Experimental and numerical investigation of development, rearrangement and detachment of reactive-inert particle structures on cylindrical collectors in gaseous environment

反应性惰性颗粒结构沉积在气体流场中的集热器上有多种应用。用于从废气或过程气体中去除颗粒的多孔过滤介质中的烟尘(活性)和灰烬(惰性)，以及用于煤尘气化的固定床反应器中的煤尘(活性)、灰烬(惰性)和破碎的填充材料(惰性)都是这种颗粒结构的例子。沉积的结构可以从收集器中分离出来，并穿透多孔介质。例如灰尘通过烟尘颗粒过滤器的渗透或煤尘在固定床反应器中的输送。沉积颗粒的再夹带是发生输送现象所必需的。根据L 1972年的研究，当气体速度高于1米/S时，惰性粒子可以从单纤维中分离出来。反应粒子结构对剥离的影响尚不清楚。首先，用煤烟和沉积在40微米厚金属纤维上的4-20微米玻璃球进行的实验证实了L的结果。在这些实验中，当温度为22℃时，颗粒结构在3.5m/S(表观速度)以上分离，在410℃时，碳烟发生反应，再卷吸仅发生在48 cm/S处，此外，随着温度的升高，颗粒结构收缩和变形。这些实验表明，在较低的流速下，颗粒结构中的活性成分会导致捕收器脱离。在本研究项目中，应研究气速、温度、捕收器直径、捕集器上的颗粒数量、反应/惰性颗粒的百分比、颗粒沉积的结构、惰性颗粒的大小、反应颗粒的大小和工艺过程对反应-惰性颗粒结构的影响。应使用单个圆柱形收集器，以实现对脱离现象的基本了解，而不受所用多孔介质的具体结构的影响。应在卡尔斯鲁厄理工学院进行圆柱形收集器中活性-惰性颗粒结构脱离的实验研究。沉积的颗粒结构应用称重和显微镜进行表征。对于粒子脱离的量化，应该使用重排图像分析和光片技术。此外，应该在Bergische University Wuppertal模拟粒子脱离。这些模型增强了对模型的进一步理解，并允许在模型验证后计算脱离其他几何形状和应用。本研究项目的目的是研究惰性-反应性颗粒结构的再夹带。再夹带颗粒的数量、分布和结构与气流速度、温度、工艺程序、分离结构的粒度分布、惰性和反应性分数的关系是特别有趣的。这种依赖关系的模型将被开发出来，并在实验中得到验证。

Reactive-inert particle structure depositions on collectors in gas flow fields occur in several applications. Soot (reactive) and ash (inert) in porous filter media used to remove particles from exhaust gases or process gases, but also coal dust (reactive), ash (inert) and fractured packing material (inert) in fixed bed reactors for coal dust gasification, are examples for such particle structures. Deposited structures can detach from the collector and penetrate through the porous media. Examples are the penetration of ash through soot particle filters or the transport of coal dust in fixes bed reactors.Re-entrainment of deposited particles is necessary for the occurrence of transport phenomena. Inert particles can detach from single fibres at gas velocities higher than 1 m/s according to Löffler 1972. The influence of reacting particle structures on detachment is not known jet.First experiments with soot and 4 – 20 micrometer glass spheres deposited on a 40 micrometer thick metal fibre confirm the result by Löffler. In these experiments the particle structures detach at more than 3,5 m/s (superficial velocity) if the temperature was 22°C. At 410°C the soot reacted and re-entrainment took place at only 48 cm/s. In addition the particle structures shrank and deformed at elevated temperatures. These experiments shows that reactive components in particle structures can cause detachment from collectors at lower flow velocities. In this research project the detachment of reactive-inert particle structures in dependence of gas velocity, temperature, diameter of the collector, amount of particles on the collector, percentage of reactive/inert particles, structure of particle deposits, size of inert particles, size of reactive particles and process procedure should be investigated. Single cylindrical collectors should be used in order to achieve fundamental understanding of detachment phenomena independent of the concrete structure of the used porous media.Experimental research of the detachment of reactive-inert particle structures from cylindrical collectors should be made at the Karlsruher Institute of Technology. The deposited particle structure should be characterized by weighing and microscopy. For quantification of particle detachment an rearrangement image analysis and a light-sheet-technique should be used.Also the detachment should be modelled at the Bergische Universität Wuppertal. These models enhance further understanding and allow calculation of detachment from other geometries and applications after the model is verified.The aim of this research project is to investigate re-entrainment of inert-reactive particle structures. Dependence of the number, distribution and structure of re-entrained particles on the airflow velocity, temperature, process procedure, particle size distribution of separated structures, inert- and reactive- fraction is of special interest. Models of this dependence will be developed and verified experimentally.