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Comparison of numerical approaches to model FCC particles in gas-solid bubbling fluidized bed

CHEMICAL ENGINEERING SCIENCE 2015年 134卷 269-286页

作者： Vashisth, S. Motlagh, A. H. Ahmadi Tebianian, S. Salcudean, M. Grace, J. R. Univ British Columbia Dept Chem & Biol Engn Vancouver BC V6T 1Z3 Canada Univ British Columbia Dept Mech Engn Vancouver BC V6T 1Z4 Canada

A comparative study has been carried out to determine the ability of computational fluid dynamics (CFD) and computational particle fluid dynamics (CPFD) codes to predict the hydrodynamics of FCC particles in a bubbling fluidized bed. Simulations were conducted in both 2-dimensional (2-D) and 3-dimensional (3-D) CFD configuration and in a 3-D CPFD model. The new structure based force-balance (FB) model of Ahmadi Motlagh et al. (2014. Chem. Eng. Sci. 120, 22-36.) was incorporated in CFD to simulate the behavior of FCC in the bubbling fluidization regime. This model modifies the conventional drag correlation by considering the effect of interparticle forces on the formation of agglomerates inside the bed, updating the drag calculations by replacing the particle diameter in the Wen and Yu correlation by an agglomerate diameter. The effects of superficial gas velocity, particle diameter, particle-particle restitution coefficient and specularity coefficient on voidage are examined. The sensitivity of different gas-solid drag closures in CFD are tested and compared. Experimental time-average axial and radial voidage profiles were simulated with varying degrees of agreement with experimental data obtained using different advanced experimental techniques in the 'Traveling fluidized bed" (Dubrawski et al., 2013. Powder Technol. 235, 203-220;Tebianian et al., 2014. Extending the comparison of voidage measurement and modeling techniques in fluidized beds. In: Proc 11th International Conference on fluidized Bed Technology, (Eds.), J. Li, X.J. Bao and W. Wang. Chemical Industry Press, Beijing 137-142.). Both the FB and CPFD models were successful in resolving key issues in 3-D, whereas 2-D models tended to seriously underpredict particle volume fraction, especially near the wall. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： fluidized bed computational fluid dynamics computational particle fluid dynamics Voidage Validation

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CPFD simulations of corn stalk gasification in a circulating fluidized bed

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CHEMICAL ENGINEERING RESEARCH & DESIGN 2024年 205卷 246-256页

作者： Liu, Hongpeng Wang, Zhixue Huang, Yanze Zhou, Mo Jia, Chunxia Gu, Zengyi Sun, Baizhong Wang, Qing Northeast Elect Power Univ Engn Res Ctr Oil Shale Comprehens Utilizat Sch Energy & Power Engn Minist Educ Jilin 132012 Peoples R China Yantai Longyuan Power Technol Co Ltd Yantai 264001 Peoples R China Datang Northeast Elect Power Test Res Inst Co Ltd Changchun 130000 Peoples R China

Gasification is one of the most widely-used methods for biomass utilization owing to its environmental friendliness and high economic benefits. In this study, a three-dimensional compressible computational particle fluid dynamics (CPFD) model of a 20 MW circulating fluidized bed (CFB) gasifier was established using the EulerLagrangian method. The model, which incorporates heat and mass transfer, phase behavior, and chemical reaction, was validated using experimental data. Then, it was applied to investigate the effects of steam-to-biomass (S/B) ratio and carbon dioxide-to-biomass (C/B) ratio on gasification performance of corn stalk. The results indicate that increasing the S/B ratio reduces the gasifier temperature and significantly reduces the tar yield, while increasing the C/B ratio slightly reduces the tar yield. Furthermore, an appropriate increase in the amount of steam in the gasifier is significantly beneficial to the yield of H2, while the addition of CO2 is somewhat beneficial to the production of CO. Hence, selecting suitable gasification agents can effectively increase the H2/ CO ratio of the produced syngas.

