Mathematical modeling of combustion in a grate-fired boiler burning straw and effect of operating conditions under air- and oxygen-enriched atmospheres

Yu, Zhaosheng; Ma, Xiaoqian; Liao, Yanfen

doi:10.1016/j.renene.2009.10.006

Cited by 64 publications

(29 citation statements)

References 22 publications

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“…11) which was created as a result of DOE, helps us to determinate the interaction among maximal ash-temperature vs. secondary air-velocity, and oxygen MFR in the secondary air inlet. The temperature in the secondary combustion chamber increases when oxygenenriched air is used [4,7,12,16] and this phenomena is clearly seen by the temperature comparisons in this picture. In this way we can predict and avoid the damage that can be caused by this phenomenon.…”

Section: Resultsmentioning

confidence: 73%

“…Several other authors have used the FLUENT solver code [3,[5][6][7][8][9][10][11][12] but, in this study, the CFX V12.0 solver code in the Workbench 2 environment, which was developed by Ansys, Inc., was applied. In addition, the reactions for gaseous combustion are also defined and the entire model is solved.…”

Section: Geometry Meshing and Boundary Conditionsmentioning

confidence: 99%

“…In order to meet these goals, WTEP with bedcombustion was numerically investigated by using the computational fluid dynamics (CFD) approach [1][2][3][4][5][6][7][8][9][10][11][12][13], by the non-stationary calculation of the ANSYS CFX 12.0 code in a WORKBENCH 2 environment. Firstly, this process depends on many input parameters such as proximate and ultimate analyses, the season of the year, primary and secondary inlet air velocities and, secondly, on output parameters such as the temperatures or mass fraction of the combustible products.…”

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confidence: 99%

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Numerical optimization of a waste-to-energy plant's operating parameters using CFD

Kapitler¹,

Samec²,

Kokalj³

2011

THERM SCI

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The combustion process for using municipal solid waste as a fuel within a waste to energy plant calls for a detailed understanding of the following phenomena. Firstly, this process depends on many input parameters such as proximate and ultimate analyses, the season of the year, primary and secondary inlet air velocities and, secondly, on output parameters such as the temperatures or mass fraction of the combustible products. The variability and mutual dependence of these parameters can be difficult to manage in practice. Another problem is how these parameters can be tuned to achieving optimal combustible conditions with minimal pollutant emissions, during the plant-design phase. In order to meet these goals, a waste-to-energy plant with bed combustion was investigated by using computational fluid-dynamics approach. The adequate variable input boundary conditions based on the real measurement are used and the whole computational work is updated using real plant geometry and the appropriate turbulence, combustion, or heat transfer models. The operating parameters were optimized on output parameters through a trade-off study. The different operating conditions were varied and the combustible products were predicted and visualized. Finally, the response charts and matrix among the input and output parameters during the optimization process are presented, which monitored the dependence among these parameters. emissions, during the WTEP project phase. In order to meet these goals, WTEP with bedcombustion was numerically investigated by using the computational fluid dynamics (CFD) approach [1][2][3][4][5][6][7][8][9][10][11][12][13], by the non-stationary calculation of the ANSYS CFX 12.0 code in a WORKBENCH 2 environment. By using this complex numerical tool, the input and output parameters were followed and their mutual interaction visualized. Mathematical models for boundary-condition predictions were developed, such as FLIC [6,[8][9][10][11]] and the TAMARA [3] test project to find out combustible products distribution within the gaseous phase above the fuel bed and along the moving grate. The combustion of MSW during the gaseous combustion phase has many phases such as moisture evaporation, waste devolatilisation, combustion of volatiles, mixing and fixed carbon combustion during heterogeneous chemical reactions [10]. So the input boundary conditions have to be harmonized using these phenomena. Some optimization methods are described in literature [5,14,15], but these work do not discuss the interaction among the parameters, as used here. Models description

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Section: Resultsmentioning

confidence: 73%

Section: Geometry Meshing and Boundary Conditionsmentioning

confidence: 99%

mentioning

confidence: 99%

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Numerical optimization of a waste-to-energy plant's operating parameters using CFD

Kapitler¹,

Samec²,

Kokalj³

2011

THERM SCI

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“…Sin embargo, este proceso se da a altas temperaturas, lo que favorece la emisión de sustancias con grave impacto en el ambiente y la salud pública, tales como NOx, SOx, HCl, CO, MP, PCDDs y PCDFs, donde se destacan las PCDDs y PCDFs por sus propiedades físico-químicas y por ser clasificados como agentes cancerígenos (Castaldi et al, 2017;García, Vaca, y Talero, 2013;Ibarluzea y Basterretzea, 2004;Kumar y Samadder, 2017a). Los incineradores a gran escala más usados para procesar los RSU, suelen ser calderas de parrilla móvil bajo regímenes de combustión directa, las cuales operan con aire primario (superior al estequiométrico), y aire secundario para garantizar la oxidación del material sólido carbonoso, por lo que alcanzan temperaturas en torno a los 1.500 K (Yu, Ma, y Liao, 2010). Yang, Sharifi, y Swithenbank (2007) plantean modificar el régimen de operación de los sistemas tradicionales basados en combustión a condiciones sub-estequiométricas, reduciendo el aire primario entre un 50% y 60%.…”

