材料期刊网

目的：对海洋平台导管架外加电流阴极保护设计通电点的选择等问题进行分析，为海洋平台导管架阴极保护设计提供指导。方法利用BEASY CP数值模拟软件，通过数值模拟计算方法对导管架外加电流阴极保护系统设计的基础问题进行了研究，包括保护对象的确定、通电点的设置、辅助阳极选型和阳极数量及安装位置等。结果导管架外加电流阴极保护设计时，若只考虑海水浸渍部分，则无法使导管架海水和海泥部分均得到有效保护。设置通电点时，考虑电阻（1.01×10-6Ω/m）和不考虑电阻两种情况下导管架的保护电位相近，绝对误差不超过1 mV，通电点的位置对保护效果影响较小。阴极保护输出电流为17 A时，三种不同直径（300、600、900 mm）辅助阳极阴极保护系统的保护相近，保护电位在803~899.2 mV(vs. CSE)之间。三种不同阳极设计方案的输出电流分别为17、17、16.5 A，对应的保护效果分别为803.34~899.20 mV（vs. CSE）、802.96~850.64 mV（vs. CSE）、800.36~848.26 mV（vs. CSE）。2#阳极的保护效果比1#阳极的保护效果均匀，两支阳极方案在最低保护效果下所需电流比单支阳极更小且保护更均匀。结论设计外加电流阴极保护系统时，应当充分考虑与待保护对象相连接的所有金属结构物。对于小型导管架而言，金属电阻对导管架外加电流阴极保护系统的电位分布影响很小，因此通电点的选择较容易。外加电流阴极保护系统设计时应考虑电流密度对辅助阳极的消耗影响，选取适当尺寸的阳极。通过数值模拟方法，可以优化阳极数量和位置，从而实现保护电流较小且保护效果更均匀，并满足一定的经济性要求。

ABSTRACT:ObjectiveThe position of the structure where the electric current flows into and several other problems were studied in the designing process of impressed current cathodic protection for offshore jacket, and the achievement could offer a reference for cathodic protection of platform offshore jackets.MethodsIn this paper, several problems in the design of im-pressed current cathodic protection for offshore jacket, including protected objects, power point, the selection of auxiliary anode, the number and the locationof auxiliary anode, were studied by the numerical simulation software, BEASY CP.ResultsIf only considering the part of offshore jacket surrounded by seawater, the structure could not be protected effectively by the impressed current cathodic protectionsystem. The protective potential of the two design schemes including and excluding resistance (1.01×10-6Ω/m) was close to each other and the absolute error was less than 1 mV. The protective potential was less affected by the setting of power point. The distribution of protective potential with three different diameters of auxiliary anode, 300 mm, 600 mm and 900 mm, were all in the range of803~899.2 mV (vs. CSE). The protective potential of three anode design schemes with 17 A, 17 A and 16.5 A output current respectively, were 803.34~899.20 mV (vs. CSE), 802.96~850.64mV (vs. CSE) and 800.36~848.26 mV (vs. CSE), respectively. It can be seen that the protective effect of 2#anode scheme was better than 1# anode scheme, and the anode scheme with two anodes was the best. ConclusionAll metal structures should be considered in the de-signing process of the impressed current cathodic protection system for offshore jacket. For small jacket, the protective potential was less affected by metal resistance, so the power point was easy to determine. It was important to consider the influence of current density on anode consumption and select the suitable anode size in the process of cathodic protection system design.The number and setting location could be optimized by numerical simulation method in order to obtain a better protective effect and reduce the requirement of protective current.