关键词： Corn Stalk computational particle fluid dynamics Gasification Circulating fluidized bed Gasification agent

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A CPFD model for a bubbly biomass-sand fluidized bed

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POWDER TECHNOLOGY 2015年 275卷 39-50页

作者： Fotovat, Farzam Abbasi, Alireza Spiteri, Raymond J. de Lasa, Hugo Chaouki, Jamal Ecole Polytech Dept Chem Engn Montreal PQ H3C 3A7 Canada Univ Western Ontario Chem Reactor Engn Ctr Dept Chem & Biochem Engn London ON Canada Univ Saskatchewan Dept Comp Sci Saskatoon SK S7N 0W0 Canada

This study reports a computational particle fluid dynamics model for the numerical simulation of a sand fluidized bed with 8 wt.% and 16 wt.% biomass loadings. The proposed CPFD model, based on a Barracuda framework, is validated using experimental data obtained in a 15.2 cm diameter bed with a 22.5 cm static height. This fluidized bed unit is equipped with a pair of fiber optic sensors allowing one to obtain both the bubble size and bubble velocity frequency distributions in an ample range of experimental conditions. In addition to this, the first-, second-, and third-order statistical moments of the bubble size and the bubble velocity distributions are calculated for each one of the operating conditions studied. On this basis, the present study demonstrates that the proposed CPFD model reproduces the asymmetric character of both bubble size and bubble velocity distributions. In addition, the simulated and experimental bubble size and bubble velocity distributions yield close first-, second-, and third-order statistical moments. Accordingly, one can ascertain that the proposed CPFD model is quite satisfactory for establishing fluid flow patterns in sand-biomass fluidized bed gasifiers. (C) 2015 Elsevier B.V. All rights reserved.

关键词： computational particle fluid dynamics fluidized bed Sand Biomass Gasifier

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Gasification operational characteristics of 20-tons-Per-Day rice husk fluidized-bed reactor

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RENEWABLE ENERGY 2021年 169卷 788-798页

作者： Park, Sung Jin Son, Seong Hye Kook, Jin Woo Ra, Ho Won Yoon, Sang Jun Mun, Tae-Young Moon, Ji Hong Yoon, Sung Min Kim, Jae Ho Kim, Yong Ku Lee, Jae Goo Lee, Do-Yong Seo, Myung Won Korea Inst Energy Res KIER Clean Fuel Res Lab 152 Gajeong Ro Daejeon 34129 South Korea Kyungwon Tech KW Tech 81 Yatap Ro Seongnam 13497 Gyeonggi Do South Korea

Converting rice husk into energy is a promising method of generating renewable energy and reducing greenhouse gas emissions. The characteristics of rice husk gasification were investigated at an equivalence ratio (ER) of 0.20-0.35 and a gasifier temperature of 700-850 degrees C in a 20-tons-per-day (TPD) bubbling fluidized-bed gasifier system. The optimal conditions of the gasification operation were an ER of 0.20 and gasifier temperature of 800 degrees C. The low heating value of the gas product and cold gas efficiency were 1373.18 kcal/Nm(3) and 70.75%, respectively. After passing the generated gas through the gas cleaning units, it was confirmed that the tar in the product gas was removed with an efficiency of 98%. The cleaned product gas was used for the operation of 400 kW e gas engine. Pressure loss often occurred at the bottom of the gasifier during the gasification operation;we found that the agglomerates generated by the gasification process caused it. computational particle fluid dynamics simulations were performed to investigate the fluidizing characteristics of agglomerates. To prevent the pressure loss caused by the agglomerates, the stable control of temperature inside the gasifier is needed and an ash removal device remove agglomerates should be installed to maintain stable long-term operation. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： Gasification Rice husk Equivalence ratio Tar removal computational particle fluid dynamics

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Simulation analysis of gas-solid flow characteristics and water evaporation in flue gas semi-dry desulphurization process based on CPFD method

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CANADIAN JOURNAL OF CHEMICAL ENGINEERING 2023年第11期101卷 6352-6371页

作者： Liu, Peng Wu, Xuan Li, Haiguang Bo, Yuxuan Wei, Nan Inner Mongolia Univ Sci & Technol Sch Energy & Environm Baotou Peoples R China Inner Mongolia Univ Sci & Technol Sch Energy & Environm Baotou 014010 Peoples R China

