烟气冷凝除湿脱污气液固环境中活性离子迁移反应及其耦合机理研究

Dehumidification and decontamination during flue gas condensation is the deep condensation of the wet flue gas after the desulfurization of the coal-fired power plant. This method can obtain the latent heat of vaporization and remove the gas-liquid-solid pollutants. This method can also eliminate smoke plumes and recover water resources, slowing the haze at some degrees. As a new flue gas purification treatment method, the condensation, deposition and corrosion characteristics of water vapor and various gas-liquid-solid pollutants during the condensation process of flue gas need to be studied, especially the component and concentration change of the active ions. The project focuses on the key scientific issues in the condensation process of flue gas, which selects typical corrosion-resistant materials as the research object. The first step is to theoretically model and experimentally study the phase transition process of water vapor and various gaseous pollutants and the deposition process of solid pollutants to obtain the gas-liquid-solid three-phase heat and mass transfer characteristics of the flue gas. Secondly, the corrosion characteristics of the metal surface with different materials and wall temperatures in the condensation process of the flue gas are studied to reveal the migration law, chemical reactions and coupling mechanism of active ions. Finally, the surface of austenitic stainless steel treated with super-hydrophobic technology is put forward. The inhibition of super-hydrophobic surface on film condensation and reactive ion migration will be investigated. The research of this project can enrich the basic theoretical system of cooperative dehumidification and decontamination during the condensation process of flue gas, laying the theoretical and technical foundation for system design, material selection and haze governance.

烟气冷凝除湿脱污是将燃煤机组脱硫后的湿烟气进行深度冷凝，在回收汽化潜热的同时脱除多种气液固态污染物、消除烟羽并回收水资源，从源头上减缓雾霾。作为新型烟气净化处理方法，烟气冷凝除湿脱污过程中水蒸气与多种气液固污染物冷凝沉积规律及其腐蚀迁移特性亟需研究，尤其是烟气冷凝过程中活性离子成分与浓度的变化规律。项目围绕烟气冷凝过程中的关键科学问题，以典型耐腐蚀材料为对象，首先通过理论建模和实验研究水蒸气与多种气态污染物的相变过程及固态污染物的沉积过程，获得烟气中气液固三相的传热传质特性；其次研究烟气冷凝过程中不同材料与壁温下换热壁面的腐蚀特性，揭示材料中活性离子的迁移规律、化学反应及其耦合作用机理；最后对奥氏体不锈钢表面进行超疏水工艺处理，探索超疏水表面对壁面膜状凝结及活性离子迁移的抑制作用。本项目研究可丰富烟气冷凝过程中协同除湿与脱污的基础理论体系，为系统设计、选材调控及铁腕治霾奠定理论和技术基础。

烟气冷凝除湿脱污是将燃煤机组湿法脱硫后的烟气进行深度冷却，同时脱除多种污染物、消除烟羽和回收水资源，实现从源头上治理雾霾。本项目系统地研究了烟气冷凝除湿脱污过程气液固三相传热传质特性，活性离子向换热壁面的迁移规律、化学反应及耦合作用机理研究，超疏水金属表面处理工艺对壁面膜状凝结及活性离子迁移的抑制机理研究。换热器冷却水温相较烟气中水蒸气露点温度的过冷度控制着水蒸气在烟气中的异相成核率，冷却水温越低，烟气中异向成核率越大，污染物脱除量越大；提出了提出新的冷凝换热无量纲数组合，Ln和P，分别描述烟气的“相对湿度”和“绝对湿度”，在成熟的传统显热换热关联式的基础上新增显热换热修正系数和潜热换热修正系数，用于计算有冷凝工况发生时的显热换热系数和潜热换热系数，使冷凝换热公式具有广泛的适用性；探究活性离子向壁面的迁移规律及表面超疏水工艺对其抑制机理，Cl-是破坏金属氧化层的关键元素，聚二甲基硅氧烷、纳米SiO2粉末、纳米Al2O3粉末对AlSi10Mg进行超疏水改性可大幅提高其抗腐蚀能力；提出冷凝除湿脱污装置的微元叠加数字设计优化方法，首次实现冷凝换热器数字精确设计，直接支撑双碳时代富氢燃气锅炉余热冷凝回收节能降碳10%，使冷凝除湿脱污换热器全生命周期碳排放最低。丰富了烟气冷凝过程中协同除湿与脱污的知识体系，为系统设计选材及系统调控提供理论和技术依据。