Effects of vortex finder length on flow field and collection efficiency of cyclone in an industrial‐scale circulating fluidized bed boiler: Numerical study

Hwang, In Sik; Jeong, Hyo Jae; Hwang, Jungho

doi:10.1002/er.5430

Cited by 13 publications

(8 citation statements)

References 26 publications

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“…More details on related parameters, formulations, and sub‐models used in our simulations can be discovered in the Fluent User's Guide 30 and other related studies 26,27,35,37‐39 …”

Section: Materials and Methodologymentioning

confidence: 99%

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Effect of sand particle size on the hydrodynamics of a dual fluidized bed cold flow system applied for waste‐to‐energy gasifiers

Dinh

Hsiau

et al. 2022

Intl J of Energy Research

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Summary Since the dual fluidized bed (DFB) system has been increasingly adopted for waste‐to‐energy gasification, a three‐dimensional computational fluid dynamics full‐loop model of a DFB cold flow system has been developed to predict the pressure and sand circulation rate (SCR) under various operating conditions. The pressure data were recorded at 18 specified points along the system height. In addition, the SCRs were determined at the two crucial positions connecting the riser and the gasifier and vice versa. The simulation results were then validated against the experimental data, taking into account the effects of the sand particle size (ds), the air inlet velocity in the riser (v0,riser), and the initial gasifier bed height (h0,gasifier). It could be observed in the riser that the flow structures of the smaller ds(s) were almost scattering patterns, while those of the bigger ones were mainly clusters. Compared with bigger ds(s), more homogeneous pressure distributions in the riser and higher bed expansion in the gasifier were obtained with smaller ones. A compromise between the system performance and pre‐treating cost for the feedstock particle sizes should be considered further to achieve the best system performance. On the other hand, the increases of the v0,riser and the h0,gasifier enhanced the gasifier bed pressure, facilitating the downward sand flow back to the riser via the LLS. Although some minor discrepancies existed between the simulation and experimental data, the predicted tendencies agreed well with the measured ones. It was also found that a system operating with ds = 500 μm, at v0,riser = 4.0 m/s and h0,gasifier = 0.25 m yielded stable flow characteristics and optimal global SCR. Moreover, some unexpected phenomena predicted and verified with the experimental observations could be avoided or minimized using suitable particle sizes of the feedstock and operating parameters. In sum, the better validation results with lower errors than our previous study, the more reasonable air‐sand flow patterns, and the substantial predictions of undesirable problems are the significant improvements of this study, providing valuable information for effectively designing and operating the practical DFB hot flow systems. Novelty Statement This study developed a 3D computational fluid dynamics full‐loop model of a DFB cold flow system for predicting the pressure and sand circulation rates under various operating conditions of particle size, inlet velocity, and initial bed height. The better validation results against the experimental data, the more reasonable air‐sand flow patterns, and the substantial predictions of undesirable problems are the significant improvements of this study, providing helpful information for designing and operating the DFB hot flow gasifiers.

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“…More details on related parameters, formulations, and sub‐models used in our simulations can be discovered in the Fluent User's Guide 30 and other related studies 26,27,35,37‐39 …”

Section: Materials and Methodologymentioning

confidence: 99%

“…More details on related parameters, formulations, and sub-models used in our simulations can be discovered in the Fluent User's Guide 30 and other related studies. 26,27,35,[37][38][39] Table 2 describes the case study of different particle sizes of sand together with their specific parameters used in the simulations.…”

Section: Mathematical Modelmentioning

confidence: 99%

Effect of sand particle size on the hydrodynamics of a dual fluidized bed cold flow system applied for waste‐to‐energy gasifiers

Dinh

Hsiau

et al. 2022

Intl J of Energy Research

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“…Razmi et al reported that lengthening the vortex finder can improve the separation efficiency. Hwang et al . observed that the separation efficiency first increases and then decreases as the vortex finder becomes longer in a circulating fluidized bed (CFB) system.…”

Section: Introductionmentioning

confidence: 99%

“…Razmi et al 8 reported that lengthening the vortex finder can improve the separation efficiency. Hwang et al 9 observed that the separation efficiency first increases and then decreases as the vortex finder becomes longer in a circulating fluidized bed (CFB) system. Tian et al 10 attributed the change in the separation efficiency with the vortex finder length to the short-circuit flow when the vortex finder is located in the cylindrical section.…”

Section: Introductionmentioning

confidence: 99%

Double-Eccentric Design for the Vortex Finder of a Cyclone Separator

Yao

Huang

Zhou

et al. 2022

Ind. Eng. Chem. Res.

