【作者】 刘保余；

【导师】 綦耀光；

【作者基本信息】 中国石油大学 ， 机械设计及理论， 2010， 博士

【摘要】 管道内检测器是一种对长输管道进行在线无损检测的有效设备,随着西气东输、川气东送等工程相继投入使用,我国长输天然气管道的安全成为影响国计民生的重要因素,因此,开展在线输气管道内检测器研究意义重大。由于天然气的可压缩性和干燥性,内检测器的平稳运移系统的研究和检测磁路的设计,成为实现输气管道检测和达到输气管道检测精度要求的关键。本文从上述两个关键问题为切入点,对输气管道内检测器的驱动运移、检测系统等主要部分进行了理论分析和实验研究。建立了不同驱动皮碗结构在不同管路状态下运移的动力学方程,设计制作了运移装置模拟实验台,对输气管道内检测器检测系统进行了设计和优化,建立了现场模拟试验系统,对现场实验样机进行了检测实验,通过研究认为:使用漏磁检测技术对输气管道缺陷进行内检测是可行的,通过分析输气管道缺陷形成的机理和缺陷信号的特征,对干燥高压气体环境下的检测系统进行研究和设计,解决了管壁内、外缺陷的识别问题,优选并验证了磁化器和传感器的提离值,对周向励磁检测技术进行了理论探讨和数值模拟并提出了非均匀磁场内缺陷信号的判读和修正办法;经现场试验验证,该技术对漏磁信号的采集和对缺陷的识别能够满足输气管道的要求,可以检出直径大于2mm、深度大于1.5mm或直径大于3mm,深度大于1mm的以上的管道缺陷;提出并验证了输气管道内检测最佳的检测速度区间,管道缺陷的检出率随着检测器移动速度的增加而降低,当检测器移动速度大于4m/s时,其检出率急剧下降,由此可得出对输气管道进行内检测,速度控制是完成有效检测的关键。建立了不同结构驱动器的运动动力学分析模型,深入研究了常规驱动皮碗、弹性底板驱动皮碗、伞型驱动皮碗等皮碗结构、压差与驱动器运移状态的关系,得到:常规和弹性底部皮碗驱动器在水平管路内运移时,皮碗的唇部结构、材料选择和管路障碍是影响检测器稳定运行的显著因素;在起伏管路内,皮碗唇部悬臂梁长度L对稳定运行的影响最显著;在底部刚度、推动压差、唇部悬臂梁长度L在一定范围内取值时,内检测器可以在水平管道内平稳运移,但难以实现在起伏管路内稳定运移;通过合理的改进驱动器唇部结构和底部刚度,可以实现在给定的压差和有限起伏高度内,内检测器在给定的速度范围内稳定运动的要求;采用新型伞状变刚度驱动皮碗,可以在更大起伏高度内实现内检测器稳定运行的目的。设计制造了可供现场模拟检测实验用的试验台和Ф1016输气管道内检测器原型机,进行了工业输气条件下的现场模拟试验。现场试验表明:检测器的运移速度控制是输气管道内检测的关键,通过合理设计驱动皮碗的结构可以实现检测器在起伏20度以内的输气管道的平稳运行;通过对所采集的模拟缺陷信号的统计分析,验证了缺陷与漏磁信号之间的定量关系,内外伤识别的可行性,检出率与速度的关系以及磁路设计的合理性,为输气管道内检测器的设计提供理论依据和设计模板。更多还原

【Abstract】 Inner Inspection PIG is a kind of effective equipment which was used to test the gas and oil pipeline. As the West-East natural gas pipeline and the Sichuan-East gas pipeline are put into service, the safety of our gas pipelines has become a significant issue which impact national economy and people’s livelihood, so it is very important to study the Inner Inspection PIG. Because of the compressibility and aridity of the gas, the steady motion and optional magnetic circuit are the keys to meet the need of inspection precision. The dissertation begins with the two critical items mentioned above, and studies the main parts of Inner Inspection PIG such as drive system and inspection system on theory and experiment. The dynamic equations of different drive cups in various pipeline have been establish , the model test bed of move device has been created , the system of smart PIG has been designed and optimized .The site simulant experiment system has been built, and the prototype of Inner Inspection PIG has been tested .The following has been got through the research:It is feasible to inspect the defect of gas pipeline by the technology of magnetic flux leakage. Through analyzing formation mechanism and signals character of defects, detecting system in dry and high pressure gas environment has been studied and designed, the internal and external defects identification has been solved. The lift-off of magnetizer and sensor has been chosen and verified.It studies on the theoretical discussion and numerical simulation on circumferential MFL technology and puts forward the identification and modification method of defects signals in non-uniform magnetic field. The technology can detect the defects which diameter is more than 2mm and depth is more than 1.5mm or diameter more than 3mm and depth more than 1mm and it can fit the need of the gas pipeline inspection. It proposes and verifies the optimal detection in terval of velocity.The relevance ratio drops with the speed of Inner Inspection PIG raising, and when the speed is more than 4m/s the relevance rate will drop dramatically. Controlling the speed is a key to get an effective detection when we inspect the gas pipelines.The motion and dynamics analysis model of driver cups with different structure has been created ,the relationship of the cups structure ,which including common drive cup, elastic bottom cup and umbrellashaped dirve cup, difference in pressure and the moving state of driver has been researched. The conclusions are: when common cup and elastic bottom cup move in level pipeline, the lip structure of cup, material and obstruct in pipeline are the major factors which affect the steady motion of Inner Inspection PIG. In undulant pipeline, the length of cantilever beam of cup lip affect the steady motion of Inner Inspection PIG significantly. If the stiffness, driving pressure and the length of cantilever beam of cup lip are unchanged, Inner Inspection PIG can move steadily in level pipelines , but it is hardly to complete the steadily movement in undulant pipeline . By improving the structure of the driver lip and the stiffness of the bottom, Inner Inspection PIG can moves steadily in limited undulant pipeline and certain different pressure .If the new umbrellashaped cup, which can change its stiffness is used, Inner Inspection PIG can move steadily in more undulant pipeline. The test bed, which could be used in simulatiom experiments has been designed and built.The gas pipeline prototype,namedФ1016 inner inspection PIG has been manufactured and several site simulation experiments have been done. The site experiments results show that velocity control is the key in gas pipeline inspection.The speed can be controlled in 20 degree fluctuation pipeline by changing the structure of driver cup. And BIG can move steadily in 20 degree fluctuation pipeline. A certain quantitative relation between defects and MFL signails has been verified.The simulation experiments also show that it is feasible to identify the internal and externail defects, and there is relationship between velocity and relevance ratio, the reasonableness in magnetic circuit design. Theoretical basis and designing template have been given on designing inner inspection in gas pipeline.更多还原