Study of char gasification by carbon dioxide. 2. Continuous gasification in fluidized bed

Abstract

Coal char gasification with carbon dioxide was performed in a fludized bed. The continuous pyrolysis of the char was carried out in the nitrogen stream to evaluate the amount of gas produced by thermal decomposition. The gasification reaction was analyzed by assuming the reaction takes place independently after the pyrolysis is completed. The bubble size under the gasification condition was measured by use of the electroresistivity probe. The bubbling bed model and the thermogravimetrically obtained rate equation were used for the prediction of the conversions of both char and carbon dioxide, where the bubbling bed model was modified to give the stoichiometrically consistent material balance between the consumed char and carbon dioxide. The results of the fluidized bed gasification could be well explained by the modified bubbling bed model, where the effective bubble size was chosen as the bubble size observed at the middle height of the bed by the electroresistivity probe.

Density functional theory molecular modelling and experimental particle kinetics for CO2–char gasification

“…and XRD [6,[16][17][18][19]. This work highlighted the effect of structural properties of chars in gasification reaction mechanism and continues to elucidate the intricacies of coal gasification.…”

CO2 gasification kinetics of two alberta coal chars

“…The mechanism of this reaction is not yet fully understood but, it is generally beliwed that C02 adsorption on the surface of char (oxygen transfer) foliowed by CO desorption (carbon removal) are the main steps determining the apparent rate (Ergun, 19.56;Walker et al, 19.59;Freund, 1986;Matsui et al, 1987aMatsui et al, , 1987b. The mechanism of this reaction is not yet fully understood but, it is generally beliwed that C02 adsorption on the surface of char (oxygen transfer) foliowed by CO desorption (carbon removal) are the main steps determining the apparent rate (Ergun, 19.56;Walker et al, 19.59;Freund, 1986;Matsui et al, 1987aMatsui et al, , 1987b.…”

“…Les xperimental data for C02 gasification of coal chars E have been reported using TGA, fixed bed, laminar flow (drop tube) or fluidized bed reactors. The mechanism of this reaction is not yet fully understood but, it is generally beliwed that C02 adsorption on the surface of char (oxygen transfer) foliowed by CO desorption (carbon removal) are the main steps determining the apparent rate (Ergun, 19.56;Walker et al, 19.59;Freund, 1986;Matsui et al, 1987aMatsui et al, , 1987b. This mechanism can be further simplified by proposing the Langmuir-Hinshelwood type rate expression (Koenig et al, 1985;Muhlen et al, 1985;Strange and Walker, 1976).…”