Dynamic Optimal Control Of Reverse Osmosis Seawater Desalination

The shortage of water resources is increasingly apparent with the development of the global economy and population.To alleviate the growing water shortage,seawater reverse osmosis technology has become the best freshwater resource acquisition technology with the best development prospect.However,the operation cost of the seawater desalination system based on high pressure is still high,which limits the further application of the reverse osmosis desalination technology.Therefore,the study on the operation optimization of reverse osmosis process based on understanding the working principle of reverse osmosis system will help the energy-saving operation of reverse osmosis desalination plant.In this paper,on the basis of the analysis of the principle of the reverse osmosis system and the establishment of the model,the following three aspects are carried out:1.The background of reverse osmosis seawater desalination was introduced comprehensively.According to the theory of conservation of mass and dissolved diffusion,a mathematical model of reverse osmosis process was established.Considering solving the problem caused by nonlinear differential equations in the model equations,this paper uses the simultaneous method of finite element orthogonal collocation to solve it.Then,the parameters obtained from this model are compared with the actual plant data,which verifies the accuracy and effectiveness of the model,and lays the foundation for subsequent optimization and calculation.2.In order to ensure the rapidity and accuracy of the optimization of the reverse osmosis desalination system,the discrete precision and meshing problem of the simultaneous discrete dynamic optimization problem were studied.The moving finite element method based on noncollocation point error estimation was proposed.The improved algorithm adopts the idea of adaptive iterative optimization,which ensures the accuracy of the solution while minimizing the number of finite elements,and the computation time is also greatly reduced.In order to verify the effectiveness of the algorithm,a number of dynamic optimization control examples were used to verify the method.Based on this,the method was applied to the operation optimization of the seawater desalination system,which effectively reduced the number of finite element and significantly reduced the optimization calculation time.3.The reverse osmosis water production and water production process of the seawater desalination system were combined to carry out operation optimization research so as to reduce the operation cost,a real-time operation optimization control strategy based on water load rolling prediction was proposed.This strategy uses the tou power price and intermediate water storage to improve the potential of energy saving and cost reduction.A new time-series water load forecasting method was adopted to improve the forecasting accuracy.The load forecasting method was revised by rolling forecasting and correcting strategy.Based on this,optimal operation pressure and optimal operation flow curve are obtained by rollingly solving the optimization operation proposition.The calculation results show that the proposed method can solve the large of load changes,which is more practical and safe than the conventional prediction methods.