碱性吸附剂对燃煤烟气中SO_(3)的吸附特性

Adsorption characteristics of SO_(3) from coal flue gas by alkaline adsorbent

炉膛内高温燃烧和选择性催化还原(SCR)催化剂产生的SO_(3)会严重损害设备和运行安全。本研究在模拟烟气条件下考察了Ca(OH)_(2)、Mg(OH)_(2)、NaHCO_(3)、NaHSO_(3)四种碱性吸附剂对SO_(3)的吸附性能,并研究了烟气气氛和温度对优选吸附剂的SO_(3)吸附能力的影响。采用热重分析研究了吸附剂的分解过程,对反应前后的吸附剂形貌结构特性进行了研究。结果表明:NaHCO_(3)和NaHSO_(3)两种吸附剂在中高温下都具有良好的吸附效果;NaHCO_(3)和NaHSO_(3)在自身分解和吸附SO_(3)的过程中释放气体产物而改善了吸附剂孔隙结构,提高了吸附剂对SO_(3)的吸附效果;烟气中的SO_(2)与SO_(3)在NaHCO_(3)上的吸附过程中存在竞争吸附,降低了NaHCO_(3)对SO_(3)的吸附效果;SO_(2)作为NaHSO_(3)吸附SO_(3)反应的产物,会抑制吸附剂对SO_(3)的吸附;SO_(2)抑制了NaHSO_(3)吸附SO_(3)的反应,导致NaHSO_(3)孔隙结构更加密集,对SO_(3)的吸附效果快速下降。本研究为烟道内喷射碱性吸附剂控制SO_(3)排放提供了一定的理论基础和参考。

The SO_(3) produced by high temperature combustion and selective catalytic reduction(SCR)catalyst in the furnace can seriously damage equipment and operational safety.In this study,the SO_(3) absorption performance of four alkaline adsorbents,Ca(OH)_(2),Mg(OH)_(2),NaHCO_(3) and NaHSO_(3),was investigated under simulated flue gas conditions.In addition,the effect of flue gas atmosphere and temperature on the SO_(3) adsorption capacity of the preferred adsorbents was studied.The decomposition process of the adsorbent was analyzed using thermogravimetric analysis,and the morphological structural properties of the adsorbent before and after the reaction were compared.The results showed that both NaHCO_(3) and NaHSO_(3) adsorbents had good absorption effects at medium and high temperatures.NaHCO_(3) and NaHSO_(3) improved the pore structure of the adsorbent by releasing gas products during their own decomposition and SO_(3) absorption,which improved the absorption effect of the adsorbent for SO_(3).SO_(2) in the flue gas competed with SO_(3) in the adsorption process on NaHCO_(3) adsorption,reducing the absorption effect of NaHCO_(3) for SO_(3).SO_(2) as a product of the reaction of NaHSO_(3) for SO_(3) absorption could be inhibited the absorption of SO_(3) by the adsorbent.SO_(2) as a reaction product of SO_(3) absorption by NaHSO_(3) would inhibit the absorption of SO_(3) by the adsorbent.SO_(2) inhibited the reaction of SO_(3) absorption by NaHSO_(3),resulting in a more dense pore structure of NaHSO_(3) and a rapid decrease in the absorption effect for SO_(3).This study provided some theoretical basis and reference for the control of SO_(3) emissions by in-flue injection of alkaline sorbents.