Effect of elevated temperature and silica sand particle size on minimum fluidization velocity in an atmospheric bubbling fluidized bed

Al-Farraji, A.; Taofeeq, Haidar

doi:10.1016/j.cjche.2020.07.054

Cited by 10 publications

(11 citation statements)

References 28 publications

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“…Fluidized bed (FB) gasifiers are preferred for biomass gasification because of their better mixing and uniform heat transfer characteristics. In fluidized bed gasifiers, bed materials, such as silica sand is used because it provides greater uniformity of temperature for the mixture within the bed and also increases the coefficient of heat transfer [3].…”

Section: Introductionmentioning

confidence: 99%

“…Knowledge of the fluidized bed hydrodynamics is of fundamental importance because their design, optimization and operation depends on parameters such as pressure drop, fluidization velocity and bed porosity/voidage [3]. In the design of the air distributor plate of the fluidized bed gasifiers, the air distributor pressure drop (∆PDP) should be satisfied at the minimum fluidization point (mf) to ensure proper fluidization of the bed materials and to avoid non-uniform gas distribution.…”

Section: Introductionmentioning

confidence: 99%

“…Although fluidized bed gasifiers are operated at elevated temperatures, the prediction of their hydrodynamic parameters is based mostly on models at room temperature conditions [3]. Studies on the fluidized bed hydrodynamics at elevated temperatures are scanty which could be attributed to the challenges encountered when operating high temperature laboratory scale fluidized units.…”

Section: Introductionmentioning

confidence: 99%

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Numerical and Experimental Investigation of Fluidized Bed Hydrodynamics at Elevated Temperatures

Njuguna

Ndiritu

Gathitu

et al. 2023

JERA

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Fluidized bed gasifiers operate at elevated temperatures, and experimental measurements for the hydrodynamic parameters at high temperatures are difficult and time consuming, making computational fluid dynamics simulation useful for such investigation. In this study, Opensource computational fluid dynamics code, OpenFOAM, was used to investigate temperature effect on the fluidized bed hydrodynamics on a 3D fluidized bed model using Eulerian-Eulerian approach. Silica sand of particle sizes of 500, 335 and 233 m was used as the bed materials under temperatures between 25 and 400 °C. To validate the simulation model, a laboratory scale fluidized bed unit was used to conduct experiments for the same range of temperature and sand particle sizes. The results revealed that the temperature of the bed materials greatly affect fluidized bed hydrodynamics. The minimum fluidization velocity increased with the sand particle diameter but decreased with the temperature. On the other hand, the bed porosity at the minimum fluidization point increased marginally with both the temperature and the particle size of the bed materials. Further analysis showed that the expanded bed height increased with the temperature for a specific superficial velocity while the bubbles grew in size with both the air flow rates and the temperature. The numerical model results were compared with the experimental results based on minimum fluidization velocity, bed porosity and pressure drop at the minimum fluidization point. The hydrodynamic results of the numerical model were in good agreement with the experimental results.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Numerical and Experimental Investigation of Fluidized Bed Hydrodynamics at Elevated Temperatures

Njuguna

Ndiritu

Gathitu

et al. 2023

JERA

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“…The velocity at the inlet of the fluidized bed is found a key factor affecting the fluidization performance and the fluidization quality of the powder; such velocity also affects the working efficiency of powder unloading and the residual rate of the powder. 1–3 However, in the fields of bulk cement, lime powder, and ore powder unloading, the fluidized bed is mostly centralized on commercial functional application. Few reports are available on the basic research on the uniformity of the velocity distribution ( V u ) in the fluidized bed.…”

Section: Introductionmentioning

confidence: 99%

Design of a novel flat-cloth airway in powder tank based on Taguchi optimization

Wang

Yan

Zeng

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part C:

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The fluidized bed is a key structure in the field of material transportation and is widely used in special automobile and construction powder transportation. A novel flat-cloth airway structure for powder unloading was proposed based on the traditional fluidized bed in this study. To analyze the uniformity of the velocity distribution ( Vu) in the fluidized bed and clarify the interaction mechanism between the geometric structure of the fluidized bed and airflow, 16 geometric structures of the fluidized bed for powder unloading were designed. Different schemes of the fluidized bed were numerically calculated by computational fluid dynamics, and the advantages of each scheme were analyzed by the Taguchi method and multiple regression. The length of the annular vortexes at the inlet of the airways becomes shorter than before as the number of airways increases. Airway height ( H), airway angle ( θ) and airway arc length ( L) exert statistically significant effects. Specifically, H (Delta = 6.45 rank =1) has the greatest effect on signal-to-noise ratios, L (Delta = 2.60 rank =2) has the second greatest effect and θ (Delta = 1.82 rank =3) has the least effect. The optimal combination of geometrical parameters of the fluidized bed is 15 mm H, 51° θ and 200 mm L.

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“…The bed is widely used in such fields as chemical reactors and the material transfer industry. Scholars in various countries have carried out many studies on the basic theory of the fluidized bed, 1–3 and they found that the fluid velocity of the fluidized bed is a key factor that affects the fluidization performance and affects the working efficiency of powder unloading and the residual rate of the powder. 4 To quantify the flow uniformity in gas-solid fluidized beds, Morse and Shuster measured the quality of fluidization and voidage distribution in the fluidized beds.…”

Section: Introductionmentioning

confidence: 99%

Design optimization of a fluidized bed with a novel air chamber using the CFD-Taguchi method

Wang

Yan

Zeng

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part C:

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The gas–solid fluidized bed is the key structure of industrial fluidization, and it is widely used in fields such as chemical reactors and industrial material conveying. To study the uniformity of velocity distribution ( Vu) in a fluidized bed and clarify the interaction mechanism between the geometric structure of the air chamber and the gas flow, in this paper, 16 novel chamber structures for powder unloading were designed based on the Taguchi method. Computational fluid dynamics was used to simulate the different chamber schemes, and the effects of various geometric factors on the response were analyzed based on the Taguchi method. The effect of the novel optimization model for powder unloading was verified by tests. The results show that the optimal combination of geometrical parameters is air chamber capacity ( V) at level 4, separation ratio ( K) at level 1 and clearance of splitter plate ( δ) at level 1, and δ has the greatest effect on the Vu1 and Vu2 in the fluidized bed. With the increase in δ and K, the velocity of the airflow away from the inlet side increases, and the area of the vortex near the splitter plate increases. Compared with the baseline model, the fluidized bed with the novel air chamber can effectively reduce the residual rate of powder unloading.

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Effect of elevated temperature and silica sand particle size on minimum fluidization velocity in an atmospheric bubbling fluidized bed

Cited by 10 publications

References 28 publications

Numerical and Experimental Investigation of Fluidized Bed Hydrodynamics at Elevated Temperatures

Numerical and Experimental Investigation of Fluidized Bed Hydrodynamics at Elevated Temperatures

Design of a novel flat-cloth airway in powder tank based on Taguchi optimization

Design optimization of a fluidized bed with a novel air chamber using the CFD-Taguchi method

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