VUV/UV/(OCl-)高效氧化吸收船舶废气SOx与NOx的机理研究

Confronted with the serious situation of ships emission abatement, there is an urgent need for international shipping to develop more efficient, economical and integrated ship emission treatment technologies. Wet scrubbing technologies have attracted much attention due to the advantages of simultaneous treatment of multi-gas pollutants, and lower investment and operating costs. However, the challenge of efficient oxidation and absorption of NOx under seawater environment remains a key issue for this kind of technology. Therefore, a high-efficient oxidation-absorption new method for the SOx and NOx from ships exhausts by VUV/UV/(OCl–) process (i.e. Hypochlorite irradiated by 185 nm VUV and 254 nm UV) was proposed in this project. Additionally, the reaction mechanisms of SOx and NOx removal involved by free radicals generated from the VUV/UV/(OCl–) process would be revealed quantitatively. First, experiments will be conducted to investigate some relevant factors on desulfurization and denitrification performance of the VUV/UV/(OCl–) method. Second, the types and reaction mechanisms of the free radicals involved in desulfurization and denitrification will be elucidated through direct detection and indirect capture experiments. Last, the chlorine produced by seawater electrolysis instead of the hypochlorite will be used to perform further experiments, as seawater can be accessed easily onboard at a lower cost. Then, a kinetic model will be developed, which is expected to describe main reaction characteristics of desulfurization and denitrification by VUV/UV/electrolyzed seawater method. Verified by experiments, this kinetic model will be used to quantitatively evaluate roles of free radicals involved in desulfurization and denitrification under seawater environment. Research results of this project would provide the essential theoretical support for the research and development of an efficient, economical and integrated treatment technology for ships exhausts.

面对严峻的船舶废气减排形势，研发高效、经济的船舶废气一体化处理技术是目前国际航运业的迫切需求。尽管湿法洗涤具有可同时处理多种有害气体污染物、投资运行成本低等优点而备受关注，但这类技术实船应用的关键是解决海水环境下高效氧化吸收NOx的难题。因此，本项目提出基于VUV/UV/(OCl-)体系（185 nm VUV+ 254 nm UV辐照次氯酸盐）高效氧化吸收船舶废气SOx与NOx的新方法，并定量揭示该体系生成自由基参与脱硫脱硝的反应机理。实验研究相关因素对该方法脱硫脱硝性能的影响规律；运用直接检测与间接捕获手段，阐明参与反应的自由基的种类与反应机理；鉴于实船海水取用便利，利用海水电解制氯替代次氯酸盐，建立描述VUV/UV/电解海水脱硫脱硝主要反应特征的动力学模型，用于量化评价海水环境中自由基参与反应的作用程度，并实验验证。研究成果可为研发高效、经济的船用一体化烟气处理技术提供必要的理论支撑。

受国际社会对航运业减排的法规压力日益严苛，船舶尾气排放经济高效处理技术仍是船舶工业向绿色化转型升级的重大需求。为此，本项目提出了一种基于VUV/UV/(OCl-)体系（185 nm VUV+ 254 nm UV辐照次氯酸盐）高效氧化吸收船舶废气SOx与NOx的新方法。围绕阐明VUV/UV/(OCl-)体系脱硫脱硝机理及反应速率这一关键科学问题，项目主要从脱硫脱硝性能影响因素、VUV/UV/(OCl-)体系脱硫脱硝机理、VUV/UV/电解海水体系脱硝反应动力学模型3方面开展了系统性研究工作。取得主要成果包括：① 从气相、液相和光强三个方面开展系统性试验，总结了VUV/UV/(OCl–)氧化吸收SOx与NOx的性能规律，相比常规普通氧化剂参与的氧化吸收尾气净化方法，本方法真空紫外光源辐照次氯酸盐使得氧化吸收能力大幅提升（约5倍），这为实船开发高效紧凑的湿法后处理洗涤装置提供了重要数据支撑；② 利用直接离子色谱产物检测分析反应前后氮、元素质量平衡，自由基间接捕获脱硫脱硝对比试验，以及电子自旋共振检测活性自由基等多种途径，阐明了脱硫脱硝过程光化学反应生成活性自由基的参与脱硫脱硝的主要反应途径，并结合脱硫脱硝试验现象，揭示了VUV/UV/(OCl–)体系脱硫脱硝的主要反应机理；③ 考虑实船海水取用便利，进一步开展VUV/UV/电解海水体系脱硫脱硝的反应动力学研究，结合自由基稳态动力学理论计算方法，建立了VUV/UV/电解海水体系脱硫脱硝的简化动力学模型，确定了海水环境中活性自由基参与脱硫脱硝的微观反应机理及VUV/UV/电解海水体系总NO吸收速率方程，这为进一步试验放大和化工过程设计提供了关键数据支撑，同时也为高级氧化技术与船舶污染物排放控制技术两个领域的交叉创新提供了新思路。