Method of operation
Seawater cannot be used directly due to its high salt content. There are two main methods for desalination of seawater, namely distillation and reverse osmosis.
Distillation is mainly used for super large-scale seawater desalination and places with abundant heat energy. The application of reverse osmosis membrane method is very wide, and the salt rejection rate is very high, so it is widely used. The reverse osmosis membrane method firstly extracts seawater and performs preliminary treatment to reduce the turbidity of the seawater and prevent the growth of bacteria, algae and other microorganisms, and then use a special high-pressure pump to pressurize the seawater into the reverse osmosis membrane. Due to the high salt content of the seawater Therefore, the seawater reverse osmosis membrane must have the characteristics of high desalination rate, corrosion resistance, high pressure resistance, and pollution resistance. The salt content of the seawater after the reverse osmosis membrane treatment is greatly reduced, and the TDS content rises from 36000 mg/to 200 mg/ Liters around. The water quality after desalination is even better than tap water, so that it can be used by industry, commerce, residents, ships, and naval vessels.
Seawater has high salt content, high hardness, and is highly corrosive to equipment, and the seasonal changes in water temperature make the reverse osmosis desalination system much more complicated than the conventional brackish water desalination system, and the engineering investment and energy consumption are also much higher. . Therefore, it is extremely important to reduce project investment and energy consumption through careful process design and reasonable equipment configuration, thereby reducing the unit water cost and ensuring the stable operation of the system.
Whether it is seawater desalination or brackish water desalination, feedwater pretreatment is the key to ensuring the long-term stable operation of the reverse osmosis system.
Bacteria and algae
Taking into account various factors such as traffic, it is difficult to add chemical reagents to kill bacteria and algae. In the development process of this project equipment, a seawater sodium hypochlorite generator is specially used.
Coagulation filtration is designed to remove colloidal and suspended impurities in seawater and reduce turbidity.
In order to prevent the production of insoluble inorganic salts such as CaCO3 and CaSO4 due to the concentration of seawater during the desalination process, scale precipitation on the surface of the reverse osmosis membrane and system pipes, the seawater should be added with an anti-scaling agent before entering the reverse osmosis desalination system.
In addition to adding NaClO for oxidation, an activated carbon filter is added, and the fruit-shaped granular activated carbon with higher mechanical strength can effectively adsorb organic matter and peculiar smell, improve the water quality of reverse osmosis water, and reduce the pollution of the reverse osmosis membrane. Extend the service life of the membrane.
The security filter adopts 316L filter and 5µm filter element to filter the seawater before the high-pressure pump, to block particles larger than 5µm in diameter in the seawater, to ensure the safety of the high-pressure pump, energy recovery device and reverse osmosis membrane element, and long-term operation.
High-pressure pump and energy recovery device
High-pressure pumps and energy recovery devices are important equipment to provide energy conversion and energy saving for reverse osmosis seawater desalination. According to the flow and pressure required for reverse osmosis desalination, the single-stage centrifugal pump we selected has a flow rate of 60m3/h and a head. 640Psi; The energy recovery device is HTC-300, with a hydraulic turbine structure, which can use the pressure of reverse osmosis to discharge concentrated seawater to increase the reverse osmosis inlet pressure by 30%, effectively reducing energy consumption.
The reverse osmosis membrane element is the core component of reverse osmosis seawater desalination. The element has better than 99% pressure resistance, oxidation resistance and pollution resistance. The reverse osmosis device adopts a first-stage and one-stage combination structure with 6 membrane elements connected in series and 6 pressure header pipes in parallel, and is equipped with low-pressure automatic flushing discharge and low-pressure automatic flushing replacement of desalinated water, and automatic switching discharge device for unqualified product water. In this system, high and low pressure protection and high pressure pumps are also provided, and the interlocking of the cleaning pumps is also provided.
We can customize product specifications according to your requirements. If you have any needs or questions, please contact us.