Study On Integrated Optimal Control Strategy Of Reverse Osmosis Desalination System

With the intensification of the global water resources crisis,seawater desalination technology has developed rapidly.Reverse Osmosis Seawater Desalination(SWRO)has great advantages in cost and process compared with other desalination technologies.It is considered to be the most promising desalination technology.The operating cost of membrane reverse osmosis seawater desalination system is still high,which is greatly affected by membrane module performance and other parameters.Based on the characteristics and mechanism of reverse osmosis process,the system dynamic operation optimization method and related technology research are developed in this paper.Support for reducing the operating costs of membrane reverse osmosis desalination systems.Based on this,the main research contents of this paper are as follows:1.The research survey of reverse osmosis desalination optimization operation is analyzed,and the related strategies and specific implementation techniques of dynamic optimization are given.On this basis,combined with the process characteristics of the typical reverse osmosis seawater desalination system,and based on the dissolution and diffusion theory of reverse osmosis membrane and the mass law of conservation,the overall model of the system containing strict mechanism description of many differential algebra forms is established.Then,the discrete strategy and simultaneous solution method based on finite element orthogonal configuration are given.The system solution and simulation are completed on GAMS platform,which lays a foundation for the next step.2.Considering that the realization of the optimization operation of membrane reverse osmosis desalination system needs to solve the process dynamic model quickly and accurately.The discrete precision and finite element division problem of finite element configuration are studied,and a fast grid dynamic partitioning strategy based on non-configuration point is proposed.The strategy first calculates the change with time of state variables in the condition that the finite element fixed and the configuration points are the roots of 3rd and 4th order Radau equation,and then gives a new dynamical divide strategy about finite element mesh based on error analysis and equation characteristics until the discrete error meets the requirements.The proposed strategy can be verified by two dynamic examples and SWRO system optimization propositions,which can reduce the number of finite elements and ensure the accuracy requirements.3.According to the process of reverse osmosis seawater desalination,it is proposed to combine the water production process with the water supply process,and make full use of the SWRO system water storage buffer function and the change of load,electricity price and feed temperature to further reduce the energy cost of reverse osmosis seawater desalination.However,this method needs to obtain the accurate change of the average water load and seawater feed temperature in the future.For this reason,a dynamic operation optimization strategy of SWRO system based on water load and temperature prediction is proposed.The self-regression and correction strategy is used to calculate the water load,real-time prediction and update of seawater temperature.And based on this,re-optimize and re-optimize the operation trajectory,and achieve the goal of reducing system operation cost through rolling optimization.The simulation results in different cases show that the proposed strategy can better predict the operating cost of SWRO system under the condition of load and seawater temperature change,and it is more realistic.