中温烟气脱硫中蒸汽活化对钙基脱硫剂孔结构影响的实验研究

Experimental study on effect of sorbent pore structure by steam activation in the medium temperature desulfurization process

采用将脱硫剂搭载在多孔的玻璃棉上,避免了传统的流化过程所导致的脱硫剂的磨损和破碎.分析了蒸汽活化后脱硫剂孔隙结构的变化,证实了中温条件下蒸汽活化改善了孔的结构,增加了中孔的数量,并使脱硫剂发生明显的破碎,从而减弱了产物层的扩散阻力,使SO2和CaO的接触和反应变得有利.并证实了对脱硫反应贡献最大的是100～5000nm的中孔,而不是导致比表面积迅速增加的微孔,同时还发现,600℃时的脱硫反应比300℃情况下使脱硫剂产生更大量的破碎,导致更多的孔间隙.因此从物理结构上也解释了脱硫反应在600℃时的钙利用率要高于300℃时的情况.

In the medium temperature desulfurization process, the spent sorbent reactivated by the steam could increase the calcium utilization markedly. In order to study the mechanisms of the steam reactivation, the fixed bed reactor was adopted with the sorbernt carried on the glass cotton to prevent its attrition and fragmentation in the traditional fluidizing bed. The pore structure of the sorbent before and after steam reactivation was compared and analyzed, results suggested that the steam reactivation improved the pore distribution and produced more fragments in the sorbent, and reduce the diffusion resistivity through the product layer accordingly, and make the SO_2 and unreacted CaO contact and react more favorably. It was also verified that the medium pores play an much more important part than the micro pores in the desulfurization process. Furthermore it was discovered that more fragments and more space between the sorbent particles was produced in the desulfurization at 600℃ than at 300℃. It therefore suggested that the pore structure of the sorbent could explain the higher calcium utilization for desulfurization at 600℃ than that at 300℃.