立体旋流筛板旋-穿耦合流动机制的研究

The absorption column in wet flue gas desulphurization system have some shortcomings, such as easy to scale, poor processing capacity, equipment size is large, et al. For those reasons, we proposed a novel internal- tridimensional rotational flow sieve tray(TRST), which can make the gas-liquid phase form two coupled flow patterns, rotational flow and perforated flow. In addition, with a gas-liquid cocurrent flow operation, it can be achieving a mass process with high efficiency, large flux, low pressure drop and difficult to scale. In this project, firstly, taking the macroscopic pressure drop as the research object when gas-liquid cocurrent flow through the tray, to determine the resistance loss under different operation and tray structure parameters conditions. Combined with analysis of differential pressure pulsation time domain signal, power spectrum and flow pattern photos, to understand the interaction of gas-liquid phase under different flow pattern and flow pattern operation field. Secondly, taking the micro-structure of liquid flow flied in the tray as the research object, measuring the liquid phase velocity distribution and flow track of bubbles. Combined with CFD simulation to establish the mathematical equations of gas-liquid flow. Fully grasping the coupling law between gas-liquid phase, rotational flow and perforated flow. Finally, based on the experimental results, to establish a hydrodynamics performance evaluation index of the TRST and to optimize the tray structure. The successful implementation of this project has laid a technical foundation for deep understanding the working principle of TRST, and provided the theoretical basis for the research on the mass transfer in the future. Meanwhile, it also has some reference value for the specific problems such as the complicated flow in a similar internal structure.

针对湿法脱硫系统中吸收塔易结垢，处理能力差，设备尺寸大等缺点，提出一种新型塔内件结构—立体旋流筛板（TRST），使气液两相形成旋流与穿孔流的耦合流动，配合气液并流的操作形式，实现高效、大通量、低压降、不易结垢的传质过程。本项目首先以气液并流通过塔板的宏观压降为研究对象，确定不同操作及塔板结构参数下的阻力损失。辅以差压脉动时域信号，功率谱及流型图像分析，掌握不同流型下的气液两相作用规律及流型操作域。其次以塔板内液相流场微观结构为研究对象，通过PIV实验确定液相速度分布及气泡的流动轨迹。辅以CFD模拟建立气液两相流动数学模型，全面掌握气液两相间，旋流与穿孔流间的耦合规律。最后依据实验结果，建立塔板流体力学性能评价指标，并对塔板结构进行优化。本项目对深入了解TRST工作原理奠定了技术基础，对后续塔板传质理论研究提供理论依据，同时对相近内件结构的复杂流动等具体问题也有一定借鉴和参考价值。

立体旋流筛板（Tridimensional rotational flow sieve tray-TRST）是一种新式穿流型塔板，其通过耦合旋流与穿孔流动来强化气液两相的接触与混合，进而增强气液传质效率。同时，将TRST与气液并流操作模式有机结合应用，可实现防液泛、大通量、低压降，高操作弹性、抗堵等优点的生产过程。本项目重点研究TRST内气液两相的流体力学特性，探究旋-穿两种流动形式的耦合机制。在冷模吸收塔实验平台上准确测定了TRST的干、湿板压降，考察了操作和塔板结构等变量对压降的影响，建立了压降预测模型；将TRST的干、湿板压降与同操作条件下筛板、浮阀等塔板进行了对比，确定TRST具有显著的阻力能耗优势；基于压力脉动时域信号和频域功率谱分析，同时结合流动图像拍摄和处理，识别了TRST内气液两相流型，并准确划分了流型操作域；利用CFD模拟技术研究了TRST的空间流场结构，分析了各操作和塔板结构变量下速度、压力、相含率等参数分布规律，掌握了旋-穿流动的形成原因。基于速度矢量特征判别了穿孔流体的流动方向，揭示了旋-穿流动的转变机制；采用简化的立体旋流筛板单元分离旋-穿流体，测定了旋-穿流体的体积分配规律，建立了旋流比预测模型，揭示了旋-穿流动的耦合机制；基于阻力和湍流强度特征建立了塔板综合性能评价指标，确定了TRST最优结构参数，并参照中试塔规模，对TRST进行了放大预测。此外，开展了部分TRST传质性能方面预研工作，考察了操作和塔板结构参数对气相总体积传质系数的影响，建立了传质系数预测模型。综上所述，本项目相关结论和成果可为后续TRST传质机理的深入研究，以及工业应用推广奠定坚实的理论支持和数据支撑。