Gasification of chars from tetralin liquefaction of &lt; 1.5 g cm−3 carbon-rich residues derived from waste coal fines in South Africa

Uwaoma, R.C.; Strydom, Christien A.; Matjie, R.H.; Bunt, John R.

doi:10.1007/s10973-021-10609-5

Cited by 5 publications

(18 citation statements)

References 39 publications

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“…Other researchers have established that chars with a higher gasification reactivity usually have lower apparent activation energies. 13,26 However, the reported E a estimated from all parameters of the solid residue chars indicate that IR SR char had significantly lower E a values (accompanied by 5. Preasphaltenes/asphaltenes (PAAs) were removed prior to FTIR spectroscopic analysis.…”

Section: Characterization Of Solid Fractions Obtained During Liquefac...mentioning

confidence: 93%

“…The demineralization method's efficiency was quantified by assessing the demineralization efficiency, E d , expressed as a percentage. To determine the achieved demineralization efficiency, E d , the following formula was employed 13 :…”

Section: Demineralization Experimentsmentioning

confidence: 99%

“…The reactivity at 50 and 90% (R 0.5 and R 0.9 ) conversion was calculated using eqs 17 and 18, where t is the time at conversion in minutes. The fractional carbon conversions (X), initial reactivities (R i ), and average final reactivities (R fa ) were evaluated using eqs 19−21 7,13…”

Section: Characterization Of Feed Materials and Residues 241 Proximat...mentioning

confidence: 99%

“…Notably, liquefaction solid residues account for approximately one-third of the coal input, and their utilization is important in reducing the overall cost of the liquefaction process. , Managing the solid waste generated by the chemical industry has gained much attention, with coal liquefaction residues representing about 25–30% of the feed coal . The residues generated through liquefaction comprise not only unreacted coal macerals and intrinsic mineral components but also residual oil, as well as asphaltenes and preasphaltenes (PAAs) . Employing thermal conversion through gasification presents an economically viable solution to improve the process output.…”

Section: Introductionmentioning

confidence: 99%

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Direct Liquefaction of South African Vitrinite- and Inertinite-Rich Coal Fines

Meyer,

Strydom,

Bunt

et al. 2024

ACS Omega

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In this investigation, coal fines enriched with inertinite were used for direct liquefaction experiments. For comparison, a vitrinite-rich coal typically utilized in coal-to-liquid processes was also employed. To assess the impact of mineral matter content, demineralization was used to remove most of the inorganic constituents. The findings revealed that the inertiniterich coal exhibited lower liquefaction conversions due to a reduced proportion of reactive macerals and elevated levels of inorganic mineral matter. These conversion values exhibited a strong correlation with the quantity of reactive macerals present in the parent coals. For the inertinite-rich coal, the presence of inorganic mineral matter impeded the liquefaction process but facilitated the CO 2 gasification reactions of the derived chars. To evaluate their potential in gasification processes, CO 2 gasification experiments were conducted and the reactivities and apparent gasification activation energies of both coal chars, liquefaction residue chars, and preasphaltene and asphaltene (PAA) chars were calculated. These calculations were carried out using the random pore model (RPM) and volumetric reaction model (VRM). The chemistry, reactivity, and kinetics of residue gasification conversion are not thoroughly understood, yet they hold significant importance in optimizing syngas production within gasification processes. The findings from this work highlight significant differences in liquefaction conversion values, product distribution, and composition. These differences are influenced by factors such as maceral composition, inorganic mineral matter content, hydrogen-donor capabilities of the solvent, and liquefaction reaction temperatures. Additionally, these variables affect the CO 2 gasification reactivity of liquefaction solid residue chars.

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Section: Characterization Of Solid Fractions Obtained During Liquefac...mentioning

confidence: 93%

Section: Demineralization Experimentsmentioning

confidence: 99%

Section: Characterization Of Feed Materials and Residues 241 Proximat...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Direct Liquefaction of South African Vitrinite- and Inertinite-Rich Coal Fines

Meyer,

Strydom,

Bunt

et al. 2024

ACS Omega

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“…Typically, the gas is switched to CO 2 or to a CO 2 -inert gas mixture after the heating to an isothermal temperature. Nearly, all works published in the present journal on CO 2 gasification used this method as illustrated by a selection in the References [21][22][23][24][25]. However, the stabilization of the CO 2 concentration in the furnace needs some time; it may take 20 min or even more [26,27].…”

Section: Introductionmentioning

confidence: 99%

Kinetics of the CO2 gasification of woods, torrefied woods, and wood chars. Least squares evaluations by empirical models

Várhegyi

Wang

Skreiberg

2023

J Therm Anal Calorim

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The gasification kinetics of chars forming from biomass materials was studied by kinetic equations of type dX/dt = Af(X) exp(− E/(RT)) where X is the conversion of the sample, A is the pre-exponential factor, E is the activation energy and f(X) is a suitable model function. The theoretically deduced f(X) models in the literature are rarely applicable for chars of biomass origin because of chemical and physical inhomogeneities and irregularities. Hence, empirical f(X) functions were determined by a method proposed four years ago (Várhegyi in Energy Fuels 33:2348–2358, 2019). The parameters of the models were obtained by the method of least squares. Thermogravimetric experiments from an earlier work were reevaluated to explore the possibilities of the approaches employed. The experiments belonged to untreated birch and spruce woods; torrefied woods; chars prepared at a higher temperature; and chars formed at high heating rates (ca. 1400 °C min−1). Common kinetic features were found for the CO2 gasification of the chars studied. The reliability of the results was carefully tested by evaluating smaller and larger groups of the experiments and comparing the results. The method proved to be suitable for the determination of realistic f(X), E, and A from single modulated experiments, too. The models described well the gasification of chars forming from different woods through a wide range of temperature programs and thermal pretreatments.

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