直流杂散电流下埋地金属管线的腐蚀与防护研究

发布时间：2018-08-23 20:08

【摘要】：杂散电流主要形成局部腐蚀,管道流入杂散电流的一段被称为阴极,流出的部分被称为阳极。一般在阳极区会发生金属的腐蚀,如果破损部分没有被及时发现,长期的腐蚀会造成管道穿孔,造成不可估量的严重事故。直流杂散电流的危害远远高于交流杂散电流,本文主要研究直流杂散电流对埋地金属管道的影响。本论文采用数值模拟方法加入到杂散电流腐蚀的研究中,用COMSOL Mulitiphysics软件中的腐蚀模块进行研究,用物理模拟进行验证。本文的研究内容如下:(1)本文首先研究了不同的二维模型,研究了单根管道模型、平行管道模型及垂直管道模型,得出用牺牲阳极的方法可以保护管道,未受管道模型的模型电解质电势为0 V-1 V左右,保护管道的电势降到了负值,得到了保护。(2)本文用数值模拟的方法分别研究了三维模型单根管道模型、平行管道模型、互成度角管道的模型模型,分别对它们进行了相应的阴极保护研究,随着土壤电导率的增大电解质电势呈现增大的趋势说明土壤电导率增大促进腐蚀,随着外电压的增大电解质电势呈现增大的趋势说明外电压也可以促进腐蚀。可以采取相应的措施减少外电压及选择土壤电导率较小的地方进行施工。电解质电势随着外电压的增大而增大;不同的埋设角度不会影响电解质电势的数值,对电解质电势的趋势会有一定影响。(3)实验对验证数值模拟具有重要的作用,实验模拟的结果与数值模拟的出的结果基本上是一致的,采用杂散电流收集网和排流的措施可以有效减小杂散电流腐蚀,其中极性排流能使电势降到-0.85 V以下,对管道有很好的保护效果。
[Abstract]:Stray current mainly forms local corrosion. A section of stray current is called cathode and the outflow part is called anode. Generally, metal corrosion occurs in the anode area. If the damaged part is not found in time, long term corrosion will lead to pipeline perforation, resulting in incalculable serious accident. The harm of DC stray current is much higher than that of AC stray current. The effect of DC stray current on buried metal pipeline is studied in this paper. In this paper, numerical simulation method is applied to the study of stray current corrosion, and the corrosion module in COMSOL Mulitiphysics software is used to study it, and the physical simulation is used to verify it. The main contents of this paper are as follows: (1) in this paper, different two-dimensional models are studied, including single pipe model, parallel pipeline model and vertical pipeline model. It is concluded that sacrificial anode can be used to protect pipeline. The electrolyte potential of the model without the pipeline model is about 0 V -1 V, and the potential of the protection pipe is reduced to negative value. (2) in this paper, the single pipe model and the parallel pipe model of the three dimensional model are studied by numerical simulation. The corresponding cathodic protection studies were carried out on the models of interdependency angle pipes. With the increase of soil conductivity, the electrolyte potential showed an increasing trend, which indicated that the increase of soil conductivity promoted corrosion. The electrolyte potential increases with the increase of external voltage, indicating that external voltage can also promote corrosion. The corresponding measures can be taken to reduce the external voltage and select the places where the soil conductivity is low. Electrolyte potential increases with the increase of external voltage, and different embedding angles will not affect the value of electrolyte potential, but will have a certain effect on the trend of electrolyte potential. (3) experiments have an important role in the verification of numerical simulation. The results of experimental simulation are basically consistent with those of numerical simulation. The stray current corrosion can be effectively reduced by using stray current collection network and drain current, in which the polarity drain can reduce the potential below -0.85 V. It has a good protective effect on the pipeline.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG174

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