A deep insight into carbon conversion during Zhundong coal molten salt gasification

Xu, Mian; Hu, Hongyun; Yang, Yuhan; Huang, Yongda; Xie, Kang; Liu, Huan; Li, Xian; Yao, Hong

doi:10.1016/j.fuel.2017.12.051

Cited by 33 publications

(5 citation statements)

References 37 publications

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“…Since CO was practically the only product during gasification, the carbon to CO conversion, X C , the instant CO production rate, R CO (min −1 ), and the cumulative CO yield, Y CO (mol), were determined by using the following expressions [43,44]:…”

Section: Gasification Experimentsmentioning

confidence: 99%

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CO2 Gasification Reactivity and Syngas Production of Greek Lignite Coal and Ex-Situ Produced Chars under Non-Isothermal and Isothermal Conditions: Structure-Performance Relationships

et al. 2022

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The presented work explores the structural properties, gasification reactivity, and syngas production of Greek lignite fuel (LG) and ex-situ produced chars during CO2 gasification. Three different slow pyrolysis protocols were employed for char production involving torrefaction at 300 °C (LG300), mild-carbonization at 500 °C (LG500), and carbonization at 800 °C (LG800). Physicochemical characterization studies, including proximate and ultimate analysis, X-ray Diffraction (XRD), and Raman spectroscopy, revealed that the thermal treatment under inert atmospheres leads to chars with increased fixed carbon content and less ordered surface structures. The CO2 gasification reactivity of pristine LG and as-produced chars was examined by thermogravimetric (TG) analysis and in batch mode gasification tests under both isothermal and non-isothermal conditions. The key parameters affecting the devolatilization and gasification steps in the overall process toward CO-rich gas mixtures were thoroughly explored. The gasification performance of the examined fuels in terms of carbon conversion, instant CO production rate, and syngas generation revealed an opposite reactivity order during each stage. TG analysis demonstrated that raw lignite (LG) was more reactive during the thermal devolatilization phase at low and intermediate temperatures (da/dtmax,devol. = 0.022 min−1). By contrast, LG800 exhibited superior gasification reactivity at high temperatures (da/dtmax,gas. = 0.1 min−1). The latter is additionally corroborated by the enhanced CO formation of LG800 samples under both non-isothermal (5.2 mmol) and isothermal (28 mmol) conditions, compared to 4.1 mmol and 13.8 mmol over the LG sample, respectively. The pronounced CO2 gasification performance of LG800 was attributed to its higher fixed carbon content and disordered surface structure compared to LG, LG300, and LG500 samples.

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Section: Gasification Experimentsmentioning

confidence: 99%

“…Equation (4), used to evaluate the carbon to CO conversion, X C , contains two terms. The first term stands for the CO production during the devolatilization stage, whereas the second term corresponds to the CO formation associated with the Boudouard reaction (C + CO 2 → 2 CO) during the gasification stage [43,44].…”

Section: Gasification Experimentsmentioning

confidence: 99%

CO2 Gasification Reactivity and Syngas Production of Greek Lignite Coal and Ex-Situ Produced Chars under Non-Isothermal and Isothermal Conditions: Structure-Performance Relationships

et al. 2022

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“…It is also plausible that molecules of used salt react themselves with carbon fuels at a higher temperature, which is known as carbonate gasification. ,,, A proposed reaction scheme for this interaction is shown in eq . ,, Although most previous studies investigated coal conversion (especially gasification) in the presence of ternary eutectic, ,,− it is possible to convert a common biomass to valuable carbonaceous materials in the presence of molten carbonate salts. There are plenty of variables that may affect the final carbon product, such as the effect of the heating rate, type of biomass, ratio of molten carbonate used, operational pressure, and effect of injected gas.…”

Section: Introductionmentioning

confidence: 99%

“…It is also plausible that molecules of used salt react themselves with carbon fuels at a higher temperature, which is known as carbonate gasification. 2,15,20,34 A proposed reaction scheme for this interaction is shown in eq 1. 2,24,35…”

Section: Introductionmentioning

confidence: 99%

Modification of Biochar Formation during Slow Pyrolysis in the Presence of Alkali Metal Carbonate Additives

et al. 2019

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In this work, slow pyrolysis of sawdust of Eucalyptus pilularis biomass and ternary molten carbonate eutectic [Li2CO3, 43.5%; Na2CO3, 31.5%; and K2CO3, 25% (mole percentage)] in thermogravimetric analysis at three different temperatures, 600, 750, and 900 °C, was studied. These salts affect the slow pyrolysis process, including changes in the volatile release mechanism and the morphology of remnant char material. The initial results show that, in the presence of molten carbonate, biomass particles make bubble-shaped larger particles, which result in less volatile emissions and more char residue. It is suggested that the ternary eutectic has a chemical diluent and catalytic role, particularly in the case of higher salt doping. Results from scanning electron microscopy images give strong evidence that molten carbonates capture volatiles inside swelling carbon particles, which causes the generation of various sizes of pores as well as char-making reactions, and at a higher temperature, the bubble-shaped particles will rupture. Swelling of this nature has previously only been observed clearly in coal precursors; however, this is the first observation in a biomass-based system. Also, at a temperature above 750 °C, decomposition of molten carbonate generates CO2 and carbon/carbonate gasification produces CO as well as a more “activated” biochar.

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“…Meanwhile, molten salt can in-situ capture of various pollutants like HCl and H 2 S [6]. More importantly, lignite containing alkali and alkaline earth metals can be dissolved into the salt during the molten salt pyrolysis, reducing damage to devices [7].…”

Section: Introductionmentioning

confidence: 99%

The effects of temperature and molten salt on solar pyrolysis of lignite

Zeng

Xie

et al. 2019

Energy

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Molten salt pyrolysis driven by concentrated solar radiation is well positioned to utilize solar energy and lignite effectively. This study focused on the effects of temperature (500, 600, 700 and 800 C) and molten carbonate salt (Li 2 CO 3-Na 2 CO 3-K 2 CO 3) on properties of char obtained from lignite pyrolysis, as well as gas and tar products for revealing their formation mechanism and transformation process. Molten salt pyrolysis of HulunBuir lignite produced more gas products and less char compared to conventional pyrolysis owing to the enhanced heat transfer and catalytic effect of molten salt. The char yield decreased from 58.4% to 43.4%, and the gas yield (especially CO 2 , H 2 and CO) increased from 28.3% to 46.1% at 800 C. CO 2 , CO and H 2 production increased about 60.43%, 103.42% and 65.2% at 800 C, respectively. Additionally, the presence of molten salt improved the tar quality with more hydrocarbon content (maximum increase of 5.8%) and less oxygenated compounds. The structure and reactivity relationship of char was characterized by XRD, BET, SEM, FTIR, Raman spectroscopy and TGA. Molten salt generated char had a higher reactivity due to the increase of disorder, surface area, microporosity (maximum of 71.74%) and active sites.

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A deep insight into carbon conversion during Zhundong coal molten salt gasification

Cited by 33 publications

References 37 publications

CO2 Gasification Reactivity and Syngas Production of Greek Lignite Coal and Ex-Situ Produced Chars under Non-Isothermal and Isothermal Conditions: Structure-Performance Relationships

CO2 Gasification Reactivity and Syngas Production of Greek Lignite Coal and Ex-Situ Produced Chars under Non-Isothermal and Isothermal Conditions: Structure-Performance Relationships

Modification of Biochar Formation during Slow Pyrolysis in the Presence of Alkali Metal Carbonate Additives

The effects of temperature and molten salt on solar pyrolysis of lignite

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