题名 | 载氧体与可燃固体废弃物化学链燃烧特性研究 |
作者 | 刘永强 |
学位类别 | 硕士 |
答辩日期 | 2013-07 |
授予单位 | 中国科学院研究生院 |
授予地点 | 北京 |
导师 | 王志奇 |
关键词 | 化学链燃烧 固体废弃物 载氧体 热解 |
学位专业 | 化学工程 |
中文摘要 | 随着经济的发展和人民生活水平的提高,固体废弃物的产生量与日俱增,其污染问题越来越严重,而处理现状却是不容乐观。利用可燃固体废弃物高挥发性的特点,提出利用两段化学链燃烧法处理可燃固体废弃物,即可然固体废弃物先热解再与载氧体进行反应,利用热解-化学链燃烧方式,可有效实现废弃物的减量化、资源化和无害化。本论文采用机械混合法、浸渍法和共沉淀法等方法制备了一系列载氧体,综合载氧体的反应性、稳定性和经济性等因素,最终选用机械混合法制备的铜基载氧体Cu80Si950作为实验用载氧体。利用磁悬浮热重分析仪和管式炉分别研究了铜基载氧体与气体燃料模型物CH4和固体燃料模型物石墨的化学链燃烧特性。气体的化学链燃烧结果表明,机械混合法制备的Cu80Si950载氧体强度高,具有良好的转化率和循环稳定性,是化学链燃烧的一种比较理想的载氧体;其与石墨粉固体燃料进行化学链燃烧时氧转化率约为50% 。利用扫描电镜(SEM)、X射线衍射仪(XRD)和颗粒强度测定仪对多循环反应中各个反应阶段载氧体进行分析。结果表明,Cu80Si950载氧体随着循环次数的增加,结构会发生重组,强度有较大衰减,随后结构变得整齐,强度趋于稳定。本论文通过磁悬浮热重分析仪对17种典型的可燃固体废弃物热解特性进行了研究,根据热解特性,在两段式反应平台上进行热解-化学链燃烧实验,考察了载氧体在热解-化学链燃烧中的载氧能力和转化率,并以塑料燃料PS为例,对固体废弃物多循环热解-化学链燃烧过程中载氧体的形貌结构、组成以及强度变化情况进行了研究。实验结果表明:常见可燃固体废弃物的主要热解温度分布在250~550℃之间,热解失重率为60~70%,方便于采用热解-化学链燃烧方式处理。反应过程中,载氧体表现出较高的载氧能力,转化率可达100%。PVC的化学链燃烧中载氧体会出现失活,实验证明PVC的热解产物HCl会毒害铜基载氧体,采用预处理、调控升温程序和添加脱氯剂等方式可避免载氧体失活。多循环实验结果表明:在反应之初,载氧体内发生了物质转换和组分迁移,原始的结构发生较大改变,机械强度骤降,但此过程中也消除了不稳定因素;多次循环之后载氧体结构趋于规则,强度基本保持不变,使得载氧体的在循环反应过程中能够保持相对稳定的机械强度。载氧体Cu80Si950稳定的表现为更多循环更长时间的热解-化学链燃烧反应提供了保证。 |
英文摘要 | With the development of economy and the improvement of people’s living standard, the amount of solid waste is increasing dramatically, and the pollution of it is more and more serious, but its disposal is unsatisfied. Considering the characteristics of high volatile content in combustible solid waste (CSW), a two- stage of chemical looping combustion (CLC) method, CSW first pyrolysis and then pyrolysis gas react with oxygen carrier, was proposed to deal with CSW. Pyrolysis-chemical looping combustion (PCLC) can provide maximum volume reduction, energy recovery and harmless disposal.Cu-based oxygen carrier Cu80Si950 prepared by mechanical mixing was selected from a series of carriers developed by methods including mechanical mixing, impregnation and co-precipitation, according to reactivity, economy and other factors. CLC of model compound CH4 of gas fuels and graphite of solid fuels with Cu80Si950 oxygen carrier were carried out in a thermo-gravimetric analyzer (TGA) and a tubular furnace respectively. The CLC experiment results of gas fuel proved that Cu80Si950 oxygen carrier had a high mechanical strength, excellent conversion and recycle stability, which make it a promising oxygen carrier for CLC process. While the CLC experiment results of solid fuel showed a low conversion of oxygen carrier. Scanning electron microscope (SEM), X-ray diffraction (XRD) and strength analyzer have been utilized to characterize the oxygen carrier of each reaction stages. The results showed that Cu80Si950 oxygen carrier changed morphology and decreased crushing strength dramatically after CLC process. Meanwhile, Cu80Si950 oxygen carrier after experiencing several loops displayed a tending to structural regularization and keeping crushing strength constantly, which case to greater durability of the oxygen carrier after repeated oxidation and reduction cycles. Pyrolysis characteristics of 17 typical CSWs were analyzed in the TGA. The PCLC experiments on these typical components of CSWs with Cu-based oxygen carrier were performed in a two-stage reaction platform to study the transport capacity and conversion of oxygen carrier. And the morphology, structure, composition and strength change of the oxygen carrier during multi-cycle PCLC process with solid waste fuels were characterized. The results indicated that the main pyrolysis temperature of most CSWs ranged from 250℃ to 550℃, and the weight loss of pyrolysis process of the solid waste fuels was about 60~70%, which favored a two-stage PCLC method. High oxygen transport capacity of oxygen carrier was achieved and conversion reached 100% during reaction. HCl gas produced from pyrolysis of PVC would poison Cu-based oxygen carrier when CLC of PVC was conducted, and the inactivation could be avoided by applying pretreatment, adjusting heating program and adding dechlorinating agent. Multi-cycle PCLC experiment showed that at the beginning of the reaction, the oxygen carrier underwent material conversion and component migration, which lead to a radically change of original structure, sudden drop in mechanical strength, and the factors causing physical and chemical instability were simultaneously eliminated . Therefore, oxygen carrier structure after several cycles tended to be inerratic which made the mechanical strength of the oxygen carrier in the process of looping reaction relatively stable. The stable performance of oxygen carrier Cu80Si950 provided a guarantee for more cycles and longer pyrolysis-chemical looping combustion. |
语种 | 中文 |
学科主题 | 热化学转化 |
公开日期 | 2013-07-13 |
内容类型 | 学位论文 |
源URL | [http://ir.qibebt.ac.cn:8080/handle/337004/1519] ![]() |
专题 | 青岛生物能源与过程研究所_热化学转化事业部 |
推荐引用方式 GB/T 7714 | 刘永强. 载氧体与可燃固体废弃物化学链燃烧特性研究[D]. 北京. 中国科学院研究生院. 2013. |
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