Devolatilization of a single fuel particle in a fluidized bed under oxy-combustion conditions. Part B: Modeling and comparison with measurements

Bu, Changsheng; Leckner, Bo G; Chen, Xiaoping; Gómez–Barea, Alberto; Liu, Daoyin; Pallarès, David

doi:10.1016/j.combustflame.2014.08.011

Cited by 43 publications

(19 citation statements)

References 31 publications

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“…14. Similar trends are observed for the four kinds of fuel: the flame temperatures are higher in O 2 / N 2 than in O 2 /CO 2 due to the higher specific heat of CO 2 [13], especially at low O 2 concentration. The temperature difference between the two atmospheres decreases with increasing O 2 concentration.…”

Section: Flame Temperaturesupporting

confidence: 82%

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Devolatilization of a single fuel particle in a fluidized bed under oxy-combustion conditions. Part A: Experimental results

Leckner

Chen

et al. 2015

Combustion and Flame

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Section: Flame Temperaturesupporting

confidence: 82%

“…Besides, two-color pyrometry was adopted to estimate the temperature of the homogeneous flame. In an accompanying article [13] a theoretical interpretation of the results is carried out.…”

Section: Introductionmentioning

confidence: 96%

Devolatilization of a single fuel particle in a fluidized bed under oxy-combustion conditions. Part A: Experimental results

Leckner

Chen

et al. 2015

Combustion and Flame

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“…The voxi and vgas were obtained by testing the char reaction rate in O2/N2, N2/CO2 and N2/H2O atmospheres at the same partial pressure of reactant. Besides, the C-O2 oxidation is also affected by oxygen diffusion in the boundary layer [25] , so the reaction rate of oxidation in O2/CO2 and O2/H2O atmospheres can be calculated by v oxi,O2 19) where voxi,O2/N2, voxi,O2/CO2, voxi,O2/H2O represent the reaction rate of oxidation in O2/N2, O2/CO2 and O2/H2O atmospheres, respectively; DO2/N2, DO2/CO2 and DO2/H2O represent the diffusivity of oxygen in O2/N2, O2/CO2 and O2/H2O atmospheres, respectively. The reaction rate of gasification in O2/CO2 and O2/H2O atmospheres can be given by v gas,O2…”

Section: Calculation Of Carbon Consumption Ratementioning

confidence: 99%

“…Scala and Chirone [16,17] studied the combustion characteristics of a single char particle in a FB reactor and found the Char-CO2 gasification was the main reaction in O2/CO2 combustion. Additionally, a series of studies on combustion characteristics of single coal particle also have been performed in a FB under O2/CO2 atmosphere [18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Combustion characteristics of lignite char in a fluidized bed under O2/N2, O2/CO2 and O2/H2O atmospheres

Duan

Tong

et al. 2019

Fuel Processing Technology

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Oxy-fuel combustion, O2/H2O combustion has many advantages over O2/CO2 combustion, and has gradually gained more and more attention recently for carbon capture from coal-fired power plant. The unique physicochemical properties (thermal capacity, diffusivity, reactivity) of H2O will definitely influence the coal combustion process. In this work, the combustion characteristics of lignite char were investigated in a fluidized bed combustor under O2/N2, O2/CO2 and O2/H2O atmospheres with different oxygen concentration (15 %-27 %) and bed temperature (837-937 o C). Results indicated that the average reaction rate (raverage) and the peak reaction rate (rpeak) of lignite char in O2/H2O atmosphere was lower than that in O2/CO2 atmospheres at low oxygen concentrations. However, as the oxygen concentration increased, the rpeak and raverage in O2/H2O atmosphere was significantly improved and exceeded that in O2/CO2 atmosphere. The calculation of the activation energy based on the shrinking core model showed that the order of activation energy under different atmospheres is: O2/CO2 (28.96 kJ/mol) > O2/H2O (26.11 kJ/mol) > O2/N2 (23.31 kJ/mol). Furthermore, with the increase of the bed temperature, the active sites occupied by gasification agent were significantly increased, the active sites occupied by oxygen decreased correspondingly.

