Review
Thermodynamics
Falah Alobaid, Naser Almohammed, Massoud Massoudi Farid, Jan May, Philip Rossger, Andreas Richter, Bernd Epple
Summary: This review provides significant knowledge on the development and application of CFD mathematical models in gas-solid fluidized beds. The review is divided into three parts: mathematical modeling, state-of-the-art studies, and conclusion and prospects. It covers various numerical models, their assumptions, and their application in chemical and energy process engineering. The review also analyzes the pros and cons of applying CFD models to fluidized-bed systems and highlights current research trends and future opportunities.
PROGRESS IN ENERGY AND COMBUSTION SCIENCE
(2022)
Article
Engineering, Environmental
Claudio Tregambi, Francesca Di Lauro, Sara Pascual, Pilar Lisbona, Luis M. Romeo, Roberto Solimene, Piero Salatino, Fabio Montagnaro
Summary: The aim of this study is to investigate the feasibility of ThermoChemical Energy Storage (TCES) using the Calcium Looping (CaL) process through a dedicated experimental campaign in fluidized bed under realistic process conditions suitable for CaL-CSP integration. The research found that the deactivation of limestone becomes more pronounced when it is co-processed with silica sand. The interaction between sand and lime reduces the porosity and reactivity of the sorbent, leading to a decrease in process efficiency.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Mechanics
Joshua Kok Tong Koe, Eldin Wee Chuan Lim
Summary: The presence of an immersed tube in slugging fluidized beds affects bubble formation, slug length distribution, and pressure fluctuations. In deep beds, the immersed tube regulates slug size and prevents significant increases in mean slug size or variability.
Article
Chemistry, Physical
Jia-Hong Kuo, Chiou-Liang Lin, Chang-Yu Ho
Summary: This study explores the impact of fluidization and gasification parameters on the hydrogen composition in syngas. The results indicate that using zeolite as bed material and increasing the Steam/Biomass ratio can enhance the hydrogen content in syngas.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Article
Chemistry, Multidisciplinary
Lili Zhang, Ziwei Xu, Tian-liang Feng, Maoshuai He, Thomas Willum Hansen, Jakob Birkedal Wagner, Chang Liu, Hui-Ming Cheng
Summary: This study uses environmental transmission electron microscopy to observe for the first time the breaking of symmetry during the growth of a single-wall carbon nanotube. It reveals the role of topological defects and the importance of the tube-catalyst interface.
Article
Engineering, Chemical
Xiaoyang Wei, Justin Weber, Ronald W. Breault
Summary: Gas-solid circulating fluidized beds (CFBs) are widely used as reactors in industry, and the performance heavily relies on the interaction between gas and clusters. This study numerically quantified the gas-cluster interaction and proposed an empirical correlation to quantify the interaction, contributing significantly to the design and optimization of CFBs.
Article
Engineering, Chemical
Xiaoyang Wei, Jiangshan Liu, Jesse Zhu
Summary: This study focuses on capturing the instantaneous solids holdup in bubbling and turbulent fluidized beds using an optical fiber probe, and quantifying the degree of local segregation with the intermittency index. By analyzing the signal details, phases such as bubble phase, bubble cloud, and emulsion phase can be easily identified and characterized in terms of solids holdup and time fraction. Finally, the influences of column diameter and static bed height on scale-up effects were systematically analyzed.
Article
Engineering, Chemical
Shijie Yu, Xiaoxiao Yang, Jie Xiang, Hui Zhou, Qinghai Li, Yanguo Zhang
Summary: This study statistically analyzed the effects of bed size on voidage in gas-solid bubbling fluidized beds. Results showed that with increasing bed size, voidage and its dispersion degree decreased, while asymmetry and steepness degree increased. Bed size had a stronger impact on voidage at lower axial positions.
