O2/H2O燃烧方式下石灰石的间接硫化反应特性

摘要

A tube furnace (TF) and thermogravimetric analyzer (TGA) were used to investigate the indirect sulfation of limestone under O2/H2O combustion compared with O2/N2 and O2/CO2 combustion. It focused on the effects of combustion atmosphere and steam concentration on the calcium conversion ratio of the limestone. Besides, the sulfated products were collected for X-ray fluorescence (XRF), X-ray powder diffraction (XRD), pore structure characteristics and scanning electron microscopy (SEM) analysis. The results indicate that the indirect sulfation reaction has a negligible difference at the kinetically-controlled stage under different atmosphere but it is greatly enhanced at the diffusion-controlled stage under O2/H2O atmosphere compared with O2/N2 and O2/CO2 atmosphere. This is due to the fact that the presence of steam promotes the solid-state diffusion in the product layer. Besides, the calcium conversion ratio has no obvious increase when increasing the concentration of steam under O2/H2O atmosphere.%利用水平管式炉和热重实验台架，对O2/H2O、O2/N2和O2/CO23种不同燃烧方式下石灰石的间接硫化反应特性进行了研究。重点探究了燃烧方式、水蒸气浓度对石灰石间接硫化反应的影响规律与机理。同时，对硫化产物进行了X射线荧光光谱（XRF）、X射线衍射（XRD）、孔结构特性和扫描电镜（SEM）分析。结果表明，O2/H2O燃烧方式相比于相同氧浓度下的O2/N2和O2/CO2燃烧方式，石灰石间接硫化反应的钙转化率在化学反应控制阶段基本相同，在扩散控制阶段 O2/H2O 燃烧方式下的钙转化率有显著的提高。主要原因是水蒸气促进了硫化反应后期产物层内的固态离子扩散。此外，O2/H2O燃烧方式下，不同的水蒸气浓度对石灰石的钙转化率基本没有影响。