should be inspected for any signs of corrosion, leakage, damage, or malfunctioning.
A freshwater generator is a vital equipment on a ship that provides freshwater for various needs. By using vacuum distillation technology, it can produce freshwater from seawater efficiently and economically. However, it also requires proper maintenance and care to ensure its smooth operation and long service life.