Characterizing 3D granular flow structures in a double screw mixer using X-ray particle tracking velocimetry

Kingston, Todd A.; Geick, Taylor A.; Robinson, Teshia R.; Heindel, Theodore J.

doi:10.1016/j.powtec.2015.02.061

Cited by 39 publications

(30 citation statements)

References 27 publications

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“…The DEM model was further validated by comparing with the experimental results [11,34] in terms of biomass mean residence time at different screw rotation speeds as shown in Figure 4. The corresponding operating conditions are listed in case 1-1, 1-2 and 1-3 in Table 1.…”

Section: Model Validationmentioning

confidence: 99%

“…Solid particle mixing processes have been analyzed based on several experimental approaches such as sampling [8,9], X-ray tracking [10,11], positron emission particle tracking (PEPT) [12] and digitized image analysis methods [13]. Tsai and Lin [9] qualitatively studied the effects of screw parameters (pitch, flight diameter, flight thickness and shaft diameter) and operating conditions (rotation speed) on the mixing quality in a single screw feeder.…”

Section: Introductionmentioning

confidence: 99%

“…Error bar shows the standard deviation of biomass particle residence time in the simulation. Experimental data came from[11,34].…”

mentioning

confidence: 99%

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Numerical study of particle mixing in a lab-scale screw mixer using the discrete element method

Heindel

Wright

2017

Powder Technology

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This study employs the Discrete Element Method (DEM) to simulate particulate flow and investigate mixing performance of a lab-scale double screw mixer. The simulation employs polydispersed biomass and glass bead particles based on experiments conducted in previous studies. Visual examination of particle distribution and statistical analysis of particle residence times of experimental data served as model validation. Statistical analysis indicates a maximum 9.8% difference between the experimental and simulated biomass particle mean residence time, and visual observations suggest the simulation captures the particle mixing trends observed in the experiments. Results indicate that the particle mean mixing time, non-dimensionalized by ideal flow time in the plug flow reactor, varies between 1.008 and 1.172, and it approaches 1 with increasing biomass feed rate. The mixing index profile in the axial direction shows a mixing-demixing-mixing oscillation pattern. Increasing screw pitch length is detrimental to mixing performance; decreasing the solid particle feed rate reduces the mixing degree; and increasing the biomass to glass bead size ratio decreases mixing performance. A comparison of a binary, single-sized biomass and glass particles mixture to a multicomponent mixture indicates that the binary system has similar mixing pattern as a multicomponent system. These findings demonstrate that DEM is a valuable tool for the design and simulation of double screw mixing systems.

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Section: Model Validationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical study of particle mixing in a lab-scale screw mixer using the discrete element method

Heindel

Wright

2017

Powder Technology

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“…Kingston et al [91] employed two sources simultaneously to perform X-ray stereography in a double screw mixer, which improved the accuracy of location detection while considerably reduced the time required to perform the experiment. A binary mixture of red oak chips with glass beads was used while the tracer particle's attenuation was improved by dipping a limited number of red oak chips in potassium iodide and coating them with a layer of silver paint.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Review of noninvasive methods to characterize granular mixing

Nadeem

Heindel

2018

Powder Technology

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Granular mixing is a common process observed in a variety of industries such as construction, chemical processing, food handling, and cosmetics and pharmaceutical manufacturing. Over the years several methods have been devised to characterize granular mixing and to provide information on the quality of the mixture as well as mixing end points. In this work, three different noninvasive measurement categories are reviewed, namely: velocimetric, spectroscopic, and tomographic techniques. Velocimetric techniques such as Particle Image Velocimetry (PIV) and Radioactive particle tracking (RPT) are able to provide the trajectories and velocities of individual particles during the mixing process. Spectroscopic techniques focus on the chemical composition of the sample and are well suited for applications where there is little difference in the physical properties of the constituents such as particle size and density. Tomographic techniques such as X-ray computed tomography (CT) and Magnetic Resonance Imaging (MRI) provide information such as the spatial distribution of the different constituents in the sample and are useful in determining dead zones and inhomogeneities. A few other techniques are also discussed, particularly passive acoustic methods which, though can neither provide spatial distribution nor individual particle trajectories, are still useful and can be employed to determine mixing end points. The objective of the work is to provide a comparative assessment of the various noninvasive techniques and discuss their ability to effectively characterize the mixing process. The reported techniques will be reviewed thoroughly based on their functionality, viability, and characterization capability. The advantages and disadvantages of the various techniques are summarized and a comparison of the utility of the techniques in various applications is discussed.

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“…However, due to the opaque nature of most granular materials, optical visualization of granular mixtures is limited. To study the internal structure of granular flows, newly developed methods such as particle image velocimetry (de Jong et al, 2012;Dhenge et al, 2013), magnetic resonance imaging (Hardy et al, 2007), positron emission particle tracking (Leadbeater et al, 2012;Portillo et al, 2009), X-ray radiography Okamoto, 2006, 2008), X-ray stereography (Kingston et al, 2015;, and near-infrared spectroscopy (Koller et al, 2011) have been developed. Each of these techniques allows the internal structure and movements of the granular materials to be better understood and are invaluable to increasing the fundamental understanding of granular mechanics.…”

Section: Non-invasive Characterizationmentioning

confidence: 99%

The effects of scale on granular mixing in a double screw pyrolyzer

Marmur

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Characterizing 3D granular flow structures in a double screw mixer using X-ray particle tracking velocimetry

Cited by 39 publications

References 27 publications

Numerical study of particle mixing in a lab-scale screw mixer using the discrete element method

Numerical study of particle mixing in a lab-scale screw mixer using the discrete element method

Review of noninvasive methods to characterize granular mixing

The effects of scale on granular mixing in a double screw pyrolyzer

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