Section: Introductionunclassified

“…El gas será oxidado con el aire secundario buscando aumentar la eficiencia de combustión global, y reduciendo los impactos ambientales negativos, asociados a la formación de emisiones contaminantes, por lo que se considera un proceso más sostenible que la incineración (Arena, 2012;Castaldi et al, 2017;Luz et al, 2015). En las calderas de parilla móvil la transformación termoquímica del sólido se desarrolla de modo similar al lecho fijo, donde los principales sub-procesos son el secado, la devolatilización, la oxidación y la reducción (Yang et al, 2007;Yu et al, 2010).…”

Section: Introductionunclassified

Generación de Energía a partir de Residuos Sólidos Urbanos. Estrategias Termodinámicas para Optimizar el Desempeño de Centrales Térmicas

Montiel-Bohórquez

Pérez

2019

Inf. tecnol.

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ResumenSe determinan estrategias termodinámicas para la conversión energética de Residuos Sólidos Urbanos (RSU) en plantas de incineración bajo condiciones sub-estequiométricas. La valoración energética de RSU es una alternativa para mitigar los impactos ambientales que genera su disposición final, siendo la producción de RSU de la ciudad de Medellín (Colombia) de aproximadamente 1800 ton/día. El análisis se lleva a cabo mediante un modelo en equilibrio termoquímico del proceso de gasificación, donde se estudia el efecto del contenido de humedad y la relación equivalente combustible-aire en el proceso termoquímico. El potencial energético de los RSU de la ciudad es de 28 a 44 MW eléctricos. Las estrategias termodinámicas para aprovechar energéticamente los RSU en plantas de incineración bajo condiciones sub-estequiométricas, de modo autotérmico y evitando la fusión de cenizas, establecen que el proceso se debe llevar a cabo con una relación equivalente combustible-aire de gasificación entre 1.5 y 3.3, independiente del contenido de humedad de los RSU. Palabras clave: valoración energética; residuos sólidos urbanos; equilibrio termoquímico; gasificación AbstractIn this study, thermodynamic strategies are determined for the energy conversion of Municipal Solid Wastes (MSW) in incineration plants under sub-stoichiometric conditions. Energy generation from MSW is an alternative to mitigate the environmental impacts derived by their final disposal, being the production rate of MSW in Medellin city (Colombia) of about 1800 ton/day. The analysis is conducted by means of a thermochemical equilibrium model of the gasification process, where the effect of moisture content and fuelair equivalence ratio on the thermochemical process is studied. The energy potential of MSW from the city is between 28 and 44 MWe. The thermodynamic strategies for energy recovery from MSW in incineration plants at sub-stoichiometric conditions, under auto-thermal regimens and avoiding ash fusion, establish that the process must be carried out with a fuel-air equivalence ratio between 1.5 and 3.3, regardless of the moisture content of the MSW.

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Analysis of Residence Time Distributions of Different Solid Biomass Fuels by using Radio Frequency Identification (RFID)

Kruggel‐Emden

Wirtz

2014

Energy Tech

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The residence time distributions of different typical solid biomass fuels such as wood pellets, wood chips, and wood cubes are measured on a scaled model of a forward‐acting grate in continuous operation by using radio frequency identification (RFID). A variation of motion patterns, grate operational conditions, and bed material is performed. Based on the residence time distributions, diffusion coefficients are derived, which are a measure for mixing on the grate and are of importance as input parameters of fuel–bed models in CFD simulations of grate‐firing systems. RFID measurements have the advantage to be capable of tracking multiple particles without requiring visual contact. Residence time distributions are obtained without any artifacts introduced by the feeding equipment or manual charging. It is found that the diffusion coefficients obtained are in agreement with the results of other measurements performed in literature. The diffusion coefficients increase with enhanced stroke length and stroke velocity as well as with decreasing bed layer thickness and particle sizes. Particle shape has a strong influence on longitudinal mixing and the diffusion coefficients.

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Mathematical modeling of combustion in a grate-fired boiler burning straw and effect of operating conditions under air- and oxygen-enriched atmospheres

Cited by 64 publications

References 22 publications

Numerical optimization of a waste-to-energy plant's operating parameters using CFD

Numerical optimization of a waste-to-energy plant's operating parameters using CFD

Generación de Energía a partir de Residuos Sólidos Urbanos. Estrategias Termodinámicas para Optimizar el Desempeño de Centrales Térmicas

Analysis of Residence Time Distributions of Different Solid Biomass Fuels by using Radio Frequency Identification (RFID)

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