Coal conversion submodels for design applications at elevated pressures. Part II. Char gasification

Liu, Gui-Su; Niksa, Stephen

doi:10.1016/j.pecs.2004.08.001

Cited by 227 publications

(172 citation statements)

References 46 publications

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“…As a result of the increase in oxygen content in the gasifying agent, CO 2 production increases sharply, mainly due to coal oxidation. The significant decrease in H 2 production is a consequence of oxygen being much more reactive to carbon than steam [24]. What is more, some of the H 2 produced might have burned up if oxygen were present.…”

Section: Gasifying Agent Compositionmentioning

confidence: 99%

High-pressure co-gasification of coal with biomass and petroleum coke

Fermoso

Arias

Plaza

et al. 2009

Fuel Processing Technology

180

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The effect of the main operation variables (temperature, pressure and gasifying agent composition) on gas production and other process parameters, such as carbon conversion, cold gas efficiency and high heating value, during the steam-oxygen gasification of a bituminous coal were studied. It was observed that temperature and oxygen concentration were the most influential variables during the gasification process. In addition, co-gasification tests of binary blends of a bituminous coal with different types of biomass (up to 10 %) and petroleum coke (up to 60 %), as well as ternary blends of coal-petcoke-biomass (45-45-10 %) were conducted in order to study the effect of blending on gas production and carbon conversion.

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Section: Gasifying Agent Compositionmentioning

confidence: 99%

High-pressure co-gasification of coal with biomass and petroleum coke

Fermoso

Arias

Plaza

et al. 2009

Fuel Processing Technology

180

View full text Add to dashboard Cite

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“…In this study the carbon conversion and the cold gas efficiency are defined with Eqs. (4) and (5). Finally the lower heating value (MJ/N m 3 ) is the calorific value of the dry gas on a volumetric basis.…”

Section: Effect Of Operation Variablesmentioning

confidence: 99%

“…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].…”

mentioning

confidence: 99%

“…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.…”

mentioning

confidence: 99%

“…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.…”

mentioning

confidence: 99%

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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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