Article
Thermodynamics
Dongxiang Wang, Shuang Fu, Xiang Ling, Hao Peng, Xinjun Yang, Fangyang Yuan, Jiyun Du, Wei Yu
Summary: This study investigated the transition of flow regimes in a spout-fluidized bed reactor (SFBR) using spectral analysis of pressure drop fluctuations and visual observation. The turbulent fluidization transition velocity was analyzed using the standard deviation of pressure gradient, and an empirical model was proposed to predict this velocity. The results showed that the flow regime transition in the SFBR is primarily influenced by the coalescing and breaking up of bubbles formed around the air distributor and spout. The turbulent fluidization in the SFBR does not exhibit obvious jet flow, but rather the formation of clusters, leading to superficial homogeneity in both the spout and annulus zone. The transition from spout-fluidization to slugging fluidization depends on the velocity of the spouted gas.
Article
Engineering, Chemical
Yandaizi Zhou, Jingrui Xu, Jesse Zhu
Summary: The gas-solid fluidized bed reactor with Group C+ particles showed higher reaction conversion and better contact efficiency compared to the one with Group A particles. This is attributed to the smaller bubbles, slower rise velocity, and longer residence time in the Group C+ fluidized bed, leading to improved fluidization quality and enhanced gas-solid contact.
Article
Engineering, Chemical
Huibin Xu, Siyi Shen, Weiyu Wang, Chi Ma, Hao Zhang, Maolong Zhang
Summary: Understanding the mixing behaviors of different particles is crucial for improving the performance of pressurized fluidized beds. In this study, a numerical simulation based on the CFD-DEM method was conducted to investigate the mixing characteristics and bubble behavior of binary Geldart-D particles in a pressurized bubbling fluidized bed. The results showed that increasing the fluidization gas velocity and operating pressure promoted particle mixing, while higher operating pressure and fluidization number created a stable and uniform distribution of particles in the fluidized bed.
Article
Engineering, Environmental
Aakash M. Patel, Ray A. Cocco, Jia Wei Chew
Summary: The clustering phenomenon in fluidized bed systems is important, but relationships can be unclear due to multiple factors interacting. Machine learning tools, like SOM analysis, can help classify data sets and identify key influences. This study identified two distinct data assemblies in CFB riser, with clusters formed by non-monodisperse systems being smaller, indicating that multiple particle types hinder cluster growth. More research is needed to uncover the mechanisms behind different clusters in monodisperse versus nonmonodisperse particle systems.
CHEMICAL ENGINEERING JOURNAL
(2021)
Article
Engineering, Chemical
Tao Sheng, Zhiheng Gu, Jingyuan Sun, Yao Yang, Zhengliang Huang, Congjing Ren, Jingdai Wang, Yongrong Yang
Summary: The fluidization behavior of Geldart D particles in the deep fluidized bed was studied using pressure fluctuation measurement, high-speed camera, and intrusive acoustic emission (AE) detection method. The study showed that, with the increase of gas velocity, the deep fluidized bed of Geldart D particles experienced three different fluidization regimes: the slow bubble regime, slugging regime, and the turbulent regime. The study also revealed the occurrence of stratified fluidization in the pseudo-2D fluidized bed due to the wall effect.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2023)
Article
Engineering, Chemical
Song Chen, Wang Jiarui, Wang Simin, Wen Jian
Summary: This research investigates the flow dynamics in bubbling and turbulent fluidized beds containing both Geldart-A and B particles. The results show that as the superficial gas velocity decreases, the binary mixture segregation is enhanced, while a larger flotsam packing ratio promotes a homogeneous distribution of flotsam.
Article
Engineering, Chemical
Salma Benzarti, Hatem Mhiri, Herve Bournot
Summary: In this study, the effect of ring baffle configuration on fluidization system hydrodynamics was investigated using a multifluid Eulerian CFD model and the Kinetic Theory of Granular Flow. It was found that the incorporation of ring baffles improved system mixing and reduced wall backflow, with limited impact of baffle shape on system hydrodynamics.
Article
Engineering, Chemical
Boyu Deng, Yi Zhang, Man Zhang, Hao Kong, Tuo Zhou, Xinhua Yang, Hairui Yang
Summary: This study investigated the influence of particle clusters on the gas-solid flow behavior in circulating fluidized beds through experimental measurements. The results showed a weak dependence of cluster properties on fluidization states, and proposed a modified cluster solid holdup model that has higher prediction accuracy under specific conditions.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Engineering, Chemical
Quanhong Zhu, Libo Zhang, Weikang Hao
Summary: This study aimed to define and determine the minimum fluidization velocity in magnetized fluidized beds (MFB) based on physics principles, resolving controversies in the field. Different methods and requirements for determining U-mf were identified for MFB with different types of particles. Experimental results showed that U-mf remained invariant in both types of MFB.
