Dependence of bituminous coal gasification on pressure in a turbulent circulating fluidized bed

Duan, Feng; Zhang, Lihui; Huang, Yaji

doi:10.1002/apj.640

Cited by 6 publications

(5 citation statements)

References 17 publications

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“…[1,2] Recently, the pressurized CFB coal-gasification technology is attracting more attention because of its large-scale potential. [3] Coal gasification is a complex process coupled with gas-solid flow, heat and mass transfer, and chemical reactions. Good understanding of the coupling mechanism between gas-solid flow and chemical reactions in gasification process is needed for the design and scaling up of CFB reactors.…”

Section: Introductionmentioning

confidence: 99%

“…Circulating fluidized bed (CFB) reactors have been widely used in coal gasification and combustion because of many advantages such as fuel flexibility and low pollutant emissions . Recently, the pressurized CFB coal‐gasification technology is attracting more attention because of its large‐scale potential . Coal gasification is a complex process coupled with gas–solid flow, heat and mass transfer, and chemical reactions.…”

Section: Introductionmentioning

confidence: 99%

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Computational fluid dynamics simulation and parametric study of coal gasification in a circulating fluidized bed reactor

Zhang

Lei

Xiao

2015

Asia-Pacific J Chem Eng

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A computational fluid dynamics model based on the Eulerian-Eulerian multiphase framework was implemented to simulate the coal gasification processes in a circulating fluidized bed gasifier. The standard k-ε turbulence model is used for gas phase, and the solid phases are modeled with kinetic theory of granular flow. A lumped chemical reaction model was compiled based on the chemical percolation devolatilization model and the METC Gasifier Advanced Simulation gasification model. The user-defined functions are developed to calculate rates of chemical reactions and to recirculate solids from the riser exit to the solid recycle inlet. Sensitivity analysis was performed on char-steam gasification reaction to choose an appropriate kinetic rate in this study. The calculated gas composition out of the riser was first compared with experimental data; then, the flow fields such as solid volume fraction, solid velocity, and species profiles were analyzed, indicating that the model gave reasonable predictions. Furthermore, the effects of the operating temperature, the steam/coal ratio, and the air/coal ratio on the exiting gas composition were numerically studied, and the predicted trends vs these parameters are reasonable and consistent with the findings in the literature, which shows the applicability of the Eulerian multiphase model to simulate coal gasification processes in circulating fluidized bed gasifiers.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Computational fluid dynamics simulation and parametric study of coal gasification in a circulating fluidized bed reactor

Zhang

Lei

Xiao

2015

Asia-Pacific J Chem Eng

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“…Compared with the BFB gasification, the CFB gasification has a larger unit capacity, higher carbon conversion, and better mass and heat transfer between gas and solids . The best gasification results in our CFB experiments are listed in Table .…”

Section: Resultsmentioning

confidence: 98%

Coal Char Gasification on a Circulating Fluidized Bed for Hydrogen Generation: Experiments and Simulation

et al. 2015

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Char is the solid product of coal pyrolysis and its utilization is closely related to the scale of coal pyrolysis and tar processing. Char gasification is a promising choice for char utilization as it can provide hydrogen, which is needed for tar hydrogenation and chemical synthesis. However, reliable and mature coal char gasification technology has not yet been developed. The fluidized bed has been adopted as a gasifier in many studies, and its gasification temperature is relatively low. In this work, the feasibility of char gasification using a fluidized bed has been studied. A pyrolyzed bituminous coal char was gasified in a mixture of O2 and steam using a circulating fluidized bed. The height of the fluidized bed is 2360 mm and the inner diameter is 66 mm. The reactor is made of Ni‐Cd alloy steel, and a loopseal was used for solid circulation. In the experiments, the gasification temperature was varied between 870 and 900 °C, and the effects of O2/char and steam/char mass ratios on the gasification results were analyzed. The volume fraction of combustible gas, dry gas yield, carbon conversion, and lower heating value of the best case were 43.92 %, 1.64 Nm3 kg−1, 0.85, and 5.17 MJ N m−3, respectively. In addition, a simple model and a complex model were established by using Aspen Plus software. The two models were used to simulate char gasification, and the simulation results were validated with the experimental results. The results indicated that the complex model is more accurate than the simple model and is more suitable to simulate char gasification in a circulating fluidized bed.

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“…In addition to the cold flow investigation in PCFB, some notable hot flow investigations have been found in the literature. Duan et al [14] reported that higher operating pressure improves both heat transfer and carbon conversion than for atmospheric CFB reactors. Mac-Neil and Basu [15] investigated char combustion rate in a 5.5 kW PCFB reactor.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic experiments on a small-scale circulating fluidized bed reactor at elevated operating pressure, and under an O2/CO2 environment

et al. 2017

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Pressurized circulating fluidized bed technology is a potentially promising development for clean coal technologies. The current work explores the hydrodynamics of a small-scale circulating fluidized bed at elevated operating pressures ranging from 0.10 to 0.25 MPa. The initial experiments were performed at atmospheric pressure with air and O 2 /CO 2 environments as the fluidization gas to simulate the hydrodynamics in a circulating fluidized bed. A comparison between the effects of air and O 2 /CO 2 mixtures on the hydrodynamics was outlined in this paper for particles of 160 μm diameter. A small but distinct effect on axial voidage was observed due to the change in gas density in the dense zone of the bed at lower gas velocity, while only minimal differences were noticed at higher gas velocities. The hydrodynamic parameters such as pressure drop and axial voidage profile along the height were reported at two different bed inventories (0.5 and 0.75 kg) for three mean particle sizes of 160, 302, and 427 μm and three superficial gas velocities. It was observed that the operating pressure had a significant effect on the hydrodynamic parameters of bed pressure drop and axial bed voidage profiles. The effect of solids loading resulted in an exponential change in pressure drop profile at atmospheric pressure as well as at elevated pressure. The experimental results on hydrodynamic parameters are in reasonable agreement with published observations in the literature.

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Dependence of bituminous coal gasification on pressure in a turbulent circulating fluidized bed

Cited by 6 publications

References 17 publications

Computational fluid dynamics simulation and parametric study of coal gasification in a circulating fluidized bed reactor

Computational fluid dynamics simulation and parametric study of coal gasification in a circulating fluidized bed reactor

Coal Char Gasification on a Circulating Fluidized Bed for Hydrogen Generation: Experiments and Simulation

Hydrodynamic experiments on a small-scale circulating fluidized bed reactor at elevated operating pressure, and under an O2/CO2 environment

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