Multiscale Investigations of Reactive Bubble Blows

鼓泡塔广泛应用于化工、石化、生化、金属等行业。特别是在反应鼓泡塔中，其效率受局部流体动力学的影响。为了提高任何装置的效率，必须考虑局部流体动力学和化学反应的相互作用，而启动状态整体设计方法没有考虑到这一点。然而，CFD对流体动力学的局部描述是存在的，但当必须建立与局部反应条件的耦合时，仍然存在一些挑战：1.气泡相互作用对反应的影响2.气泡尺寸对气泡行为的影响3.高时空分辨率下反应和流体动力学的相互作用(气泡诱导湍流)如文献中给出的，通过实验和数值研究孤立地研究了单个现象，但主要忽略了这些现象的相互作用。在本研究项目中，采用了一种新的多尺度实验和数值方法。首先从描述良好的测试系统开始，然后是SP进展中定义的工业相关(有机)系统。在第一步中，将在高空间和时间分辨率的测试池(&lt；500um L)中进行实验，以研究气泡相互作用(弹跳、膜排水)对传质和反应的影响。此外，文丘里池中的实验允许对被逆流捕获的孤立的单分散气泡群(&lt；10个气泡)进行流体动力学和反应研究。最后，将在2D鼓泡塔(多分散)中进行实验，模拟真实的圆柱形鼓泡塔。考虑到局部气泡的大小，将通过光学探头测量流体动力学和反应的影响。流体力学和湍流通过激光测量技术(PIV、LIF、PDA)进行解析，是程序验证的基础；对于反应气泡相互作用，采用无网格求解器(FPM)，无需重建即可跟踪界面。因此，它可以分解靠近界面的任何位置的反应，并支持在流体动应力下单个气泡和成群气泡在靠近界面的反应中的实验描述。然后，大规模仪器的建模基于欧拉-欧拉模型，以保持较低的计算成本。根据实验结果，对湍流模型进行了选择和优化。实施与pH和温度相关的反应可以首先描述和详细分析反应气泡柱。该项目的结果将有助于更好地了解流体力学和反应在不同尺度上的相互影响。因此，数值调查将提高布局的准确性，减少时间和成本密集型试点试验的工作量。

Bubble columns are widely used in chemical, petrochemical, biochemical and metal industry. Especially in reactive bubble columns, the efficiency is influenced by the local hydrodynamics. To increase the efficiency of any apparatus, the mutual interaction of the local hydrodynamics and chemical reactions must be considered, which is not covered by the state-of-the-start integral design methods. However, local description of hydrodynamics by CFD exists, but there are still some challenges to overcome when a coupling with local reaction conditions has to be established:1. Influence of the bubble interaction onto the reaction 2. Influence of the bubble size on bubble behavior 3. Mutual interaction of reaction and hydrodynamics at high time and space resolution (bubble induced turbulence)As given in literature, individual phenomena were isolated investigated by experiments and numerical studies, but the interaction of these phenomena were mainly neglected. In this research project, a new multi-scale experimental and numerical approach is used. Initially the start is with well described test systems followed by the industrial relevant (organic) systems defined in the progress of the SPP.In a first step, experiments in a test cell (<500µl) will be performed with a high spatial and time resolution to investigate the effect of bubble interactions (bouncing, film drainage) on the mass transfer and reactions. Furthermore, experiments in a Venturi cell allow hydrodynamics and reaction investigations of an isolated monodisperse bubble swarm (<10 bubbles) being spatially captured by the counter-current flow. Finally, experiments in a 2D bubble column (polydisperse) will be performed, mimicking a real cylindrical bubble column. The influence of the hydrodynamics and the reactions will be measured taking into account the local bubble size by optical probes. The hydrodynamics and turbulence are resolved by laser based measurement techniques (PIV, LIF, PDA) and is the basis for code validation.For the reactive bubble interactions, a mesh free solver (FPM) is used, which is able to track the interface without reconstruction. Hence, it can resolve the reactions at any location close to the interface and will support the experimental description at hydrodynamic stress of single and swarm bubbles on the reaction close to the interface. The modeling of a large-scale apparatus is then based on the Euler-Euler model to keep the computational costs low. Based on the experimental results, a turbulence model will be selected and optimized. The implementation of the pH- and temperature dependent reactions allows a first description and detailed analysis of the reactive bubble column.The result of the project will lead to a better understanding of the mutual influence of hydrodynamics and reaction on different scales. The numerical investigations will therefore increase the accuracy of layout and reduce efforts for time and cost intensive pilot experiments.