Nitrogen oxide removal using seawater electrolysis in an undivided cell for ocean-going vessels
Nitrogen oxide removal using seawater electrolysis in an undivided cell for ocean-going vessels
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DOI：
10.1039/c6ra24537d
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发表时间：
2016-12
期刊：
影响因子：
3.9
通讯作者：
Shaolong Yang;Zhitao Han;Xinxiang Pan;Zhijun Yan;Yu Jingqi
中科院分区：
文献类型：
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作者：
Shaolong Yang;Zhitao Han;Xinxiang Pan;Zhijun Yan;Yu Jingqi
针对船用低速柴油机氮氧化物（NOx）排放严重危害人类健康和环境的问题，在实验室规模的洗涤反应器中研究了海水电解条件下电生氯脱除NOx的方法。在无隔膜电解槽中电解海水制备电氯。结果表明，活性氯浓度随电流密度和电解时间的增加而线性增加。电解5分钟后，随着盐度从3.2到37.8 ppt的变化，能耗从83到6.1 kW h/（kg [Cl 2]）下降。有人建议，利用船上海水淡化厂的浓缩海水就地生产活性氯是一种具有成本效益的解决办法，而且能耗较少。在此基础上，进一步研究了海水/电解液稀释比、进口NO和SO2浓度以及洗涤液初始pH值对脱硝效率的影响。当pH值为7时，随着稀释比从2.4增加到96，电生氯气的NOx去除率从98.9%下降到20.2%。HOCl对NO的吸收速率高于OCl−。NO吸收速率随入口NO浓度的增加而线性增加。当SO2浓度从207 ppm增加到814 ppm时，NOx去除率略有下降，但SO2去除率几乎保持在100%。通过评价pH值对电生氯气脱硝效率的影响，探讨了可能的反应机理和途径。提出的方法湿式洗涤使用电产生的氯气被证明是一个潜在的后处理策略，以控制氮氧化物排放的大型船舶柴油机。
As massive nitrogen oxide (NOx) emissions from marine slow speed diesel engines have caused serious health and environmental problems, NOx removal using electro-generated chlorine under seawater electrolysis was studied in a lab-scale scrubbing reactor. Electro-generated chlorine was prepared by seawater electrolysis in an undivided cell. Results showed that active chlorine concentration increased linearly with the increase of current density and electrolysis time. Energy consumption decreased from 83 to 6.1 kW h per (kg [Cl2]) with the salinity varying from 3.2 to 37.8 ppt after 5 min of electrolysis. Onsite generation of active chlorine using concentrated seawater from desalination plants operated on a ship was suggested to be a cost-effective solution with less energy consumption. Then, effects of dilution ratio (seawater/electrolyte), inlet NO and SO2 concentration, and initial pH value of scrubbing solution on NOx removal efficiency were further investigated. NOx removal efficiency of electro-generated chlorine at pH value of 7 decreased from 98.9% to 20.2% with the dilution ratio increasing from 2.4 to 96. The NO absorption rate by HOCl was proved to be higher than that by OCl−. NO absorption rate increased linearly as inlet NO concentration increased. When SO2 concentration increased from 207 to 814 ppm, NOx removal efficiency decreased slightly, but SO2 removal efficiency was almost kept at 100%. The possible reaction mechanism and pathways were discussed by evaluating the pH-dependant NOx removal efficiency using electro-generated chlorine. The proposed method of wet scrubbing using electro-generated chlorine was demonstrated to be a potential after treatment strategy to control NOx emissions from large marine diesel engines.