The gasification of wood-char spheres in CO2N2 mixtures: analysis and experiments

Dasappa, S.; Paul, P.J.; Mukunda, H. S.; Shrinivasa, U.

doi:10.1016/0009-2509(94)80040-5

Cited by 61 publications

(59 citation statements)

References 17 publications

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“…As seen in Fig. 2 the general shape of the conversion curves (except PC and PB) versus time is globally almost linear, as observed in previous studies [19,21,31,32].…”

Section: Char Reactivitysupporting

confidence: 70%

The effect of char properties on gasification reactivity

Duman

Uddin

Yanık

2014

Fuel Processing Technology

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In this study, CO 2 gasification of raw and acid-washed chars obtained from various types of lignocellulosic biomasses (woody and agricultural waste biomasses) was studied under isothermal conditions (850°C) using thermal gravimetric analysis. The effect of surface area and alkali/earth alkali metals on the reactivity of the chars was investigated. The different kinetic models were used to fit with the reactivity data by using least square method. The gasification of chars with higher surface area was found to be faster than that of chars having lower surface area. The acid treatment decreased the overall gasification rate for each raw chars. However, although the AI (alkali index) values of chars obtained from agricultural biomasses had equal or higher than that of woody biomass chars, their initial rates were considerably lower. It was concluded that indigenous alkali metals of chars have a remarkable influence of gasification reactivity but an adequate surface area should be provided to react with CO 2 .

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“…As seen in Fig. 2 the general shape of the conversion curves (except PC and PB) versus time is globally almost linear, as observed in previous studies [19,21,31,32].…”

Section: Char Reactivitysupporting

confidence: 70%

The effect of char properties on gasification reactivity

Duman

Uddin

Yanık

2014

Fuel Processing Technology

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“…As porosity increases, the ratio of internal surface area to volume (A s ) increases allowing additional surface reaction to occur, and thereby increasing K. Similarly, as the ambient oxygen concentration is increased, the corresponding increase in oxygen flux for the present diffusion limited case leads to almost a linear increase in K, as seen in Figure 8. While the porosity also increases the predicted value ofṁ p , the relative increase in K is significant because of the term (1 − φ b ) in Equation (20). Figure 9 shows the corresponding variation of the particle surface temperature as a function of oxygen concentration and particle porosity.…”

Section: Parametric Investigation Of Porosity Oxygen Concentration mentioning

confidence: 88%

“…For the interface conditions between the porous reaction layer and the homogeneous gas phase, one approach is to impose integrated conservation equations across the surface of the particle [7,20,23]. In this approach, the porosity is kept constant within the particle and unity in the gas phase.…”

Section: Porosity Function φ(R)mentioning

confidence: 99%

“…Only a handful of investigations have considered full transport and reaction within the pore structure [6,7,20,21], however with highly simplified heterogeneous and homogeneous kinetic models. In contrast, the present effort includes not only the reaction of carbon with O 2 , H 2 O, and CO 2 , but also reactions of carbon with radical species.…”

Section: Introductionmentioning

confidence: 99%

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Oxidation of isolated porous carbon particles: Comprehensive numerical model

Kassebaum

Chelliah

2009

Combustion Theory and Modelling

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A general mathematical formulation and a numerical solution approach are developed to model the oxidation of an isolated porous carbon particle in a quiescent atmosphere under quasi-steady conditions. A key element of the approach developed is the ability to decouple the internal surface area effects from the surface kinetic rates. The governing equations are integrated numerically from the centre of the particle to the edge of the gas-phase thermal mixing layer, with a novel transition layer introduced at the particle external surface. The numerical approach developed is then applied to a range of particle sizes and porosities in an enriched oxidizing environment. The existence of limiting combustion regime as a function of particle size, porosity, and ambient oxygen mole fraction is explored based on the model developed. Comparisons of the predicted particle mass burning rate and surface temperature with recent experiments, as well as the limiting or extinction conditions, are also presented.

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“…Moreover, Struis et al [19] studied the gasification reaction of coal chars in CO 2 , and found the increased phenomenon of gasification reaction rate at the end of stage (X = 0.7-1). Dasappa et al [33] reported that the particle size of coal chars could remain constant until X ≈ 0.7 during CO 2 gasification, and the particles disintegrated rapidly thereafter. According to references mentioned above and experimental results (see Fig.…”

Section: Characteristics Of Parameter and Trpmmentioning

confidence: 98%