DOC《（作者-出版年制 格式范本,红色是提醒注意之处）》

(作者-出版年制 格式范本,红色是提醒注意之处) 流化床燃煤固硫渣特性及其建材资源化研究 重庆大学博士(硕士)学位论文 学生姓名:XXX 指导教师:XXX 专业:XXX 学科门类:XX学 重庆大学材料科学与工程学院 二OO七年十月 Study on Properties and Utilization in Building Materials of bottom ashes from Circulating Fluidized Bed Combustion A Thesis Submitted to Chongqing University in Partial Fulfillment of the Requirement for the Degree of Doctor (Master) of Engineering by 学生姓名 Supervisor: Prof.

(导师姓名) Major: (专业) College of Material Science and Engineering of Chongqing University , Chongqing, China. April,2007 空一行 摘要空一行 流化床燃煤固硫技术是先进的燃烧技术,但这一技术的推广应用因流化床燃煤固硫渣没有成熟和经济的综合利用途径受到严重限制.由于人们对流化床燃煤副产物的认识程度还很有限,基础资料十分缺乏,在一定程度上影响了流化床燃煤固硫渣的资源化利用.本论文较为系统地分析了流化床燃煤固硫渣的特性,并根据现行规范,提出一套新的活性评定方法.在此基础上,对燃煤固硫渣活性的影响因素、激发方法、体积膨胀性能进行了较为系统的试验研究,并利用XRD、SEM等微观手段研究了燃煤固硫渣的自硬性、活性激发及膨胀机理.最后对燃煤固硫渣建材资源化利用进行了比较深入的研究. 流化床燃煤固硫渣的特性研究结果表明:(1)因为燃烧温度、燃烧环境、燃烧程度、脱硫剂、脱硫效率等的影响,与普通煤粉锅炉的灰渣相比,流化床燃煤固硫渣有其特殊的火山灰活性,同时因为含有SO

3、f-CaO而具有自硬性和膨胀性,是一种特殊的火山灰材料.(2)流化床燃煤固硫渣中的SO3和f-CaO因为特殊的生成条件而具有特殊的性质.SO3是在850~900℃的温度下形成的,是以Ⅱ-CaSO4形态存在,且具有与天然硬石膏和400℃煅烧石膏不一样的溶解特性.首次从f-CaO的形成过程、颗粒微观结构、晶型和光学参数以及水化历程等方面证明了f-CaO颗粒被固硫产物无水硫酸钙包裹的颗粒特征,f-CaO颗粒被Ⅱ-CaSO4包裹使其水化速度减慢和活性较低;

SO3以Ⅱ-CaSO4形态存在和f-CaO颗粒被Ⅱ-CaSO4包裹均对流化床燃煤固硫渣的活性和体积稳定性产生不利影响.(3)现行活性评定方法因流化床燃煤固硫渣性质的特殊而存在较大的局限性,不能直接套用现行的方法进行活性评定.根据现行活性评定方法的原理,结合其特性,首次系统提出了 熟料胶砂28天抗压强度比测定 、 自硬性评价 、 自硬强度测定 的综合评定方法,该方法与现行方法有较好的相容性,且能真实、直观地反映流化床燃煤固硫渣的活性及其对强度的贡献.(4)流化床燃煤固硫渣的活性主要来源于无定形的SiO2和Al2O3物质,除成分中活性SiO2和Al2O3的含量对其火山灰活性有影响外,成分中SO

3、f-CaO含量和细度在一定范围内对其活性发挥有一最佳值.(5)常规的化学激发方法能激发流化床燃煤固硫渣的活性,但仅从强度的角度看,其激发的效果并不理想;

蒸汽养护和蒸压养护的结果表明湿热养护对燃煤固硫渣活性激发程度较高,特别是蒸压养护,激发效果更为明显.(6)流化床燃煤固硫渣水化时存在严重的体积膨胀问题,其膨胀主要是由于水化反应过程中钙矾石的生成和富余的硬石膏后期溶解结晶生成二水石膏的体积膨胀所产生.首次确认了富余的硬石膏后期溶解结晶生成二水石膏对固硫渣体积膨胀的作用.(7)细度提高对流化床燃煤固硫渣膨胀稳定时间的提前有利,掺加粉煤灰和熟料有利于膨胀率的减小及膨胀稳定期的提前,流化床燃煤固硫渣水化反应的液相碱度越大,膨胀越严重. 流化床燃煤固硫渣的特性研究表明其利用有较大的难度,但针对其特性在建材中利用是可能的.作为混凝土细骨料,由于其活性可以改善骨料与水泥浆体的界面结构,故可以提高混凝土的抗弯强度;

作为混凝土掺合材可以充分发挥流化床燃煤固硫渣的活性,可以部分补偿混凝土的收缩,从新拌混凝土的性能和混凝土耐久性的考虑最好与粉煤灰复合使用;

无论是作为水泥混凝土的掺合材,还是细骨料,流化床燃煤固硫渣均影响新拌混凝土的性能.利用燃煤固硫渣的活性和膨胀性能,可以配制低收缩率的燃煤固硫渣―粉煤灰内墙用抹面砂浆,也可以配制燃煤固硫渣―粉煤灰―熟料外墙用抹面砂浆.流化床燃煤固硫渣与石灰、粉煤灰或水泥混合,必要时掺加激发剂,从强度上看完全可以满足公路工程对路基混合料的要求. 关键词:流化床,燃煤固硫渣,活性,膨胀,资源化(不多于5个) ABSTRACT Due to lack of effective ways to utilize the bottom ashes of circulating fluidized bed combustion (CFB ashes), it is difficult to use widely the advanced technology of circulating fluidized bed combustion and defulfurization. In this paper, the properties of the CFB ashes are systematically analyzed and then a series of methods are proposed to evaluate the reactivity of CFB ashes. Meanwhile, the factors influencing and the method activating the reactivity of CFB ashes, and the expansion properties are investigated experimentally. The spontaneous setting, and the mechanism of activation of reactivity of CFB ashes and its expansion are investigated by XRD and SEM. Finally, the utilization in building materials of CFB ashes is studied. The results show that: (1) The CFB ashes is different from the ashes of common coal boiler for there are great difference in forming condictions such as the combustion temperature, combustion environment, the degree of combustion, desulfurizer and the efficiency of desulfurization. While CFB ashes have the properties of cement and expansion for its containing SO3 and f-CaO, so it is a special pozzolanic material. (2) The SO3 and f-CaO have their properties for their typical forming condition. SO3 is fixed in ashes at 850~900℃, and it exists in Ⅱ-CaSO4 and has different solubility with the natural anhydrite and the plaster calcined at 400℃. It is the first time to prove that the particles of f-CaO is coated withⅡ-CaSO4 by investigating the process of forming f-CaO, the microstructure, spathic type and optic parameter and the hydrating process. Results also show that the microstructure can slow down the hydrating and deteriorate the reactivity of CFB ashes. (3) The current method evaluating reactivity of pozzolanic materials has great limits to evaluate the CFB ashes. A series of new methods are developed which can evaluate the reactivity and its devotion to strength really and directly. (4) The reactivity of CFB ashes is attributed to the amorphous SiO2 and Al2O3, but the SO3 and f-CaO of CFB ashes can influence its reactivity and expansion, and there is an optimum content. The higher reactivity can be achieved if the fineness is bigger. (5) The common method can activate its reactivity, but the result of activation is not ideal in the point of strength. It shows that steam curing and high-pressure steam curing is best to activate CFB ashes, especially for high-pressure steam curing. (6) Th........