Effect of particle size on the MILD combustion characteristics of pulverised brown coal

Saha, M.; Dally, Bassam B.; Medwell, Paul R.; Chinnici, Alfonso

doi:10.1016/j.fuproc.2016.04.003

Cited by 87 publications

(43 citation statements)

References 44 publications

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“…It must be mentioned that the excess O 2 primarily provides a better combustion environment, benefitting the reaction kinetics and reducing the penalty from unburnt solid fuel. Some studies have shown that the burnout of coal was reduced under MILD combustion condition . The carbon burnout is significantly affected by the particle residence time, particle size, and reaction rate .…”

Section: Resultsmentioning

confidence: 99%

Application of chemical looping air separation for MILD oxy‐combustion in the supercritical power plant with CO₂ capture

Chen

Sun

et al. 2018

Energy Science & Engineering

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Chemical looping air separation (CLAS) is a novel and promising technology for oxygen production. This paper presents the application of CLAS to the supercritical power plant for MILD oxy‐combustion. Compared with the reference conventional supercritical power plant, the power generation efficiency of the CLAS integrated MILD oxy‐combustion plant is only reduced by about ~1.37% points at the baseline case. CO2 compression process imposes additional ~3.97% points efficiency penalty, which is inevitable to all of the CO2 capture technologies. The net power efficiency of the CLAS integrated MILD oxy‐combustion plant is ~37.37%. Even though a higher reduction reactor temperature could boost the power efficiency and a higher oxidization reactor temperature reversely decreases the power efficiency, the influence of reactor temperature is marginal. The performance of CLAS integrated MILD oxy‐combustion plant is not sensitive to excess CO2 and O2 ratio. Different oxygen carriers have different suitable operating region, but possess similar power efficiency. The carbon capture rate of the CLAS integrated MILD oxy‐combustion plant is up to ~100%, resulting in a virtually carbon‐free fossil power plant.

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Section: Resultsmentioning

confidence: 99%

Application of chemical looping air separation for MILD oxy‐combustion in the supercritical power plant with CO₂ capture

Chen

Sun

et al. 2018

Energy Science & Engineering

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“…8,9,13 This is due to the fact that hydrocarbons are mainly released during the devolatilization process. Similar results can be found in previous studies.…”

Section: Detailed Analysis Of No X Emissionsmentioning

confidence: 99%

“…[2][3][4][5][6][7][8][9][10][11][12][13] The essence of this technology for coal combustion is to achieve strong recirculation of the injected streams so that the coal particles are heated and combusted in a highly substoichiometric condition. [2][3][4][5][6][7][8][9][10][11][12][13] The essence of this technology for coal combustion is to achieve strong recirculation of the injected streams so that the coal particles are heated and combusted in a highly substoichiometric condition.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of further NO _x emission reduction for coal MILD combustion by combining fuel‐rich/lean technology

Zeng

et al. 2019

Int J Energy Res

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Summary This paper numerically examines the feasibility of further reducing NOx emission from a semi‐industrial scale coal MILD (moderate and intense low‐oxygen dilution) combustion furnace by adopting fuel‐rich/lean technology. The implementation is achieved by separating the original fuel jet into two parallel jets which will be used as rich and lean streams. An effort has been made to develop a 13‐step reaction mechanism and NOx evolution UDFs (user defined functions) for better understanding the interactions between MILD combustion and fuel‐rich/lean technology. The experiment of the reference case (Combustion and Flame 156.9 (2009): 1771‐1784) is well reproduced by the present numerical simulation, indicating high reliability of developed models. The validity of the further reduction of NOx emission is assessed by the comparison among inner‐fuel‐rich (IFR), outer‐fuel‐rich (OFR), and reference cases resulting from the adjustment of the fuel supply through the two fuel‐rich/lean jets. The results show that both IFR and OFR configurations succeed in achieving further reduction of NOx emission as compared with the reference case, which stems from both thermal and fuel paths. Specifically, the decrease of thermal‐NO emission originates from the contraction of high‐temperature regions (>1800 K), where nearly 94% reduction occurs within the temperature range of 1800 K and 1950 K while only 6% within 1950 K and 2030 K despite their high temperature sensitivity. The reduction of the fuel‐NO emission is mainly attributed to the promoted NO reduction on char surface and neutralization with HCN and NH3. Generally, the NOx emission can be minimized by enlarging the equivalence ratio difference between rich and lean jets, and the OFR configuration exhibits a higher potential than the IFR counterparts. However, since a relatively high temperature (1623 K) secondary air was used in the experiment, the maximum NOx reduction potential was limited to only 2.5%.

