A comparative reactivity and kinetic study on the combustion of coal–biomass char blends

Kastanaki, Eleni; Vamvuka, Despina

doi:10.1016/j.fuel.2005.11.004

Cited by 200 publications

(80 citation statements)

References 18 publications

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“…It should be noted that in their study, the flow of nitrogen in a TGA did sweep the volatile products away from the devolatilizing fuels, therefore, the devolatilizing gas could not easily interact with the char, and thus the additive behavior of the products prevailed. These observations are well contrasted with results of [43,47,82,83] who identified some synergy.…”

Section: Devolatilization/pyrolysiscontrasting

confidence: 89%

A Review of Thermal Co-Conversion of Coal and Biomass/Waste

2014

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Abstract:Biomass is relatively cleaner than coal and is the only renewable carbon resource that can be directly converted into fuel. Biomass can significantly contribute to the world's energy needs if harnessed sustainably. However, there are also problems associated with the thermal conversion of biomass. This paper investigates and discusses issues associated with the thermal conversion of coal and biomass as a blend. Most notable topics reviewed are slagging and fouling caused by the relatively reactive alkali and alkaline earth compounds (K 2 O, Na 2 O and CaO) found in biomass ash. The alkali and alkaline earth metals (AAEM) present and dispersed in biomass fuels induce catalytic activity during co-conversion with coal. The catalytic activity is most noticeable when blended with high rank coals. The synergy during co-conversion is still controversial although it has been theorized that biomass acts like a hydrogen donor in liquefaction. Published literature also shows that coal and biomass exhibit different mechanisms, depending on the operating conditions, for the formation of nitrogen (N) and sulfur species. Utilization aspects of fly ash from blending coal and biomass are discussed. Recommendations are made on pretreatment options to increase the energy density of biomass fuels through pelletization, torrefaction and flash pyrolysis to reduce transportation costs.

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Section: Devolatilization/pyrolysiscontrasting

confidence: 89%

A Review of Thermal Co-Conversion of Coal and Biomass/Waste

2014

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“…Other authors [34][35][36] also observed a similar behaviour. Their coal-biomass blend curves resembled those of the coal sample, as this component was present in a larger proportion during the co-combustion of different coal and biomass blends.…”

Section: Interactions Between the Components Of The Blendssupporting

confidence: 69%

Kinetic models comparison for non-isothermal steam gasification of coal–biomass blend chars

Fermoso

Gil

Pevida

et al. 2010

Chemical Engineering Journal

121

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The non-isothermal thermogravimetric method (TGA) was applied to a bituminous coal (PT), two types of biomass, chestnut residues (CH) and olive stones (OS), and coalbiomass blends in order to investigate their thermal reactivity under steam. Fuel chars were obtained by pyrolysis in a fixed-bed reactor at a final temperature of 1373 K for 30 min. The gasification tests were carried out by thermogravimetric analysis from room temperature to 1373 K at heating rates of 5, 10 and 15 K min -1 . After blending, no significant interactions were detected between PT and CH during co-gasification, whereas deviations from the additive behaviour were observed in the PT-OS blend.However, for the two coal-biomass blends, the gasification behaviour resembled that of the individual coal, as this component constituted the larger proportion of the blend. The temperature-programmed reaction (TPR) technique was employed at three different heating rates to analyze noncatalytic gas-solid reactions. Three nth-order representative gas-solid models, the volumetric model (VM), the grain model (GM) and the random pore model (RPM) were applied in order to describe the reactive behaviour of the chars during steam gasification. From these models, the kinetic parameters were determined.The best model for describing the reactivity of the PT, PT-CH and PT-OS samples was the RPM model. VM was the model that best fitted the CH sample, whereas none of the models was suitable for the OS sample.

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“…In the algae chars, the temperature corresponding to the first oxidation peak increased from 433.5 °C to 472.8 °C with the increase in gasification temperature from 760 to 960 °C. Earlier studies on the combustion of biomass pyrolysis chars reported peak decomposition to occur at 378 °C for olive kernels, 412 °C for cotton residue, and 509 °C for wood (Kastanaki and Vamvuka 2006). It is worth noting that, in the current study, the third decomposition stage, i.e., char oxidation, for the raw algae took place at a higher temperature, 515.7 °C, than for the gasification chars.…”

Section: Tga Characterization Of Raw Algae and Biocharmentioning

confidence: 47%

Gasification of Phycoremediation Algal Biomass

Sharara¹,

Sadaka²

2015

BioResources

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Microalgae have been utilized in wastewater treatment strategies in various contexts. Uncontrolled algal species are a cheap and effective remediation strategy. This study investigates the thermochemical potential of wastewater treatment algae (phycoremediation) as a means to produce renewable fuel streams and bio-products. Three gasification temperature levels were investigated in an auger gasification platform: 760, 860, and 960 °C. Temperature increases resulted in corresponding increases in CO and H2 concentrations in the producer gas from 12.8% and 4.7% at 760 °C to 16.9% and 11.4% at 960 °C, respectively. Condensable yields ranged between 15.0% and 16.6%, whereas char yields fell between 46.0% and 51.0%. The high ash content (40% on a dry basis) was the main cause of the elevated char yields. On the other hand, the relatively high yields of condensables and a high carbon concentration in the char were attributed to the low conversion efficiency in this gasification platform. Combustion kinetics of the raw algae, in a thermogravimetric analyzer, showed three consecutive stages of weight loss: drying, devolatilization, and char oxidation. Increasing the algae gasification temperature led to increases in the temperature of peak char oxidation. Future studies will further investigate improvements to the performance of auger gasification.

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A comparative reactivity and kinetic study on the combustion of coal–biomass char blends

Cited by 200 publications

References 18 publications

A Review of Thermal Co-Conversion of Coal and Biomass/Waste

A Review of Thermal Co-Conversion of Coal and Biomass/Waste

Kinetic models comparison for non-isothermal steam gasification of coal–biomass blend chars

Gasification of Phycoremediation Algal Biomass

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