激光诱导击穿光谱应用于电站锅炉受热面组织结构和性能诊断的研究

发布时间：2018-07-08 20:13

本文选题：激光诱导击穿光谱技术 + 锅炉受热面　；参考：《华南理工大学》2016年博士论文

【摘要】：在火力发电行业,承受高温高压的金属材料的安全问题至关重要。据统计,由于金属材料失效引起受热面爆管等事故占火电厂各类非计划停运事故的50%以上。一旦计划外停运和发生故障,将会造成巨大经济损失和人员伤害,对社会产生不利的影响。受热面材料在长期的高温高压服役过程中,其微观组织结构会发生一系列的变化,最终导致裂纹的产生和力学性能的下降,进一步导致发生爆管等事故的几率大大增加。受热面材料的这种组织结构变化和机械性能退化称为老化。由于缺乏快速有效的监测技术,现役电厂往往通过未到期更换受热面材料等措施来降低受热面爆管事故的发生率,从而确保机组运行安全性。而已有的受热面失效检测技术存在各自的局限性,对检测环境和被检测部件的要求高,无法在受热面材料还在服役状态时对其失效趋势进行预测分析。激光诱导击穿光谱技术(Laser-Induced Breakdown Spectroscopy,LIBS)是近年来发展起来的一种原子发射光谱分析技术。它能够分析物质的成分和含量,具有对分析物损伤小、多元素同步检测、快速、可实现远距离检测等优点,同时激光诱导击穿光谱技术也受基体效应的影响。对于传统的定量分析而言,基体效应的存在是不利因素,然而恰恰可以利用基体效应来反映被检测对象的组织结构特性。本文正是利用基体效应的存在尝试将LIBS技术引入到电厂锅炉受热面的检测中。利用LIBS对电厂受热面材料进行检测,通过等离子体特性来反映受热面材料的组织结构与特性,为发展锅炉受热面高温失效趋势预测分析技术提供理论依据。论文在调研了受热面失效分析的技术水平和研究现状的基础上,阐述了本论文的研究背景与意义。并介绍了常用的受热面失效分析无损检测方法,阐述了LIBS的发展历程以及LIBS在金属材料领域的相关研究以及对基体效应的研究,提出了本文的研究内容。基于LIBS的原理以及等离子体的物理特性,搭建了一套可以适用于不同管径受热面管材检测的LIBS实验装置。为了深刻理解本文主要的研究对象12Cr1MoV和T91钢,对其的特性和失效机理进行了详细的分析。利用单色仪并配合示波器对对不同金相组织的12Cr1MoV的等离子体特性进行了分析。根据12Cr1MoV钢的含量选取一些特征谱线来对比分析,主要对比了同一元素的离子线和原子线以及不同金相组织样品间的等离子体时间演化特性。并分析了等离子体强度与金相组织之间的关系。同时还研究了金相组织同为回火索氏体但碳化物颗粒大小不同的T91的等离子体时间演化特性。分析了不同抗拉强度T91的等离子体特性,引入PCA分析方法对其进行区分,并建立了谱线强度、离子线和原子线的谱线强度比与抗拉强度之间的线性关联性。最后利用LIBS技术对不同老化等级的T91进行研究。分析其等离子体特性(等离子体温度、电子密度、等离子谱线强度)与老化等级之间的关系。建立了离子线与原子线的谱线强度比与老化等级之间的关联性,同时也建立了合金元素与基体元素的谱线强度比和老化等级以及硬度之间的关联性。所得到的Cr/Fe和Mo/Fe的谱线强度比与老化等级和硬度呈现良好的线性关联性,为发展受热面失效趋势预测分析的新方法以及LIBS技术在新领域和新方向的发展奠定了理论基础和实践依据。
[Abstract]:In the thermal power industry, the safety of metal materials under high temperature and high pressure is very important. According to statistics, more than 50% of the non planned outage accidents in the fire power plant caused by the failure of metal materials are caused by the failure of the metal materials. In the course of long term high temperature and high pressure service, a series of changes will occur in the microstructure and structure of the heated surface material, which leads to the formation of the crack and the decline of the mechanical properties. The probability of the accidents of the detonator is greatly increased. The structural change and mechanical properties of the heated surface materials are called the deterioration of the mechanical properties. Aging. Due to the lack of rapid and effective monitoring technology, active power plants often reduce the incidence of detonating accidents in the heated surface by means of undue replacement of heat surface materials and so on, thus ensuring the safety of the units, and the existing failure detection techniques of the heated surface have their own limitations and high requirements for the detection environment and the detected components. Laser-Induced Breakdown Spectroscopy (LIBS) is an atomic emission spectrum analysis technique developed in recent years. It can analyze the composition and content of the material, which has small damage to the analyte and the same element. For the traditional quantitative analysis, the existence of the matrix effect is an unfavorable factor. However, the matrix effect can be used to reflect the structural characteristics of the detected image. This paper is using the matrix effect. The LIBS technology is introduced into the thermal surface testing of the power plant boiler. Using LIBS to detect the heat surface materials of the power plant, the structure and characteristics of the materials are reflected through the plasma characteristics, and the theoretical basis is provided for the development of the prediction and analysis technology for the high temperature failure trend of the heating surface of the boiler. On the basis of the technical level and research status of failure analysis, the research background and significance of this paper are expounded. The common nondestructive testing methods for the failure analysis of heating surface are introduced, the development course of LIBS and the related research of LIBS in the field of metal materials and the research on the matrix effect are discussed. The research content of this paper is put forward. On the basis of the principle of LIBS and the physical characteristics of the plasma, a set of LIBS experimental equipment which can be applied to the detection of pipe material with different pipe diameter is set up. In order to understand the main object of this paper, 12Cr1MoV and T91 steel, the characteristics and failure mechanism are analyzed in detail. The monochromator is used and the oscilloscope is used for different gold. The plasma characteristics of the phase organized 12Cr1MoV are analyzed. According to the content of the 12Cr1MoV steel, some characteristic spectral lines are selected to compare and analyze the plasma time evolution characteristics between the ions and the atomic lines of the same element, as well as the samples of different metallographic structures, and the relationship between the plasma intensity and the metallographic structure is analyzed. At the same time, the plasma time evolution characteristics of the T91 with different size and size of the carbide particles are studied. The plasma characteristics of different tensile strength T91 are analyzed, and the PCA analysis method is used to distinguish them, and the spectral line strength, the spectral line strength ratio of the ion line and the atomic line and the tensile strength are established. In the end, LIBS technology is used to study the T91 of different aging grades. The relationship between plasma characteristics (plasma temperature, electron density, plasma spectral intensity) and aging grade is analyzed. The correlation between the spectral line intensity ratio of the ion line and the atomic line and the aging grade is established, at the same time, the relationship between the plasma intensity ratio and the aging grade is established. The correlation between the spectral line strength ratio of the alloying elements and the matrix elements and the aging grade and hardness. The spectral line strength ratio of Cr/Fe and Mo/Fe has a good linear correlation with the aging grade and hardness. It is a new method for developing the prediction and analysis of the failure trend of the heating surface and the development of the LIBS technology in the new and new directions. The theoretical basis and practical basis.
【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TM621.2

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