Variation Behavior of Pore Structure of Coal Chars during Gasification Process-Effect of Coal Grade, Pyrolysis Condition, and Reactant Gases-.

Morimoto, Tatsuya; Arakita, Kazumasa; Kametani, Tomohiko; Oda, Hirokazu

doi:10.1252/kakoronbunshu.30.47

Cited by 5 publications

(5 citation statements)

References 11 publications

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“…It is observed that the SSA of XLTL, YFB, and JZA increases at the preceding stage of chars O 2 /CO 2 reaction. This investigation is consistent to the reported results of the literature for some coals, which is caused by many micropore enlargement as well as new pores occurrence of coal chars during combustion at O 2 /CO 2 , and then decreases for X > 0.5, which is prevailingly brought about by the collapse of pore during chars combustion. For investigating the structure changes of coal chars during reaction at O 2 /CO 2 , MDRPM of this work and DRPM presented by Bhatia et al can be considered as being appropriate for simulating SSA of three chars O 2 /CO 2 reaction process.…”

Section: Resultssupporting

confidence: 92%

Section: Resultssupporting

confidence: 92%

“…Thus, the reaction rate in air is proportional to the superficial area for char pores sizes >10 Å. In addition, it was observed that the pore structural variation of char particles during reaction was related with closed pores and submicropores, , which should be taken into account when using the DRPM and the RPM. It also indicates that the superficial area of pores varies as the rate of chars reaction, which should be mainly affected by some aspects (coal type, reaction atmosphere, reaction temperature, and so on).…”

Section: Mathematic Modelingmentioning

confidence: 99%

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Modified Discrete Random Pore Model Considering Pore Structure Evolution to Depict Coal Chars Combustion in O₂/CO₂

Fei

et al. 2017

Energy Fuels

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The O 2 /CO 2 combustion of coal chars currently considered as one of the promising technologies has a remarkable effect on reducing greenhouse gas emissions, and it is of importance to investigate the mathematical model of pore evolution at char reaction process, while discrete random pore model (DRPM) can be usually considered as the mathematic modeling of pore evolution for effective prediction of char combustion at O 2 /CO 2 . In this work, pore structure variation of three chars during reaction at O 2 /CO 2 were presented by the N 2 isothermal adsorption/desorption method. The universally used assumption of proportional relation of superficial area and combustion rate was improved for application to coal chars, indicating true superficial area associated with the reaction rate should be corresponding to the pore superficial area 2πl(r 0 + θΔr/2). Therefore, a new pore structure model (MDRPM) was created to simulate carbon conversion of three coals combustion process in O 2 /CO 2 when chemical reaction is considered. Compared with the Liu model, the Struis model, as well as the Bhatia model (DRPM), carbon conversion calculated by the MDRPM was more consistent to experimental values for three char reaction process. According to these models, the combustion characteristic of coal chars in O 2 /CO 2 was investigated.

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Section: Resultssupporting

confidence: 92%

Section: Resultssupporting

confidence: 92%

Section: Mathematic Modelingmentioning

confidence: 99%

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Modified Discrete Random Pore Model Considering Pore Structure Evolution to Depict Coal Chars Combustion in O₂/CO₂

Fei

et al. 2017

Energy Fuels

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“…Therefore, it is important to clarify the factors that affect the gas−solid reaction of the char to analyze the gasification process. Coal and its char have an abundance of submicropores, of which the surface areas have been thought to be predominant in the char reactivity. − The pore structures of a solid such as char, which varies sequentially over the course of the gas−solid reaction, should be expressed quantitatively. Several gas−solid reaction models taking into account pore structures 1,2 have already been proposed.…”

