Simulation and experimental studies on fluidization properties in a pressurized jetting fluidized bed

Cao, Jiantao; Cheng, Zhonghu; Fang, Yitian; Jing, Huijuan; Huang, Jiejie; Wang, Yang

doi:10.1016/j.powtec.2007.11.033

Cited by 48 publications

(17 citation statements)

References 11 publications

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“…5 compare well with the experiments at JJ = 4 em but at y = 8 em the 2D data deviates from the other data. Similar discrepancies have been shown by others [3,[25][26][27]]. …”

supporting

confidence: 90%

Modeling a Biomass Fluidizing Bed With Side Port Air Injection

Deza

Battaglia

Heindel

2009

Volume 1: Symposia, Parts A, B and C

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Fluidized beds are used to gasify materials such as coal or biomass in the production of producer gas. Modeling these reactors using computational fluid dynamics is advantageous when performing parametric studies for design and scale-up. While two-dimensional simulations are easier to perform than threedimensional simulations, they may not capture the proper physics. This paper compares two-and threedimensional simulations with experiments for a reactor geometry with side port air injection. The side port is located within the bed region so that the injected air can help promote mixing. Of interest in this study is validating the hydrodynamics of fluidizing biomass. Two operating conditions of the fluidized bed are studied for superficial gas velocities of 1.5Umf and 3.0Umf , where Umf is the minimum fluidization velocity. The material used to represent biomass is ground walnut shell because it tends to fluidize uniformly and falls within the Geldart type B classification. The simulations are compared to experimental data of time-averaged local gas holdup values using X-ray computed tomography. Results indicate that for the conditions of this study, two-dimensional simulations overpredict the gas holdup trends when compared to the experiments. However, the three-dimensional simulations compare exceptionally well with the experiments, thus predicting the fluidization hydrodynamics, irrespective of flowrate or complexity due to the side air port. Furthermore, the study demonstrates the importance of using a three-dimensional model for bubbling fluidized beds with complex physics.

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“…5 compare well with the experiments at JJ = 4 em but at y = 8 em the 2D data deviates from the other data. Similar discrepancies have been shown by others [3,[25][26][27]]. …”

supporting

confidence: 90%

Modeling a Biomass Fluidizing Bed With Side Port Air Injection

Deza

Battaglia

Heindel

2009

Volume 1: Symposia, Parts A, B and C

View full text Add to dashboard Cite

show abstract

“…The experimental data and 3D simulations are local time-average values along a ray that passes through the centerline of the bed and side injection port at the given z height. The variations in the experimental data are attributed to the non-uniform inlet conditions that result from the 62 discrete air inlet holes of the distributor plate, and similar discrepancies have been shown by others [36][37][38][39]. The 3D prediction compares very well with the experiment, whereas the 2D simulation significantly overpredicts the presence of gas near the lower region of the bed (Fig.…”

Section: Two-and Three-dimensional Simulationssupporting

confidence: 79%

Effects of Mixing Using Side Port Air Injection on a Biomass Fluidized Bed

Deza

Heindel

Battaglia

2011

Journal of Fluids Engineering

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Fluidized beds are being used in practice to gasify biomass to create producer gas, a flammable gas that can be used for process heating. However, recent literature has identified the need to better understand and characterize biomass fluidization hydrodynamics, and has motivated the combined experimental-numerical effort in this work. A cylindrical reactor is considered and a side port is introduced to inject air and promote mixing within the bed. Comparisons between the computational fluid dynamics (CFD) simulations with experiments indicate that three-dimensional simulations are necessary to capture the fluidization behavior of the more complex geometry. This paper considers the effects of increasing side port air flow on the homogeneity of the bed material in a 10.2 cm diameter fluidized bed filled with 500-600 μmground walnut shell particles. The use of two air injection ports diametrically opposed to each other is also modeled using CFD to determine their effects on fluidization hydrodynamics. Whenever possible, the simulations are compared to experimental data of time-average local gas holdup obtained using X-ray computed tomography. This study will show that increasing the fluidization and side port air flows contribute to a more homogeneous bed. Furthermore, the introduction of two side ports results in a more symmetric gas-solid distribution.

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“…The direction of the holes in the distributor is set parallel to the FB wall inclination. Some papers studied the conical fluidized bed with conical distributor which is roughly stands for ash-agglomerating fluidized bed coal gasifier (Cao et al, 2008;Bi and Kojima, 1996;et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Conical Fluidized Bed with Arc Design for Improved Performance of Gas Distributor

Hamawand

Silva

Jawad

2015

SET

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Particles distributions along a conical fluidized bed were predicted by an alternative arrangement of the minimum fluidization velocity equation. The proposed approach introduces two new equations which present the particle diameter in the bed as function of: height in the bed (Z), angle of inclination of the fluidized bed wall (θ), input flow rate (Q o ), and gas distributor diameter (D o , 2r o ). A novel arc-shaped design of the gas distributor was suggested, which provides enhanced distribution of the gas and enables greater control on the direction of the gas inlet. The model showed that the inclination of the fluidized bed wall should not exceed a critical angle, which can be determined with the set of equations specially developed for this purpose, to prevent inhomogeneous fluidization across the bed and accumulation of particles along the walls.By applying the Box Wilson Method, theoretical data were obtained for constant column diameter at the base (0.05 m), and varying bed height, Z, (range: 0.5 to 1.5 m), velocity of gas inlet, U, (range 0.25 to 1 m s -1 ), and balance factor, a, (range: 0.5 to 1, a new factor), respectively. The angle of inclination of the wall was first predicted based on the above parameters, and subsequently, the particle size distribution along the column was determined. Theoretically the novel arc-shaped distributor design has shown the potential of generating homogeneous fluidization regimes along the bed.

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Simulation and experimental studies on fluidization properties in a pressurized jetting fluidized bed

Cited by 48 publications

References 11 publications

Modeling a Biomass Fluidizing Bed With Side Port Air Injection

Modeling a Biomass Fluidizing Bed With Side Port Air Injection

Effects of Mixing Using Side Port Air Injection on a Biomass Fluidized Bed

Conical Fluidized Bed with Arc Design for Improved Performance of Gas Distributor

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