Regional Cathodic Protection Numerical Simulation Of Gas Stations And Anode Location Optimization Study

The coating and the cathodic protection are the important method which suppress the metal material corrosion, and applied in distance buried pipeline in the country widespread. However, anticorrosion of pipeline in gas transmission station haven't been paid enough attention, which only used the coating ,and had caused the serious corrosion consequence. Because there are density pipelines in gas transmission station, cause screening and interference,only use the special cathodic protection method, namely regional cathodic protection.In the country, regional cathodic protection started relatively late, applied in gas transmission station successful still. But, the method which designed regional cathodic protection were based on rules of thumb derived from trial and error case studies. In order to achieve the protection has used the large safety factor, and adjusted auxiliary anode position frequently, consumed plenty of time and money. Consequently, potential distribution and location of auxiliary anode are key to improve cathodic protection design. At present, the calculation methods of cathodic protection are divided into two classes: formula methods for objects of simple symmetry and numerical methods for complex object. Along with computer promotion and application as well as modern numerical method production and development, the finite difference method (FDM), the finite element method (FEM) and the boundary element method (BEM) applied in the current density and potential distribution research of buried pipelines cathodic protection one after another, the numerical method solution has been widely accepted by the guard potential and the distribution of current density question. So the mathematical model may be set to optimize anode position based on potential distribution numerical calculation.In the thesis, potential distribution and location of auxiliary anode were analysised from the analytic method and the numerical method of regional cathodic protecion. The analytic method applied in field convenient, and the numerical method have more precise result. According stable electric field theory, the mathmatic model have been set up, which make possion equation as dominate formula, and cathodic polarization curves was boundary conditions. In solving model, taking advantage of BEM, image method and axisymmetric method, fundamental solution have been deduced ,then combined Green's formula to seek boundary integral equation. Finally according boundary discreting formed of 3D boundary integral equation by constant element. In calculation, to obtain potential distribution could use gauss column principal component elimination solved coefficient matrix,and deal with nonlinear boundary conditions by piecewise linear fitting. According the potential distribution, deep well anode location optimized, and regional cathodic protection was set up which make potential well-distribution and electric power output minimization. Moreover using genetic algorithms to solve model. Finallythrough example, it's confirmed that the theory and method are accuracy.