Effects of limestone calcination on the gasification processes in a BFB coal gasifier

Armstrong, Lindsay-Marie; Gu, Sai; Luo, Kai

doi:10.1016/j.cej.2011.01.102

Cited by 41 publications

(38 citation statements)

References 44 publications

(41 reference statements)

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“…In this study, the highest operating temperature is less than 1273 K; therefore, higher temperature makes these two reactions take place more quickly, which will consume more H 2 O and CO 2 , and produce more CO and H 2 . Moreover, higher temperature is beneficial for char combustion reaction to produce more CO. For these reasons, the concentrations of CO and H 2 increase with the operating temperature, which is consistent with the findings from literature …”

Section: Resultssupporting

confidence: 92%

“…Coal is composed of char, volatile matter, moisture, and ash, and the gas phase consists of 11 species (CO 2 , CO, H 2 , H 2 O, O 2 , N 2 , NH 3 , H 2 S, CH 4 , C 2 H 2 , and tar). In this work, char is assumed as pure carbon, and the contents of hydrogen, oxygen, nitrogen, and sulfur in the coal are released as gaseous species during pyrolysis.…”

Section: Methodsmentioning

confidence: 99%

“…Zhou et al performed a two‐dimensional CFD simulation of coal combustion in a CFB boiler; Nikolopoulos et al conducted transient three‐dimensional simulation of coal combustion process in a pilot power plant . As for the coal gasification simulation, several studies have been found on the bubbling fluidized bed (BFB) gasifier using reacting TFM . The majority of these simulations are performed on the coal combustion processes in CFB reactors and the coal gasification processes in BFB reactors, but few studies on coal gasification processes in CFB reactors are found (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…However, these models are usually derived from some specified operating conditions and coal types, and usually do not give the stoichiometry for individual gaseous species. The empirical correlations developed by Loison and Chauvin give the stoichiometry of each gaseous species and have been widely used by researchers, but they do not account for the effects of important operating conditions such as temperature, heating rate, and pressure. To overcome these limitations, the structural pyrolysis models based on the coal network structure such as chemical percolation devolatilization (CPD) model and FLASHCHAIN model have been developed.…”

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: Resultssupporting

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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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“…However, their models considered a single solid phase for the coal and sand which is computationally more efficient but unrealistic, as different solid materials exhibit different material properties, for example, density, diameter, and so on. Separate phases for different solid phases have been carried out and it was found that the use of multiple phases better represented the segregative tendencies of the bed due to different material properties.…”

Section: Introductionmentioning

confidence: 99%

Multifluid Modeling of the Desulfurization Process within a Bubbling Fluidized Bed Coal Gasifier

Armstrong

Luo

et al. 2013

AIChE Journal

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The desulfurization process to a two-dimensional (2-D) and three-dimensional (3-D) Eulerian–Eulerian computational fluid dynamic (CFD) model of a coal bubbling fluidized gasifier is introduced. The desulfurization process is important for the reduction of harmful SOx emissions; therefore, the development of a CFD model capable of predicting chemical reactions involving desulfurization is key to the optimization of reactor designs and operating conditions. To model the process, one gaseous phase and five particulate phases are included. Devolatilization, heterogeneous, and homogeneous chemical reactions as well as calcination and desulfurization reactions are incorporated. A calcination-only model and a calcination plus desulfurization model are simulated in 2-D and 3-D and the concentrations of SO2 leaving the reactors are compared. The simulated results are assessed against available published experimental data. The influence of the fluidized bed on the desulfurization is also considered

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An extensive simulation of coal gasification in bubbling fluidized bed: Integration of hydrodynamics into reaction modelling

2014

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The simulation of the coal gasification process in a bubbling fluidized bed reactor was performed in order to estimate the performance of the gasifier and assess the optimal operating conditions. A Eulerian‐Eulerian computational fluid dynamics (CFD) simulation has been developed to predict the hydrodynamic behaviour of the fluidization regime in the bed. This not only provides insight into the hydrodynamics of the bubbling fluidized bed reactor, but also yields hydrodynamics parameters, such as bubble diameter and velocity, solid volume fraction, velocity of gas and solid particles, which can be subsequently used for reaction modelling of the coal gasification process. The predicted hydrodynamic parameters from the CFD simulation are integrated into the kinetics of gasification chemical reactions taking place in the bubble, cloud, and emulsion phases. Instantaneous devolatilization and drying of the feedstock are also considered in the model. The comparison of the predicted results with experimental measurements showed that most of the predicted molar gas compositions in the produced gas were within 15 % of the experimental data. The model was further used to predict the performance of the gasifier at different operating conditions. The results indicated that the temperature range of 800–850 °C, steam‐to‐coal ratios of 0.5–1.5 kg/kg, and air‐to‐coal ratios of 2.0–2.5 kg/kg are suitable conditions for syngas (hydrogen and carbon monoxide, H2 + CO) production. Depending on the application of the produced syngas, the required H2‐to‐CO ratio can be achieved by controlling the air‐ and steam‐to‐coal ratios.

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Effects of limestone calcination on the gasification processes in a BFB coal gasifier

Abstract: The impact of limestone calcination on the gaseous composition is observed.

Cited by 41 publications

References 44 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

Multifluid Modeling of the Desulfurization Process within a Bubbling Fluidized Bed Coal Gasifier

An extensive simulation of coal gasification in bubbling fluidized bed: Integration of hydrodynamics into reaction modelling

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