Effects of additives on stabilization and inhibition of mercury re-emission in simulated wet gas desulphurization slurry
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摘要: 针对湿法脱硫系统中汞还原再释放问题，选用Na2S、2，4，6-三硫醇基钠代三嗪（TMT-18）、二硫代氨基甲酸盐类（DTCR-2）和Fenton试剂作为添加剂，探究其对脱硫浆液中汞再释放现象的影响。结果表明，四种添加剂均能有效抑制该现象的发生。1.0倍化学计量比的Na2S足够与浆液中Hg2+结合成HgS，从而将还原再释放的汞含量降低至5.27%。重金属捕集剂TMT-18和DTCR-2的最佳投加量分别为3.0倍和1.0倍化学计量比，通过与Hg2+结合形成有机螯合物将浆液中的汞固定在螯合产物中，从而降低Hg2+的还原，再释放的汞含量分别降低至5.09%和4.62%。具有强氧化性的Fenton试剂，当H2O2浓度为0.3 mol/L，[Fe2+]/[H2O2]=1:8时，浆液中仅有2.31%的汞被还原再释放。四种添加剂中Fenton对于浆液中汞还原再释放的抑制效果最好。Abstract: In view of the problem of mercury re-emission in wet flue gas desulfurization system, Na2S, 2, 4, 6-trimercaptotiazine trisodium (TMT-18), sodium dithiocarbamate (DTCR-2) and Fenton reagents were added into the desulfurization slurry to study their effects on mercury re-emission. The results show that the 4 additives could effectively inhibit the mercury re-emission. 1.0 time stoichiometric ratio of Na2S is enough to combine with Hg2+ in the slurry into HgS. Thereby the ratio of mercury re-emission reduces to 5.27%. The optimum dosage of heavy metal chelating agents TMT-18 and DTCR-2 are 3.0 and 1.0 time stoichiometric ratio. They combine with Hg2+ to form organic chelate mercury and then fix it. So the ratio of mercury re-emission reduces to 5.09% and 4.62%, respectively. After adding Fenton reagent with a strong oxidizing into the slurry, the ratio of reduced mercury reduces to only 2.31% when H2O2 concentration is 0.3 mol/L and the ratio of[Fe2+]/[H2O2] is 1:8. Fenton reagent has the best effect on mercury re-emission in the simulated wet gas desulphurization slurry among 4 additives.
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Key words:
- Na2S /
- TMT-18 /
- DTCR-2 /
- Fenton reagent /
- mercury re-emission /
- WFGD
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图 2 Na2S对汞再释放的影响
Figure 2 Effect of Na2S on elemental mercury emission
(pH=5.5, S(Ⅳ)=5 mmol/L, t=45 ℃)
图 3 添加Na2S后汞在浆液中的分布
Figure 3 Distribution of mercury in the gas, liquid and solid fraction when Na2S added
(pH=5.5, S(Ⅳ)=5 mmol/L, t=45 ℃)
: solid fraction; : liquid fraction; : gas fraction
图 4 TMT-18对汞再释放的影响
Figure 4 Effect of TMT-18 on elemental mercury emission
(pH=5.5, S(Ⅳ)=5 mmol/L, t=45 ℃)
图 5 添加TMT-18后汞在浆液中的分布
Figure 5 Distribution of mercury in the gas, liquid and solid fraction when TMT-18 added
(pH=5.5, S(Ⅳ)=5 mmol/L, t=45 ℃)
: solid fraction; : liquid fraction; : gas fraction
图 6 DTCR-2对汞再释放的影响
Figure 6 Effect of DTCR-2 on elemental mercury emission
(pH=5.5, S(Ⅳ)=5 mmol/L, t=45 ℃)
图 7 添加DTCR-2后汞在浆液中的分布
Figure 7 Distribution of mercury in the gas, liquid and solid fraction when DTCR-2 added
(pH=5.5, S(Ⅳ)=5 mmol/L, t=45 ℃)
: solid fraction; : liquid fraction; : gas fraction
图 8 添加Fenton试剂后汞在浆液中的分布
Figure 8 Distribution of mercury in the gas, liquid and solid fraction when Fenton reagent added
(pH=5.5, S(Ⅳ)=5 mmol/L, t=45 ℃, H2O2=0.3 mol/L)
: solid fraction; : liquid fraction; : gas fraction
图 9 H2O2对汞再释放的影响
Figure 9 Effect of H2O2 on elemental mercury emission
(pH=5.5，S(Ⅳ)=5 mmol/L，t=45 ℃)
图 10 添加H2O2后汞在浆液中的分布
Figure 10 Distribution of mercury in the gas, liquid and solid fraction when H2O2 added
(pH=5.5, S(Ⅳ)=5 mmol/L, t=45 ℃)
: solid fraction; : liquid fraction; : gas fraction -
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