Factors affecting the reactivity of chars and cokes during low-temperature (640 .degree.C) steam gasification

Ginter, D.M.; Somorjai, G. A.; Heinemann, H.

doi:10.1021/ef00039a010

Cited by 16 publications

(9 citation statements)

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“…In recent years, preliminary efforts [4][5][6] have been put into petroleum coke gasification. The low reactivity of petroleum coke, derived from its carbon structure, low combustible volatile and low ash content, is the key problem in the application of petroleum coke as the feedstock of entrained bed gasifier.…”

Section: Introductionmentioning

confidence: 99%

Catalytic effect of black liquor on the gasification reactivity of petroleum coke

2010

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Section: Introductionmentioning

confidence: 99%

Catalytic effect of black liquor on the gasification reactivity of petroleum coke

2010

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“…Numerous investigations of coal gasification reactivity have been carried out by pyrolyzing the coal in a separate step, prior to gasification (e.g., refs −13). However, there are strong indications that details of the two separate steps significantly affect measured gasification reactivities. ,,− Chitsera et al observed that at elevated temperatures and pressures, longer soak times during pyrolysis and aging in the atmosphere had negative effects on the reactivity of chars in steam at 40 bar. During steam gasification at 1000−1300 °C in a pressurized thermogravimetric balance, Peng et al .…”

Section: Introductionmentioning

confidence: 99%

Coal Gasification in CO₂ and Steam: Development of a Steam Injection Facility for High-Pressure Wire-Mesh Reactors

1998

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The development of a steam injection facility and a new control system for steam gasification experiments in a high-pressure wire-mesh reactor have been described. The design is based on preheating the steam path to prevent condensation during experiments. Steam is allowed to contact the coal sample only instants before the temperature of the sample is ramped. Results from experiments in helium, CO 2 , and steam at pressures up to 30 bar (1000 °C s -1 to 1,000 °C) have been compared for experiments extending to 60 s at peak temperature. The occurrence of a minimum in the conversion vs pressure diagrams, previously observed by numerous researchers, appears to be related to the reactivity of the gasifying agent and the holding time. The minimum, observed at shorter holding times in steam compared to CO 2 , appears related to the consumption of secondary char deposited during the pyrolysis stage. At 10 and 20 bar, the sample appears to be completely consumed in steam in about 60 s, while after 60 s in CO 2 , the process appeared to have reached completion at about 92% at 30 bar (∼80% at 10 bar), apparently due to deactivation of char by prolonged exposure to high temperatures. By contrast, chars withdrawn from a pilotplant gasifier fluidized with steam and air appear to be relatively unreactive. Larger particle sizes used in the pilot plant (d p < 3 mm vs 105-152 µm) tend to enhance tar repolymerization and longer exposures at high temperature, required for the consumption of these larger particles, appear to have reduced the reactivity of the pilot-plant chars.

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“…There is hardly any reaction function model reported specifically on the catalyst regeneration via coke-steam gasification. However, the reaction kinetics of coal char , and petroleum coke , gasification has been fully studied. The typical reaction models ,, for coke gasification are mainly involved in the shrinking core model and homogeneous model, respectively.…”

Section: Materials and Methodsmentioning

confidence: 99%

“…The previous studies were mainly involved in regenerating coke-containing catalyst via air combustion, − and few publications for FCC catalyst regeneration via coke gasification are found. However, the characteristics and kinetics of coke-steam gasification for carbonaceous materials have been widely studied, − such as coal, petroleum coke, and oil shale, mainly using thermogravimetric (TG) analysis. TG measurement for the reaction kinetics is based on the weight loss data of the samples at different atmospheres under a specified heating program.…”

Section: Introductionmentioning

confidence: 99%

Characteristics and Kinetics of Coked Catalyst Regeneration via Steam Gasification in a Micro Fluidized Bed

Zhang

Mei-qin

Sun

et al. 2014

Ind. Eng. Chem. Res.

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Petroleum residue cracking combined coke gasification (RCCG) process was proposed to regenerate the catalyst via coke-steam gasification for syngas production, thus to solve the problem of excessive heat generated via coke combustion in the industrial fluid catalytic cracking (FCC) process. A commercial FCC catalyst and a bifunctional (BF) catalyst were used as the candidates for the RCCG process, and the BF catalyst was specially designed with both catalytic effects of oil cracking and coke gasification. The regeneration characteristics and kinetics of FCC and BF catalysts were studied using a micro fluidized bed. The results showed that high-quality syngas was produced when regenerating the catalysts via steam gasification and the sum of H2 and CO in the produced gas was over 80 vol % under electrically heated condition.The gasification rate first increased with increasing carbon conversion and then slowly decreased. In comparison with FCC catalyst, the regeneration time of BF catalyst was shortened by more than 30% via addition of alkaline metal oxides and adjustment of its pore size. Homogenous model (HM) and shrinking core model (SCM) were used to calculate the regeneration kinetic parameters of coked catalysts. It was found that the activation energies from these two models were close to each other, while HM had a better fitting relevance for the data than SCM. The activation energy of BF catalyst regeneration was about 115 kJ·mol–1, lower than that of FCC catalyst (150 kJ·mol–1), demonstrating that BF catalyst was easier to regenerate via coke gasification and also justified its bifunctional characteristics. The activation energy of coke gasification on BF catalyst could be further decreased to 45 kJ·mol–1 when introducing 3% oxygen as the gasification reagent.

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Factors affecting the reactivity of chars and cokes during low-temperature (640 .degree.C) steam gasification

Cited by 16 publications

References 1 publication

Catalytic effect of black liquor on the gasification reactivity of petroleum coke

Catalytic effect of black liquor on the gasification reactivity of petroleum coke

Coal Gasification in CO₂ and Steam: Development of a Steam Injection Facility for High-Pressure Wire-Mesh Reactors

Characteristics and Kinetics of Coked Catalyst Regeneration via Steam Gasification in a Micro Fluidized Bed

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Factors affecting the reactivity of chars and cokes during low-temperature (640 .degree.C) steam gasification

Cited by 16 publications

References 1 publication

Catalytic effect of black liquor on the gasification reactivity of petroleum coke

Catalytic effect of black liquor on the gasification reactivity of petroleum coke

Coal Gasification in CO2 and Steam: Development of a Steam Injection Facility for High-Pressure Wire-Mesh Reactors

Characteristics and Kinetics of Coked Catalyst Regeneration via Steam Gasification in a Micro Fluidized Bed

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Coal Gasification in CO₂ and Steam: Development of a Steam Injection Facility for High-Pressure Wire-Mesh Reactors