Effect of the jet direction of gas nozzle on the residence time distribution of solids in circulating fluidized bed risers

Yoo, Hoanju; Moon, Hokyu; Choi, Seungyeong; Park, Yong Ki; Cho, Hyung Hee

doi:10.1016/j.jtice.2016.12.018

Cited by 15 publications

(4 citation statements)

References 36 publications

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“…On the other hand, abrupt shape riser (Figure 9) also showed the same trend, where solid holdup tends to decreasing from 0.35 to 0.27 as the gas velocity increases from 4 m/sec to 7.7 m/sec. These findings are consistent with earlier findings on solid holdup in CFB riser (Issangya et al, 1999;Yin et al, 2012;Efhaima and Al-Dahhan, 2015;Mabrouk et al, 2005;Yoo et al, 2017) and the same nature of solid holdup was examined in a bubbling fluidized bed system as well (Wang et al, 2007).…”

Section: Resultssupporting

confidence: 92%

“…Furthermore, an earlier experimental study on a multi-solid fluidized bed revealed that with increasing the circulation rate of fine particles, the movement of coarse particles continuously decreases (Win et al, 1995). In the multi-phase flow system, drag force is a significant term and it may be responsible for the particle entrainment inside the CFB riser (Yoo et al, 2017;Prabhansu et al, 2020). Earlier research on riser geometry revealed that exit with sharp angle could be better for particle reflection and recirculation internally through the riser (Issangya et al, 2000;.…”

Section: Introductionmentioning

confidence: 99%

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Three-dimensional CFD simulation and experimental validation of particle segregation in CFB riser

Dwivedi

Pramanick

Karmakar³

et al. 2020

HFF

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Purpose The purpose of this paper is to perform the computational fluid dynamics (CFD) simulation with experimental validation to investigate the particle segregation effect in abrupt and smooth shapes circulating fluidized bed (CFB) risers. Design/methodology/approach The experimental investigations were carried out in lab-scale CFB systems and the CFD simulations were performed by using commercial software BARRACUDA. Special attention was paid to investigate the gas-particle flow behavior at the top of the riser with three different superficial velocities, namely, 4, 6 and 7.7 m/s. Here, a CFD-based noble simulation approach called multi-phase particle in cell (MP-PIC) was used to investigate the effect of traditional drag models (Wen-Yu, Ergun, Wen-Yu-Ergun and Richardson-Davidson-Harrison) on particle flow characteristics in CFB riser. Findings Findings from the experimentations revealed that the increase in gas velocity leads to decrease the mixing index inside the riser. Moreover, the solid holdup found more in abrupt riser than smooth riser at the constant gas velocity. Despite the more experimental investigations, the findings with CFD simulations revealed that the MP-PIC approach, which was combined with different drag models could be more effective for the practical (industrial) design of CFB riser. Well agreement was found between the simulation and experimental outputs. The simulation work was compared with experimental data, which shows the good agreement (<4%). Originality/value The experimental and simulation study performed in this research study constitutes an easy-to-use with different drag coefficient. The proposed MP-PIC model is more effective for large particles fluidized bed, which can be helpful for further research on industrial gas-particle fluidized bed reactors. This study is expected to give throughout the analysis of CFB hydrodynamics with further exploration of overall fluidization.

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Three-dimensional CFD simulation and experimental validation of particle segregation in CFB riser

Dwivedi

Pramanick

Karmakar³

et al. 2020

HFF

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“…With some experimental results it was found that pressure drop in any CFB system is affected by riser air velocity and also velocity inside the Lvalve. Some researchers [48] focused for explaining the results regarding pressure drop in riser section as shown in Figure 7. During the study it is found that when the riser velocity increases the pressure drop inside the riser section continuously decreases.…”

Section: Pressure Drop Inside Risermentioning

confidence: 99%

A Brief Review on Hydrodynamic Behaviour Analysis of Coal Gasification in a Circulating Fluidized Bed Gasifier

Dwivedi¹,

Karmakar²,

Pramanick³

et al. 2019

IJHT

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In this paper a brief review on hydrodynamic characteristic of coal gasification is presented. Firstly an introduction of hydrodynamics then parameters related to hydrodynamics is discussed. In the last several decades Coal gasification is an important method to use of coal resources. The hydrodynamic characteristics have an important role to design of Circulating fluidized bed gasifiers. Circulating fluidized bed (CFB) gasifiers widely use due to their high reaction rates and high thermal efficiency. The present study includes some hydrodynamics properties of coal gasification such as effect of pressure and temperature, solid hold up, solid circulation rate, gas-solid contact, particle residency time, coal feeding rate and coal feeding position. During the brief review on hydrodynamics characteristics of coal each section of CFBs such as riser, cyclone, stand-pipe and loop seal have been considered.

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“…Studying the residence time distribution of gas and particles can help to know the mixing behaviors. For a typical circulating fluidized bed (CFB) riser, by using the particle tracer response technique, the particle residence time distribution and solid mixing behaviors have been investigated by some researchers. − Useful models and equations were proposed as references for engineering design. Besides, some researchers studied the gas mixing behaviors in the riser.…”

Section: Introductionmentioning

confidence: 99%

Mixing of Jet Gas with Catalyst Particles in Fluid Catalytic Cracking Risers

Yan

Fan

et al. 2019

Ind. Eng. Chem. Res.

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The residence time distributions of upward and downward gas injections in a fluid catalytic cracking riser were investigated by large-scale cold model experiments. The tanks-in-series model was employed to describe the local mixing of feed jets with catalyst particles. The model parameter M at various axial and radial measuring points was obtained by using the helium tracer method. On this basis, M was fitted with the jet–catalyst flow momentum ratio and the axial height. By knowing M of the full mixing zone of the riser, this method calculates the influence height of jets above the injection point. Results show that the downward feed offers a fuller mixing environment for jets and catalysts in their initial contact region. Besides, the influence height above the nozzles in the downward injection scheme is over 50% shorter than that of the upward jet case. This study confirms that the downward jets can provide a more ideal environment for jet–catalyst mixing.

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Effect of the jet direction of gas nozzle on the residence time distribution of solids in circulating fluidized bed risers

Cited by 15 publications

References 36 publications

Three-dimensional CFD simulation and experimental validation of particle segregation in CFB riser

Three-dimensional CFD simulation and experimental validation of particle segregation in CFB riser

A Brief Review on Hydrodynamic Behaviour Analysis of Coal Gasification in a Circulating Fluidized Bed Gasifier

Mixing of Jet Gas with Catalyst Particles in Fluid Catalytic Cracking Risers

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