气体穿越固液两相液池过程气泡动力学行为及其对颗粒运动分离影响机制

The flow and separation processes of solid-liquid two-phase under the bubble dynamic behaviors widely exist in the industrial production. They are an important basic research problem in the field of engineering thermo physics. Having the industrial application of gas passing through the solid-liquid two-phase suspension in the pool as the background, the bubble dynamic behaviors in the solid-liquid two-phase suspension and the influence of bubble dynamic behaviors on the particles movement and solid-liquid separation are studied in this project. The technical routes and methods of experimental study and numerical simulation, macroscopic and microcosmic analysis, qualitative and quantitative analysis are adopted. The coupled mathematical models are built with gas-liquid two-phase dynamics and discrete particle dynamics in the frame of Euler-Lagrange. The bubbles dynamic behaviors such as bubble generation, expansion, detachment, rising, coalescence and collapse in solid-liquid two-phase suspension are revealed. This research explores some suitable feature parameters to describe the behaviors of bubble. The interaction mechanism of three-phase was analyzed. The influence of bubble dynamic behaviors on particle movement and separation are revealed，and the interrelationship between the two is analyzed. The difficulties of this project include the observation and description of bubble behaviors and particle movement and separation in the experiment, the interaction between bubble and particle and the effective numerical simulation of three-phase flow. The successful implementation of this project will make a great contribution to further enriching the separation theory and method system of gas-liquid-solid three-phase flow, and provides theoretical guidance for the related industrial applications and technical basis in Inner Mongolia Autonomous Region.

气泡行为作用下的固液两相流动、分离过程存在着复杂气液固三相流动体系，其一直是一个重要基础研究问题。本项目以气体穿越液池中固液两相过程的工业应用为背景，以固液两相中气泡动力学行为及其对颗粒运动、固液分离的影响为研究对象。综合采用实验与数值模拟、宏观与微观分析、定性与定量分析相结合的技术路线和方法。在欧拉-拉格朗日框架下创建气液两相动力学与离散颗粒动力学耦合数理模型及数值模拟。揭示固液两相中气泡生成、膨胀、脱离、上升、聚并、破碎等动力学行为；探寻适宜描述气泡行为的特征参数及其规律；分析气泡-颗粒-液体三相间相互作用机制；揭示气泡行为对颗粒运动分离的影响规律，剖析两者之间内在关联。本项目难点：气泡行为与固液流动分离过程实验观测与表征；气泡-颗粒间动力学分析与建模；三相流动有效数值模拟方法。本项目成功实施，将有助于丰富气液固三相流动分离理论与方法体系，为自治区相关工业应用提供理论指导和技术基础。

气泡行为一直是工业领域广泛存在的现象，其行为特性对工艺过程的稳定高效运行起到重要影响作用，因此针对气泡行为特性的认识一直是重要基础研究问题之一。本项目以气体穿越液池中固液两相过程的工业应用为背景，综合采用实验与数值模拟方法，对气泡的运动行为及其对颗粒运动分离的影响进行了研究。首先对比分析了不同管口布置方式下的气泡在液池中生成、长大、脱离和穿越液池上升等系列行为特性。通过研究发现，气泡等效直径在顶部浸没方式下为最大，而气泡形状变化在侧部和底部浸没方式下较为剧烈。气泡上升呈现出直线形、折线形和螺旋形运动轨迹；随后开展气液两相压差波动信号混沌特性、Volterra自适应短期预测和LSTM循环神经网络预测研究，开发了一套基于信号处理的气泡-液体两相流动预测分析方法，实现对气泡运动流型在线辨识和预测；实验研究了穿越固液两相液池过程中的气泡运动行为特征，获得颗粒浓度、颗粒粒度、管口管径、活性剂种类对气泡尺寸、气泡形态、气泡上升速度等气泡行为影响规律。通过研究发现，固液悬浮液中的颗粒粒度和颗粒浓度的增加，抑制了气泡尺寸增长。而表面活性剂的加入，对小颗粒粒度、低颗粒浓度悬浮液中气泡轨迹、尺寸、上升速度的调控效果更明显；提出了一套三相流动预测模型及其数值模拟方法，将计算气液界面的VOF模型和跟踪离散颗粒受力运动的DPTM确定性轨道模型相结合，建立了CFD-DPTM-VOF气泡-颗粒-液体三相流动数学模型，实现气体穿越固液两相液池过程中气泡-颗粒-液体三相流动数值预测，研究了穿越固液两相液池上升过程中，气泡运动对液体中不同粒径颗粒运动及其分布的影响规律；最后将所建立的多相流动预测模型应用到气流床煤气化炉激冷室内气体穿越液池过程以及半干法脱硫塔内部气液固流动过程，从而为实际运行提供指导。本项目研究从理论和实践方面进一步认识了气体穿越液池过程中的气泡行为和颗粒运动特征，丰富了三相流动认知体系，为该过程的实际应用提供一定指导和理论支撑。