Article
Engineering, Environmental
Shuyue Li, Yongmin Zhang, Wenjie Wang, Huan Wang
Summary: This study comprehensively evaluates the effect of particle density on hydrodynamics during the initial fluidization stage. It finds that empirical correlations for high-density particles may have significant errors in predicting the minimum fluidization velocity (Umf), and the predicted errors tend to increase with increasing particle density. Furthermore, the fluidization performance tends to deteriorate as the particle density increases.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Engineering, Chemical
Wenjian Cai, Xietian Xia, Xiang Li, Xing Chen, Zenghui Xu, Huilin Lu
Summary: A low density ratio-based kinetic theory is used to predict the hydrodynamics of carbon dioxide fluid-particle mixtures in high-pressure carbon dioxide fluidized beds. The presence of both particle waves and particle aggregates is observed along the height of the bed. The occurrence of particle aggregates is identified based on the standard deviation of solid volume fractions in aggregative fluidization. The study also analyzes the effects of carbon dioxide fluid temperature and pressure on volume fraction and velocity distributions in high-pressure carbon dioxide fluidized beds.
Article
Chemistry, Multidisciplinary
Fei Xing, Min Li, Shaokai Wang, Yizhuo Gu, Wei Zhang, Yanjie Wang
Summary: This study investigates the electrical resistance variation of CNT/epoxy composite film during the curing process and finds that it is closely related to resin rheological properties, thermal expansion, and curing shrinkage. The opposing effects of thermal expansion and condensation caused by the wetting tension of the liquid resin are observed. The electrical resistance increases with an increase in temperature due to thermal expansion, but drops due to crosslink shrinkage of epoxy resin. The internal stress caused by curing shrinkage at the high-temperature platform results in an increase in electrical resistance.
Article
Engineering, Chemical
Salma Benzarti, Hatem Mhiri, Philippe Bournot
Summary: Fluidized beds have been crucial in processing industries for almost a century. However, their scaling up has been hindered by complex hydrodynamic behavior and diverse solids handling. This study simulated the hydrodynamic behavior of a 2D circulating fluidized bed under different superficial gas velocities and found that the gas/solid feeding configuration significantly affects the flow structure.
Article
Chemistry, Multidisciplinary
Lu Qiu, Feng Ding
Summary: Revealing the true picture of the carbon nanotube growth front at the catalyst surface is crucial for understanding the mechanism of controlled CNT growth. Through simulation experiments, it has been found that a clean CNT-catalyst interface dominates the growth kinetics during real CNT experimental growth, indicating the feasibility of controlling CNT growth by tuning the CNT-catalyst interface.
Article
Engineering, Chemical
Tianle Zhang, Wenjuan Bai, Qianpeng Dong, Dianming Chu, Yinrui Yu, Chao Yan, Yan Li, Yan He
Summary: In this study, a pilot-scale tapered fluidized bed without a distributor was used to address issues encountered during the scale-up process. The hydrodynamics of gas-CNT agglomerate particle flow in the bed were investigated using differential pressure fluctuation measurements and bubble behavior analysis. Mathematical analysis methods were employed to gain a comprehensive understanding of the fluidization dynamics. The findings showed that the distributor-less TFB exhibited stable fluidization and reduced wall effects, indicating its potential for large-scale application.
Article
Engineering, Environmental
V. L. Kuznetsov, S. I. Moseenkov, A. V. Zavorin, G. V. Golubtsov, V. V. Goidin, O. S. Rabinovich, A. I. Malinouski, M. Yu. Liakh
Summary: The problem of the loss of homogeneous fluidization and the formation of large clumps of MWCNTs during their catalytic synthesis in a fluidized bed reactor has been studied experimentally and theoretically. The study found that high-performance catalysts with the ability to produce agglomerates of MWCNTs with high cohesion, together with a high concentration of catalyst particles in the fluidized bed volume, play a crucial role in the formation of large clumps of MWCNTs. A relationship between the chemical components of the catalyst and the cohesive properties of the MWCNT agglomerates formed on it has been established. An approximate semi-analytical scheme for calculating the formation and growth of large fractal agglomerates (clumps) of MWCNTs during their catalytic synthesis in a fluidized bed has been developed.
CHEMICAL ENGINEERING JOURNAL
(2022)
