改性石灰吸收HCl气体过程中的物理化学特性

Physical and Chemical Characteristics of Modified Limes when Used as HCl Dry Absorbents

用NaOH溶液处理CaO生成的改性石灰在350～760℃温度段对HCl气体吸收效率较原始石灰有显著的提高.通过对改性石灰吸收HCl气体过程中物理化学特性的研究来分析改性机理,研究表明:改性石灰的表面结构不规则,晶体规则化程度也较低,煅烧时分解速度较慢,新反应面的出现速度适应反应持续进行的要求,反应后的产物层多孔,这些均有利于对HCl的吸收.原始石灰在不同温度下反应后的产物种类相同,而改性石灰的产物成分在各温度下不一致.此外先生成的产物如CaCl2·2H2O可与未反应的石灰结合形成固溶体CaCl2·Ca(OH)2·H2O.

When CaO is treated by NaOH solution modified lime was obtained and its retention capabilities for gaseous HC1 were enhanced as compared to the original lime within a temperature range of 350-760#### . In this paper,physical and chemical characteristics of modified lime were investigated for the purpose of analyzing modification mechanism. It was found that the micro-structure of the modified lime was more irregular on out-surface and its crytallization was not so perfect as the original lime as shown by X-Ray diffraction intensity, and the velocity of lime calcination was slowed down, therefore the appearing of new reaction surface was better controlled to fit the reaction process. In addition, the modified lime was more porous on outer-surface after reaction, which were more favorable to the gaseous HC1 absorption reaction. For the original lime, similar products formed at different reaction temperatures, while for the modified lime,different product components appeared at different reaction temperatures. The first formed product like CaCl2·2H2O can react with un-reacted lime to form solid solution CaCl2· Ca(OH)2 ·H2O in the later reaction process.