Study On Pressure Stability Control Of Seawater Desalination Equipment Before Membrane

Water is the source of life and the necessity of industrial production.China is a populous country with a huge demand for water resources.However,the per capita available freshwater in China is only 1/4 of the world average level and belongs to a water-poor country.China has abundant seawater resources.The development of seawater desalination technology to alleviate the shortage of fresh water has become a hot social issue.Reverse osmosis membrane is an important component in reverse osmosis desalination equipment and the core of reverse osmosis desalination project.However,reverse osmosis membrane is also fragile.If the pressure impact before and after the membrane is too large or the pressure difference fluctuation before and after the membrane is too large,the reverse osmosis membrane will be destroyed,thus affecting the quality of seawater desalination and reducing the service life of the membrane.In this paper,a closed-loop pressure control method was adopted to solve the problem of unstable pressure in front of reverse osmosis membrane,and a new desalination and energy recovery device was developed,which improved the production efficiency.Firstly,the working principle of seawater desalination and its energy recovery system was introduced.The system was mainly divided into seawater desalination part and energy recovery part.In the seawater desalination part,hydraulic cylinder was used to pressurize the seawater.The piston rod of the seawater cylinder and hydraulic cylinder was rigidly connected.The closed-loop pressure control method was used to stabilize the seawater pressure in front of the reverse osmosis membrane at about 7 MPa.The energy recovery part was to continue pressurizing the desalination system by utilizing the energy of high-pressure concentrated seawater which did not pass through the reverse osmosis membrane.Secondly,the mathematical model of the hydraulic system of seawater desalination was established and simulated in Simulink software.In the simulation,the PID controller was established,and the parameters of the PID controller were adjusted by trial and error method.BP neural network PID controller was added to the model.Finally,the relevant equipment was debugged in the field,and the simulation test of seawater desalination was carried out in the laboratory.