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“…It is also important to note that the chars are more sensitive to intraparticle processes such as thermoplasticity, crosslinking, swelling, and fragmentation, among others, hindering their prediction (Khan & Jenkins, 1985;Speight, 2013). Studies have focused mainly on devolatilization during the oxy-fuel coal combustion in conventional boilers (small particle sizes) (Gil et al, 2012;Pielsticker et al, 2016; Su et al, 2015), but little research has addressed the implications by the change of reaction atmosphere when the particle size increases, either in fluidized bed reactors (with heating rates from 100K/s to 10 000K/s) or in some fixed bed applications (with heating rate of 100K/min) where the behavior of the oxy-combustion changes completely (Bu et al, 2015(Bu et al, , 2016. In practical applications, devolatilization of coal is strongly influenced by the operational parameters that are dependent on the equipment and coal properties (Yu, Lucas, & Wall, 2007), making the interpretation of results for oxy-fuel coal combustion complicated.…”

Section: Introductionmentioning

confidence: 99%

Effects of pyrolysis atmosphere on the porous structure and reactivity of chars from middle and high rank coals

Valdés¹,

Guerrero²,

López³

et al. 2018

Ing. Inv.

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The influence of a CO 2 or N 2 -based atmosphere on the porous structure and microstructure of the chars obtained from the nonisothermal slow devolatilization (10 °C/min), from room temperature to 900 °C, of two coals of different rank (Semi-Anthracite (SA) and High Volatile Bituminous type C (HVBC)) and different particle size distribution was studied. Physicochemical characterization (ultimate and proximate analysis), structural and morphological characterization by Raman spectroscopy, FE-SEM, BET surface area, and volume and diameter microporous by CO 2 adsorption measurements were carried out for all the chars. It was found that the kinetic parameters, the physicochemical properties, and reactivity of the chars are different, depending on the pyrolysis atmosphere. It was also determined that for the char from SA coal with particle size greater than 0.7 mm, the BET surface area increases when the atmosphere is enriched with CO 2 . This effect appears to be promoted by the interaction of different processes such as intraparticle side reactions (softening, nucleation and coalescence of bubbles, crosslinking, among others), differences in the thermal diffusivity of N 2 and CO 2 , and the reactive effects of the latter. Additionally, tests of oxidative reactivity of chars showed that the char formed in a CO 2 atmosphere is more reactive than that formed in N 2 . With the results of Raman analysis and kinetic parameters quantified, it was concluded that the reaction atmosphere determined the degree of ordering achieved by the char structure and that the thermodiffusive properties of the reaction atmosphere promoted structural differences in the char even at low heating rates.Keywords: Slow pyrolysis, Pore size distribution, large coal particles, Oxy-combustion, reactivity. RESUMENSe estudió la influencia de una atmósfera basada en CO 2 o N 2 sobre la estructura porosa y la microestructura de carbonizados de carbón obtenidos de la pirólisis lenta no isotérmica desde temperatura ambiente hasta 900 °C de dos carbones de diferente rango (Semi-Antracita (SA) y Bituminosos Alto en Volátiles tipo C (BAVC)), y de diferentes distribuciones de tamaño de partícula. Para todos los carbonizados se realizó la caracterización fisicoquímica (Análisis ultimo y próximo), la caracterización morfológica y estructural por combinación de técnicas como espectroscopia Rama, Microscopia electrónica de barrido por emisión de campo (FE-SEM), área superficial (BET -Brunauer-Emmett-Teller) y volumen y diámetro de microporos por mediciones de adsorción en CO 2 (Horvath-Kawazoe (HK) method). Se encontró que los parámetros cinéticos, las propiedades fisicoquímicas y la reactividad de los carbonizados de carbón son diferentes dependiendo de la atmósfera de pirólisis. También se determinó que para el carbonizado de carbón de SA, con un tamaño de partícula mayor de 0,7 mm, la superficie BET aumenta cuando la atmósfera se enriquece en CO 2 . Este efecto parece ser promovido por la interacción de diferentes procesos como las reacciones secund...

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Devolatilization of a single fuel particle in a fluidized bed under oxy-combustion conditions. Part B: Modeling and comparison with measurements

Cited by 43 publications

References 31 publications

Devolatilization of a single fuel particle in a fluidized bed under oxy-combustion conditions. Part A: Experimental results

Devolatilization of a single fuel particle in a fluidized bed under oxy-combustion conditions. Part A: Experimental results

Combustion characteristics of lignite char in a fluidized bed under O2/N2, O2/CO2 and O2/H2O atmospheres

Effects of pyrolysis atmosphere on the porous structure and reactivity of chars from middle and high rank coals

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