基于O3/NaClO协同氧化吸收法的船舶尾气同时脱硫脱硝性能与机理研究

The exhaust gas emitted from ocean-going ships contains a large amount of gaseous pollutants, such as SOx and NOx, resulting in a serious damage to the air environment and human health. Thus, there is a great demand on technologies for multi-pollutants removal from marine exhaust gas in shipping industry. In this context, a novel method of simultaneously removing SOx and NOx from marine exhaust gas by using the synergistic effect of ozone (O3) and sodium hypochlorite (NaClO) has been proposed in this project. It combines O3 injection with wet scrubbing in the same reactor in order to improve the utilization of O3 oxidants. The effects of wet scrubbing conditions on self-decomposition and denitrification performance of O3 will be investigated theoretically and experimentally, and the relevant influencing mechanism will be explored. Furthermore, NaClO will be added in the wet scrubbing solution to combine with O3, aiming to reduce the power consumption for O3 production. The effects of various operating parameters on simultaneous removal of SOx and NOx by using O3/NaClO will be studied, and the relevant reaction mechanism will be discussed. Then active chlorine solution will be prepared by seawater electrolysis, which is used to replace the NaClO solution effectively. The performance and influencing mechanism of simultaneous desulphurization and denitrification by the combination of O3 and electrolyzed seawater will be investigated in detail, and the key process conditions will be optimized. In the end, a novel method of multi-pollutants removal from marine exhaust gas would be developed, which could meet the requirements of marine applications and was financially viable for vessels. This work would also provide the essential theoretical guidance and technical support for the practical application onboard.

由于船舶排放的废气中含有大量的SOx、NOx等气体污染物，对世界环境造成了严重的危害，从而使船舶废气多污染物综合处理技术成为当前全球航运业的迫切需求之一。为此，本项目创新性地提出一种基于臭氧（O3）/次氯酸钠（NaClO）协同氧化吸收的船舶尾气同时脱硫脱硝方法。通过O3注入同位结合湿法洗涤，实现O3的高效利用，研究湿法洗涤对O3自分解及脱硝性能的影响规律，并揭示相关作用机理；在此基础上，向湿法洗涤液中加入NaClO，通过O3/NaClO协同氧化，有效减少O3的用量，进而减少电耗，研究O3/NaClO协同氧化脱硫脱硝性能及强化方法，并探讨相关反应机理；通过电解海水高效制氯，有效替代NaClO溶液，研究O3/电解海水协同氧化脱硫脱硝性能及影响机理，进而优化关键工艺条件。通过本项目的开展，最终形成一种适合船舶实用、经济可行的船舶尾气污染物综合处理方法，并为相关技术的实船化应用提供必要的理论支撑。

在全球范围内，船舶普遍采用柴油机作为动力装置，每年消耗近3亿吨燃油，排放了大量的SOx、NOx、颗粒物等污染物，对生态环境与人类健康造成了严重危害。虽然船舶采用低硫油技术，可有效减少SOx排放，但会显著增加运营成本。湿法洗涤脱硫技术已在船舶领域成功应用，但很难与SCR脱硝技术相集成。因此，航运业亟需一种经济高效的船舶尾气同时脱硫脱硝技术与产品。本项目创新性地提出一种基于臭氧/次氯酸钠协同氧化吸收的船舶尾气同时脱硫脱硝方法。该方法的关键在于利用湿法洗涤对烟气进行降温，避免同位注入臭氧的高温自分解，并通过臭氧与湿法氧化剂相协同，有效提高臭氧的利用率，同时降低臭氧的使用量，从而提高工艺的实用性与可行性。针对该方法，本项目重点开展了四个方面的研究工作：研究湿法洗涤对臭氧自分解特性和脱硝性能的影响，结果表明湿法洗涤显著地提高了同位注入臭氧的利用率，并揭示了相关作用机理；研究对比了不同添加剂对臭氧氧化脱硝性能的强化作用，结果表明亚硫酸钠-三乙醇胺（TEOA）同时作为湿法添加剂，可有效地提高NOx去除率；研究臭氧注入与次氯酸钠湿法洗涤同位结合的协同脱硫脱硝性能，结果显示当O3/NO摩尔比为0.5、循环洗涤液中NaClO浓度为25 mM时，即可实现对NO的全部氧化，此时SOx去除率接近100%，且NOx脱除率可达70%以上；研究臭氧注入与电解海水湿法洗涤同位结合的协同脱硫脱硝性能，发现电解海水与NaClO溶液的脱硝效果基本相同，且由于海水具有较高的碱度，可有效促进脱硫效果。本项目研究结果充分证明湿法洗涤技术与臭氧高级氧化脱硝技术之间具有良好的集成性，两者同位协同提高了臭氧利用率，且通过臭氧与次氯酸钠协同显著减少了臭氧的使用量。研究成果可为开发体积紧凑、成本低、功耗少的烟气脱硫脱硝一体化工艺提供有益的借鉴，且可为臭氧注入-湿法洗涤同位协同脱硫脱硝技术在船舶领域的应用提供一定的理论指导与技术支持。