Effect of biomass particle size and air superficial velocity on the gasification process in a downdraft fixed bed gasifier. An experimental and modelling study

Fluixá, Francisco V. Tinaut; Melgar, Andrés; Pérez, Juan F.; Horrillo, Alfonso

doi:10.1016/j.fuproc.2008.04.010

Cited by 221 publications

(84 citation statements)

References 38 publications

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“…Syamlal and Bisset [35] and Tinaut et al [36] reported a model treating the biomass drying step as a chemical reaction with kinetic rate constants obtained from Arrhenius law. Lee et al [37] and Di…”

Section: Dryingmentioning

confidence: 99%

A CFD study of biomass pyrolysis in a downer reactor equipped with a novel gas–solid separator-II thermochemical performance and products

Hassan

Ocone

et al. 2015

Fuel Processing Technology

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Highlight A CFD model is used to simulate biomass fast pyrolysis in a downer reactor. An Eulerian-Eulerian approach with a single global pyrolysis reaction is used. A novel gas-solid separator was used to control the gas residence time. Predicted pyrolysis yield is in good agreement with reported literature data. AbstractA Eulerian-Eulerian CFD model was used to investigate the fast pyrolysis of biomass in a downer reactor equipped with a novel gas-solid separation mechanism. The highly endothermic pyrolysis reaction was assumed to be entirely driven by an inert solid heat carrier (sand). A one-step global pyrolysis reaction, along with the equations describing the biomass drying and heat transfer, was implemented in the hydrodynamic model presented in part I of this study (Fuel Processing Technology, V126,(366)(367)(368)(369)(370)(371)(372)(373)(374)(375)(376)(377)(378)(379)(380)(381)(382). The predictions of the gas-solid separation efficiency, temperature distribution, residence time and the pyrolysis product yield are presented and discussed. For the operating conditions considered, the devolatilisation efficiency was found to be above 60% and the yield composition in mass fraction was 56.85% bio-oil, 37.87% bio-char and 5.28% non-condensable gas (NCG). This has been found to agree reasonably well with recent relevant published experimental data. The novel gas-solid separation mechanism allowed achieving greater than 99.9% separation efficiency and < 2 s pyrolysis gas residence time. The model has been found to be robust and fast in terms of computational time, thus has the great potential to aid in future design and optimisation of the biomass fast pyrolysis process.

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Section: Dryingmentioning

confidence: 99%

A CFD study of biomass pyrolysis in a downer reactor equipped with a novel gas–solid separator-II thermochemical performance and products

Hassan

Ocone

et al. 2015

Fuel Processing Technology

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show abstract

“…Furthermore most of the char used for gasification reactivity test is prepared in a separate reactor. The various kinds of biomass species have so far been tested by many researchers while under different conditions, so the unified comparison between various kinds of biomass under the unified condition was difficult (Tinaut et al, 2008;Fushimi et al, 2003;Okumura & Okazaki, 2009;Marquez-Montesinos et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Effect of Carbonaceous Deposit on Bed Particles During Rapid Pyrolysis on Gasification Rate of Biomass Char in Fluidized Bed

Murayama¹,

Iwasaki²,

Suganuma³

et al. 2014

EER

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Gasification characteristics were evaluated for various biomass samples such as softwoods and hardwoods. They were pyrolyzed at 1000 °C in a small scale fluidized bed under rapid heating condition with N 2 flow. After keeping 10 min at the temperature, the produced char was gasified with 25% CO 2 at 1000 °C. Char gasification characteristic was investigated by monitoring CO producing rate and the effects of woody biomass species on gasification rate and its time variation were examined. The conversion rate, dX/dt was plotted against the value of conversion. As a result, the following characteristic curves were observed mainly for softwoods; at nearly conversion X = 0.05, high reactivity peak was found, CO production was decreased first rapidly and then slowly until X = 0.5, and then almost followed volume reaction behavior. In order to elucidate the cause of this phenomenon, the high temperature char with bed material of alumina in the bed was cooled down under the N 2 flow to the room temperature and the char and alumina particles were separated by sieving. The alumina particles became black which suggests existence of some carbonaceous materials. Then each sample was introduced into the fluidized bed and separately gasified in the same bed. The gasified gas analyses showed that gasification rapidly proceeded for alumina particles only at the first stage of its gasification which explained the peak of gas evolution at low conversion of the continuous in situ pyrolysis/gasification experiments. In case of hardwoods, the amount of carbonaceous materials remaining in bed materials was quite small and it does not affect the results of the in situ pyrolysis/gasification experiments. Gasification difference of the char separately collected depended on their own properties rather than the common properties in their group.

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“…The model describes the influences of moisture content, pressure, equivalence ratio and initial temperature input on dry gas composition, unconverted char, calorific value of gas, gasification efficiency, outlet gas temperature and endothermic heat released in char bed. Tinaut and Francisco (2008) (Tinaut et al, 2008) presented a one-dimensional stationary model for a downdraft gasifier. The model is based on the mass and energy conservation equations, the energy exchange between solid and gas phases, and the heat transfer by radiation from the solid particles.…”

Section: Introduction *mentioning

confidence: 99%

The Impacts of Operational Conditions on Charcoal Syngas Generation using a Modeling Approach

Wang¹,

Hong²

2013

Journal of The Korean Society of Agricultural Engineers

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Effect of biomass particle size and air superficial velocity on the gasification process in a downdraft fixed bed gasifier. An experimental and modelling study

Cited by 221 publications

References 38 publications

A CFD study of biomass pyrolysis in a downer reactor equipped with a novel gas–solid separator-II thermochemical performance and products

A CFD study of biomass pyrolysis in a downer reactor equipped with a novel gas–solid separator-II thermochemical performance and products

Effect of Carbonaceous Deposit on Bed Particles During Rapid Pyrolysis on Gasification Rate of Biomass Char in Fluidized Bed

The Impacts of Operational Conditions on Charcoal Syngas Generation using a Modeling Approach

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