Experimental studies on gasification of the Shenmu coal char with CO2 at elevated pressures

Wang, Mingmin; Zhang, Jiansheng; Zhang, Shouyu; Wu, Jinhu; Yue, Guangxin

doi:10.1007/s11814-008-0216-x

Cited by 7 publications

(6 citation statements)

References 10 publications

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“…The control experiments were performed under the same conditions except for the total gas flow rate, to eliminate the external diffusive limitation effects on the activation kinetics. In this paper, no detectable differences were observed when the total gas flow rate was varied from 200 mL/min to 300 mL/min, which indicated that the gasification process was predominantly controlled by kinetic limitation 15,16 …”

Section: Methodsmentioning

confidence: 66%

“…In this paper, no detectable differences were observed when the total gas flow rate was varied from 200 mL/min to 300 mL/min, which indicated that the gasification process was predominantly controlled by kinetic limitation. 15,16 The sample mass submitted to each test was approximately 15 mg, evenly overspread on the bottom of the ceramic crucible. At the beginning of each gasification experiment, the TGA apparatus was heated at a rate of 5 K/min from indoor to target temperature in inert gas.…”

Section: Gasification Kineticsmentioning

confidence: 99%

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Kinetic study of CO ₂ gasification on coal char and extraction residue char from direct coal liquefaction

Liu

Fang

et al. 2020

Int J Energy Res

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Summary Extraction residue (ER) is, in this study, considered as an insoluble portion derived from a novel extraction process with direct coal liquefaction residue, which is the byproduct from 1000 kton/y direct coal liquefaction and oil production process in Ordos, China. ER mostly consists of unreacted coal and minerals, spent catalyst, and solvent. It is considered as a hazardous waste in China. Gasification is a promising way to employ ER, as the carbon resource contained in it could be adequately utilized, so strongly reducing the environmental impact of this material. In this paper, a kinetic study is carried out concerning CO2 gasification (in thermobalance) of ER char, coal char, and their blends. The results show that, at temperatures ranging from 1123 to 1323 K, the reactivity of ER char is much larger than that of coal char, and the reactivity of ER/coal char blends increases when the ER fraction increases, consistently resulting in between the reactivities shown by ER char and coal char alone. The partial pressure of CO2 promotes the reactivity of all samples. BET surface area resulted three times larger for ER char vs coal char, while pore surface area and pore volume were four times larger. Moreover, the relevant parameters of the random pore model for CO2 gasification of ER char, coal char, and their blend #2 (with 20% ER) were obtained; the activation energy resulted 210.6, 240.5, and 232.8 kJ/mol, and the reaction order 0.30, 0.45, and 0.40, respectively.

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Section: Methodsmentioning

confidence: 66%

Section: Gasification Kineticsmentioning

confidence: 99%

Kinetic study of CO ₂ gasification on coal char and extraction residue char from direct coal liquefaction

Liu

Fang

et al. 2020

Int J Energy Res

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“…Synthetic gas (H 2 + CO) via gasification is the most important intermediate product in the highly efficient technologies [2,3]. Steam and carbon dioxide (CO 2 ) are two regular gasification agents and can usually control the overall conversation process [4]. Although it has been widely used as a gasification agent, CO 2 gasification is important as it is the slowest among gasification reactions and considered as the rate determining step, as well as the key to making a balance between air or oxygen and steam to generate optimum heat for driving endothermic gasification reactions [5,6].…”

Section: Introductionmentioning

confidence: 99%

Influences of Ash-Existing Environments and Coal Structures on CO2 Gasification Characteristics of Tri-High Coal

et al. 2020

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Two kinds of tri-high coals were selected to determine the influences of ash-existing environments and coal structures on CO2 gasification characteristics. The TGA results showed that the gasification of ash-free coal (AFC) chars was more efficient than that of corresponding raw coal (RC) chars. To uncover the reasons, the structures of RCs and AFCs, and their char samples prepared at elevated temperatures were investigated with SEM, BET, XRD, Raman and FTIR. The BET, SEM and XRD results showed that the Ash/mineral matter is associated with coal, carbon forms the main structural framework and mineral matters are found embedded in the coal structure in the low-rank tri-high coal. The Raman and FTIR results show that the ash can hinder volatile matters from exposing to the coal particles. Those results indicate that the surface of AFC chars has more free active carbon sites than raw coal chars, which are favorable for mass transfer between C and CO2, thereby improving reactivity of the AFC chars. However, the gasification reactivity was dominated by pore structure at elevated gasification temperatures, even though the microcrystalline structure, functional group structure, and increase in the disorder carbon were improved by acid pickling.

