Research On Installation And Laying Method And Mechanical Property Analysis Of OTEC Large Diameter CWP

With the shortage of resources and environmental pollution caused by the over exploitation of fossil energy,as a sustainable and clean energy,ocean temperature difference energy has gradually become the focus of resource development and research at home and abroad.The installation and laying technology of large diameter cold water pipe(CWP)is the most novel and challenging technology for marine thermoelectric power generation.Whether the cold water pipe can be installed and laid safely and efficiently has become a key link for the successful operation of marine thermoelectric power generation.Because the research and development of marine thermoelectric power generation in China is still in the laboratory theoretical research and experimental stage,and the research and Exploration on the installation and laying technology of cold water pipe is in the initial stage,it is very necessary to carry out the research on the installation and laying technology of cold water pipe.Taking CWP as the research object,this thesis optimizes the installation and laying scheme of cold water pipe,analyzes the mechanical problems of cold water pipe structure and installation and laying design,and focuses on the nonlinear mechanical behavior of floating and sinking method in laying cold water pipe.Compare and analyze the laying methods of S-lay,J-lay,rolling pipe laying and floating drag laying.Based on the advantages and disadvantages of the laying method and combined with the structural characteristics of the cold water pipe,select and establish a scheme suitable for the rapid installation and laying of the cold water pipe,i.e.floating sinking laying.ABAQUS finite element software is used to analyze the cold water pipe under the combined action of inner and outer wall and insulation layer,and the stress-strain simulation is carried out to explore the flexural stiffness of composite cold water pipe.Based on the layer by layer separation method,the bending stiffness of each layer of cold water pipe is calculated and equivalent simulated;At the same time,the influence of equivalent ring plate of sandwich structure on the bending stiffness of pipeline is analyzed.The results show that the effect of insulation layer on the overall bending stiffness of cold water pipe is very small and can be ignored;The bending stiffness of cold water pipe decreases with the increase of ring plate spacing.Based on the nonlinear beam theory,the mathematical model of cold water pipe laying process is established to study the variation law of cold water pipe deformation and stress;Combined with the external load conditions,the pipeline balance differential equation is established.Based on the singular perturbation method,combined with the installation and laying boundary conditions,it is numerically solved by MATLAB software.Using orcaflex hydrodynamic software,the simulation analysis model of floating and sinking laying process is established to analyze the mechanical behavior of underwater cooling water pipe installation and laying.Analyze and compare the numerical solution results and finite element simulation results to verify the feasibility of floating and sinking laying.This study can improve the reliability of laying and installation of large-diameter cold water pipes with temperature difference energy,and has good engineering practical significance for realizing the rapid laying and installation of large-diameter non-metallic marine pipelines.