Introduction
Desalination plants are used to produce fresh water from sea water.
Desalination Methods
A typical desalination plant will consist of either:
- A low pressure evaporator and reverse osmosis (RO) plant combined.
- A single low pressure evaporator only.
- A single reverse osmosis plant only.
Low pressure evaporators are installed where there is an abundance of waste heat, typically this heat would be supplied from a power station when the site is located on land, or an engine when the plant is located on board a ship.
Merchant navy marine vessels tend to favour low pressure evaporators as this allows them to utilise the waste heat from the engine to produce fresh water. RO plants are favoured on smaller marine vessels as they can operate without a heat source.
Where no heat source is available, a desalination plant will utilise RO membranes only.
Reverse Osmosis
Seawater enters the casing of a reverse osmosis tube at approximately 60 bar pressure. Water molecules pass through a semi-permeable membrane, but the salt cannot due to its larger size. The result is that desalinated water (fresh/sweet water) enters the middle of the RO membrane whilst ‘salty’ water is retained on the outside of the membrane. The fresh water is then discharged from the RO tube and further treated prior to final distribution to consumers.
3D Model Components
This 3D model shows all major areas associated with a typical desalination plant process, these include:
- Sewater Inlet
- Travelling Screens (Screening)
- Sand Filter (Filtering)
- Flotation Unit (Particle Settlement)
- Chemical Dosing Basin
- Reverse Osmosis (RO) Membranes
- Holding Tank
Additional Resources
https://en.wikipedia.org/wiki/Desalination
https://www.watercorporation.com.au/Our-water/Desalination
https://science.howstuffworks.com/environmental/earth/oceanography/how-does-desalination-work.htm