Reverse osmosis seawater desalination technology is widely applied over the world. There are several kinds of main devices in it, such as feed pump, multi-media filter, security filter, HP pump, RO system, etc. Here is their function introduction in detail as follows.
Feed pump is selected to provide sustained and stable feedwater flow and pressure. Famous Made-in-China CNP pump is strong anti-corrosion, high-efficiency, small noise, stable and reliable performance.
It is used for turbidity removal treatment of raw water. The filter equipped with two kinds of refined quartz and manganese sand adopts pressure filtration. It has the advantages of large cutting capacity, high filtration rate, and longer filtration period, which could effectively remove larger suspended solids and colloid to meet the requirements of the membrane inlet water quality (turbidity <1NTU) and to make the sure normal operation of post-treatment.
If you want to know more about the filter, please read How Multi Medium Filter Works in Desalination Systems.
Ultrafiltration is a kind of membrane separation technology driven by pressure difference on both sides of the membrane. Under the effect of the static pressure difference, larger particles in raw water greater than membrane hole are trapped by the membrane, and small particles less than membrane hole can pass through the membrane, so as to realize the separation process. This separation principle is considered as mechanical screening. It has small hole diameter and can intercept bacteria, viruses, colloid, oil, suspended solids and large organic molecules, etc. Too large scale seawater desalination system, in order to protect reverse osmosis membrane and prolong membrane lifespan, it is also necessary to adopt ultrafiltration. The SDI of ultrafiltration production usually can reach to less than 3, the production quality is better than that of multi-media filter.
Security filters are installed at the entrance to the reverse osmosis equipment in order to prevent particles from entering the reverse osmosis membrane. As there is much TDS in the seawater, the material of security filter adopts 316L filter with 10um and 5um precision. Particles in the water greater than 5um are trapped by 5um filter to ensure HP pump, energy recovery device and membrane module safe, reliable and stable in the long-term operation.
HP Pump and Energy Recovery Device:
Reverse osmosis high-pressure pump is the main running equipment, which provides a power source for the operation of the reverse osmosis device. Energy recovery device is the device for recovering energy from high pressure concentrated seawater of the reverse osmosis system. The energy recovery of advanced PX series of ERI company can be up to 98%, which can reduce the cost of fresh water production by 60%. The high-pressure pump and energy recovery device provide the energy conversion and energy saving for reverse osmosis seawater desalination system according to water flow and pressure selection.
Reverse osmosis membrane is the core of the reverse osmosis seawater desalination system, which is used to remove the ions, organic matter, colloidal particles, bacteria and other impurities in the water, so that water is desalinated. The principle is that the semi-permeable membrane separates water and salt solution, water would naturally permeate for the salt solution side under the osmotic pressure. If certain pressure larger than osmotic pressure is applied on the salt solution, water would permeate in the opposite direction. This phenomenon is called “reverse osmosis”. RO permeate is purified, removing 98% TDS from the feed water. RO brine is concentrated with TDS about two times of the feed water.
The cleaning system is mainly used for the protection of the reverse osmosis membrane of seawater desalination system. The fresh water is automatically carried out on the reverse osmosis membrane for cleaning when finishing fresh water every time, and the chemical agents are used for cleaning and maintaining the reverse osmosis membrane to ensure the stability of the system. Please check How to Clean Seawater Reverse Osmosis System for more details.