Article
Engineering, Chemical
Kasama Sirisomboon, Porametr Arromdee
Summary: The main aim of this study was to investigate gas-solid flow behaviors in a twin cyclonic fluidized-bed combustor in swirling mode. Three different turbulence models were studied to select the most appropriate one for computational simulations. The results showed that the size of bed particles, excess air, and secondary to total air ratio all had significant effects on fluidization behavior in the swirling fluidized bed.
Article
Engineering, Chemical
Zhiwei Zhao, Yandaizi Zhou, Xiaojun Bao, Jesse Zhu, Haiyan Liu
Summary: Group C particles, initially considered non-fluidizable, have been shown to fluidize effectively with the addition of nanoparticles, improving gas-solid contact surface area and enhancing gas-phase catalytic reaction performance. Reactors using Group C+ particles achieved higher n-butane conversion and MAN yield compared to those using Group A particles under identical conditions, making them more efficient for industrial processes.
Article
Engineering, Chemical
Shen Wang, Tao Song, Kolja Jarolin, Timo Dymala, Maksym Dosta, Stefan Heinrich, Laihong Shen
Summary: This study investigates the mixing evolution behavior of biomass pellets at different gasification stages and determines the real-time distribution of particles through visualization experiments and image processing techniques. The migration paths of biomass pellets during gasification are revealed, and the improvement of binary mixing and adaptability to different biomass loadings are discussed.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Engineering, Chemical
Le Xie, Jundong Zhu, Chongwen Jiang
Summary: A new three-fluid Eulerian model coupled with kinetic theory was developed to investigate mixing behaviors of binary-mixture particles in a pilot-scale fluidized bed reactor. The numerical results show that size segregation of particles can be easily achieved under high air velocity and large particle size ratio conditions.
Review
Energy & Fuels
Hengjun Gai, Peiyi Yang, Qiang Zhang, Mengqi Lin, Hongbing Song, Meng Xiao, Tingting Huang, Quanhong Zhu
Summary: Circulating fluidized bed reactors are widely used in the energy industry for gas-solid reactions. They can be classified into two categories based on fluidization regimes: dilute-dense and dual-dense. The concept of dual-dense gas-solid circulating fluidization has not been well understood, hindering its commercial application. This review provides a detailed analysis of the dual-dense system, including mechanism, structural and operating parameters, particle circulation prediction, gas-solid flow simulation, and potential applications, while identifying existing controversies and unresolved issues.
Article
Energy & Fuels
Jinliang Tao, Weikang Hao, Quanhong Zhu
Summary: The study revealed that in magnetized fluidized beds, particle size and density differences affect segregation phenomena, with an increase in gas velocity leading to higher required magnetic field intensity. Smaller and lighter magnetizable particles require a stronger magnetic field to prevent segregation under the magnetization-LAST operation mode.
CHEMICAL ENGINEERING AND PROCESSING-PROCESS INTENSIFICATION
(2021)
Article
Energy & Fuels
Laura L. Trinkies, Marlene Crone, Michael Tuerk, Manfred Kraut, Roland Dittmeyer
Summary: In this study, mono- and bimetallic Pd and Pt catalysts were deposited via supercritical fluid reactive deposition (SFRD) on TiO2 coated additively manufactured substrates. The focus of this work was to evaluate the suitability of these catalysts for the direct synthesis of H2O2 in the liquid phase. The results showed that all catalysts exhibited high activity and productivity, with PdPt bimetallic catalysts showing the highest productivity and an increase in Pd loading leading to a decrease in productivity. Comparison with literature data demonstrated the high suitability of the SFRD method for the proposed application, with the added benefits of simplicity and environmental friendliness in catalyst production.
CHEMICAL ENGINEERING AND PROCESSING-PROCESS INTENSIFICATION
(2024)
Article
Energy & Fuels
Xiongbao Hu, Zuguo Shen, Yu Wang
Summary: It is impossible to control the outer wall temperature of the micro-combustor below the maximum allowable temperature of commercial thermoelectric generators simply through increasing the equivalent heat transfer coefficient. Three simple strategies were developed to improve temperature uniformity, yet none of them could ensure full temperature control.
CHEMICAL ENGINEERING AND PROCESSING-PROCESS INTENSIFICATION
(2024)