Coal gasification in CO2 atmosphere and its kinetics since 1948: A brief review

Irfan, Muhammad; Usman, Muhammad R.; Kusakabe, Katsuki

doi:10.1016/j.energy.2010.10.034

Cited by 434 publications

(244 citation statements)

References 195 publications

(281 reference statements)

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“…It is also evident that the gasification rate depends strongly on the temperature indicating chemical reaction rate control within the temperature range tested. These values are slightly higher than results published using TGA analysis for substantially smaller samples (100 mg) where char conversion was undertaken with single oxidising gases (such as CO 2 and H 2 O) in individual reactions [16]. …”

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confidence: 54%

“…With increasing the pressure further, the surface will be saturated with oxygen surface complexes which means that increases in pressure will not lead to the formation of further C(O) and the reaction rate will not increase so the impact of pressure becomes less significant to independent [19,25]. It appears that at pressures up to 1.65 MPa the controlling mechanism is adsorption because the oxygen surface complexes are increasing and at higher pressures, above 2.2 MPa the oxygen surface complexes approach saturation and the pressure effect becomes insignificant [16,19]. Furthermore during C-CO 2 and C-H 2 O gasification the reaction rate decreases as the pressure increases due to the increased inhibiting effect by CO and H 2 respectively [16,19].…”

Section: Effect Of Pressurementioning

confidence: 99%

“…It appears that at pressures up to 1.65 MPa the controlling mechanism is adsorption because the oxygen surface complexes are increasing and at higher pressures, above 2.2 MPa the oxygen surface complexes approach saturation and the pressure effect becomes insignificant [16,19]. Furthermore during C-CO 2 and C-H 2 O gasification the reaction rate decreases as the pressure increases due to the increased inhibiting effect by CO and H 2 respectively [16,19]. Fig.…”

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confidence: 94%

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Experimental study on the impact of reactant gas pressure in the conversion of coal char to combustible gas products in the context of Underground Coal Gasification

Konstantinou

Marsh

2015

Fuel

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Underground Coal Gasification (UCG) is the process by which unmineable coal resources are converted in situ into a combustible gas. Pressurised oxidants such as steam and air or oxygen are injected into the coal seam in order to react with coal and form a product gas. The main gases produced are H 2 , CO, CH 4 and CO 2 , in proportions depending on temperature, pressure and the composition of the reactant gases injected [1][2][3]. Although it can be challenging to accurately measure or reproduce these conditions in a reliable fashion, it is generally believed that at high enough temperatures, free oxygen reacts completely with the solid carbon within a relatively short distance from the injection point. The heat evolved acts to pyrolyse the adjacent coal and the char formed then reacts with carbon dioxide, steam or other gases formed by combustion and pyrolysis [4][5][6]. The key substance, and hence driver of the net gasification process under these conditions is therefore CO 2 which is produced during the oxidation zone [5,7,8]. At the reduction zone CO 2 and steam, which is either introduced deliberately into the cavity or is flowing into the cavity from the oxidation of the surrounding strata, reacts with char and produces around 60% of the total gas product (by volume) during the UCG process. The remaining 40% is produced during the devolatilisation phase, although this is highly dependent on reactor condition, the type of coal and the gaseous reactants [4]. Fig. 1 illustrates the three reaction zones of a reacting channel during a UCG process, which are the oxidation, reduction and pyrolysis zones. During the oxidation zone, as the coal is consumed more coal falls into the growing void, which creates a high coal surface area available for reaction and permits contact between the hot gases and the coal [5,7]. This area is the final reduction zone which converts excess CO 2 to CO and is responsible for the uniform quality of the product gas. Measurement of the upstream gas composition in the oxidation zone has shown comparatively low heating values which demonstrate that the reactions in the oxidation zone do not have such a significant effect on the product gas composition [8,9]. Finally the pyrolysis zone is where the devolatilisation of the coal takes place, forming char that contains active sites for subsequent gas-solid reactions.Experimental study on the impact of reactant gas pressure in the conversion of coal char to combustible gas products in the context of Underground Coal Gasification AbstractThis paper describes an experimental investigation to determine the impact of pressurised reactor conditions within the reduction zone of a gasification process employing a semi-batch reactor with a bituminous coal. The conditions examined with this bespoke pressurised rig were designed to be representative of an Underground Coal Gasification (UCG) process, at pressures up to 3.0 MPa and temperatures up to 900 °C; coal samples were approximately 36 g per test. Current published literature suggests that one ...

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confidence: 54%

Section: Effect Of Pressurementioning

confidence: 99%

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confidence: 94%

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Experimental study on the impact of reactant gas pressure in the conversion of coal char to combustible gas products in the context of Underground Coal Gasification

Konstantinou

Marsh

2015

Fuel

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“…Irfan et al (2011) reviewed coal gasification with CO 2 as gasification agent, and obtained that the most used reactor is thermogravimetric analyzer (TGA). Fu and Wang (2001) obtained kinetics parameters of char-CO 2 gasification and investigated the relationship between kinetics parameters and coal types.…”

Section: Introductionmentioning

confidence: 99%

“…To date, a large body of useful data in the area of coal or char gasification has been delivered, regarding both the experiments and kinetics study (Everson et al 2006;Fan et al 2007;Irfan et al 2011Irfan et al , 2012Li et al 2014;Liu et al 2015). However, rarely little research has been conducted to investigate the gasification reactivity of high-sodium coal fly ash obtained from large scale CFB gasifier.…”

Section: Introductionmentioning

confidence: 99%

Steam gasification reactivity of a high-sodium coal fly ash obtained from a pilot scale CFB gasifier

Zhang

Zhu

2018

Int J Coal Sci Technol

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Circulating fluidized bed (CFB) gasification has several advantages for the utilization of low rank coals. However, the carbon content of fly ash is usually very high, which greatly influences the gasification efficiency. The purpose of this research is to investigate the gasification reactivity of a high-sodium Zhundong (ZD) coal fly ash obtained from a pilot-scale 2.5 t/d CFB gasification system. The experiments were carried out in a thermogravimetric analyzer with steam as gasification agent, and fast pyrolyzed ZD char was also investigated as a reference sample. The results show that increasing temperature accelerates the gasification rate both for fly ash and ZD char. Fly ash has higher gasification rate at the initial gasification stage. On the contrary, ZD char has higher reaction rate even at higher carbon conversion stage. Via distributed activation energy model, the average activation energy of ZD char and fly ash is calculated to be 94.4 and 91.2 kJ/mol, respectively. The integrated model study reveals that the reaction order of ZD char is about 0.74, whereas the reaction order of fly ash decreases from 1 to 0.59 when temperature increases from 900 to 1050°C. The gasification reactivity of ZD coal fly ash is quite different with literature research on those fly ashes with rarely little catalytic elements in coal ashes. The interesting results are related with the unique properties of ZD coal fly ash and the transformation of sodium during gasification process.

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Coal Characterization for Gasification

2014

Industrial Coal Gasification Technologies Covering Baseline and High‐Ash Coal

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Coal gasification in CO2 atmosphere and its kinetics since 1948: A brief review

Cited by 434 publications

References 195 publications

Experimental study on the impact of reactant gas pressure in the conversion of coal char to combustible gas products in the context of Underground Coal Gasification

Experimental study on the impact of reactant gas pressure in the conversion of coal char to combustible gas products in the context of Underground Coal Gasification

Steam gasification reactivity of a high-sodium coal fly ash obtained from a pilot scale CFB gasifier

Coal Characterization for Gasification

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