钙基载氧体及其在可燃固体废弃物化学链燃烧中的应用研究

QIBEBT-IR > 热化学转化研究组

	钙基载氧体及其在可燃固体废弃物化学链燃烧中的应用研究
	毕文卓
导师	吴晋沪
	2015-05
学位授予单位	中国科学院大学
学位授予地点	北京
学位专业	化学工程
关键词	可燃固体废弃物化学链燃烧载氧体硫酸钙 Pvc
摘要	可燃固体废弃物的焚烧会产生二噁英和重金属等有毒污染物，使得人们更加关注城市生活垃圾的处理问题。开发减量化、资源化和无害化的可燃固体废弃物燃烧技术已经成为各国研究的热点。化学链燃烧技术具有CO2内分离、低NOx排放等优点，而且可以实现与O2的非接触燃烧，有可能抑制二噁英的生成。因此，化学链燃烧技术在可燃固体废弃物高效资源化利用方面具有很好的前景。本文以廉价、易得且环境友好的CaSO4为主体，采用浸渍法研究了Fe2O3对载氧体活性的影响。利用磁悬浮热重分析仪（TGA）考察了载氧体的热稳定性、反应性和循环性，通过X射线衍射（XRD）和透射电子显微镜（SEM）对载氧体的晶体结构和表面形貌进行分析。结果表明，Fe2O3的加入可增大载氧体的比表面积从而加快载氧体与燃料气体的反应速率，反应时间缩短了50 %。CaSO4/Fe2O3载氧体在1100 ℃内仅有2 %质量损失，热稳定性良好。反应过程中会产生副反应产物CaO，随着循环次数增加，CaO逐渐累积导致循环性变差，经过六次循环反应，35.4 %的CaSO4/Fe2O3载氧体失去了载氧能力。研究了惰性载体（甘油、硅溶胶和拟薄水铝石）和制备条件对钙基载氧体机械强度和反应性能的影响。结果表明，添加惰性载体可以提高钙基载氧体的机械强度，机械强度最大值分别为69.5 N、45.7 N和 5.74 N。随着煅烧温度的升高和煅烧时间的增加，添加甘油的载氧体机械强度降低，而添加硅溶胶和拟薄水铝石的载氧体机械强度逐渐增大。惰性载体的加入可明显缩短CaSO4载氧体与CH4的还原反应时间，添加硅溶胶和甘油后载氧体反应时间由100 min分别缩短为15 min和25 min。在自行搭建的两段炉反应平台上考察了PVC热解气与CaSO4/Fe2O3载氧体的反应，当mPVC/m_oc超过8时，CaSO4/Fe2O3载氧体完全反应，其失重率为50.0 %。反应产物主要是CaS，同时有少量副反应生成的CaO及其与Fe2O3和HCl反应生成的Ca2FeO3Cl，与金属载氧体相比CaSO4/Fe2O3载氧体失活比例较小，副反应生成的CaO能吸收一部分可燃固体废弃物产生的HCl和Cl2。利用高分辨色谱/质谱联用仪（GC/MS）检测PVC在化学链燃烧中二噁英产生量。结果表明，用化学链燃烧技术处理PVC能有效抑制二噁英的产生，单位PVC的二噁英生成量由34172.5 pg/g降到2270.9 pg/g，毒性当量由732.8 pg I-TEQ/g降到290.2 pg I-TEQ/g。这主要是由于在化学链燃烧过程中燃料不与O2直接接触，抑制了二恶英的从头合成反应。
其他摘要	The incineration of combustible solid waste could produce dioxins, heavy metal pollution and other toxic pollutants. Thus the problem of municipal solid waste disposal is paid more attention. It has become a research hotspot to make combustible solid waste reduce, reuse and recycle. Chemical looping combustion is a promising technique with inherent separation of CO2, low NOx emission and may decrease the generation of dioxins in solid waste disposal because it provides no free oxygen in the process. Chemical looping combustion has a very good prospect in the aspect of combustible solid waste efficient utillzation. Based on the CaSO4 which is cheap and enviroment friendly, the effection of Fe2O3 to oxygen carrier activity was studied by impregnation method. The thermal decomposition, activity and reduction/oxidation cycle behaviors of the oxygen carrier were investigated using the thermogravimetric analyzer (TGA). X-ray diffraction (XRD) and scanning electron microscope (SEM) have been utilized to characterize the structure and surface topography of oxygen carrier. The results showed that the addition of Fe2O3 could improve the specific surface area of oxygen carrier which could enhance the reaction rate with fuel gas. The reaction time was reduced by 50 %. The CaSO4/Fe2O3 oxygen carrier showed good heat stability and lost only 2 % mass in 1100 0C. The side reaction could product CaO in the process which could accumulate and affect the regeneration ability with the increase of cycling times. 35.4 % of CaSO4/Fe2O3 oxygen carrier lost the regeneration ability after six times cycle reaction. The effection of binders (glycerinum, silica sol and pseudo-boehmite) and preparation conditions were studied to mechanical strength and reaction ability of Ca-based oxygen carrier. The results showed that the addition of binders could improve the mechanical strength of Ca-based oxygen carrier. The maximum of mechanical strength were 69.5 N, 45.7 N and 5.74 N respectively. The mechanical strength of oxygen carrier with glycerinum decreased with the increase of calcination temperature and time while that of oxygen carrier with silica sol and pseudo-boehmite increased. The addition of binders could shorten the reaction time between CaSO4 and CH4. The reaction time of oxygen carrier with silica sol and glycerinum reduced from 100 min to 15 min and 25 min respectively. The reaction between PVC pyrolysis gas and CaSO4/Fe2O3 oxygen carrier was investigated in a two-stage reactor. When mPVC/m_oc was over 8, CaSO4/Fe2O3 oxygen carrier reacted completely and its weight loss rate was 50.0 %. The main reaction product was CaS. The by-product were CaO and Ca2FeO3Cl which was the product of Fe2O3 and HCl. The deactivation rate of CaSO4/Fe2O3 oxygen carrier was smaller than that of metal oxygen carrier. CaO which was produced by side reaction could absorb a part of HCl and Cl2 which was produced by combustible solid waste. Dioxin was detected by high resolution gas chromatography/ mass spectrometer (GC/MS). The results showed that chemical looping combustion could inhibit the generation of dioxin effectively. The yield of dioxin produced per gram of PVC is decreased from 34172.5 to 2270.9 pg/g and the yield of TEQ produced pergram of PVC are decreased from 732.8 to 290.2 pg I-TEQ/g. This is because the fuel can’t contact with O2 directly in the chemical looping combustion process which inhibits the de novo of dioxin.
作者部门	热化学转化事业部
学科领域	工学
公开日期	2020-09-01
学位类型	硕士 ; 学位论文
语种	中文
文献类型	学位论文
条目标识符	http://ir.qibebt.ac.cn/handle/337004/8090
专题	热化学转化研究组
作者单位	1.中国科学院大学 2.中科院青岛生物能源与过程研究所
推荐引用方式 GB/T 7714	毕文卓. 钙基载氧体及其在可燃固体废弃物化学链燃烧中的应用研究[D]. 北京. 中国科学院大学,2015.