【作者】 高廷岩；

【导师】 戴光； 杨大明；

【作者基本信息】 东北石油大学 ， 化工过程机械， 2011， 硕士

【摘要】 石油化工企业和储运站等存在着大量地面管道,这些管道不断的将油、气等介质输送到各自目的地。此类管道在运行过程中通常受到来自内外环境的联合影响,由于外部空气、输送介质、管内积液、压力波动等原因,极易发生管壁腐蚀而直接影响管道的使用寿命。因此如何了解管道的腐蚀状况,有目的地对管道进行维修,减少事故发生,延长管道的服役时间,就成了检测人员关心的主要问题。漏磁检测法因具有检测速度快、灵敏度高、不受管内介质影响等优点被广泛地应用于工业管道的检测,近些年来漏磁检测无论在其理论研究还是工程应用中都取得了很大的成就。本文针对石化工业地面管道特点,设计出一种检测结构,该结构能采用三个分离式磁化单元组合的形式,结构中各个磁化单元的衔铁、永久磁铁和极靴与待检测的管道形成闭合磁回路,通过采集及分析磁回路中产生的漏磁场信息,从而确定管道壁上存在的缺陷。该种检测结构简单、体积小,可以通过调整磁化结构间的相对角度满足不同直径管道的检测需要,扫描面积大、效率高。文中利用有限元方法建立三维静态漏磁检测模型,模型以单个磁化结构为基础,继而建立了多个磁化单元有限元分析模型。应用Ansys软件提供的优化设计方法,对本研究的三磁化单元检测结构进行优化设计,通过确定合理的优化设计变量、状态变量和目标函数,使得本设计的管道外多磁化单元检测结构,能够实现对直径为6mm,深度为管壁厚度的40%缺陷进行较好的检测;使得磁化结构下方的管道磁化强度分布更加合理、易于描述,同时满足对管道缺陷检测的要求和管道均匀磁化的要求。基于优化设计的结构尺寸,通过计算得到不同磁化单元个数、磁化结构间距漏磁场分布曲线,对比分析由于多个磁化结构的引入所引起的缺陷漏磁场叠加规律、各磁化单元间的相互影响。采用有限元计算得到优化尺寸,作为漏磁检测仪结构设计尺寸,对样机结构进行磁化结构、行进结构等设计,最终确定样机整体结构。在实验室条件下尺寸,完成样机的装配、调试,建立管道外多磁化单元检测系统。对磁化单元间的相互影响、不同位置及尺寸的腐蚀缺陷检测效果、及不同管径管道检测效果进行了实验研究,并将部分实验数据与数值模拟结果进行对比,验证有限元分析的正确性。更多还原

【Abstract】 There are massive ground pipes in petrochemical enterprises and storage stations, these pipelines transported oil, gas, and other media to their destination constantly. Such pipeline usually suffer from both internal and external environment influence in operation process, because of outside air, transmission medium, tube effusion, pressure fluctuations and other reasons, pipeline corrosion easily happened. Therefore, how to understand pipeline corrosion situation, to maintenance with purpose, to reduce accidents, to prolong the pipeline duty time, became the main problem for examination person. Magnetic flux leakage testing have been widely used in industry pipeline detection because of its fast inspection speed, high sensitivity, do not suffer between medium influence etc, and the magnetic flux leakage testing have made great achievements whether in theory research or engineering applications in recent years.In this paper, a multi-magnetize structure for ground pipeline in petrochemical industry was designed, this structure comprise three units, armature, permanent magnet, pole piece, form a closed magnetic circuit along with pipeline. It can be detected whether defects exist in pipeline through acquiring and analyzing MFL information. There are characteristics of Small volume and Simple structure we designed structure, in addition, each unite can be adjusted relative angle to meet the requirement for detection of pipes with different size.3D static magnetic flux leakage testing model was established, using finite element model in this paper, based on single magnetized structure. Applied the optimization method Ansys software provides for this three magnetized unit testing structure, through the determination of reasonable optimization design variables, the state variables and the objective function, makes this multi-magnetized testing structure can achieve well defects detection of 6mm and depth of 40% for the thickness; make the field of magnetized pipeline distribute more reasonable and easy to describe, and satisfy the requirements of defect detection and magnetic field reasonableness simultaneously. Based on the size of optimization design, magnetic field leakage curves of different magnetization unit number, structure spacing were gained. Then contrast and analyze the law of magnetic leakage field and inter-influence of units.Take the optimized size as structure size of MFL device, magnetization structure and other structures were designed, complete the assemblage and debugging of device, finally established pipeline testing system under the condition of laboratory. The inter-influence of units, the effect of corrosion defection and different diameter pipeline, were gained through experiments, the experimental data validate the correctness of finite element analysis results.更多还原