铬铝锆砖的损毁机理及无铬化耐火材料体系设计研究

发布时间：2018-06-26 07:18

本文选题：铬铝锆砖 + 结合剂　；参考：《武汉科技大学》2016年博士论文

【摘要】：水煤浆气化技术是高效洁净使用煤的重要途径,气化炉则是其中关键的高温反应容器。为了保证气化炉的安全高效运行,耐火材料的长寿与稳定是必要前提。由于氧化铬在气化炉渣中极低的溶解度,氧化铬含量超过75wt%的磷酸盐结合铬铝锆材料是目前气化炉内衬的主流材质。然而,有研究报道了磷酸盐在高温还原气氛下可能分解,磷酸盐结合铬铝锆砖在还原气氛下的损毁机理有待进一步研究。另一方面,氧化铬原料成本高,并且其在高温下可能转化成六价铬而产生环境污染的问题。因此,提高铬铝锆材料的寿命,进一步开发满足气化炉使用要求的无铬化内衬材料势在必行。针对铬铝锆材料长寿化问题,本文首先研究了烧成和模拟使用气氛对磷酸盐结合铬铝锆砖结构与性能的影响。进而设计了水泥结合和有机聚合物结合的铬铝锆浇注料,并研究了该材料在不同气氛下的抗气化炉渣侵蚀性能。为实现气化炉内衬材料的无铬化,首先从热力学与动力学两方面研究了典型耐火组元与气化炉渣在高温下的反应,阐述了渣与耐火组元的相互作用机理,为无铬化材质体系选择提供理论依据。在此基础上提出了烧成Al_2O_3-C、 Al_2O_3-TiO2-C和Al_2O_3-MgAl_2O_4-C三种无铬化材料体系,系统研究了这三种材料的烧结性能、显微结构、孔结构和抗渣侵蚀性能,评估了其作为新型水煤浆气化炉用无铬化内衬材料的可能性。研究结果表明：埋碳条件下烧成时,磷酸盐结合铬铝锆砖出现较多孔洞,降低了材料的抗侵蚀性能。水泥结合和有机聚合物(Isobam)结合的铬铝锆浇注料在还原气氛下都表现出了比空气中更好的烧结性能和抗渣侵蚀性。刚玉、尖晶石与非氧化物复合,制成氧化物-非氧化物复合材料是一种可能的新型无铬化内衬材料体系。低碳Al_2O_3-C材料,无论是空气中还是埋碳条件下,其抗气化炉渣渗透性能都明显优于铬铝锆材料。向A12O3-C材料引入2wt%的Ti02,可以促进材料在烧成过程中原位形成Ti(C,N), Ti(C,N)的形成有利于在侵蚀过程中提高渣的粘度,改善材料的抗渣侵蚀性能。适量尖晶石的引入,有利于提高Al_2O_3-MgAl_2O_4-C材料的抗渣侵蚀性能。
[Abstract]:Coal water slurry gasification technology is an important way to use coal efficiently and cleanly, and gasifier is one of the key high temperature reaction vessels. In order to ensure the safe and efficient operation of gasifier, the longevity and stability of refractories is the necessary prerequisite. Due to the extremely low solubility of chromium oxide in gasifier slag, phosphate-bound chromium-aluminum zirconium material containing more than 75 wt% chromium oxide is the main material for gasifier lining at present. However, it has been reported that phosphate may decompose in the atmosphere of high temperature reduction, and the damage mechanism of phosphate bound chromium-aluminum-zirconium brick in reducing atmosphere needs further study. On the other hand, the cost of chromium oxide is high, and it may be converted into hexavalent chromium at high temperature, resulting in environmental pollution. Therefore, it is imperative to improve the life of chromium-aluminum-zirconium material and further develop the chromium-free lining material to meet the requirements of gasifier. In order to solve the problem of the longevity of Cr-Al-Zr material, the effect of sintering and simulated atmosphere on the structure and properties of phosphate-bound chromium-aluminum-zirconium brick was studied in this paper. Furthermore, the castable of chromium, aluminum and zirconium combined with cement and organic polymer was designed, and the corrosion resistance of the material to gasifier slag in different atmosphere was studied. In order to realize chromium-free gasifier lining material, the reaction of typical refractory components and gasifier slag at high temperature was studied from the aspects of thermodynamics and kinetics, and the interaction mechanism between slag and refractory components was expounded. It provides a theoretical basis for the selection of chromium-free material system. On the basis of this, three kinds of chromium-free material systems have been put forward, such as the sintering, microstructure, pore structure, and slag erosion resistance of the three kinds of materials, namely, Als / AID _ 2O _ 3-TiO _ 2-C and Al _ 2O _ 3-MgAl _ 2O _ 4-C, respectively. The possibility of using it as a new type of chromium-free lining material for coal water slurry gasifier was evaluated. The results show that the phosphate bound chromium-aluminium-zirconium brick has a lot of holes when it is sintered under the condition of buried carbon, which reduces the corrosion resistance of the material. The cementitious and organic polymer (Isobam) bonded castables exhibited better sintering properties and slag erosion resistance than in air in reducing atmosphere. Corundum, spinel and nonoxide composites are a possible new chromium-free lining material system. The permeability resistance of low carbon Al _ 2O _ 3-C material, whether in air or buried carbon, is obviously better than that of chromium-aluminum-zirconium material. The addition of 2wt% Ti02into A12O3-C can promote the formation of Ti (Con N) in situ during the sintering process. The formation of Ti (Con N) is beneficial to increase the viscosity of slag and improve the slag corrosion resistance of the material. The addition of appropriate amount of spinel can improve the slag corrosion resistance of the Al2O3-MgAl2O4-C material.
【学位授予单位】：武汉科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TQ175.1

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