The gas-solids flow in an industrial-scale semi-dry method desulphurization tower is simulated by the computational particle fluid dynamics (CPFD) approach. Compared with previous studies on desulphurization towers, this study focuses on analyzing particle distribution characteristics such as particle volume fraction, temperature distribution, and residence time. The simulation fully considered the particle-fluid, particle-particle, and particle-wall interactions in the desulphurization tower. Based on these considerations, the effects of flue gas inlet velocity and temperature on the gas-solid distribution characteristics of the desulphurization tower are simulated. An optimization scheme for adjusting the gas-solid flow in the desulphurization tower is proposed. The research results show that the error between the CPFD simulation data and experimental data is small and the changing trend is consistent. The particles in the bed of the desulphurization tower show a typical core-annulus flow. The distribution of gas and particles in the bed has a serious deviation with the increase of the flue gas inlet velocity and temperature. As the axial height of the desulphurization tower increases, the flue gas velocity, temperature, particle concentration, and water vapour distribution in the bed become more uniform. The relatively stable operating conditions for the gas-solid flow in the desulphurization tower is that the flue gas inlet velocity and temperature are 15 m/s and 393 K, respectively. Under these operating conditions, the pressure loss caused by the venturi accounted for 73.6% of the total pressure loss of the desulphurization tower. When the particle radius is between 0-150 mu m, the particle size and the flue gas inlet velocity have the greatest influence on the particle residence time. Finally, the distribution of gas and particles before and after the adjustment of the desulphurization tower is compared, which showed that adjusting the bottom structure of the

关键词： computational particle fluid dynamics gas-solid two-phase flow multiphase particles-in-cell semi-dry method flue gas desulphurization structure optimization

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CPFD simulation of a fast fluidized bed steam coal gasifier feeding section

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CHEMICAL ENGINEERING JOURNAL 2011年第1期174卷 341-350页

作者： Abbasi, Alireza Ege, Paul E. de lasa, Hugo I. Univ Western Ontario Dept Chem & Biochem Engn London ON N6A 5B9 Canada Reactech Proc Dev Inc Markham ON Canada

Coal gasification in fluidized beds is a process that can be strongly influenced by gas-solid suspension flow patterns. Fast fluidized beds can be designed to maximize coal gasification yields providing an optimum syngas composition with minimum operational upsets. In order to accomplish this, a comprehensive model for steam coal gasification is valuable. With this end, a 2D CPFD (computational particle fluid dynamics) dynamic model is considered in the present study. The proposed model uses a Lagrangian-Eulerian approach and describes the flow patterns in the gasifier feeding section, as well as the local particle velocities, particle solid fractions and gas composition. As a reference and for comparison, an ideal PFR (plug flow reactor) model is also considered. It is found that compositions from the 2D CPFD model provide close gas compositions with respect to the PER. It is observed that the 2D CPFD model is valuable for predicting particle flows in the feeding near region keeping it unaffected by fast fluidized bed upsets such as suspension chocking. It is also found that the 20 CPFD model is particularly useful for describing fast fluidized beds operation involving significant amounts of rich ash recycled feeds. (C) 2011 Published by Elsevier B.V.

关键词： Coal gasification fluidized beds computational particle fluid dynamics Suspension chocking

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CPFD modeling and experimental validation of gas-solid flow in a down flow reactor

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COMPUTERS & CHEMICAL ENGINEERING 2016年 90卷 79-93页

作者： Lanza, A. Islam, M. A. de Lasa, H. Univ Western Ontario Fac Engn Chem Reactor Engn Ctr 1151 Richmond St London ON N6A 5B9 Canada

This manuscript reports the fluid dynamics in the developed flow region of a cocurrent gas-solid down flow fluidized bed unit. Gas-solid flows are simulated using a computational particle fluid dynamics (CPFD) numerical scheme and experimental data from the CREC-GS-Optiprobes. This model represents clusters in a downer unit. It is hypothesized that in downers, clusters are formed via a Random particle Selection Method (RPSM) ensuring cluster dynamic stability. To accomplish this, a statistical particle selection of clusters (SPSC) method is developed. This hybrid model is validated with experimental data obtained in a 2 m height and 2.57 cm diameter column. Observed time-averaged axial and radial velocities and solid concentration profiles are successfully simulated by the Hybrid CPFD/CREC-GS-Optiprobes Data Model. These findings support: (a) a narrow distribution of particle cluster residences, (b) the relatively flat radial solid concentrations and solid cluster velocities, and (c) a valuable approach for establishing slip velocities in downer units. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： fluidized downer unit computational particle fluid dynamics particle clusters

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Multi-scale simulation of particle density effects on hydrodynamics in dense gas-solid fluidized beds

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POWDER TECHNOLOGY 2024年 435卷

