A new char combustion kinetic model 1. Formulation

Barranco, Richelieu; Rojas, Andrés; Barraza, Juan; Lester, Edward

doi:10.1016/j.fuel.2009.02.005

Cited by 24 publications

(10 citation statements)

References 30 publications

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“…The Nusselt number represents the ratio of the convective and conductive heat transfer of a fluid, two mechanisms of heat transfer, whereas the dimensionless number I relates to the main recovery mechanisms in the flotation, comparing the flotation kinetics, which considers recovery by true flotation, with the hydrodynamic features of the process defining recovery by entrainment [32]. The Rayleigh method has also been useful to develop kinetic models of other processes as char combustion for pulverized coal, where the physical characteristics of the char, the chemical characteristics of the coal/char combustion process and the composition of the coal are related to the chemical reaction rate coefficient through dimensionless numbers [33].…”

Section: Formulation Of the New Mathematical Model For Coal Flotationmentioning

confidence: 99%

A new mathematical model for coal flotation kinetics

Guerrero¹,

Barraza-Burgos²

2017

DYNA

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This study describes the development and formulation of a novel mathematical model for coal flotation kinetic. The flotation rate was considered as a function of chemical, operating and petrographic parameters for a global flotation order n. The equation for flotation rate was obtained by dimensional analysis using the Rayleigh method. It shows the dependency of flotation kinetic on operating parameters, such as air velocity and particle size; chemical parameters, such as reagents dosage and solids content; and mineral and maceral composition of coal. The flotation rate equation integrates the kinetic coefficient and the intrinsic characteristics of coal with dimensional consistency, and it is expressed by three dimensionless numbers which have physical chemical meaning. The model also exhibits similarities with traditional transport phenomena models represented by dimensionless numbers and predicts the flotation kinetic constant of a Colombian coal sample showing a good correlation between experimental and calculated values.Keywords: coal flotation; flotation rate; kinetic model. Un nuevo modelo matemático para la cinética de flotación de carbonesResumen Este estudio describe el desarrollo y formulación de un nuevo modelo matemático para la cinética de flotación de carbón. La velocidad de flotación se considera una función de parámetros químicos, operacionales y petrográficos para la flotación global de orden n. La ecuación de velocidad de flotación se obtuvo por análisis dimensional usando el método de Rayleigh. Este método muestra la dependencia de la cinética de flotación sobre los parámetros de operación tales como velocidad del aire y tamaño de partícula; parámetros químicos tales como dosis de reactivos y contenidos de sólidos; y composición mineral y maceral del carbón. La ecuación de velocidad de flotación integra el coeficiente cinético y las características intrínsecas del carbón con consistencia dimensional, y se expresa por tres números adimensionales que tienen significado químico físico. El modelo también muestra similitudes con los modelos tradicionales de fenómenos de transporte representados por números adimensionales y predice la constante cinética de flotación de un carbón Colombiano mostrando buena correlación entre los valores experimentales y calculados.Palabras clave: flotación de carbón; tasa de flotación; modelo cinético.

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Section: Formulation Of the New Mathematical Model For Coal Flotationmentioning

confidence: 99%

A new mathematical model for coal flotation kinetics

Guerrero¹,

Barraza-Burgos²

2017

DYNA

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“…The second-stage processes such as char combustion and gas-phase reactions, where the later one also includes volatile combustion and pollutants formation, need to be considered in the reaction mechanism for overall performance modeling of boiler furnaces. Available literature explains that char oxidation proceeds according to global [7] and semi-global kinetics [27]. Furthermore, char oxidation process is largely affected by coal ash content, particle size, temperature, pore structure, and its associated diffusion process.…”

Section: Competing Two-step Reaction Scheme Known Asmentioning

confidence: 99%

“…Pulverized coal combustion is a multistage and multiscale process occurring both at the particle level and on reactor scale. Comprehensive process modeling of coal combustion needs to include physical models for various processes such as coal drying [2,3], devolatilization [4][5][6], gas-phase and char combustion reactions [7][8][9][10][11], and other pollutant formation reactions [12][13][14][15][16]. In addition, any numerical model should also be sensitive to the operating parameters, thermophysical properties, and the reactivity of coal.…”

Section: Introductionmentioning

confidence: 99%

A new framework for modeling coal devolatilization and combustion in boiler furnaces

et al. 2017

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Summary This paper presents a new framework for the modeling of coal‐fired boiler furnaces. The input required for the model is the ultimate analysis of a coal sample. The model accounts for devolatilization followed by gas‐phase combustion. The devolatilization model used in this work is taken from published literature with slight modifications to match the numerical predictions with experimental measurements. This work also develops a reactor network model for simulating the performance of boiler furnaces. For the seamless integration of kinetic models of coal devolatilization and combustion with furnace numerical model, the thermochemistry data of several hypothetical and intermediate species involved in devolatilization chemistry are evaluated in the form of 14 coefficient National Aeronautics and Space Administration polynomials. The capability of the model for predicting the furnace temperature and product composition is demonstrated by simulating a single‐zone model. Copyright © 2017 John Wiley & Sons, Ltd.

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“…Char samples were manually crushed and sieved to a particle size of less than 100 lm. For this particle size range, it has been reported that the chemical reaction controls the kinetic of reaction and the effect of reactant diffusion is negligible [16]. In order to further minimize the interference of mass and heat transfer on gasification reaction, an initial set of experiments was performed.…”

Section: Gasification Experimentsmentioning

confidence: 99%

Alternative Reducing Agents in Metallurgical Processes: Gasification of Shredder Residue Material

Lotfian

Ahmed

El-Geassy

et al. 2016

J. Sustain. Metall.

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Shredder residue material (SRM) contains plastic material, which has a potential to replace metallurgical coal for reduction during bath-smelting processes. Among the important parameters affecting its implementation are the gasification and the reactivity of char. Therefore, prior to considering its application in metallurgical processes, the gasification characteristics of the produced char need to be studied. Although the char produced from SRM contains lower fixed carbon compared with coal char, it has a porous structure and high surface area, which makes it highly reactive during gasification experiments. In addition to physiochemical properties, the catalytic effect of ash content of SRM char is attributed to its higher reactivity and lower activation energy compared with coal char. Furthermore, the effect of devolatilization heating rate on the gasification characteristics of produced char is investigated. It was found that the devolatilization heating rate during char production has a considerable effect on morphological properties of the char product. Moreover, the gasification reactivity of char produced at a fast devolatilization heating rate was the highest, due to the less crystalline structure of the produced char. Keywords Shredder residue material Á Char Á Gasification Á Reducing agent Á Bath smelting List of Symbols X Char conversion w 0 Initial weight of char w ? Saturation value of the weight-loss curve w(t) Sample weight at a time t r Gasification rate of the isothermal gasification q Gasification rate of the nonisothermal gasification E a Activation energy A Preexponential factor R S Reactivity index s 50 Time (in minute) required to reach the carbon conversion of 50 % w C Weight of carbon in the sample remaining unreacted at the time t The contributing editor for this article was Veena Sahajwalla.

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A new char combustion kinetic model 1. Formulation

Cited by 24 publications

References 30 publications

A new mathematical model for coal flotation kinetics

A new mathematical model for coal flotation kinetics

A new framework for modeling coal devolatilization and combustion in boiler furnaces

Alternative Reducing Agents in Metallurgical Processes: Gasification of Shredder Residue Material

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