Research Of Fault Diagnosis Method For Large-scale Reverse Osmosis Desalination System

With the improvement of human living standards and the rapid growth of population,industrialization and urbanization,the desalination technology to solve the problems caused by water shortage has attracted the attention of scholars both at home and abroad,relevant departments of the government and international organizations.Among numerous methods of seawater desalination,the method of reverse osmosis has been widely used because of its low energy consumption,high efficiency and high quality of the produced water.The operation of the reverse osmosis systems is influenced by the seawater quality and the performance of RO membrane.In order to ensure the normal operation of the large-scale desalination projects,the fault diagnosis of large-scale seawater desalination system is essential to avoid significant economic losses and labor losses.Due to the complexity and large scale of the system,the single fault diagnosis method cannot reflect the state of a system failure completely.Besides,it is unable to solve the problems found in the diagnosis of large-scale seawater desalination system.Under the background of the 100,000t/d seawater desalination program on the LiuHeng Island of Zhoushan,the study analyzes the factors affecting the system operating,which takes the membrane components and energy recovery device as the main research object.On the basis of in-depth analysis of the failure mechanism of energy recovery device,it constructs a fault tree with the top event named as “the fault of energy recovery device”.In the process of generating BDD,the analysis of the system fault tree and the rules of an improved component connection method were used;the ordering of importance of cut sets can be determined based on the length of Huffman codes.As long as we complete the ordering of the cut sets within the groups,the basic events included by these cut sets will be checked to determine the fault source.By using the D-S evidence theory,this study introduces the details of the basic concepts,synthetic rules and the basic information fusion process of the theory.With the help of the experimental examples,the study establishes a fault diagnosis model of RO seawater desalination system,proposes the basic probability assignment method in line with the characteristics of reverse osmosis desalination system,and demonstrates the feasibility and credibility of the information fusion fault diagnosis technology.Based on.NET C# programming language and SQL Server 2005 database,we researchers develop a calculation and analysis software which is based on the information fusion of the D-Sevidence theory,introducing the process of calculation analysis and the main function of the software,to improve the computational efficiency and reduce the labor and the error rate of artificial calculation.