作者： Li, Shuyue Zhang, Yongmin Wang, Wenjie Mao, Zhihong China Univ Petr State Key Lab Heavy Oil Proc Beijing 102249 Peoples R China

Gas -solid fluidization has gained prominence in chemical engineering, particularly for processes involving highdensity particles. However, a notable dearth of research on the fundamental fluidization of high -density particles exists, distinct from the well -studied low -density particles. This knowledge gap presents significant challenges in designing and operating fluidized beds for such processes. In this study, we employ the CPFD scheme to comprehensively investigate how particle density affects hydrodynamics. Simulation results consistently align with experiments for pressure drop and minimum fluidization velocity, underscoring the model reliability. Importantly, typical empirical correlations for predicting minimum fluidization velocity display substantial inaccuracies, particularly for high -density particles. Additionally, we identify marked disparities in fundamental fluidization behavior between high and low -density particles, with increasing density leading to deteriorating fluidization performance, characterized by larger bubbles, defluidized regions, gas streaming, and reduced bed expansion ratios. Investigating high -density particle gas -solid fluidization systems promises valuable theoretical insights, bridging the gap between theory and practice.

关键词： computational particle fluid dynamics Bubbling fluidized bed particle density Minimum fluidization velocity Hydrodynamics

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Biomass fast pyrolysis prediction model through data-based prediction models coupling with CPFD simulation

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JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS 2022年 162卷 105448-105448页

作者： Kim, Tae-Hoon Choi, Myung Kyu Choi, Hang Seok Purdue Univ Northwest Dept Comp Informat Technol Hammond IN 46323 USA Yonsei Univ Dept Environm Engn 1 Yonseidae Gil Wonju 26493 Gangwon Do South Korea

Biomass fast pyrolysis has been traditionally investigated through experiments or numerical simulations including hydrodynamics, transport phenomena of heat and mass, and chemical reactions. Instead of traditional methods, this study utilized data-based prediction algorithms to model a biomass fast pyrolyzer using a spouted fluidized bed, to predict the yields of major products. We used the labeled dataset generated by the computational particle fluid dynamics (CPFD) simulation to train the data-based prediction models, and used the reaction temperature and gas residence time as inputs. Eight data-based prediction models, including machine learning and deep learning, were selected and compared. The selected data-based prediction methods indicated better agreement with the CPFD product yields than those of the lumped process models. This study provides new guidelines for modeling fast pyrolysis reactions using CPFD and data-based prediction methods.

关键词： Fast pyrolysis Biomass computational particle fluid dynamics Machine learning Regression

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Regulating the crude oil-to-chemical process in a multizone fluidized bed reactor using unconventional catalyst formulations

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POWDER TECHNOLOGY 2024年 438卷

作者： Cui, Mengmeng Dikhtiarenko, Alla Kulkarni, Shekhar R. Shoinkhorova, Tuiana Al Aslani, Isa Alabdullah, Mohammad Mazumder, Jahirul Flores, Ruben Medina Alahmadi, Arwa Alfilfil, Lujain Osorio, Isidoro Morales Almajnouni, Khalid Gascon, Jorge Castano, Pedro King Abdullah Univ Sci & Technol KAUST Kaust Catalysis Ctr KCC Thuwal 239556900 Saudi Arabia Res & Dev Ctr Fuels & Chem Div Saudi Aramco Saudi Arabia King Abdullah Univ Sci & Technol Phys Sci & Engn PSE Div Chem Engn Program Thuwal Saudi Arabia

Crude oil catalytic cracking to petrochemicals in one step is a profitable pathway for future refineries yet it has significant hurdles. We investigated adding silicon carbide to the formulation and adjusting the crude oil-to-chemicals process in a multizone fluidized bed reactor by improving the morphology for hydrodynamics and thermal conductivity for heat transfer to promote the catalytic cracking performance. First, we synthesized and characterized catalysts with various SiC sizes and contents to select the best based on morphology. Then, we compared this catalyst against an industrial benchmark catalyst using computational particle fluid dynamics to understand the catalyst circulation and heat transfer in realistic crude oil-to-chemicals process conditions. Finally, we performed catalytic cracking experiments using this catalyst and the benchmark under optimal conditions. The higher light olefin yield from the unconventional catalyst formulation validated our workflow for regulating the crude oil-to-chemical process.

关键词： fluidized bed reactor computational particle fluid dynamics Hydrodynamics Heat transfer Spray-dried catalyst Silicon carbide

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