Kinetics of heterogeneous reactions with coal in context of underground coal gasification

Samdani, Ganesh; Ganesh, Anuradda; Aghalayam, Preeti; Sapru, R.K.; Lohar, B.L.; Mahajani, Sanjay M.

doi:10.1016/j.fuel.2017.02.088

Cited by 17 publications

(7 citation statements)

References 15 publications

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“…The volumetric model (VM), the shrinking core model (SCM), and the random pore model (RPM). Several studies have shown good agreement between experimental results and the three presented models, regardless of the differences in their theoretical background [27][28][29][30]. However, as there is not any relationship established between the biomass characteristics and the decomposition mechanism, no theoretical models were presupposed in this study.…”

Section: Isoconversional Model Free Approachmentioning

confidence: 76%

Steam gasification behavior of tropical agrowaste: A new modeling approach based on the inorganic composition

Millán

Vargas

Nzihou

2019

Fuel

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The steam gasification and co-gasification reactivity and kinetics of coconut shells, oil palm shells and bamboo guadua were studied from an isothermal thermogravimetric analysis, with temperatures ranging from 750°C to 900°C, and steam partial pressures from 3 to 10 kPa. In the analyzed experimental range, inorganics were identified as the most influential parameter in biomass reactivity and kinetics. Accordingly, a new modeling approach is proposed to predict the gasification behavior of lignocellulosic agrowaste based on their inorganic composition. A good agreement between the experimental and modeled data was found, showing that the proposed approach is suitable for the description and prediction of the gasification behavior of biomasses with different macromolecular structure and within a wide range of inorganic composition, and H/C and O/C ratios near 1.5 and 0.8 respectively. This kinetic model could constitute a valuable tool for reactor design and scale-up of steam gasification facilities using tropical lignocellulosic feedstocks.

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Section: Isoconversional Model Free Approachmentioning

confidence: 76%

Steam gasification behavior of tropical agrowaste: A new modeling approach based on the inorganic composition

Millán

Vargas

Nzihou

2019

Fuel

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“… 22 Kinetic and thermodynamic equilibrium models are commonly used numerical simulation models of UCG. 23 , 24 Most of the attention is on the composition of the produced gas (H 2 , CO, CH 4 , etc.) and the temperature distribution in the gasifier under the condition of single coal thickness.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of the Temperature Distribution and Evolution Law of Underground Lignite Gasification

Zhou

Chen

et al. 2022

ACS Omega

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To study the temperature distribution characteristics and evolution law of underground lignite gasifiers, a three-dimensional heat conduction model of underground lignite gasification was constructed. Moreover, the effects of different coal thicknesses, advance speeds of the flame working face, and surrounding rock types on the gasifier were analyzed. The results show that with the increase in the coal thickness, the transfer range and distance of temperature in the roof, floor, and coal seam gradually increase, as does the coal quantity in the three zones. The heat loss rate of the gasifier decreased gradually with the coal seam thickness. When the advance speed of the flame working face is 0.5 m/d, the ideal gasification coal thickness range of lignite is 2.5–17.5 m. With the increase in the gasification rate, the maximum transfer distance of temperature to the roof and floor, the average temperature of the gasifier, and the coal quantity of the three zones gradually increase. Conversely, the coal thickness corresponding to the intersection of the coal quantity of the oxidation and reduction zones and the heat loss rate of the gasifier gradually decrease. When the coal seam below 2.5 m is gasified, the gasification rate can be increased appropriately. When the coal seam is above 13 m, increasing the gasification rate will make the coal quantity in the oxidation zone close to or even higher than that in the reduction zone. Regarding the surrounding rock types comprising a combination of siltstone, mudstone, sandy mudstone, and fine sandstone, the most favorable roof and floor type for underground coal gasification is the combination of fine sandstone and sandy mudstone (without considering the sealing and mechanical properties). These results provide important theoretical support for the industrialization of underground coal gasification.

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“…Coal pyrolysis − is a fundamental part of coal combustion as it is the basis of coal gasification − and distillation . A significant amount of research has been performed, although most − of it has focused on the detailed mechanism of low-temperature (<1100K) coal pyrolysis.…”

Section: Introductionmentioning

confidence: 99%

The Phenomena of Secondary Weight Loss in High-Temperature Coal Pyrolysis

2017

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Studies on coal pyrolysis via a thermogravimetric analyzer (TGA) are typically performed under a variety of temperature increases beginning at ambient temperature. A main limitation in these procedures is that the reaction temperatures (generally lower than 1000 °C) are typically lower than those met in pulverized coal boilers and ash flow temperatures (AFTs; generally higher than 1100 °C). In this paper, five Chinese coals are clarified to low-or mid-AFT coals as their AFTs increase. They were then prepared in TGA at several temperatures below or above their AFTs under N 2 atmosphere for approximately 30 min after a heating procedure at a rate of 80 °C/min. The coal and residual char samples were collected and analyzed via X-ray diffraction and compared to the chemical thermodynamic calculation. The secondary weight loss appeared between 1200 and 1450 °C in the TG curves of four mid-AFT coals but not the low-AFT coal. The results showed that this secondary weight loss was caused by the carbothermal reduction and carbothermal reduction nitridation reaction between minerals and carbon, which led to the appearance of silicon carbide, aluminum nitride, and silicon nitride. The low concentrations of SiO 2 and Al 2 O 3 and high concentrations of Fe 2 O 3 and CaO inhibited the secondary weight loss process in high-temperature coal pyrolysis. The reason why the secondary weight loss was not present in low-AFT coal was possibly due to low-melting eutectic noncrystal matters consisting of calcium oxide and ferrum oxide. These fused low-melting eutectic noncrystal matters stopped the carbothermal reaction at high pyrolysis temperatures and inhibited the production of SiC, AlN, and Si 3 N 4 .

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Kinetics of heterogeneous reactions with coal in context of underground coal gasification

Cited by 17 publications

References 15 publications

Steam gasification behavior of tropical agrowaste: A new modeling approach based on the inorganic composition

Steam gasification behavior of tropical agrowaste: A new modeling approach based on the inorganic composition

Numerical Simulation of the Temperature Distribution and Evolution Law of Underground Lignite Gasification

The Phenomena of Secondary Weight Loss in High-Temperature Coal Pyrolysis

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