| 抑制双碱法烟气脱硫浆液中SO2-3的重金属催化氧化 |
| 摘要点击 3165 全文点击 2901 投稿时间：2009-05-02 修订日期：2009-07-08 |
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| 中文关键词 双碱法 烟气脱硫 亚硫酸根 重金属 催化氧化 抑制 |
| 英文关键词 dual alkali flue gas desulfurization sulfite heavy metal catalytic oxidation inhibition |
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| 中文摘要 |
| 双碱法烟气脱硫浆液中累积的重金属对SO2-3有强烈的催化氧化作用，导致有效脱硫组分损耗.投加Na2S去除浆液中的重金属离子，研究不同重金属离子浓度下SO2-3的氧化速率，以揭示Na2S沉淀法对重金属催化氧化SO2-3的抑制作用.实验表明，Mn2+对SO2-3氧化的催化作用很显著，1.0 mmol/L Mn2+可使SO2-3的初始氧化速率提高2.0倍，达0.65 mmol/（L·min）；SO2-3的催化氧化在前60 min内快速进行，Mn2+的反应级数为0.169，故此时段内控制Mn2+浓度对抑制其催化作用尤为重要.初始pH 6.50～8.50时，Na2S能有效去除浆液中重金属离子，且碱性条件更有利于重金属离子的去除.初始pH为8.50、Na2S投加量为240.0 mg/L时，脱硫浆液中Mn2+、Zn2+、Ni2+、Cd2+的去除率分别为91.0%、88.1%、85.5%和>99.9%.Mn2+对脱硫浆液中的重金属离子浓度具有指示作用.投加Na2S将Mn2+浓度由1.0 mmol/L降为5.0×10-3mmol/L，SO2-3的初始氧化速率降低64.6%，为0.23 mmol/（L·min）.在双碱法烟气脱硫中试装置中投加Na2S可使脱硫效率提高3.8%～5.1%.故以Mn2+为指示、用Na2S控制重金属离子浓度从而抑制SO2-3被催化氧化，有利于降低脱硫剂消耗、提高脱硫效率. |
| 英文摘要 |
| Heavy metals accumulated in slurry of dual alkali flue gas desulfurization (FGD) present a significant catalysis to SO2-3 oxidation,resulting in a waste of effective components for desulfurization. Na2S was adopted to precipitate heavy metal ions in FGD slurry,and the oxidation rate of SO2-3 was obtained under different concentrations of heavy metal ions,to reveal the inhibition effect of Na2S on SO2-3 oxidation catalyzed by heavy metal ions. Mn2+ showed a remarkable catalysis to SO2-3 oxidation,as the initial oxidation rate of SO2-3 was tripled to 0.65 mmol/(L·min) by adding 1.0 mmol/L Mn2+ into the slurry. SO2-3 was catalytically oxidized rapidly with the reaction order 0.169 of Mn2+ within first 60 minutes,so it is of great importance to control the concentration of Mn2+ to inhibit SO2-3 oxidation. At initial pH value of 6.50-8.50,Na2S removed heavy metal ions effectively from FGD slurry. Higher pH value favored the removal of heavy metal ions. The removal efficiencies of Mn2+,Zn2+,Ni2+ and Cd2+ were 91.0%,88.1%,85.5%,and above 99.9% respectively under the conditions of initial pH value 8.50 and Na2S dosage 240.0 mg/L. Mn2+ could be used as an indicator for the concentration of the heavy metal ions in the slurry. As the Mn2+ concentration decreased from 1.0 mmol/L to 5.0×10-3mmol/L by adding Na2S,the initial oxidation rate of SO2-3 decreased by 64.6% to 0.23 mmol/(L·min). The desulfurization efficiencies increase 3.8%-5.1% by adding Na2S in a pilot scale setup. It comes to conclusion that heavy metal ions precipitation by adding Na2S with an indicator of Mn2+ to inhibit catalytic oxidation of SO2-3 is feasible to reduce the consumption of desulfurizer in FGD slurry. |
