内预热式超临界水膜反应器内水膜边界层的防护机理和调控机制

A good application prospect for treating highly concentrated and difficultly degraded organic wastewater has been shown by supercritical water oxidation, and transpiring wall reactor can effectively alleviate both corrosion and salt plugging problem in this process. The transpiring wall reactor’s anti-corrosion performance and avoidance of salt plugging is dependent on the water film boundary layer on the inner surface of the porous wall. However, its protective mechanism and regulatory mechanism can’t be grasped for lacking of in-depth and systematic study, resulting in greatly reducing its protective effect and feed degradation efficiency for uneven distribution and unreasonable parameters of the water film. This project intends to simulate the distribution of inorganic salt by the Lagrange method, and obtain the pressure drop and ion recovery rate of porous pipe under different water film parameters by establishing the salt deposition test system. Thus, the quantitative relationship between water film parameters and salt deposition characteristics can be established. Corrosion characteristics of porous pipe in the different water temperature coupling component corrosion conditions will be carried out, and the internal relations between the water film parameters and the composition, phase structure and porosity of the corrosion products were analyzed by means of weight loss method, scanning electron microscope and energy spectrum analysis. Thus, corrosion mechanism and corrosion kinetics of porous tubes can be revealed. The optimization of water film will be carried out on the basis of the thorough degradation of waste water and the stability of hydrothermal flame, and the optimized distribution and parameters of the water film can be obtained. The results of this study will guide the design of the inner preheating transpiring wall reactor and improve the design theory.

超临界水氧化处理高浓度难降解有机废水已展现良好应用前景，水膜反应器可大大缓解工艺中的腐蚀和盐沉积问题。多孔管内壁面的水膜边界层是水膜反应器抗腐蚀和盐沉积的关键，但对其缺乏深入系统研究，无法掌握其防护机理及调控机制，进而容易出现水膜分布不佳、参数不合理等问题，不仅大大降低其防护作用，而且影响废水降解。本项目拟采用拉格朗日方法模拟无机盐的运动分布特性，并搭建盐沉积试验系统获取不同参数下的多孔管压降和离子回收率，建立水膜参数与盐沉积特性的定量关系，揭示水膜的抗盐沉积机理；采用失重法及电镜扫描、能谱分析等手段，研究多孔管在不同水膜温度耦合腐蚀组分条件下的腐蚀特性，分析各参数与腐蚀产物成分、相结构、孔隙率的内在联系，探索多孔管的腐蚀机理和动力学；在协调废水彻底降解和热液火焰稳定的基础上，开展水膜调控优化，获取优化的水膜分布和水膜参数。研究成果可指导内预热式水膜反应器的设计，并完善反应器的设计理论。

超临界水氧化处理高浓度难降解有机废水已展现良好应用前景，水膜反应器可大大缓解工艺中的腐蚀和盐沉积问题。多孔管内壁面的水膜边界层是水膜反应器抗腐蚀和盐沉积的关键，亟需掌握其防护机理及调控机制。本项目开展了无机盐颗粒在超临界水膜反应器内气固两相流特性的数值模拟，分析了无机盐颗粒直径、密度等参数对其运动分布特性的影响规律，进而掌握了操作参数与无机盐沉积的相互关系；搭建基于水膜反应器的超临界水氧化连续式试验系统，研究了废液含有无机盐时，反应器出口电导率的变化规律及无机盐回收率，获得降低无机盐沉积的条件；搭建了腐蚀试验系统，评估了多孔316L不锈钢在水膜反应器相应条件下的腐蚀特性和机理，为优化材料寿命提供指导；试验研究了水膜形成与中心反应区的传热传质特性，获得协调水膜区和反应区相互作用的方法；提出以氮气、空气、溶氧水作为保护膜的反应器及系统，研究其反应特性、保护膜分布、抗腐蚀盐沉积特性、经济性等，为相关工艺开发和应用奠定基础；研究了水膜边界层的均匀分布问题，提出通过增加蒸发水注入管和降低多孔管孔隙率来实现水膜均匀化的方法；研究了反应器的直径、长度、高径比等结构参数对反应器内的水膜形成和废水降解的规律，提出热负荷的反应器设计方法，并获得一定范围的热负荷数据，为水膜反应器提供了设计依据，同时非富了水膜反应器的设计理论。