Characterizing 3D granular flow structures in a double screw mixer using X-ray particle tracking velocimetry
Characterizing 3D granular flow structures in a double screw mixer using X-ray particle tracking velocimetry
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DOI：
10.1016/j.powtec.2015.02.061
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发表时间：
2015-07
影响因子：
5.2
通讯作者：
T. A. Kingston;T. Geick;T. Robinson;T. Heindel
中科院分区：
文献类型：
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作者：
T. A. Kingston;T. Geick;T. Robinson;T. Heindel
颗粒流在许多工业过程中经常遇到，但由于流的不透明性质而难以表征。例如，螺杆热解器正在开发用于将生物质热化学转化为生物油，但反应器内的颗粒流动和混合过程缺乏基本的了解。在本研究中，X射线粒子跟踪测速（XPTV）用于定性和定量表征双螺杆混合器中的三维（3D）颗粒流结构，该混合器在几何上复制了双螺杆热解器，通过可视化位置和速度曲线并量化单个示踪粒子的无量纲路径长度和无量纲停留时间。研究了螺杆转速、无量纲螺杆螺距、螺杆旋转方向和材料注射配置的影响。某些操作条件被证明会显着影响颗粒流结构，并且在某些情况下，导致双螺杆混合器的行为类似于两个单螺杆输送机。与以前的颗粒混合研究进行比较，以提供颗粒流动行为和混合有效性之间的联系。
Granular flows are commonly encountered in many industrial processes, but are difficult to characterize due to the opaque nature of the flow. For instance, screw pyrolyzers are being developed for the thermochemical conversion of biomass into bio-oil, but the granular flow and mixing process inside the reactor lacks fundamental understanding. In this study, X-ray particle tracking velocimetry (XPTV) is used to qualitatively and quantitatively characterize the three-dimensional (3D) granular flow structures in a double screw mixer, which geometrically replicates double screw pyrolyzers, by visualizing the position and speed profiles and quantifying the dimensionless pathlength and dimensionless residence time of individual tracer particles. The influence of screw rotation speed, dimensionless screw pitch, screw rotation orientation, and material injection configuration are investigated. Certain operating conditions are shown to significantly influence the granular flow structures and, in some instances, cause the double screw mixer to behave similar to two single screw conveyors. Comparisons with previous granular mixing studies are made to provide a link between granular flow behavior and mixing effectiveness.