Two New Advancements in Fluidization Research and Technologies

流化技术自90年前首次工业应用以来，经历了从气固流化到液固流化、气液固流化、从常规低速流化到高速流化的发展历程。在三种流化系统（g-s， l-s和g-l-s）中，还确定了各种流化机制，并进行了许多尝试来表征每种机制中的流化行为并划定边界。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，固体流速为纵坐标，在地图上放置各种流化操作，并确定未来的研究需求和技术突破的潜力。象限2是空的，粒子向上流动，液体向下流动。这实际上可以通过在反循环流化床中使用液体和比液体轻的颗粒来实现，其中颗粒的浮力大于重力，因此它们将在稳定状态下“漂浮”到柱的顶部，因此在象限2中。因此，第一个提议的项目是开发一种反液固循环流化床（i-LSCFB），用于废水处理等可能的应用。申请人是最早研究（立式）液固循环流化床（LSCFB）并探索其应用的先驱之一，主要应用于生物和环境工程领域，因此具有经验。我们将建造、委托和测试这种新设计。在得到在系统内循环的粒子后，我们将使用我们现有的一些仪器，如光纤系统，电阻层析成像（ERT），来绘制粒子浓度和粒子速度的柱状图。通过这些测量，我们将能够全面表征i-LSCFB的流动结构，从而为其应用铺平道路。第二个项目也处于流化的前沿：对高密度循环流化床（HDCFB）和循环湍流流化床（CTFB）进行充分测试，采用臭氧分解作为样品反应。气固流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。虽然高速流化有显著的好处，如更高的接触效率和减少反混，但也有一些缺点，如较低的床层密度。为响应这一要求，申请人一直致力于开发HDCFB和CTFB，它们已被证明比传统的低密度循环流化床（LDCFB）和湍流流化床（TFB）具有许多优点。作为第二个项目，我们计划对这两个以及其他更传统的操作进行真实的反应研究，以证明两个高密度操作优于其他流化床反应器的性能。对于第二个项目，我们设计并建造了一个多功能流化床装置，可以运行为鼓泡，湍流，CTFB， LDCFB和HDCFB。我们将利用臭氧分解反应作为样品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.