Article
Engineering, Chemical
Zeneng Sun, Bowen Han, Tianzi Bai, Shahzad Barghi, Jesse Zhu
Summary: The study found that as the sand volume fraction increases, the minimum fluidization velocity decreases in two different binary particle systems. Bubble size and rise velocity increase along the bed height, with a linear correlation between the two.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Engineering, Chemical
Woo Chang Sung, Hyun Seung Jung, Jong Wook Bae, Jun Young Kim, Dong Hyun Lee
Summary: This study conducted segregation tests using a cold-bed system in a pulsed fluidized bed, and investigated the effects of superficial gas velocity, pulse frequency, and amplitude on segregation efficiency. The results showed that these parameters had significant influence on segregation, and the effect of pulsation on segregation was observed under certain conditions.
Article
Engineering, Chemical
Suyang Pan, Jiliang Ma, Daoyin Liu, Xiaoping Chen, Cai Liang
Summary: This paper studies the liquid transport behaviors in a top-sprayed fluidized bed using bed conductance analysis, pressure fluctuation analysis, and bubble image processing. The results show that liquid initially gets trapped in agglomerates before converting to free liquid and spreading from the upper-middle bed to the bottom bed. The disintegrating pattern of agglomerates affects the increase and saturation of free liquid in the bed. The liquid transport process is accelerated by increasing superficial air velocity and particle diameter, while it slows down with increased liquid viscosity and surface tension.
Article
Engineering, Chemical
Hengzhi Chen, Wangyang Zou
Summary: This study investigated the behavior of bubbles in a vacuum fluidized bed and found that the diameter and rise velocity of bubbles increased with decreasing pressure, while bubble density decreased. The variation in bubble density was divided into three stages based on the net-coalescence rates. Increasing the vacuum degree resulted in larger variations in bubble size and decreased operating stability in the fluidized bed.
CHEMICAL ENGINEERING COMMUNICATIONS
(2023)
Article
Energy & Fuels
Rajan Jaiswal, Britt M. E. Moldestad, Marianne S. Eikeland, Henrik K. Nielsen, Rajan Kumar Thapa
Summary: This study investigates the bubble properties of a bubbling fluidized bed reactor using computational particle fluid dynamic simulations and electrical capacitance tomography measurements. The results show that the bubble properties, such as average diameter, rise velocity, and frequency, are significantly influenced by the superficial gas velocity. The CPFD model and method employed in this work can be useful for studying the influence of bubble properties on conversion efficiency of a gasification reactor operating at high temperatures.
Article
Energy & Fuels
Zemin Yuan, Zhong Huang, Suxia Ma, Guanjia Zhao, Hairui Yang, Guangxi Yue
Summary: In this study, the effect of superficial gas velocity on bubble dynamics properties in a gas-solid particle system was investigated. The parameters including bubble equivalent diameter, bubble size distribution, bubble density, aspect ratio, bubble hold-up, bed expansion ratio, bubble rising and lateral velocity were derived using digital image analysis technique. The results show that superficial gas velocity has a significant effect on the bubble equivalent diameter and bubble hold-up, while having little effect on bubble size distribution and average bubble density distribution. Understanding the effect of gas velocity on bubbles dynamics properties is important for the design and optimization of fluidized bed reactors.
Article
Engineering, Environmental
Xiaoli Zhu, Yibo Liu, Xijian Jiang, Haigang Wang, Zhenbo Wang, Zhang Bai, Raffaella Ocone
Summary: The bubble behaviors of Geldart A/B, B, and D particles in a pseudo 2D pressurized fluidized bed were comprehensively investigated. The effects of pressure and particle size on bubble spatial distribution, diameter, rise velocity, fraction, and flow regimes were obtained based on a large quantity of experimental data. The results showed that the behavior of bubbles differed among the three particle types, with Geldart A/B particles exhibiting smaller and more uniformly dispersed bubbles, Geldart B particles having densely populated and larger bubbles, and Geldart D particles forming a single peak of large bubbles in the center. The study also revealed that bubble diameter decreased with increasing pressure, and the effect of pressure was more pronounced on Geldart D particles.
