冷介质诱导可凝结颗粒物（CPM）凝结团聚机制研究

Filterable particulate matter (FPM), which is usually known as soot, has been achieved ultra-low emission. Therefore, condensable particulate matter (CPM), which is in gas state in the stack and immediately condenses into granules after discharge, becomes the key object in the next stage. It is very difficult to capture insignificant amounts of the gaseous CPM directly. Thus, this project proposes the idea of making gaseous CPM to be condensed before discharge via cooling. However, CPM belongs to ultra-fine particle after condensation, and the control of ultra-fine particles has not been completely solved, which makes us come to the common key problem in the field of particle control: particle aggregation. Therefore, the synergistical implementation of condensation and agglomeration is the key to solve CPM control problem. Our previous studies have found that ultrafine particles (refering to FPM) can be agglomerated and deposited on cold surface. Meanwhile, the cold media is also the cause of CPM condensation. Therefore, this project proposes to solve the problem of CPM condensation and agglomeration by using the cold medium induction. This project intends to establish the basic knowledge system of above-mentioned method through experimental research, including exploring the law of synergistical aggregation of CPM and FPM and the influence of steam in flue gas. This method will be applied to the efficient removal of CPM. The project is in line with the major national requirement of haze control, and has important scientific value and practical significance.

可过滤颗粒物（FPM）即人们熟知的烟尘已实现超低排放，而在烟道内呈气态、排放后经冷却转变为颗粒的可凝结颗粒物（CPM）成为下一步治理的重点。直接捕集微量气态CPM很困难，为此，本项目提出通过冷却方式将气态CPM的凝结成核过程提前到排放前，然后借助常规颗粒物处理方法对其进行治理的设想。但CPM凝结后属于超细颗粒物，其治理问题也未得到彻底解决，这又归结到颗粒物治理领域的共性关键难题：颗粒团聚。因此，同步实现凝结和团聚是解决CPM治理的关键。前期研究发现：超细颗粒物可在冷介质表面发生汇流团聚和沉积，而冷介质同时也是CPM凝结的诱因。因此，本项目提出利用冷介质诱导方法解决CPM同步凝结和团聚的问题。项目拟通过实验研究建立该方法的基础理论体系；探索CPM与FPM协同团聚规律；研究烟气中水蒸气的影响；完善该机制应用于CPM高效脱除的方法体系。项目符合国家治理雾霾重大需求，具有重要的科研价值和现实意义。

可过滤颗粒物（FPM）即人们熟知的烟尘已实现超低排放，而在烟道内呈气态、排放后经冷却转变为颗粒的可凝结颗粒物（CPM）成为下一步治理的重点，而直接捕集微量气态CPM很困难，因此CPM治理是当前的重点和难点问题。在此背景下，本项目重点研究了CPM排放特性、CPM冷凝特性和转化脱除规律、燃烧过程CPM的抑制生成、CPM的吸附脱除等内容。本项目建立了精确的实验室级别CPM机理实验台，研究了中国典型煤种的CPM排放特性，发现燃煤CPM的排放浓度可达到几十毫克，超过了超低排放的标准，且包含无机和有机等复杂有害成分，环境影响不容忽视；实验证实烟气中的SO3/H2SO4是CPM中硫酸根的主要来源，可被当成CPM的重要前体物；SO3/H2SO4在烟气降温过程中，一部分冷凝在冷介质表面，一部分转化为超细颗粒悬浮于烟气中，一部分维持气态，CPM在冷凝过程中被发现也呈现类似的规律，75%冷凝于冷介质表面，25%转化为超细颗粒，称之为可凝性物质的“三态分布”凝结特性，这对进一步发展CPM的测量和控制方法提供了重要的理论指导；在热泳和扩散泳效应的作用下，超细颗粒物可在冷介质表面发生团聚和沉积，而冷介质同时也是CPM凝结的诱因，冷介质在饱和湿烟气中诱发的水蒸气冷凝过程可协同促进FPM和CPM脱除，具体研究了烟气冷凝过程中FPM的脱除、降温过程CPM的脱除、湿法脱硫过程SO3和CPM的转化和脱除等内容，FPM和CPM的脱除效率分别可达85%，可实现超低排放，这为后续发展烟气冷凝过程余热回收协同烟气净化、现有湿法脱硫工艺协同脱除CPM等技术应用提供了理论指导；另外，本项目还扩展研究了活性炭吸附CPM的方法，发现活性炭对CPM有机和无机组分均有脱除效果，且可高效脱除CPM中的剧毒成分——多环芳烃，这为活性炭协同脱除多污染物提供了优化方向；另外，还拓展进行了生物质与煤粉掺烧抑制CPM生成的研究，实验观察到最高可抑制70%CPM生成的结果，这对燃烧中CPM控制有一定的指导意义。总之，项目实现了研究目标，完成了预定的研究内容，解决了关键科学问题，得到了大量有价值的研究结论；项目申请发明专利2项，发表SCI论文20篇，培养研究生15名，取得了丰硕的研究成果。