浸没燃烧蒸发技术因具有优异的抗结垢和抗腐蚀性能，适用于含有高盐和高浓度腐殖质的渗滤液浓缩液的处理，已成为我国渗滤液浓缩液处理领域的主流工程技术之一，但处理过程中存在颗粒物释放并导致烟气拖尾的问题，这对工作人员健康和区域环境质量造成了威胁。浸没燃烧蒸发过程颗粒物形成机制研究仍是空白，难以制定科学的颗粒物控制策略。基于对蒸发尾气颗粒物排放特性及规律的识别，本论文对颗粒物跨介质迁移行为与机制开展深入研究，据此提出颗粒物的控制原理和方法，并在实际工程中进行了验证，研究成果完善浸没燃烧蒸发技术颗粒物控制理论及对指导工程项目颗粒物控制有重要意义。本研究基于3个典型浸没燃烧蒸发项目的现场测试解析了颗粒物的排放特性。蒸发尾气中的颗粒物浓度为1.64-218.35 mg/m3，其中粒径≤ 2.5 μm的颗粒物约占颗粒物总质量的75.37%-89.98%。颗粒物主要由8种常见无机离子（80.96%-86.88%）、腐殖质（1.95%-3.36%）和不溶性碳（2.57%-4.26%）组成。基于高温气泡在释放颗粒物临界温度之上的蒸发能力，提出浓缩液溶质跨介质分流系数，建立颗粒物综合释放能力模型。结果显示，腐殖质浓度和气泡温度是影响颗粒物释放的两个关键因素，且颗粒物释放的气泡临界温度为1390 K。针对浸没燃烧蒸发过程中动态气液界面难以捕捉和分析的问题，开展了腐殖质与无机离子溶液静态蒸发的模拟实验，结果表明腐殖质可通过静电力/络合作用与无机离子结合，也可作为无机离子以晶体析出的附着位点，同时发现腐殖质与无机离子复合物易在气液界面析出，该行为是浸没燃烧蒸发过程颗粒物在气液界面成型的关键。基于气液界面颗粒物受力与传热蒸发的耦合作用，构建了颗粒物成型、蓄能、闪脱和分离四阶段的跨介质迁移模型。阐明了高温气泡通过实现颗粒物表面的膜态沸腾以解除了毛细力对颗粒物的限制，从而驱动颗粒物跨介质迁移的机制。解析了颗粒物跨介质迁移过程，建立了膜态沸腾状态与气泡临界温度的对应关系；同时明晰了影响跨介质迁移的控制要素并揭示了其作用原理。基于颗粒物四阶段跨介质迁移过程，提出了“腐殖质去除-温度控制-尾气净化”的浸没燃烧蒸发颗粒物控制原理，开发了“原料预处理-浸没燃烧优化-末端布袋除尘”成套技术。成套技术应用于工程实践并发现颗粒物去除效率稳定在90%以上，排放浓度低于2 mg/m3。
Submerged combustion evaporation technology is especially suitable for the treatment of membrane-concentrated leachate containing the high concentrations of salt and refractory humus due to its excellent anti-fouling and anti-corrosion properties. This technology is one of the main engineering technologies for the membrane-concentrated leachate treatment in China. However, this technology has to face the problem of the release of particles in a large amount during project operation, which seriously endangers the health of workers and affects the quality of the regional environment. Due to the current lack of understanding of the formation mechanism of particles in the submerged combustion evaporation process, it is difficult to develop scientific particle control strategies. Here, based on the emission charateristics and emission pattern of particles, this paper conducted in-depth research on the cross-media migration behavior and mechanism of particles, proposed the principle and method of particle control, and verified it in practical engineering. This work could refine the theory of submerged combustion evaporative pollution control and lay a theoretical support for guiding engineering control of particles.The emission behaviors of particles were analyzed through the field test in three typical submerged combustion evaporation projects. The concentration of particles after the final processing unit was in the range of 1.64-218.35 mg/m3, and the particles with the size of ≤ 2.5 μm accounted for about 75.37%-89.98% of the total mass of particles. The particle size distribution showed that particles were in the range of 6-500 nm and mainly emitted at 30 nm. Particles after the final processing unit were mainly composed of inorganic ions (80.96%-86.88%), humus (1.95-3.36%), and insoluable carbon (2.57%-4.26%). Based on the evaporation capacity of bubbles above the critical temperature for particle release, a model was proposed for evaluating the particle release abilty with the introduce of cross-media split coefficient. The model results showed that the bubble temperature and humus concentration were the key factors affecting the release of particles, and the critical temperature for project operation control was proposed to be 1390 K.Aiming at the fact that the dynamic gas-liquid interface was difficult to be indentified during the submerged combustion evaporation process, static experiments of the evaporation of humus and inorganic salt were carried out. It was found that humus had the ability of precipitation at the gas-liquid interface, and it can be combined with inorganic salts through electrostatic force and complexation with inorganic ions to form the humus-inorganic ions complexes at the gas-liquid interface, which indicated that the precipitation of humus is the key condition for the formation of particles at the gas-liquid interface during the submerged combustion evaporation process.Based on the coupling effect of the force of particles at the gas-liquid interface and the heat and mass transfer between the gas and liquid, the movement behaviors of particles at the gas-liquid interface were identified, and then a formation-energy storage-flashing escape-separation model was constructed to illustrate the cross-media migration of particles. It was found that high-temperature bubbles drive particles to migrate across media by releasing capillary force constraints by heating particles to achieve film boiling, which theoretically elucidate the temperature-driven mechanism. The migration process of particles across the medium was analyzed, and the corresponding relationship between the film boiling state and the critical temperature of bubbles was established. At the same time, the factors that affect the cross-media of particles were clarified and the principle was revealed.The principle of "humus removal-temperature control-tail gas purification" for submerged combustion evaporation particle control was proposed based on the four-stage cross-media migration process of particles, and then a set of technologies of "raw material pretreatment-submerged combustion optimization-bag dust removal" was developed, which enable the removal efficiency of particles to be above 90% in evaporation projects and the concentration of particles to be lower than 2 mg/m3.