CHEMICAL ENGINEERING JOURNAL
(2023)
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
Jikai Huang, Huanan Li, Chongliang Huang, Yake Jiang, Zhigang Liu
Summary: A novel method is developed to measure the micro mixing ratio of binary solids in dense fluidizations. The mixing process within a bubbling fluidized bed is resolved and dispersion co-efficient and mixing index methods are applied. The results indicate that diffusion plays a crucial role in mixing at the bottom and top of the fluidized bed, while convection is the primary mechanism of mixing at the center.
Article
Engineering, Chemical
Tianzi Bai, Zeneng Sun, Ziang Guo, Jesse Zhu, Shahzad Barghi
Summary: In this study, a two-dimensional fluidized bed and digital image analysis were used to investigate bubble dynamics and dense phase composition. The results showed that the bubble diameter and rise velocity were influenced by the distance from the gas distributor and the excess gas velocity. The mono particle systems had higher bubble sizes and rise velocities compared to the system with nearly identical particle composition. Additionally, the dense phase composition was traced, and the overall bed density was estimated.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Engineering, Chemical
Bo Zhang, Mengyao Guo, Zongsheng Sun, Enkhsaruul Byambajav, You Zhou, Junwei Guo, Pengfei Zhao, Zhenxing Zhang, Xuan Wang, Guanghui Yan
Summary: The apparent viscosity of binary particles decreases with the increase in coal powder content, and also drops by half with increase in gas speed. Adjusting gas velocity and magnetite powder content can effectively reduce the apparent viscosity and improve separation efficiency. A modified model for predicting the apparent viscosity of binary particles showed good performance with an overall standard deviation of 13.00% from experimental results.
Article
Engineering, Environmental
Wenjuan Bai, Dianming Chu, Yan He
Summary: In this study, imaging processing technique and fractal analysis method were used to investigate bubble distribution and evolution in the carbon nanotube (CNT) growth process, revealing the different roles bubbles play at different growth stages and their relationship with CNT growth time. Additionally, the characteristics of bubbles were found to be influenced by the growth time of CNT. Moreover, the distribution tendency of CNT particles and particle productivity were shown to be similar, confirming the feasibility and reliability of the image processing technique and fractal analysis method used in this study.
CHEMICAL ENGINEERING JOURNAL
(2021)
Article
Engineering, Chemical
Runhui Zhang, Xiaoke Ku, Kun Luo, Jianzhong Lin
Summary: A comprehensive model has been developed to study the bubble dynamics and particle orientation in a binary fluidized bed, revealing the effects of particle aspect ratio and the addition of spherocylinders on mixing and bubble generation in the bed.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2022)
Article
Engineering, Chemical
Xiaoli Zhu, Yibo Liu, Yuehuan Li, Haigang Wang, Zhenbo Wang
Summary: This study experimentally investigated the bubble behaviors of Geldart B particles in a pseudo two-dimensional pressurized fluidized bed using digital image analysis technique. The results showed that increasing pressure reduces the stability of bubbles, resulting in smoother fluidization state with smaller bubbles. The elevated pressure also affects the flow regimes variation and gas-solid interaction in different local positions of the bed.
Article
Engineering, Chemical
Li Dai, Zhulin Yuan, Lei Guan, Kai Wu, Conghui Gu
Summary: This study investigates the bubble dynamics of wet Geldart-D particles in a wet 2D fluidized bed using digital image analysis. The results show that increasing liquid saturation promotes gas holding capacity of the emulsion phase, while enhanced liquid bridge forces limit bubble growth and promote bubble breakage. Small and irregular bubbles are likely to be observed in wet fluidized beds due to the growing liquid saturation.
CANADIAN JOURNAL OF CHEMICAL ENGINEERING
(2022)