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“…Char gasification with CO 2 as a gasifying agent is possible thanks to the Boudouard reaction (eq ), in which CO, one of the main components of syngas, is obtained. , This stage is the slowest; therefore, the whole process depends upon the rate of char gasification. For this reason, in numerous scientific studies, previously obtained char was subjected to the gasification process, − which became the basis for defining the impact of the temperature, pressure, or heating rate on the char gasification stage. In each case, the influence of these parameters on the process was observed, thereby reflecting a high dependence of the gasification stage upon predefined conditions.…”

Section: Introductionmentioning

confidence: 99%

Effect of Char Preparation Conditions on Gasification in a Carbon Dioxide Atmosphere

et al. 2017

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Pyrolysis conditions have a substantial impact on the properties of the resulting char and, consequently, on the kinetics of the gasification process. The aim of this study was to determine the impact of coal pyrolysis on the gasification stage. By applying the thermogravimetric method, kinetic analyses of CO 2 gasification of chars derived from Polish "Janina" coal were conducted. Gasification examinations were performed for chars prepared earlier in an argon atmosphere at various heating rates, which, after cooling, were subjected to CO 2 gasification (indirect char gasification). Examinations were also carried out in the case of chars formed during heating of coal samples in a CO 2 atmosphere (direct char gasification). Samples of chars were gasified in non-isothermal conditions of up to 1100 °C under 0.1 MPa pressure at various heating rates. The char gasification reaction order with CO 2 was determined with the use of the Coats−Redfern method, and it can be assumed that it is a first-order reaction. The activation energy and pre-exponential factor were calculated using two first-order models: Coats−Redfern method and Senum−Yang method. The results were subsequently compared to kinetic parameters calculated on the basis of the modelfree isoconversional method combined with the model-dependent Coats−Redfern method. Despite the differences in values of kinetic parameters obtained from the use of a given model, all results confirmed that the method of char preparation has an influence on the gasification stage and direct char gasification is more favorable. Activation energy obtained from the use of models based on the first-order reaction ranged between 275 and 296 kJ/mol for direct gasification of chars, while the chars gasified indirectly between 307 and 342 kJ/mol, depending upon the heating rate that was used. The model-free isoconversional method confirmed these results. The values for chars gasified directly amounted to E a = 257−277 kJ/mol, and the values for indirect char gasification obtained by the pyrolysis process at heating rates of 3, 10, and 20 K/min amounted to E a = 280−291, 287−309, and 289−305 kJ/mol, respectively.

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Experimental studies on gasification of the Shenmu coal char with CO2 at elevated pressures

Cited by 7 publications

References 10 publications

Kinetic study of CO ₂ gasification on coal char and extraction residue char from direct coal liquefaction

Kinetic study of CO ₂ gasification on coal char and extraction residue char from direct coal liquefaction

Influences of Ash-Existing Environments and Coal Structures on CO2 Gasification Characteristics of Tri-High Coal

Effect of Char Preparation Conditions on Gasification in a Carbon Dioxide Atmosphere

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Experimental studies on gasification of the Shenmu coal char with CO2 at elevated pressures

Cited by 7 publications

References 10 publications

Kinetic study of CO 2 gasification on coal char and extraction residue char from direct coal liquefaction

Kinetic study of CO 2 gasification on coal char and extraction residue char from direct coal liquefaction

Influences of Ash-Existing Environments and Coal Structures on CO2 Gasification Characteristics of Tri-High Coal

Effect of Char Preparation Conditions on Gasification in a Carbon Dioxide Atmosphere

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Kinetic study of CO ₂ gasification on coal char and extraction residue char from direct coal liquefaction

Kinetic study of CO ₂ gasification on coal char and extraction residue char from direct coal liquefaction