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In the present study, a double-eccentric design for the vortex finder of a cyclone separator was proposed to enhance the cyclone performance. Using the numerical approaches, the flow field inside the cyclone was simulated and the cyclone performance was evaluated. The orthogonal method was adopted to obtain the optimal structure of the double-eccentric vortex finder. The range analysis of the five key geometric factors in the double-eccentric design was also conducted. It was found that cyclone performance is more sensitive to the eccentricity of the vortex finder than the other factors. The best eccentric angle of the inlet of the vortex finder is 270°, which markedly improves the separation efficiency and slightly increases the pressure drop. The simulated flow field depicted that the double-eccentric vortex finder results in the strongest swirling flow in the middle and lower parts of the cyclone compared with the vortex finders of the original, non-eccentric, and single-eccentric designs. The results also reflected that off-centering the vortex finder has the most significant impact on the flow patterns. Moreover, an industrial test was carried out in a circulating fluidized bed boiler for this novel vortex finder. The fly ash of the double-eccentric vortex finder becomes finer and contains less carbon content than that of the original one, which indicates that the double-eccentric vortex finder successfully enhances the separation performance.

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“…Liu et al [15] concluded that the most efficient classification was achieved when the insertion depth of the vortexfinder was at the column-cone junction of the hydrocyclone. Hwang et al [10,16] believed that with the increase in the insertion depth of the overflow pipe, the separation efficiency showed a trend of increasing first and then decreasing. Tian et al [17] found through numerical simulation that the optimal length of overflow pipe should be 1.682.02 times of column length.…”

Section: Introductionmentioning

confidence: 99%

Effect of Internal Vortex-Finder on Classification Performance for Double Vortex-Finder Hydrocyclone

Zhang

Jiang

et al. 2022

Separations

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The double vortex-finder hydrocyclone formed by a coaxial insertion of an internal vortex-finder with a smaller diameter inside the conventional single vortex-finder used to obtain two kinds of products from the internal and external overflows in one classification has attracted wide attention. To further improve the classification performance of the hydrocyclone, the effects of the internal vortex-finder diameter and length on the classification performance were studied by numerical simulation and response surface modeling with the behavior of fluid and particle motion in the double vortex-finder hydrocyclone as the research object. The results showed that the split ratio and pressure drop of internal and external overflow increased with the diameter of the internal vortex-finder. The classification performance was optimal when the diameter ratio of internal and external overflow was 0.88, the yield of −20 μm particles was more than 80.0%, and the highest was 95.0%. Increasing the internal vortex-finder length could reduce the coarse particle content and improve the classification accuracy of the internal overflow product. When the length of the internal vortex-finder is larger than 80 mm, the +30 μm yield was lower than 20.0%, and the maximum k value was 16.3%; the k is the significant factor used to characterize the effectiveness of −20μm particle collection. The response surface modeling revealed that the internal vortex-finder diameter was the most important factor affecting the distribution rate of internal overflow. This paper is expected to advance the development of the classification industry.

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Effects of vortex finder length on flow field and collection efficiency of cyclone in an industrial‐scale circulating fluidized bed boiler: Numerical study

Cited by 13 publications

References 26 publications

Effect of sand particle size on the hydrodynamics of a dual fluidized bed cold flow system applied for waste‐to‐energy gasifiers

Effect of sand particle size on the hydrodynamics of a dual fluidized bed cold flow system applied for waste‐to‐energy gasifiers

Double-Eccentric Design for the Vortex Finder of a Cyclone Separator

Effect of Internal Vortex-Finder on Classification Performance for Double Vortex-Finder Hydrocyclone

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