油污对湿法脱硫过程中离子浸出与传质特性的影响

Effect of Oil Stain on Ion Leaching Behavior and Mass Transfer Characteristics During Wet Flue Gas Desulphurization

基于湿法烟气脱硫中试装置,进行了油污对石灰石/石膏湿法脱硫过程影响研究,测试了浆液中油污对离子浸出、SO32-氧化、传质阻力、SO2吸收速率、石膏晶体形貌的影响。结果显示:未燃尽的油污中包含大量的憎水官能团,CaCO3颗粒表面会形成一层薄薄的油膜,离子扩散传质阻力加大,Ca2+、Fe3+、Mn2+浸出量均随着油污含量增加以及pH值的降低而降低。浆液中的油污会形成胶质,降低浆液中颗粒的沉降速度,导致SO32催化氧化气氛变弱,浆液中的SO32-含量增加。气相传质总阻力随浆液中油污含量的增加而增加,油污对SO2-吸收速率有明显的抑制作用,且pH值越低,抑制作用更明显。扫描电镜照片表明:油污加入后石膏晶体形态出现杂乱的不同形状,加大了晶体颗粒的比表面积,使石膏晶体难于脱水。

In the pilot plant of wet flue gas desulphurization,the effect of oil stain on the process of limestone/gypsum wet flue gas desulphurization was studied,the relationship between oil stain and key parameters such as ions' leach,sulfite oxidation,SO2 absorption rate,mass transfer resistance and crystal morphology were investigated.The results show that: the unburned oil stain that contains much hydrophobic functional groups will form a layer of thin oil film on the surface of CaCO3,which lead to an increase in ion diffusion.The leaching concentration of Ca2+,Fe3+,Mn2+ reduce with the reduction of pH value and the increase of oil stain concentration.The oil stain of slurry will form colloid that can decrease settling velocity of particles,which will weaken the catalytic effect of sulfite oxidation.The gas phase total mass transfer resistance increases with the growth of oil stain content.Oil stain has a significant inhibitory effect on SO2- absorption rate,and the effect is especially evident when pH value is low.The scanning electron microscopy(SEM) analysis shows that crystal morphology will form random structure with additives of oil stain,which increases specific surface area of gypsum crystal and reduces the dehydration of gypsum.