Evaluation of Mixing and Mixing Rate in a Multiple Spouted Bed by Image Processing Technique

Abstract

A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. AbstractMixing efficiency is one of the most significant factors, affecting both performance and scale-up of a gas-solid reactor system. This paper presents an experimental investigation on the particle mixing in a multiple spouted bed. Image processing technique was used to extract the real-time information concerning the distribution of particle components (bed materials and tracer particles). A more accurate definition of the tracer concentration was developed to calculate the mixing index. According to the visual observation and image analysis, the mixing mechanism was revealed and the mixing rate was evaluated. Based on these results, the effects of operation parameters on the mixing rate were discussed in terms of the flow patterns. It is found that the detection of the pixel distribution of each component in RGB images is not affected by the interference of air void, thus maintaining good measurement accuracy. Convective transportation controls the particle mixing in the internal jet and spout, while shear dominants the particle mixing in the dense moving region. Global mixing takes place only when the path from one spout cell to the other is open. This path can be formed either by the bubbles or particle circulation flows. The mixing rate is linked to the bubble motion and particle circulation. Provided that there are interactions between the spout cells, any parameters promoting the bubble motion and circulation can increase the mixing rate. Finally, a mixing pattern diagram was constructed to establish the connection between the flow structure and mixing intensity.

Particle Tracking and Micromixing Performance Characterization with a Mobile Device

“…The tests were performed at 20× magnification. Following the experimentation by Betancourt [ 17 ], the solute–solvent ratio was of the fluorescent solutions (F8823; yellow-green and F8821; red fluorescent ) per of distilled water. The fluosphere solution (F8891) had a different concentration of particles per .…”

“…The work reported by [ 17 ] shows a reduction in metrics , , and the as the particles are more randomly distributed in the patterns, which implies a better mixing process. Resolution of the images can influence the performance metrics.…”

“…In the work of Baqersad et al [ 16 ], a technique based on the frequency histograms of images with linear discriminate analysis (LDA) is used to determine whether the asphalt is segregated or not. Particle mixing in a multiple-spouted bed is studied in the work of Zhang et al [ 17 ] by measuring the tracer particle concentration. The work of Fei et al [ 18 ] presents a method for assessing the uniformity and mixing time of bubbles in a direct contact heat exchanger.…”

Hydrodynamic Characterization of a Shallow Rectangular Spouted Bed Using Bed Pressure Signals and Image Processing Methods

“…Applying digital image processing methods to high-speed videos for hydrodynamic characterization has been conducted in a variety of gas−solid systems including circulating fluidized beds, 28,29 fluidized beds, 30,31 packed beds, 32,33 and spouted beds. 34,35 In this work, the hydrodynamic characterization of a rectangular spouted bed is based on systematic image processing methods proposed in our recent studies. 36−38 The current study aims to develop correlations requiring less secondary parameters (parameters that rely on experimental data) to predict key hydrodynamic parameters that are significant in the successful design of spouted beds.…”

“…As a nonintrusive method, optical techniques have gained popularity because of the continued rapid advancement of cameras, increased computational processing power, and the development of advanced image processing techniques. Applying digital image processing methods to high-speed videos for hydrodynamic characterization has been conducted in a variety of gas–solid systems including circulating fluidized beds, , fluidized beds, , packed beds, , and spouted beds. , In this work, the hydrodynamic characterization of a rectangular spouted bed is based on systematic image processing methods proposed in our recent studies. − The current study aims to develop correlations requiring less secondary parameters (parameters that rely on experimental data) to predict key hydrodynamic parameters that are significant in the successful design of spouted beds. The hydrodynamic parameters, accorded a good measure of attention, are the peak pressure drop (Δ P max ) and external spouting velocity ( U es ) of both Geldart D and B particles, the accurate knowledge of which can provide practical information for operating power and air compressor requirements and efficient evaluation in spouted-bed reactor design.…”