Kinetics of Lignite Char Gasification. Relation to CO<sub>2</sub> Acceptor Process

Curran, G.P.; Fink, C.E.; Gorin, E.

doi:10.1021/i260032a020

Cited by 4 publications

(3 citation statements)

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“…Note that apparent melt formation of the sorbents was observed in p-CHC tests at 923 and 973 K above 6 MPa. Curran et al − systematically investigated the so-called CO 2 acceptor gasification process. They studied phase equilibrium in the two binary systems CaO−Ca(OH) 2 and Ca(OH) 2 −CaCO 3 at elevated pressures and temperatures to determine the required chemical properties of the Ca-based CO 2 acceptor; they pointed out that the melts in the Ca(OH) 2 −CaCO 3 system can be produced at temperatures as low as 900 K and pressures as low as 0.9 MPa.…”

Section: Resultsmentioning

confidence: 99%

“…For this reason, knowledge of the reactivity and durability of these sorbents during the repetitive carbonation−calcination reactions is indispensable. Curran et al studied the so-called CO 2 acceptor gasification process − in which the exothermic carbonation reaction of calcined limestone was used to provide the endothermic heat for coal gasification. They systematically tested the properties of Ca-based acceptors such as reactivity, kinetics, durability for multicycle use, etc., and showed that the carbonation ratio (the molar ratio of CO 2 sorbed to CaO initially loaded) drastically decreased with cycle number.…”

Section: Introductionmentioning

confidence: 99%

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Repetitive Carbonation−Calcination Reactions of Ca-Based Sorbents for Efficient CO₂ Sorption at Elevated Temperatures and Pressures

Kuramoto

Fujimoto

Morita

et al. 2003

Ind. Eng. Chem. Res.

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In an effort to develop a novel hydrogen production process in which coal is gasified with highpressure steam in the presence of CO 2 sorbents, the fundamental CO 2 sorption characteristics of Ca-based sorbents during repetitive carbonation-calcination reactions at different pressures were investigated using a conventional TG/DTA analyzer and a laboratory-scale horizontaltube reactor. The results revealed that, as a result of sintering and crystal growth, Ca-based sorbents were significantly deactivated by high-temperature calcination treatment. As a consequence, the CO 2 uptake capacity of the sorbents decreased with cycle number under both atmospheric and pressurized conditions. An intermediate hydration treatment was found to enhance the reactivity and durability of the sorbents for multicycle CO 2 sorption. Because of the presence of eutectics in the CaO-Ca(OH) 2 -CaCO 3 ternary system, the formation of sorbent melts was observed in repetitive calcination-hydration-carbonation reactions at elevated pressures at 923 and 973 K. Even under eutectic conditions, the sorbents retained their high reactivity for CO 2 sorption.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Repetitive Carbonation−Calcination Reactions of Ca-Based Sorbents for Efficient CO₂ Sorption at Elevated Temperatures and Pressures

Kuramoto

Fujimoto

Morita

et al. 2003

Ind. Eng. Chem. Res.

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“…When coal with a larger diameter is used, however, the endothermic steam gasification of coal as well as ethe xothermic hydration and CO 2 sorption reactions of the sorbents will take place locally even if the coal particles are distributed homogeneously in the solid feedstock. In this case, the heat produced by the CO 2 sorption cannot be transferred and consumed by the gasification of individual coal particles, resulting in the partial increase in temperature of the Ca-based sorbents in the particle bed to the eutectic range 12,17,18 . Thus, we believe that the observed cake formation of the solids is attributable to the partial melting of Ca-(OH) 2 or CaCO 3 during the gasification, which was enhanced by unfavorable temperature inhomogeneity.…”

Section: Resultsmentioning

confidence: 99%

Localized Interaction between Coal-Included Minerals and Ca-Based CO₂ Sorbents during the High-Pressure Steam Coal Gasification (HyPr−RING) Process

Kuramoto

Ohtomo

Suzuki

et al. 2004

Ind. Eng. Chem. Res.

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Pulverized Japanese bituminous coal (Taiheiyo coal) samples with diameter ranges of 38−75 μm and 180−250 μm were gasified with high-pressure steam in the presence of Ca-based CO2 sorbents. The experiments were carried out at 873 and 973 K and at holding times ranging from 0 to 120 min using a laboratory-scale fixed-bed reactor, and the solid−solid reaction between the Ca-based sorbents and the coal-included minerals during the steam gasification was investigated. Local scanning electron microscopy−energy-dispersive X-ray analysis of the solid residues obtained under different conditions showed that some constituents of the coal-included minerals, such as Si and Al, were contained in the sorbent particles. The solid−solid interaction between the Ca-based sorbents and coal-included minerals became significant at the higher temperature and at longer holding periods. This interaction will locally decrease the CO2 sorption ability of the sorbents. However, when a holding time of less than 10 min was employed, the solid−solid reaction between the minerals and the sorbents was suppressed, even at 973 K, because the rate of formation of inorganic compounds through solid−solid reaction was low. In this case, our target carbon conversion (about 50%) was attainable, owing to the devolatilization during the heating period. Our results indicate that the holding time of the feedstock in the reactor should be shortened to avoid deactivation of the Ca-based sorbents during high-pressure steam gasification.

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Gasification Systems

2013

Coal‐Fired Power Generation Handbook

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Kinetics of Lignite Char Gasification. Relation to CO₂ Acceptor Process

Cited by 4 publications

References 5 publications

Repetitive Carbonation−Calcination Reactions of Ca-Based Sorbents for Efficient CO₂ Sorption at Elevated Temperatures and Pressures

Repetitive Carbonation−Calcination Reactions of Ca-Based Sorbents for Efficient CO₂ Sorption at Elevated Temperatures and Pressures

Localized Interaction between Coal-Included Minerals and Ca-Based CO₂ Sorbents during the High-Pressure Steam Coal Gasification (HyPr−RING) Process

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Kinetics of Lignite Char Gasification. Relation to CO2 Acceptor Process

Cited by 4 publications

References 5 publications

Repetitive Carbonation−Calcination Reactions of Ca-Based Sorbents for Efficient CO2 Sorption at Elevated Temperatures and Pressures

Repetitive Carbonation−Calcination Reactions of Ca-Based Sorbents for Efficient CO2 Sorption at Elevated Temperatures and Pressures

Localized Interaction between Coal-Included Minerals and Ca-Based CO2 Sorbents during the High-Pressure Steam Coal Gasification (HyPr−RING) Process

Gasification Systems

Contact Info

Product

Resources

About

Kinetics of Lignite Char Gasification. Relation to CO₂ Acceptor Process

Repetitive Carbonation−Calcination Reactions of Ca-Based Sorbents for Efficient CO₂ Sorption at Elevated Temperatures and Pressures

Repetitive Carbonation−Calcination Reactions of Ca-Based Sorbents for Efficient CO₂ Sorption at Elevated Temperatures and Pressures

Localized Interaction between Coal-Included Minerals and Ca-Based CO₂ Sorbents during the High-Pressure Steam Coal Gasification (HyPr−RING) Process