酸性红壤环境中变电站接地材料腐蚀及防护研究

发布时间：2019-02-13 09:02

【摘要】：接地装置是电力系统安全运行的基本保障,加强地网的安全建设也符合社会发展的需要。本文以酸性红壤为研究环境,开展了接地材料在选材和防腐方面的研究,为酸性红壤区接地网的改造提供理论和技术上的支持。在实验方面,首先对多种接地材料(碳钢、镀锌钢、表面钝化的镀锌钢、锌铝合金涂层钢、铜、铜覆钢、炭黑导电涂层钢以及碳聚合物导电涂层钢)进行现场埋设实验,从腐蚀电位、腐蚀形貌、腐蚀产物及腐蚀数据等方面分析接地材料的腐蚀机理及耐蚀性能。然后采用降阻剂(炭黑系降阻剂和膨润土系降阻剂)和阴极保护法对常用接地材料进行防护研究,分析不同措施的防腐效果。此外还开展了阴极保护的工程技术试验研究,分析牺牲阳极保护法和外加电流保护法的使用范围和实际保护效果。实验研究结果表明:在红壤环境中,碳钢腐蚀严重,腐蚀速率可达到6.9393g/dm2·a;镀锌钢次之,腐蚀速率可达3.2575g/dm2·a,对碳钢具有一定的保护作用,但锌层太薄,寿命有限。钝化锌层和锌铝合金涂层都可以较好地改善锌涂层的性能,延长涂层寿命,其中锌铝合金涂层效果最为显著,腐蚀速率可降低至0.6333g/dm2·a。铜及铜覆钢活性较低,耐蚀性很好。碳钢以点蚀为主,但随含水量的增加有向不均匀的全面腐蚀发展的趋势。锌及锌合金涂层具有较好的阴极保护作用,以涂层的局部腐蚀为主,基体金属不存在点蚀现象。两种有机涂层材料(炭黑导电涂层和碳聚合物导电涂层)都具有很强的耐蚀性,但存在着涂层破损的问题,易造成严重点蚀,宜与阴极保护和涂覆锌合金涂层等抗点蚀的防腐措施联合使用。炭黑降阻剂电阻率很低,具有很好的降阻效果,但其腐蚀性受其自身和接地材料结构影响很大。当其能够与接地材料紧密结合时,可以隔离腐蚀介质与接地体,减小腐蚀,但当结合松散时则会造成加速腐蚀。膨润土降阻剂不但降阻效果良好,且腐蚀性很低,其包覆碳钢的腐蚀速率可降至1.1950g/dm2·a,点蚀现象较轻。阴极保护法可较好地阻止点蚀的发生,尤其对于有机涂层材料。但保护电位不宜过负,以防止造成严重的阴极析氢现象。牺牲阳极的阴极保护法宜用于小型地网的防腐,保护度可达到约70%。外加电流阴极保护法可用于大型地网的防腐,实际保护度可达到80%。
[Abstract]:Grounding device is the basic guarantee for the safe operation of power system, and strengthening the safety construction of ground grid is also in line with the needs of social development. In this paper, the selection and anticorrosion of earthing materials in acidic red soil are studied in order to provide theoretical and technical support for the reconstruction of earthing grid in acidic red soil area. In the aspect of experiment, field experiments were carried out on a variety of grounding materials (carbon steel, galvanized steel, passivated galvanized steel, zinc-aluminum alloy coated steel, copper coated steel, carbon black conductive coating steel and carbon-polymer conductive coating steel). Corrosion mechanism and corrosion resistance of earthing materials are analyzed from corrosion potential, corrosion morphology, corrosion products and corrosion data. Then the common earthing materials were studied by using resistance reducing agent (carbon black series resistance reducing agent and bentonite series resistance reducing agent) and cathodic protection method, and the anticorrosive effect of different measures was analyzed. In addition, the engineering experiment of cathodic protection is carried out, and the scope of application and practical protection effect of sacrificial anode protection and applied current protection are analyzed. The experimental results show that carbon steel is corroded seriously in red soil environment, and the corrosion rate can reach 6.9393g/dm2 a; The corrosion rate of galvanized steel is up to 3.2575g/dm2 a, and it has some protective effect on carbon steel, but the zinc coating is too thin and its life is limited. Both passivated zinc coating and zinc aluminum alloy coating can improve the properties of zinc coating and prolong the coating life. The effect of zinc aluminum alloy coating is the most obvious, and the corrosion rate can be reduced to 0.6333g/dm2 a. Copper and copper coated steel have low activity and good corrosion resistance. Pitting corrosion is the main corrosion of carbon steel, but with the increase of water content, there is a trend of non-uniform overall corrosion. Zinc and zinc alloy coatings have good cathodic protection, the local corrosion of the coating is the main, and there is no pitting corrosion in the substrate metal. Two kinds of organic coating materials (carbon black conductive coating and carbon polymer conductive coating) have strong corrosion resistance, but there is the problem of coating damage, which is easy to cause serious pitting corrosion. It should be used in combination with cathodic protection and zinc alloy coating. Carbon black resistive reducer has low resistivity and good resistance reduction effect, but its corrosiveness is greatly affected by its own structure and grounding material structure. When it can be closely combined with the grounding material, it can isolate the corrosion medium from the earthing body and reduce the corrosion, but when the combination is loose, it will cause accelerated corrosion. Bentonite resistance reducing agent not only has good resistance reduction effect, but also has a low corrosion rate. The corrosion rate of carbon steel coated with bentonite can be reduced to 1.1950g/dm2 a, and the pitting corrosion is light. Cathodic protection can prevent pitting, especially for organic coating materials. However, the protective potential should not be too negative to prevent serious cathodic hydrogen evolution. The cathodic protection of sacrificial anode is suitable for anticorrosion of small earth net, and the protective degree can reach about 70. The applied current cathodic protection method can be used for anticorrosion of large earth net, and the actual protection degree can reach 80%.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM63;TM862

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