Kinetics of Bituminous Coal Char Gasification with Gases Containing Steam and Hydrogen

Abstract

Quantitative correlations developed to describe coal char gasification kinetics are consistent with experimental data obtained under a wide range of conditions with both differential and integral contacting systems. The correlations are developed using data obtained at constant environmental conditions with a thermobalance apparatus and a differential fluid bed system at 1500°-2000°F and 1-70 atm with a variety of gases and gas mixtures. The correlations are based on an idealized model of the gasification process which consists of three consecutively occurring stages: devolatilization, rapid-rate methane formation, and low-rate gasification./Correlations to define quantitatively the effects of pertinent intensive ^ variables on the kinetics of coal or coal char gasification reactions are necessary for the rational design of commercial systems to convert coal to pipeline gas. The available information which can be applied to the development of such correlations is relatively limited, particularly be cause the data reported from many studies conducted with integral contacting systems reflect, in part, undefined physical and chemical behavior peculiar to the specific experimental systems used. Although some differential rate data have been obtained with various carbonaceous materials, they cover only narrow ranges of the conditions potentially applicable to commercial gasification systems.For the last several years the Institute of Gas Technology (IGT) has been conducting a study to obtain fundamental information on the gasification of coals and coal chars; this information could be used with selected literature information to develop engineering correlations which 145

A model for short residence time hydropyrolysis of single coal particles

“…More complex models capable of fitting a wider range of experimental data have been proposed by Zahradnik and Glenn (1971) and Johnson (1974), but the above theory satisfies our present needs. The reactions described above, along with the appropriate rate expressions, comprise our kinetic model.…”

Tennessee Valley Authority atmospheric fluidized-bed combustor simulation interim annual report, January 1-December 31, 1979

“…At this time no clear-cut definition exists as to where slow decomposition ends and rapid decomposition begins, although Johnson (1974) reported that slow decomposition may persist with heating rates as high a·s 6000°C/min.…”

Hydrogasification of Almond Shell Chars. Influence of Operating Variables and Kinetic Study

“…Although many papers related to coal reactivity have been published, few describe detailed studies on the kinetics. [11][12][13] However, some authors have recently reported kinetic studies on the gasification process, using CO 2 , H 2 , steam, and a mixture of steam and hydrogen as gasification agents. 14,15 The uncatalyzed carbon-hydrogen reaction has been extensively studied, and several postulated mechanisms and rate expressions have been presented.…”