Application Of Numerical Simulation In The Design Of Anode Embedding Long-distance Pipeline Cathodic Protection

Numerical simulation can accurately predict the protective effect of cathodic protection, and solve the traditional drawbacks in cathodic protection design, so that the numerical simulation method has been widely applied to the field of corrosion and protection computing.In having read a lot of literatures, most scholars assumed potential of the outer surface cross-section of the pipe to be equal everywhere, they didn’t have a deep interpretation and research in the distribution of potential. In this paper, based on finite element method of numerical simulation, appling COMSOL software to calculate and discuss the cathodic protection distribution of potential of buried Pipeline cross-section, which getting a certain distribution, to apply in the actual cathodic protection design calculations of buried pipeline. Based on boundary element of numerical simulation, this paper use MATLAB programming to calculate and solve cathodic protection potential distribution for the axial of long-distance pipeline, which developing a more standardized, workable program code.In a stable passive corrosion electrostatic field, the potential distribution is in line with Laplace differential equations. In the active case, the potential distribution in line with Poisson equation, an auxiliary anode of impressed current will be seen as point source. In dealing with nonlinear boundary preclude we use a piecewise linear fitting process. The calculating used linear quadrilateral element model to establish discrete boundary integral equation format, used the Gaussian integral and sub-element method to calculate with source influence and non-point unit source influence coefficients, used the improved Newton iteration method and quasi-wave matrix method to solve linear equations, which thus obtaining the surface potential distribution of pipeline.In this paper, in contrast of calculations of appling BEASY software, the MATLAB programming which in application of three-dimensional linear quadrilateral element boundary method, are in good agreement with the error of 5.1%, in line with the conditions simulated to verify the reasonableness of the modeling idea, the accuracy of numerical methods and the reliability of the program, having some practical value in extending cathodic protection design and the effect predicting of long-distance pipeline.Simulation with MATLAB program in anode bed buried ways, soil resistivity, anode output current, anode bed laying position and other factors affecting the preparation of the potential distribution of cathodic protection, drawning up certain rules and reference conclusion in practical anode bed buried way, making cathodic protection potential distribution simulation results closer to the actual operation of the cathodic protection system.