贝壳型脱硫剂内部气体扩散特性探讨

从微观结构特征、气体扩散机理和扩散系数等方面，探讨了贝壳型脱硫剂内部的气体扩散特性，并与石灰石对比研究。扫描电镜图片表明，与石灰石相比，贝壳的孔隙结构更有利于SO2等反应气体向其内部扩散；气体扩散机理研究结果表明，气体在贝壳原样内部为过渡扩散形式，煅烧后和脱硫初期以分子扩散为主，而对于石灰石，原样和煅烧、脱硫试样内部的气体扩散均为Knudsen扩散形式；贝壳的气体有效扩散系数基本在同一数量级，分别比石灰石大2或3个数量级，即贝壳型脱硫剂的内部气体扩散特性相似，比所选石灰石的气体扩散特性优越；同时热重实验结果还表明，脱硫性能与气体扩散特性有着紧密联系。

Study on Gas Diffusion Characteristics Inside Shell-type Sorbents

Gas diffusion characteristics inside shell-type sorbents were investigated in some aspects, such as microstructural feature, gas diffusion mechanism and diffusion coefficient, which were compared with that of the limestone. Scanning electron microscope (SEM) photos indicate that the shells' microstructure is more beneficial to SO2 and other reaction gases diffusing inside them than the limestone. The research results on gas diffusion mechanism show that gas diffusion mode of the raw shells is transition diffusion, those of the calcined and sulfated shells are both molecular diffusion mainly, and those of the raw, calcined and sulfated limestones are all Knudsen diffusion. The effective diffusion coefficients of the shells are all in the same order of magnitude approximately, which are bigger 2 or 3 orders of magnitude than those of the limestone respectively. In conclusion, gas diffusion characteristics of the shell are similar, and they are better than that of the limestone. The conclusion derived from a thermogravimetric experiment is that the relation between desulfurization performance and gas diffusion characteristic is very close.