Experimental characterization of gas-liquid transport processes in a reacting bubble column using a neutralization reaction

从气相(气泡)到略带碱性的水相中二氧化碳的传递被用来定量地研究鼓泡塔中的传质，首先考虑了快速中和反应的极限情况。这个简单的系统适合于优化复杂的实验过程。此外，通过这种方式，可以在本项目第一阶段及早提供实验数据，供SPP内的数字合作伙伴进行验证和比较。在实验中，使用指示剂(例如，尿苷)和激光诱导荧光(LIF)来跟踪pH的空间和时间的变化。多亏了校准和知道流入和流出时的气体条件，才有可能以这种方式测量传质。为了避免由于气泡造成的阴影、光线折射和反射，使用了第二个与pH无关的示踪剂，允许对实验图像进行校正(双色-LIF)。测量程序首先用于孤立的气泡和气泡串，然后用于小组气泡、不同的流速和典型的气泡直径。在对测量技术进行优化后，最后考虑了一个典型的气泡群。使用高速摄像机可以及时跟踪气泡直径、气泡路径和传质。粒子跟踪测速仪(PTV)用于测量气泡的速度和轨迹，基于我们团队的现有经验。用粒子成像测速仪(PIV)测量了液体的速度。使用STEREO-PIV系统，可以获得水相的所有三个速度分量。以这种方式可以量化流体动力学对传质的影响，为SPP内的数值项目提供比较数据。由于液体性质在传质方面起着相当大的作用，因此使用不同性质的甘油/水混合物时，液体的粘度和表面张力会有所不同。在这里，将同时测量传质和流体力学。所有实验数据将尽快提供给所有项目合作伙伴和整个研究界，通过一个可在网上访问的数据库。所有对数值模拟的比较和验证感兴趣的人都可以自由地使用这些实验结果。

The transport of CO2 from the gas phase (bubbles) into a slightly basic watery phase is used to investigate in a quantitative manner mass transfer in a bubble column, first considering the limit case of a fast neutralization reaction. This simple system is appropriate to optimize the complex experimental process. Additionally, it is possible in this manner to deliver early during the first phase of this project experimental data that can be used for validation and comparison by numerical partners within the SPP. The evolution of the pH is followed in space and time in the experiment using indicators (e.g., Uranin) and Laser-Induced Fluorescence (LIF). Thanks to a calibration and knowing the gas conditions at inflow and outflow, it is possible to measure in this manner mass transfer. In order to avoid shadows, light refraction and reflection due to the bubbles, a second, pH-independent tracer is used, allowing to correct the experimental images (2-Color-LIF). The measurement procedure is used first for isolated bubbles and bubble trains, then for small groups of bubbles, varying flow rates and typical bubble diameters. After optimizing the measurement tech-niques, a typical bubble swarm is finally considered. Using high-speed cameras it is possible to track in time bubble diameters, bubble pathlines and mass transfer. Particle Tracking Velocimetry (PTV) is used to measure bubble velocities and trajectories, based on the available experience in our group. Velocities of the liquid phase are measured by Particle Imaging Velocimetry (PIV). Using a stereo-PIV system, all three velocity components of the water phase can be acquired. It is possible in this manner to quantify the impact of hydrodynamics on mass transfer, delivering comparison data for numerical projects within the SPP. Since liquid properties play a considerable role concerning mass transfer, liquid viscosity and surface tension will be varied using different glycerine/water mixtures of known properties. Here again, mass transfer and hydrodynamics will be measured simultaneously.All experimental data will be made available as soon as possible to all project partners and to the entire research community through a database accessible on the Web. All people interested by comparisons and validations of numerical simulations can freely use those experimental results.