埋地钢质燃气管网地铁杂散电流腐蚀防护模拟

Simulation of Subway Stray Current Corrosion Protection for Buried Steel Gas Pipeline Network

结合工程实例,基于COMSOL Multiphysics软件对某城市燃气管网受地铁杂散电流干扰及保护措施进行模拟仿真。建立控制方程,设置边界条件。通过将模拟数据与测试数据对比,验证了模拟仿真的可行性。模拟泄漏到土壤中的电流分别为2 A、5 A、10 A时,有、无强制接地排流时的管网管地电位分布。针对受干扰最大的管段,优化防护措施,增加镁阳极极性接地排流装置,进行管地电位的模拟。在干扰仍较为强烈的区域,增设密集镁阳极极性接地排流装置,进行管地电位的模拟。根据模拟结果得出结论:强制接地排流的防护措施对整个片区的燃气管网受干扰情况改善效果好,特别是在强制接地排流站1 km排流半径内。针对离干扰源较近的部分管段,可采取进一步的防护措施。与强制接地排流站距离较近的管道,由于管地电位负向偏移较大,容易产生防腐层脱离等现象。在增设密集镁阳极极性接地排流装置后,除与整流所距离20 m内的管段外,其余管段存在的强烈干扰已得到明显抑制。强制接地排流影响范围较大,镁阳极极性接地排流的影响范围较小,排流效果较差。在两种防护措施同时具备条件时,应优先考虑强制接地排流。

Combined with engineering examples,based on COMSOL Multiphysics software,the interference of subway stray current with gas pipeline network in a city and the protection measures are simulated.The control equations are established,and the boundary conditions are set.By comparing the simulation data with the test data,the feasibility of the simulation is verified.The pipe ground potential distribution of the pipe network with and without forced grounding drainage is simulated when the current leaking into the soil is 2 A,5 A,and 10 A,respectively.For the most disturbed pipe section,the protective measures are optimized,the magnesium anode polarity grounding drainage device is added,and the pipe ground potential is simulated.In the areas where interference is still strong,a dense magnesium anode polarity grounding drainage device is added to simulate the pipe ground potential.According to the simulation results,it is concluded that the protective measures of forced grounding discharge have a good effect on improving the interference of the gas pipeline network in the whole area,especially within 1 km discharge radius of the forced grounding discharge station.For some pipe sections that are closer to the interference source,further protective measures can be taken.Pipes that are close to the forced grounding drainage station are likely to have anti-corrosion layer detachment and other phenomena due to the large negative displacement of the pipe ground potential.After the dense magnesium anode polarity grounding discharge device is added,the strong interference of the other sections has been obviously suppressed except the pipe section within 20 m from the rectifier.The influence range of forced grounding drainage is larger,the influence range of magnesium anode polarity grounding drainage is small,and the drainage effect is poor.When both types of protective measures are available at the same time,the forced grounding discharge should be given priority.