Lignite-char gasification mechanism in mixed atmospheres of steam and CO 2 at different pressures

Yan, Qixuan; Huang, Jiejie; Zhao, Jing‐Tai; Fang, Yitian; Wang, Jianfei

doi:10.1016/j.fuproc.2015.06.035

Cited by 21 publications

(8 citation statements)

References 29 publications

(60 reference statements)

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“…The same conclusion was also obtained by Sedghkerdar [21]. The gasification characteristics of coal with H2O and CO2 were also investigated at different pressures by Li [22]. The results showed that coal gasification mechanism in mixture of CO2 and H2O was connected with relative partial pressures of two reactant gases.…”

Section: Introductionsupporting

confidence: 69%

“…The carbon reacted with steam, instead of CO2 with the steam addition increasing. It was because that H2O and CO2 would be scrambling for some active sites on coal char and H2O was more competitive than CO2 [14,19,22]. Then from the thermodynamic, PWG and WGS reaction were promoted by adding steam, and a certain amount of CO2 was generated, so CO2 conversion decreased significantly even to be the negative when the S/C ratio was above 2.0.…”

Section: Effect Of Pressure On Coal Gasification Reactionmentioning

confidence: 99%

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Thermodynamic analysis of synergistic coal gasification using blast furnace slag as heat carrier

Duan

Xie

et al. 2016

International Journal of Hydrogen Energy

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In this paper, a thermodynamic analysis of the synergistic coal/CO2/H2O gasification process with BFS (blast furnace slag) as heat carrier was performed using the Gibbs free energy minimization approach through Lagrange multiplier method. The effect of temperature, pressure and C/CO2/H2O were investigated. Carbon, CO2 and H2O conversion, H2 and CO yield, and H2/CO ratio were used to characterize the synergistic gasification performance. The results showed that the atmospheric pressure was preferable for coal gasification and the increasing of temperature caused the increase in carbon conversion and syngas production. The optimal temperature of the synergistic gasification was 800-900 ºC. Not only did it ensure the coal gasification reaction completely, but also it recovered the BFS waste heat effectively. The results clearly showed that the addition of H2O and CO2 could lead to the reduction of the carbon residue and increase of the production of H2 and CO, respectively. Meanwhile, it was beneficial to reduce the waste heat using to heating extra steam and enhance the coal/CO2 gasification reaction rate by controlling the addition of CO2 and H2O reasonably. Moreover, the production syngas application was also investigated by changing the relative CO2/C ratio and H2O/C ratio in the feed to modify the H2/CO ratio.

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Section: Introductionsupporting

confidence: 69%

Section: Effect Of Pressure On Coal Gasification Reactionmentioning

confidence: 99%

Thermodynamic analysis of synergistic coal gasification using blast furnace slag as heat carrier

Duan

Xie

et al. 2016

International Journal of Hydrogen Energy

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“…The general approach to improve the kinetics of the char gasication is the high temperature and pressurized operations. 7 Many factors have been proved to affect kinetics of coal char gasication, including char ranks, particle sizes, temperatures, the partial pressures of the reactant gases and the total system pressure, as well as gasication agents (likely O 2 , H 2 O and/or CO 2 ). [8][9][10][11][12] The water is the mostly used gasication agent, which is more reactive than CO 2 .…”

Section: Introductionmentioning

confidence: 99%

Experimental and kinetic studies of coal–CO₂ gasification in isothermal and pressurized conditions

2017

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“…Both Huang et al [15] and Everson et al [16] thought that the char-CO 2 reaction and char-steam reaction proceeded at separate active sites and the overall gasification rate should be equal to the sum of the char-CO 2 reaction rate and the char-steam reaction rate. Li et al [17] also pointed out that the reaction mechanism of lignite char gasification was in accordance with the separate reactive site reaction mechanism under lower gasification pressures, whereas it was superior to the common reactive site reaction mechanism when gasification pressures further increased. On the other hand, Chen et al [18] found that the overall gasification rate is not equal to the sum of the char-CO 2 reaction rate and char-steam reaction rate, but there was no evidence proving that the two gasifying agents competed for active sites.…”

Section: Introductionmentioning

confidence: 98%

“…Recently, some researchers [14][15][16][17][18] came to investigate interactions in the char-CO 2 -steam reaction using the Langmuir-Hinshelwood (L-H) model based on the theory of absorption and desorption. Roberts and Harris [14] found that char-CO 2 and char-steam reactions occur at the common active sites and indicated that steam and CO 2 competed for active sites of chars.…”

Section: Introductionmentioning

confidence: 99%

Gasification under CO2–Steam Mixture: Kinetic Model Study Based on Shared Active Sites

et al. 2017

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Abstract:In this work, char gasification of two coals (i.e., Shenfu bituminous coal and Zunyi anthracite) and a petroleum coke under a steam and CO 2 mixture (steam/CO 2 partial pressures, 0.025-0.075 MPa; total pressures, 0.100 MPa) and CO 2 /steam chemisorption of char samples were conducted in a Thermogravimetric Analyzer (TGA). Two conventional kinetic models exhibited difficulties in exactly fitting the experimental data of char-steam-CO 2 gasification. Hence, a modified model based on Langmuir-Hinshelwood model and assuming that char-CO 2 and char-steam reactions partially shared active sites was proposed and had indicated high accuracy for estimating the interactions in char-steam-CO 2 reaction. Moreover, it was found that two new model parameters (respectively characterized as the amount ratio of shared active sites to total active sites in char-CO 2 and char-steam reactions) in the modified model hardly varied with gasification conditions, and the results of chemisorption indicate that these two new model parameters mainly depended on the carbon active sites in char samples.

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Lignite-char gasification mechanism in mixed atmospheres of steam and CO 2 at different pressures

Cited by 21 publications

References 29 publications

Thermodynamic analysis of synergistic coal gasification using blast furnace slag as heat carrier

Thermodynamic analysis of synergistic coal gasification using blast furnace slag as heat carrier

Experimental and kinetic studies of coal–CO₂ gasification in isothermal and pressurized conditions

Gasification under CO2–Steam Mixture: Kinetic Model Study Based on Shared Active Sites

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Lignite-char gasification mechanism in mixed atmospheres of steam and CO 2 at different pressures

Cited by 21 publications

References 29 publications

Thermodynamic analysis of synergistic coal gasification using blast furnace slag as heat carrier

Thermodynamic analysis of synergistic coal gasification using blast furnace slag as heat carrier

Experimental and kinetic studies of coal–CO2 gasification in isothermal and pressurized conditions

Gasification under CO2–Steam Mixture: Kinetic Model Study Based on Shared Active Sites

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Experimental and kinetic studies of coal–CO₂ gasification in isothermal and pressurized conditions