用固体电解质涂料对贮油罐外底实施外加电流阴极保护

IMPRESSED CURRENT CATHODIC PROTECTION OF EXTERNAL TANK BOTTOM WITH SOLID-ELECTROLYTE-CONTAINING COATING

本文提出了钢质贮油罐外底阴极保护的一个新方案。在贮罐基础的最上层依次铺敷电子导电的阳极涂层和离子导电的固体电解质涂层。与罐底钢板构成保护电流的回路,用外加直流电源使罐底阴极极化。与传统的技术相比较,它的主要特点是:保护电流不会向外泄漏,与周围的金属构筑物之间不必安装绝缘法兰,并能改善罐底电位分布的均匀性。模拟罐小试和一万立方米贮油罐现场试验都表明,这个新方案是可行的。

A new approach of impressed current cathodic protection for external tank bottom has been developed. An electronically conducting anode coating was applied on the bituminous sand base for above-ground storage tank, followed by a specially formulated CK coating, which contains the solid electrolyte sodiumβ(β″)alumina as an ionically conducting component. Graphite electrodes were embedded in the CK coating to control and/or monitor the cathode potential. The multilayer structure consisting of external tank bottom, CK coating and anode coating enables the completion of current circuit. An appropriate d.c. power source was used to provide current. Compared with conventional cathodic protection techniques, the new approach has significant advantages. Due to the close proximity of cathodically proretted urface to coating anode, the cathodic protection current would not be lost outwards. As a result, the tank to be protected is not necessarily isolated from neighbouring underground metallic structures. At the same time, it also leads to more uniform distribution of protective potential. The feasibility of the proposed technique has been verified both by small simulating tank and by practical applications. Such a cathodic protection system for an above-ground storage tank of 30-m in diameter by 15.8-m in height has already been in operation successfully for two years.