Two New Advancements in Fluidization Research and Technologies

流态化自90年前首次工业应用以来，经历了从气固流态化到液-固、气-液-固流态化，从传统的低速流态化到高速流态化的发展过程。在三个流态化系统(g-S、L-S和g-L-S)中，也发现了不同的流态化状态，并对每个流态化状态下的流态化行为进行了表征和边界划分。申请人最近构思了一个笛卡尔坐标上的四象限地图，以流体速度为横坐标，以固体流量为纵坐标，将各种流态化操作放在地图上，并确定未来的研究需要和技术突破的潜力。象限2被发现是空的，那里的颗粒将向上流动，液体向下流动。这实际上可以使用液体和轻于液体的颗粒在反向循环流化床中实现，其中颗粒的浮力大于重力，因此它们将在稳定状态下漂浮到柱顶，从而在象限2中。因此，第一个拟议的项目是开发一种可能的应用，如废水处理的反液固循环流化床(I-LSCFB)。申请人是最先研究(立式)液-固循环流化床(LSCFB)并探索其应用的先驱之一，主要是在生物和环境工程领域，也有经验。我们将建造、委托并测试这一新设计。在使颗粒在系统内循环后，我们将使用一些现有的仪器，如光纤系统、电阻层析成像(ERT)，以绘制颗粒浓度和颗粒速度的柱子图。通过这些测量，我们将能够全面地表征I-LSCFB的流动结构，为其应用铺平道路。第二个项目也处于流态化的前沿：以臭氧分解为样品反应，对高密度循环床(HDCFB)和循环湍流床(CTFB)进行全面测试。气固流态化的一个趋势是向高气速方向发展，以避免气泡的不利影响。虽然高速流态化有显著的优点，如更高的接触效率和减少返混，但也有一些缺点，如较低的床层密度。针对这一要求，申请人一直致力于开发HDCFB和CTFB，这两种床已被证明比更传统的低密度循环床(LDCFB)和湍流床(TFB)具有许多优势。作为第二个项目，我们计划对这两种操作以及其他更传统的操作进行真实的反应研究，以证明两种高密度操作比其他沸腾床反应器具有更好的性能。对于第二个项目，我们设计并建造了一台多功能沸腾床装置，可以进行鼓泡、湍动、CTFB、LDCFB和HDCFB操作。我们将利用臭氧分解反应作为样本反应来研究这些操作并量化它们的相对性能。

Since its first industrial application of fluidization 90 years ago, fluidization has been developing from gas-solid fluidization to liquid-solid and gas-liquid-solid fluidization, and from conventional low-velocity fluidization to high-velocity fluidization. In the three fluidization systems (g-s, l-s and g-l-s), various fluidization regimes have also been identified and many attempts have been made to characterize the fluidization behaviour in each of those regimes and to demarcate the boundaries. The applicant has recently conceived a four quadrant map on a Cartesian coordinate with fluid velocity as abscissa and solids flowrate as ordinate, to place the various fluidization operations on the map and to identify future research need and potential for technological breakthroughs. Quadrant 2 was found empty, where particles would flow upwards and liquid downwards. This can actually be achieved using liquid and lighter-than-liquid particles in an inverse circulating fluidized bed where the particles' buoyancy force is larger than gravity, so that they would "float" to the top of the column in a steady state and therefore in quadrant 2. As a result, the first proposed project is to develop an inverse Liquid-Solid Circulating Fluidized Bed (i-LSCFB) for possible applications such as wastewater treatment. The applicant is one of the pioneers who first studied the (upright) Liquid-Solid Circulating Fluidized Bed (LSCFB) and explored it for applications, mostly in the bio and environmental engineering areas, so has the experience. We will build, commission and test this new design. After getting the particles circulated inside the system, we will use some of our existing instrumentation, such as the optical fibre system, the Electro-Resistant Tomography (ERT), to map the column with particle concentration and particle velocity. With those measurements, we will be able to fully characterize the flow structure of i-LSCFB, so as to pave the road for its applications. The second project is also at the frontier of fluidization: to fully test the high-density circulating fluidized bed (HDCFB) and the circulating turbulent fluidized bed (CTFB), using ozone decomposition as the sample reaction. One trend in gas-solid fluidization is to move towards high gas velocity so that the adverse effect of gas bubbles be avoided. While there are significant benefits of high velocity fluidization, such as much higher contact efficiency and reduced backmixing, there are also some drawbacks such as lower bed density. Responding to this request, the applicant has been devoting his time in developing HDCFB and CTFB, which have been shown to have many advantages over the more traditional low density circulating fluidized bed (LDCFB) and turbulent fluidized bed (TFB). As the second project, we plan to conduct real reaction studies over those two as well as other more traditional operations to demonstrate the superior performance of two high-density operations over the other fluidized bed reactors. For this second project, we have designed and built a multifunctional fluidized bed unit, that can be operated as bubbling, turbulent, CTFB, LDCFB and HDCFB. We shall utilize the ozone decomposition reaction as the sample reaction to study those operations and to quantify their relative performance.