石灰石微观结构及煅烧条件对CaO微观结构的影响
文献类型：学位论文
| 作者 | 袁国忠 |
| 学位类别 | 硕士 |
| 答辩日期 | 1998-06-30 |
| 授予单位 | 中国科学院研究生院 |
| 导师 | 邵曼君 |
| 关键词 | 石灰石 结构 脱硫技术 热解作用 |
| 中文摘要 | 流化床燃烧脱硫过程中，CaO的微观结构是影响脱硫效率的关键因素，因此我们系统地研究了石灰石微观结构及煅烧条件对热解产物CaO微观结构的影响。我们在管式炉中，模拟流化床燃烧脱硫的条件（温度700 ～ 900 ℃、CO_2浓度0 ～ 20%、粒径0.25 ～ 2.0mm), 对江西和门头沟两种石灰石进行了一系列的热解实验。结合扫描电镜下煅烧产物的微观结构图象和压汞法测定的数据，获得CaO中的孔隙特性（孔体积、比表面积孔隙尺寸分布等），并应用高温环境扫描电镜原位跟踪石灰石分解过程中微观结构的变化。实验中发现，门头沟石灰石与江西石灰石煅烧后产生的CaO中的孔隙呈裂缝形，孔隙尺寸分布曲线具有双峰形式，即主要由粗裂缝（几百～几千 nm)和细裂缝（几～几十 nm）组成。不同产地的石灰石的微观结构不同，导致其煅烧后产物CaO的微观结构差别较大：门头沟石灰石煅烧产物CaO中粗裂缝位于晶界上，且比江西石灰石煅烧产物的大而分布均匀；而细裂缝宽度较江西石灰石煅烧产物的小。此外，煅烧条件对CaO微观结构影响显著。江西石灰石煅烧产物CaO的粗裂缝宽度随着煅烧温度的升高先增大，然后减小；而门头沟石灰石煅烧产物的粗裂缝宽度受分解温度的影响不大。随着CO_2分压的增大，两种石灰石煅烧产物的粗裂缝宽度皆先增大，然后减小。两种石灰石煅烧产物的细裂缝宽度随着煅烧温度的升高、CO_2分压的增大而逐渐增大，导致比表面积逐渐减小。随着烧结的进行，CaO中细裂缝宽度逐渐增大，导致比表面积减小，然后裂缝减少，直到消失。但门头沟石灰石煅烧产物CaO的上述过程速度比江西石灰石煅烧产物慢。 |
| 英文摘要 | In desulfurization in fluidized bed combustor, the microstructure of calcined limestone is one of the key factors affecting sulfur removal efficiency. To study the effect of the limestone structure and calcination condition on microstructure of calcium oxide, two types of limestone were calcined in a tubular furnace with temperature in the range 700 ～ 900 ℃ and CO_2 concentration in the range of 0 ～ 20%, which conditions are similar to the reaction conditions in fluidized bed combustor. Microstructure of the calcium oxide was observed by ESEM and pores distribution was measured by mercury intrusion method. The experimental results show that the microstructures and sintering behaviors of CaO strongly depended on the type of limestone. The pores in calcium oxide, which was calcined from JX-limestone and MTG-limestone respectively, are slit-shaped and the distribution of pore size is bimodal including thicker-slit peak and thinner-slit peak, but the thicker-slit width of JX-CaO is larger than that of MTG-CaO and the thinner-slit width is smaller. Slits in MTG-CaO are located on crystalline boundary and its distribution is more homogeneous than that in JX-CaO. JX-CaO sinters faster than MTG-CaO. It was also observed that the microstructure of CaO was affected considerably by the temperature and CO_2 concentration during calcination. Thicker-slit width increase first, then decrease for JX-CaO, and it has seldom change for MTG-CaO with increase of temperature. Thicker-slit width increase first and then decrease for both CaO with increase of CO_2 concentration. Increase in temperature and CO_2 concentration result in increasing thinner-slit width and decreasing specific surface area. |
| 语种 | 中文 |
| 公开日期 | 2013-09-27 |
| 页码 | 59 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/2018]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 袁国忠. 石灰石微观结构及煅烧条件对CaO微观结构的影响[D]. 中国科学院研究生院. 1998. |
入库方式： OAI收割
来源：过程工程研究所
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