Über die Vergasung von Reaktorgraphit mit Kohlendioxid und Wasserdampf

Hedden, Kurt; Löwe, A.

doi:10.1016/0008-6223(67)90050-4

Cited by 25 publications

(10 citation statements)

References 7 publications

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“…Also considered were the high-pressure steam gasification experiments of Schmal et al [81] and Mühlen et al [15]. In addition, the gasification experiments performed with high levels of CO and H 2 by Gadsby et al [83], Long and Sykes [84], Hedden and Löwe [85], and Bjerle et al [9] were considered. The full analyses of these data are available in the supplementary material.…”

Section: Validation Of the Reaction Mechanismmentioning

confidence: 99%

Coal and biomass char reactivities in gasification and combustion environments

Tilghman

Mitchell

2015

Combustion and Flame

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Section: Validation Of the Reaction Mechanismmentioning

confidence: 99%

Coal and biomass char reactivities in gasification and combustion environments

Tilghman

Mitchell

2015

Combustion and Flame

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“…Steam Gasification: C + HZO -+ CO + Hz (endothermic, heterogeneous) For this reaction, Hedden and Lowe (1967) present kinetics which are most useful to us. Since the rates were determined using graphite, we can expect them to be higher for coalichar.…”

Section: Internal Structure and Kineticsmentioning

confidence: 99%

“…Since the rates were determined using graphite, we can expect them to be higher for coalichar. The rate is given by For this study we will assiime k , = 3.85x1O7 exp(-284 702.4/RT)m3/m2( surface area ) -S internal k I 2 = 95.7 exp(60 708.6iRT) m3/kgmole Corbon Dioxide gasification: C + COZ -+ 2CO (endothermic, heterogeneous) The rate of the carbon-carbon dioxide reaction has been studied by various investigators (see, Hedden and Lowe, 1967;Yang and Steinberg, 1977;Dutta et al, 1977). The data show considerable discrepancy in activation energies, ranging from 45 to 90 kcal/mole.…”

Section: Internal Structure and Kineticsmentioning

confidence: 99%

A single‐particle char gasification model

Srinivas

Amundson

1980

AIChE Journal

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A model is developed for the gasification of a single-char particle in an environment of water, hydrogen, carbon dioxide, carbon monoxide and methane, existing in the gasification zone of a reactor. The model, consisting of the mass and energy conservation equations, together with the Stefan-Maxwell relations includes the intraparticle effects and the change in internal surface area. It is found that the intraparticle effects and the surface area effects are significant and hence cannot be neglected, and the situation becomes more acute with increasing particle size and high temperatures. Comparisons with other models and existing empirical relations show that the model agrees well when diffusional effects are minimal, but at higher temperature and large particle size there is a significant difference. The model may be used to discriminate among various idealized models such as the homogeneous and the shrinking core model. The convective terms in the Stefan-Maxwell relations have negligible influence. The analysis can be directly used in the modeling studies of gasification reactors and will be so applied in a later paper.

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“…Even results suggest that the intrinsic rate constant (k i ) for the H 2 O reaction is very close to the value for the CO 2 reaction at 1500 ЊC. Previous work that has compared these two rates F. Rates of Oxidation of Glassy Carbon includes Hedden and Löwe, [25] who found the rate constant to be 17 times greater in H 2 O at 1000 ЊC, while Overholser A series of experiments was conducted to investigate the reactivity of glassy carbon under different temperature and and Blakely [26] found the rate to be almost an order of magnitude greater at 975 ЊC. However, it should be noted that, gas phase transport conditions, the results of which are presented in Figures 11 through 13.…”

Section: E Comparison Of the Rates For Co 2 And H 2 Omentioning

confidence: 80%

“…therefore, the rates for coke were measured at 1400 ЊC. Other studies such as those by Hedden and Löwe [25] and Some experiments also investigated the reaction between Overholser and Blakely [26] and Binford and Eyring [27] have CO 2 and glassy carbon. The material used was a SIGRADUR been limited to low pressures and temperatures, which makes G,* a 4-mm-thick disk with Ͻ100 ppm ash content.…”

Section: Effective Diffusivitymentioning

confidence: 99%

Kinetics of oxidation of carbonaceous materials by CO2 and H2O between 1300 °C and 1500 °C

Story¹,

Fruehan

2000

Metall Mater Trans B

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The kinetics of the oxidation of graphite, metallurgical coke, and glassy carbon by CO 2 and H 2 O were investigated at temperatures between 1300 ЊC and 1500 ЊC. The experimental technique employed a lance-crucible geometry with continuous gas analysis to measure the reaction rate. The experiments were designed to ensure that the carbon reaction behavior was in the limited mixed regime, where only a small volume of material close to the surface is reacting, and external gas phase mass transfer was fast. The results demonstrated the importance of internal pore structure, particularly as it develops in the reacted layer during the course of the reaction. This was believed to be responsible for the higher rates measured in graphite than in coke and the time-dependent rate increase that was observed in nonporous glassy carbon during experiments. For a commercial grade graphite and metallurgical coke, the rate constants depended strongly upon the carrier gas species, indicating that molecular diffusion was the primary transport mechanism in the pores of these materials. In contrast, for a specially purified graphite, the rate constant was found to be independent of the carrier gas species, which suggested Knudsen diffusion control dominates in this carbon. The results are in good agreement with extrapolations of previous work carried out at lower temperatures.

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Über die Vergasung von Reaktorgraphit mit Kohlendioxid und Wasserdampf

Cited by 25 publications

References 7 publications

Coal and biomass char reactivities in gasification and combustion environments

Coal and biomass char reactivities in gasification and combustion environments

A single‐particle char gasification model

Kinetics of oxidation of carbonaceous materials by CO2 and H2O between 1300 °C and 1500 °C

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