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“…Sin embargo, a pesar de ofrecer la gran ventaja de disminuir las emisiones de NOx y CO 2 , se ha demostrado en recientes estudios que la técnica tiene como desventaja la generación de cantidades considerables de inquemados sólidos al emplearse para la combustión de carbón disminuyendo la eficiencia del proceso, en la tesis doctoral de (Torres Alvarado, 2014), se concluye que cuando hay baja concentración de oxígeno durante la combustión de un material carbonoso, la reactividad disminuye conforme incrementa la conversión y lo asocian a la disminución de especies reactivas de tipo sp 3 de estructura amorfa que conlleva al aumento del grado de ordenamiento del material haciendo que este sea menos reactivo. Otros trabajos evalúan el efecto del tamaño de partícula para un carbón de bajo rango, se ve una dependencia del tamaño con el porcentaje de consumo del mismo, donde a mayores tamaños de partícula, el consumo total de carbono es menor, esto es debido a que el tamaño de partícula se asocia con el tiempo de residencia ya que partículas más grandes son más pesadas que las de menor tamaño requiriendo entonces mayor tiempo de residencia para lograr su consumo (Medwell & Chinnici, 2017).…”

Section: Introductionunclassified

Efecto del contenido de oxígeno y metano en la cinética de oxidación de un carbonizado de carbón

Laverde

Alvarado

Machado

2017

Rev. Acad. Colomb. Cienc. Ex. Fis. Nat.

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ResumenSe evaluó el efecto de la adición de metano en un carbonizado de carbón sometido a reacción con concentraciones de oxígeno bajas. Desde un punto de vista cinético, dicho efecto es determinando por la energía de activación (Ea) y por el factor preexponencial para diferentes concentraciones de oxígeno y mezclas de oxígeno y metano. Se preparó un carbonizado con un tamaño de partícula de 75 a 150 µm a partir de un carbón bituminoso altamente volátil, y se determinaron los parámetros cinéticos de la oxidación empleando el método termogravimétrico de velocidad máxima. Las variables evaluadas en la cinética de oxidación fueron la concentración de oxígeno (5, 8 y 21 %), y el efecto de la adición de metano en el medio de reacción (5, 10 y 14 % de metano mezclado con 5 % de oxígeno). Los resultados mostraron que la Ea disminuía al aumentar la concentración de oxígeno, en tanto que al agregar metano se observó un efecto promotor cuando este correspondía al 5 % de la mezcla total; sin embargo, cuando el porcentaje de metano aumentaba, la Ea también lo hacía debido a la rápida reacción del oxígeno con el metano en fase homogénea comparada con la reacción heterogénea del oxígeno con el carbonizado. La Ea obtenida con 5 % de oxígeno fue de 122,9 kJ/mol y con 21 %, de 90,69 kJ/mol; en presencia de metano al 5 % y 5 % de oxígeno, la Ea fue de 110,7 kJ/mol, y aumentó hasta 170,8 kJ/mol cuando el metano representaba el 14 % de la mezcla. © 2017. Acad. Colomb. Cienc. Ex. Fis. Nat. Palabras clave: Parámetros cinéticos; Carbonizado de carbón pulverizado; Contenido de metano; Contenido de oxígeno. Effect of oxygen and methane on the oxidation kinetics of coal char AbstractIn this work we evaluated the effect of adding methane during the oxidation process of a coal char with low oxygen concentration. We analyzed the effect from a kinetic point of view and we determined the activation energy (Ea) and the pre-exponential factor (A) with different oxygen concentrations and oxygen and methane mixtures. We used a coal char from a highly volatile bituminous coal with particle size of 75 to 150 µm; the kinetic parameters were determined by thermogravimetric method (TGA) with the high-velocity model; oxygen concentration variations were studied with 5, 8 and 21% of oxygen, as well as the effect of adding methane (5,10 and 14%) when oxidation occurred with 5% of oxygen. The results showed that the Ea decreased when oxygen concentration increased, and that adding 5% of methane to the total mixture enhanced the effect. Instead, when we increased the methane percentage, the Ea increased due to the rapid reaction of oxygen and methane in the homogeneous phase as compared with the heterogenous reaction of oxygen and coal char. With 5% oxygen the Ea value was 122.9 kJ/mol and with 21%, it was 90.69 kJ/mol; when methane was added at 5%, the Ea value was 110.7 kJ/mol, and it increased to 170.8 kJ/mol when there was 14% of methane in the mixture.

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Effect of particle size on the MILD combustion characteristics of pulverised brown coal

Cited by 87 publications

References 44 publications

Application of chemical looping air separation for MILD oxy‐combustion in the supercritical power plant with CO₂ capture

Application of chemical looping air separation for MILD oxy‐combustion in the supercritical power plant with CO₂ capture

Numerical study of further NO _x emission reduction for coal MILD combustion by combining fuel‐rich/lean technology

Efecto del contenido de oxígeno y metano en la cinética de oxidación de un carbonizado de carbón

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Effect of particle size on the MILD combustion characteristics of pulverised brown coal

Cited by 87 publications

References 44 publications

Application of chemical looping air separation for MILD oxy‐combustion in the supercritical power plant with CO2 capture

Application of chemical looping air separation for MILD oxy‐combustion in the supercritical power plant with CO2 capture

Numerical study of further NO x emission reduction for coal MILD combustion by combining fuel‐rich/lean technology

Efecto del contenido de oxígeno y metano en la cinética de oxidación de un carbonizado de carbón

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Application of chemical looping air separation for MILD oxy‐combustion in the supercritical power plant with CO₂ capture

Application of chemical looping air separation for MILD oxy‐combustion in the supercritical power plant with CO₂ capture

Numerical study of further NO _x emission reduction for coal MILD combustion by combining fuel‐rich/lean technology