用于RTO蓄热的红柱石陶瓷的研究

Andalusite Ceramics Used for RTO Heat Storage Applications

采用蓄热材料将高温烟气的余热回收利用于预热助燃空气可以提高垃圾焚烧炉的效率,降低能耗。本文以红柱石为主要原料制备了用于垃圾焚烧炉的红柱石陶瓷蓄热体材料。测试了样品的吸水率、气孔率、体积密度、抗折强度和抗热震性能,采用X射线衍射仪(XRD)、扫面电子显微镜(SEM)和热膨胀仪等现代测试手段研究了样品相组成、结构和性能。结果表明:1420℃烧成的A5和A8配方样品性能较优,吸水率为0.1-0.87%,气孔率为0.24-1.98%,体积密度为2.28-2.43 g.cm-3,抗折强度为50.03-73.09MPa,抗热震性良好。A5样品(1420℃/2h)耐酸性为98.97%,耐碱性为97.72%,热膨胀系数为6.82×10-6℃-1。相组成分析表明,A5样品主晶相的为莫来石,A8样品为莫来石、碳化硅。SEM研究结果表明,样品中气孔分布均匀,平均尺寸为5-10μm,莫来石晶体被玻璃相包裹,赋予样品较高的强度,断裂方式主要是穿晶断裂和沿晶断裂相结合的断裂模式。可满足垃圾焚烧炉中的蓄热材料的要求。

Heat storage materials are used to improve the efficiency of waste incinerator and reduce energy consumption by recycling the waste heat of high temperature flue gas and preheating the combustion air. Andalusite was used as the main material to prepare ceramics by semi-dry pressing method and pressureless sintering in this study. The water absorption, porosity, bulk density, bending strength and thermal shock resistance have been measured. The phases formed and structural changes by sintering were investigated by X-Ray diffraction （XRD）, scanning electron microscopy （SEM） and thermal dilatometer. The result shows that Samples A5 and A8 sintered at 1420~C have excellent performance with their thermal shock resistance, water absorption, porosity, bulk density and bending strength at 0.1-0.87%, 0.24~1.98%, 2.28~2.43g ＂cm-3 and 50.03~73.09MPa, respectively. The Acid resistance, alkaline resistance and linear thermal expansion coefficient of sample A5 were 98.97%, 97.92% and 6.82x10-e^C-1, respectively. Mullite was the major phase of these two samples, and SiC was also detected in sample A8 according to XRD patterns. Their pores were distributed uniformly with the average size between 5~10pm and the mullite crystal was parceled by glass phase as is indicated by SEM. The analysis of fracture surface suggests that there was a mixture of cracking mechanism （transgranular failure and intergranular failure） which gave the samples high bending strength. The as-prepared andalusite ceramics could meet the demand of heat storage material in RTO.