A Complementary Study of Ultra-Fast Magnetic Resonance Imaging and Electrical Capacitance Tomography for the Scale-up of Gas-Solid Particulate Systems

多相颗粒或颗粒系统（例如在流化床和气动输送机中）的行为呈现出严重的实验问题，因为它们是不透明的，很大程度上阻碍了光学技术的使用。此外，插入物理探针不可避免地会干扰被调查的系统。因此，很难制定可靠的比例标准或验证这些系统的数值模拟。我们的目标是利用俄亥俄州立大学（ECT）和剑桥大学（MRI）的联合专业知识，验证和探索使用两种互补的非侵入性实验技术：电容断层扫描（ECT）和磁共振成像（MRI）的测量局限性。将特别注意这些技术在验证离散元模型（DEM）预测和在气流化床中制定放大标准方面的适用性。考虑到最近这三个领域的发展，特别是ECT在工业规模流化床设计中的潜力，如果它得到适当的验证，这是及时的。这里考虑的实验技术（MRI和ECT）是互补的，因为它们的优势在于测量多相颗粒系统的不同特征。磁共振成像可以可视化固体的整体运动，以及密集固体相和稀薄固体相（气泡、射流、空洞）的颗粒速度分布。此外，还可以确定电压分布。我们还建议将MR扩展到能够在多相系统中首次直接成像气体。电痉挛疗法的主要优势在于它没有任何严重的尺寸限制，尽管设备必须是非金属的。与MRI一样，它可以确定空隙的速度，即气泡和鼻涕虫，以及空隙的分布。然而，散装固体的速度是无法确定的。重要的是，两种技术可以测量的变量中存在重叠，最重要的是空隙分布和空隙上升速度。这些测量将用于两种技术的交叉验证。

The behaviour of multiphase particulate or granular systems (e.g. in fluidised beds and pneumatic conveyors) presents severe experimental problems because they are opaque, largely preventing the use of optical techniques. Also, inserting physical probes inevitably disturbs the system under investigation. Thus, it has been difficult to develop reliable scale up criteria or validate numerical simulations of these systems. We aim to validate and explore the limitations of measurement using two complementary, non-intrusive experimental techniques: Electrical Capacitance Tomography (ECT) and Magnetic Resonance Imaging (MRI), using the combined expertise of Ohio State University (ECT) and Cambridge (MRI). Particular regard will be paid to the applicability of these techniques in the validation of the predictions of Discrete Element Modelling (DEM) and in the development of scale-up criteria in gas-fluidised beds. This is timely, given recent developments in all three of these areas, particularly in the potential that ECT could have in the design of truly industrial-scale fluidised beds, provided it is properly validated.The experimental techniques considered here (MRI and ECT) are complementary in that their strengths lie in measuring different features of multi-phase granular systems. MR enables the bulk solids motion to be visualised, as well as the particle velocity profiles, in both the dense solids phase and the lean (bubble, jet, void) phase . Furthermore, it is possible to determine voidage profiles. We also propose to extend MR to be able to image gas directly for the first time in a multiphase system. ECT has a major advantage in that it does not have any serious restrictions regarding size, although equipment must be non-metallic. As with MRI, it is possible to determine the velocity of voids, i.e. bubbles and slugs, and voidage profiles. The velocity of the bulk solids cannot be determined, however. Importantly, there is an overlap in the variables which can be measured by either technique, the most important ones being voidage profiles and the rise velocity of voids. These measurements will be used for cross-validation of the two techniques.