Thesis Advisor黄云, 李军
Degree Grantor中国科学院大学
Degree Name博士
Degree Discipline化学工程

固相反应过程在能源和化工领域普遍存在,且常伴随各种金属物质的迁移。在清洁燃烧领域,金属不仅对换热设备积灰具有影响,也是超低排放催化剂中毒的重要原因。在可再生能源领域,金属熔盐作用于光热发电站的储能材料,同时作为相变材料也引起广泛的研究兴趣,且储能材料在高温火焰场中的稳定性尚未获得广泛研究。本论文选取储能材料、有机固废两类当前清洁能源领域高关注度研究对象,研究高温火焰场中固相反应过程。论文以同轴扩散火焰燃烧器、Hencken多元扩散平焰燃烧器为基础,结合激光诱导击穿光谱(LIBS)原位光学诊断平台,研究了相变储热材料、市政污泥和沼渣在高温火焰场中的反应过程。同时,本文借助同步热分析法(STA)对储热材料热稳定性,以及市政污泥和沼渣的热解及燃烧特性进行研究,并使用扫描电子显微镜(SEM)、X-射线衍射仪(XRD),X-射线荧光光谱仪(XRF)、工业分析、元素分析以及激光粒度分析等分析测试手段,对样品性质进行表征。在高温火焰场中,碱金属硝酸盐(NaNO3或KNO3)与氧化物(SiO2或MgO)制备的定型复合相变储热材料出现形变和热分解过程。研究发现陶瓷骨架材料(SiO2或MgO)能够改善相变储热材料的热稳定性。在测量参数中,温度对硝酸盐分解的影响最大。比较STA和LIBS所测初始分解温度和分解峰值温度,Na、K的LIBS测量具有早期指示的优势,因此在预测储热材料热稳定性和化学相容性方面具有重要意义。市政污泥采用同步热分析方法研究发现热解持续发生在整个升温过程中;燃烧过程则可以分为三个阶段,包括水分析出、挥发分析出以及固定碳燃尽阶段。在污泥燃烧过程中,利用PS-LIBS探测到Na、Ca和Al元素的特征原子发射光谱。PS-LIBS利用气相击穿极限高于颗粒相从而选择性击穿颗粒相的特点,发现Na元素含量随燃烧三阶段呈现衰减-增加-衰减规律;而Ca和Al元素则变化不大。使用同轴扩散火焰燃烧器结合同步热分析技术分别对沼渣的燃烧及热解特性进行实验研究,发现沼渣的热解在整个升温过程中持续进行。沼渣的燃烧过程则可分四个阶段,包括:水分析出阶段、挥发分析出燃尽阶段、固定碳燃尽阶段和灰分反应阶段。;Solid-phase reaction processes are ubiquitous in the energy and chemical industries, and are often accompanied by the migration of various metal substances. In the field of clean combustion, metals not only have an impact on ash deposits in heat exchange equipment, but also a significant cause of ultra-low emission catalyst poisoning. In the field of renewable energy, molten salt acts on energy storage materials in concentrating solar power plants. At the same time, they have also attracted extensive research interest as phase change materials. However, the stability of energy storage materials in high temperature flame fields has not been widely studied. This thesis seclects energy storage materials and organic solid waste to study the solid phase reaction process in a high temperature flame field.Based on the coaxial diffusion flame burner and the Hencken multi-element diffusion flat flame burner, combined with the laser induced breakdown spectroscopy (LIBS) in-situ optical diagnostic platform, the thesis studies the solid phase reaction process in the high temperature flame field of the phase change heat storage materials, municipal sludge and biogas residue. At the same time, this thesis used the simultaneous thermal analysis (STA) method to study the thermal stability of thermal storage materials, as well as the pyrolysis and combustion characteristics of municipal sludge and biogas residue. Moreover, this thesis used scanning electron microscope (SEM) and X-ray diffractometer (XRD), X-ray fluorescence spectrometer (XRF), proximate analysis, ultimate analysis, laser particle size analysis and other analytical test methods to characterize the properties of the sample.Deformation and thermal decomposition were taken place in the processes that the ceramic skeleton materials (CSM, SiO2 and MgO) based alkali metal nitrate (NaNO3 or KNO3) form-stable composite phase change material in a high-temperature flame field. The study revealed that CSM improved the thermal stability of phase change heat storage materials. Among the measured parameters, temperature has the greatest influence on nitrate decomposition. Comparing the onset temperature of decomposition and peak temperature of decomposition measured by STA and LIBS, the LIBS measurement of Na and K has the advantage of early indication. Therefore, it is of great significance in predicting the thermal stability and chemical compatibility of heat storage materials.STA of municipal sludge found that pyrolysis continued to occur throughout the heating process; the combustion process could be divided into three stages, including a water loss stage, volatiles release and burnout stage and a fixed carbon burnout stage. PS-LIBS was used to detect the characteristic atomic emission spectra of Na, Ca and Al elements in the process of sludge combustion. By utilizing the gap between the excitation energies of the gas and particle phases, PS-LIBS was applied to distinguish the existence of metal elements in the particle or gas phase selectively along the combustion process. It was found that the content of Na element decayed first, then increased slightly and declined eventually with the three stages of combustion process, while the elements of Ca and Al changed little. Combining coaxial diffusion flame burner with STA technology to conduct an experimental study on the combustion and pyrolysis characteristics of biogas residue. It revealed that the pyrolysis process continued throughout the temperature increase process. The combustion process could be divided into four stages, including: water loss stage, volatiles release and burnout stage, fixed carbon burnout stage and ash reaction stage.

Document Type学位论文
Recommended Citation
GB/T 7714
黄巧. 高温火焰场中基于LIBS原位光学测量的固相反应过程研究[D]. 中国科学院大学,2020.
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