Study of fluidized bed regimes using Computational Particle Fluid Dynamics

Jaiswal, Rajan; Agu, Cornelius Emeka; Thapa, Rajan Kumar; Moldestad, Britt Margrethe Emilie

doi:10.3384/ecp18153271

Cited by 9 publications

(12 citation statements)

References 13 publications

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“…Gasification of biomass is a sustainable conversion technology to cope with an increasing environmentally friendly energy demand. The interest for gasification using fluidized bed is growing, since the process provides uniform heat transfer and fuel flexibility [1]. Ideal mixing of the fuel particles, the bed material, and the gas phase promotes excellent heat transfer in a fluidized bed.…”

Section: Introductionmentioning

confidence: 99%

A CPFD model to investigate the influence of feeding positions in a gasification reactor

Jaiswal¹,

Furuvik²,

Thapa³

et al. 2020

Int. J. EQ

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The efficiency of a gasification process is directly related to the rate of biomass conversion into product gas. The rate of fuel conversion depends on the interaction of fuel with the bed material, the gasifying agent, and the residence time of fuel particles. The interactions and the residence time depend on the fuel feeding positions along the height of the reactor. Thus, the fuel feeding position in a gasification reactor is an important parameter that influences the efficiency of the gasification process; longer residence time of the fuel particles in the bed enables efficient carbon conversion and less tar formation. In this work, in-bed and on-bed feed positions of the fuel particles have been investigated using a computational particle fluid dynamics (CPFD) model. The model is developed and validated against experimental data obtained from a bubbling fluidized bed gasification reactor. Experiments were carried out in a 20 kW pilot scale bubbling fluidized bed gasification reactor. Wood pellets of 3-30 mm length and 5 mm diameter are fed into the reactor at a mass flow rate of 2.4 kg/h. The molar flow rate of the producer gas, which typically consists of CH 4 , CO, CO 2 , and H 2 for both the in-bed and on-bed cases, is calculated by the CPFD model. The results show that CO and CH 4 concentrations increase in the product gas when the biomass is fed at the location near to the bottom of the bed, while CO 2 and H 2 increase in the case of on-bed feed. The fuel particles segregate, followed by partial combustion of the smaller fuel particles on the bed surface in the case of on-bed feed. The total mass of the bed including unreacted char is higher for on-bed feed, indicating that the char is consumed slowly. The CPFD model can predict the product gas compositions, the fuel conversion, changes in the bed hydrodynamics, and the product gas yield at different feeding positions of the fuel particles. Thus, the model can be useful for design purposes.

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Section: Introductionmentioning

confidence: 99%

A CPFD model to investigate the influence of feeding positions in a gasification reactor

Jaiswal¹,

Furuvik²,

Thapa³

et al. 2020

Int. J. EQ

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“…Change in static bed height in a bubbling fluidized bed gasifier effects the bed hydrodynamic behavior (Jaiswal, 2018), the residence time of the fuel particles and the temperature of the bed. In this section, influence of the static bed height on the product gas composition and the reactor performance are discussed.…”

Section: Effect Of Static Bed Heightmentioning

confidence: 99%

“…Gasification using fluidized bed has been considered as an flexible technology that can use a wide range of fuels. Fluidized beds provide major advantages such as uniform mixing and heat transfer (Jaiswal, 2018;Jaiswal, 2019), which enables efficient conversion of carbonaceous solid into product gases. The feedstock to the gasifier has to be cheaper and more flexible in order to make the process economically sustainable.…”

Section: Introductionmentioning

confidence: 99%

Study of agricultural waste gasification in an air-blown bubbling fluidized bed using a CPFD model

Jaiswal¹,

Thapa²,

Moldestad³

2021

Linköping Electronic Conference Proceedings

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Gasification using a fluidized bed is a promising technology to convert agricultural residues into product gases. In this work, the syngas production potential from agricultural waste (grass pellets) is studied using a Computational Fluid Dynamic (CPFD) model. The CPFD model is developed in a simulation software Barracuda virtual reactor and validated against the experimental data. Experiments are carried out in a 20 kW bubbling fluidized bed gasification reactor that operates with air as fluidizing gas. Grass pellets of size 5mm-30 mm in length and diameter of 5mm are used as the feed. The CPFD model considers the hydrodynamics of the gas-solid phase and reaction kinetics involved. Influence of the static bed height, bed temperature, and air to fuel ratio on the product gas composition (4 , , 2 , 2) and char conversion efficiency are investigated. Initial bed heights of 200 mm and 300 mm are used for the analysis. Biomass is fed at 2.46 /ℎ while the air supplied is varied to obtain the air to fuel ratio at 0.4, 0.6, 0.8, 1, and 1.2. The result shows that the increase in bed height has a significant effect on the reactor temperature but very small effect on the product gas composition and char conversion rate. An increase in bed temperature from 600℃ to 800℃ improves the gasifier performance in terms of maximum product gases yield and enhanced char conversion rate. Increase in the air to fuel ratio from 0.4-1.2 reduces the 4 , , 2 fractions in the product gas and increases the 2 concentration. The results obtained from the CPFD model are in good agreement with the experimental results and literature data. Thus, the CPFD model developed in this work can be utilized to optimize the gasification reactor used in a lab and industrial scale.

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“…Pressure drop in the bed was monitored and plotted versus the superficial air velocity. (Jaiswal et al, 2018).…”

Section: Cold Fluidized Bed Set-upmentioning

confidence: 99%

Computational modeling of fluidized bed behavior with agglomerates

Jakobsen¹,

Jaiswal²,

Furuvik³

et al. 2021

Linköping Electronic Conference Proceedings

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Fluidized bed reactors can be used for biomass gasification. The product from biomass gasification is syngas, which can be used for production of bio oil. The main challenge when using fluidized bed for gasification is ash melting and agglomeration of the bed material. Agglomeration of the bed material influences on the flow behavior in the fluidized bed reactor and thus affects the gasification efficiency. A Computational Particle Fluid Dynamic (CPFD) model is developed to predict the flow behavior in a fluidized bed gasifier. The CPFD model was validated against experimental data from a cold fluidized bed. The model was then tested against the results from a biomass gasifier, and a few modifications were needed. Glickman's scaling parameters were used to scale up from a lab-scale to a full-scale gasifier. Simulations using the modified model were performed to study the flow behavior in a full-scale gasifier with agglomerates. It was found that the CPFD model is capable of predicting the effect of agglomerates on flow behavior in a fluidized bed gasifier.

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Study of fluidized bed regimes using Computational Particle Fluid Dynamics

Cited by 9 publications

References 13 publications

A CPFD model to investigate the influence of feeding positions in a gasification reactor

A CPFD model to investigate the influence of feeding positions in a gasification reactor

Study of agricultural waste gasification in an air-blown bubbling fluidized bed using a CPFD model

Computational modeling of fluidized bed behavior with agglomerates

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