Section: Introductionmentioning

confidence: 99%

Modeling on Pore Variation of Coal Chars during CO₂Gasification Associated with Their Submicropores and Closed Pores

et al. 2005

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When predicting the variation of pore structure during CO2 gasification of coal chars using the random pore model (RPM), it is impossible to calculate exactly the ψ parameter from the pore characteristics, which were obtained by means of N2 adsorption, such as BET surface area (denoted as N2 pore characteristics), of the char prior to gasification. The values of ψ, which were calculated from the pore characteristics of chars at various carbon conversions, should be fundamentally constant, unaffected by the conversion of the char. However, this investigation exhibited a drastic decrease of ψ at the initial stage of the gasification reaction. This phenomenon is the result of a significant increase of N2 pore characteristics, of which the starting chars are extremely small. This increase might be explained by the widening of submicropores which are undetectable through the N2 adsorption method or by the reopening of closed pores inaccessible even to helium molecules, followed by the formation of new micropores exceeding the detection limit of N2. Consequently, this study introduced the volume of submicropores and closed pores into the ψ equation as correction terms. The value of ψ at the reaction starting point was close to that at the intermediate stage of reaction, indicating that the accuracy for ψ estimation was elevated and that the submicropores and closed pores should be taken into account when using RPM.

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“…The RPM lacks of ability to predict the variation of pore characteristics studied by some researchers [15][16][17][18][19] during reaction because only stable structure parameter ψ is used. On the basis of equation (9), ψ values change with the conversion.…”

Section: B Characteristics Of Parameter ψ and Mrpm Constructedmentioning

confidence: 99%

Modified Random Pore Model Study on Coal Char Reactions under O2/CO2 Atmosphere

Fei

Xiang

et al. 2010

2010 Asia-Pacific Power and Energy Engineering Conference

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Evolution characteristics of particle pore structure not only reflect reactive process, but also intensify the complicated degree of the reaction. Variation of pore structure in coal char particles is too complex to be described only by the invariable structure parameter ψ when the random pore model (RPM) is used to describe reaction process. In this paper, the structural parameter ψ in random pore model was modified by the pore properties and evolution characteristics of structural parameter were clarified and a new model, modified random pore model (MRPM), was developed. Compared with the simulation results of RPM, it was found that modified random pore model was more satisfied to explain the reaction processes of char, especially at the end of stage. The value of ψ changes with specific characteristic which could be explained by the pore structure feature. Using the MRPM, isotherm reactive characteristics of coal chars were analyzed at different temperatures under O 2 /CO 2 atmosphere.

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Variation Behavior of Pore Structure of Coal Chars during Gasification Process-Effect of Coal Grade, Pyrolysis Condition, and Reactant Gases-.

Cited by 5 publications

References 11 publications

Modified Discrete Random Pore Model Considering Pore Structure Evolution to Depict Coal Chars Combustion in O₂/CO₂

Modified Discrete Random Pore Model Considering Pore Structure Evolution to Depict Coal Chars Combustion in O₂/CO₂

Modeling on Pore Variation of Coal Chars during CO₂Gasification Associated with Their Submicropores and Closed Pores

Modified Random Pore Model Study on Coal Char Reactions under O2/CO2 Atmosphere

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Variation Behavior of Pore Structure of Coal Chars during Gasification Process-Effect of Coal Grade, Pyrolysis Condition, and Reactant Gases-.

Cited by 5 publications

References 11 publications

Modified Discrete Random Pore Model Considering Pore Structure Evolution to Depict Coal Chars Combustion in O2/CO2

Modified Discrete Random Pore Model Considering Pore Structure Evolution to Depict Coal Chars Combustion in O2/CO2

Modeling on Pore Variation of Coal Chars during CO2Gasification Associated with Their Submicropores and Closed Pores

Modified Random Pore Model Study on Coal Char Reactions under O2/CO2 Atmosphere

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Modified Discrete Random Pore Model Considering Pore Structure Evolution to Depict Coal Chars Combustion in O₂/CO₂

Modified Discrete Random Pore Model Considering Pore Structure Evolution to Depict Coal Chars Combustion in O₂/CO₂

Modeling on Pore Variation of Coal Chars during CO₂Gasification Associated with Their Submicropores and Closed Pores