Burnout of pulverized biomass particles in large scale boiler – Single particle model approach

Saastamoinen, Jaakko; Aho, Martti; Moilanen, Antero; Sørensen, Lisbet; Clausen, Sønnik; Berg, Mats

doi:10.1016/j.biombioe.2010.01.015

Cited by 42 publications

(31 citation statements)

References 22 publications

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“…While this compared favourably to experimental data presented for a single particle burning in entrained gas flow, a more robust validation would require more extensive experimentally derived data to be produced, covering the range of particle sizes. Other useful single particle modelling approaches have been set out by Haseli et al [9] and Saastamoinen et al [10].…”

Section: Introductionmentioning

confidence: 99%

Single particle flame-combustion studies on solid biomass fuels

Mason

Darvell

Jones

et al. 2015

Fuel

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Combustion of solid biomass in large scale power generation has been recognized as a key technology for the transition to a decarbonized electricity sector in the UK by 2050. Much of the near-term forecast capacity is likely to be by the conversion of existing coal-fired pulverized fuel plant [1]. In such applications, it will be necessary to ensure that the combustion behaviour of the solid biomass fuels is engineered to match, as far as practical, that of the original plant design. While biomass feedstock characteristics vary considerably, one controllable variable for pulverized fuel is the size of the particles.Useful modelling for adaptation and design of boiler plant can be improved with more detailed measurement of the real behaviour of individual particles of the varying fuels. Typical power plant biomass fuels including pine, eucalyptus and willow with particle sizes ranging from up to 3mm [2] and with differing moisture content and aspect ratios were selected for study. Single particles were supported in a water-cooled cover and then exposed above a flame, simulating biomass combustion in a furnace.Measurements of ignition delay, volatile burning time and char burn-out time were undertaken using high speed image capture. Temperatures of the surrounding environment and near to the particle surface were measured with thermocouples and thermometric imaging. Thermo-gravimetric measurements on 2 separate samples complement the single particle measurements as a means of verifying the demarcation between the different stages of combustion and providing kinetic data.Analysis of the data identified correlations between the biomass fundamental characteristics, particle size, and the observed combustion profiles. Empirical expressions for the duration of each combustion stage have been derived. These have been validated with basic modelling including the predicted devolatilisation stage calculated by the FG-Biomass model [3].

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Section: Introductionmentioning

confidence: 99%

Single particle flame-combustion studies on solid biomass fuels

Mason

Darvell

Jones

et al. 2015

Fuel

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“…There may also be a flame around the particle increasing the effective temperature of the ambient [45][46][47]. Then a numerical method can be applied to calculate the particle temperature and mass as function of time [45].…”

Section: Heating Drying and De-volatilization Of A Biomass Particlementioning

confidence: 99%

“…(10), is cumbersome as a sub-model. Drying and pyrolysis take place in narrow temperature ranges inside a biomass particle leading to steep moisture and density distributions even for relatively small particles [46]. Simplified shrinking core models for drying [49,50] and simultaneous drying and pyrolysis [51] have been presented.…”

Section: Heating Drying and De-volatilization Of A Biomass Particlementioning

confidence: 99%

Release Profile of Volatiles in Fluidised Bed Combustion of Biomass

Saastamoinen¹

2014

J Fundam Renewable Energy Appl

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A simplified model for the release profile of volatiles in fluidised and circulating fluidised beds is presented. The location of the release of volatiles in the furnace depends on the interplay of flow of fuel particles affecting their location and heating of fuel particles affecting rates of drying and pyrolysis and consequently the mass of fuel particles. The coupled equations describing heating, de-volatilization including drying, elutriation and movement of particles are solved to find the release profile. Large heavy particles remain in the dense bed whereas light particles are entrained by the gas and elutriated from the bed to the riser. The situation is dynamic, since fuel particles lose weight due to release of moisture and volatiles and decrease in size due to shrinkage affecting their movement and escape from the lower dense bed to the riser. The model is based on the following the fate of a small batch of fuel particles undergoing de-volatilization and elutriation from the dense bed. The model predicts the location of the release of volatiles and the profile of the release of volatiles in the riser. Part of volatiles is released in the dense bed and the rest above the bed in the riser.

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“…Increased energy input into biomass comminution affects the total efficiency of a power plant, and too large particles often cause problems with flame stability and burnout. Fuel characterization plays an important role in combustion modeling [6][7][8][9][10][11]. The surface area and volume of the particle are important parameters since they determine combustion rates and define residence time.…”

Section: Introductionmentioning

confidence: 99%

One way of representing the size and shape of biomass particles in combustion modeling

Trubetskaya

Beckmann²,

Wadenbäck

et al. 2017

Fuel

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a b s t r a c tThis study aims to provide a geometrical description of biomass particles that can be used in combustion models. The particle size of wood and herbaceous biomass was compared using light microscope, 2D dynamic imaging, laser diffraction, sieve analysis and focused beam reflectance measurement. The results from light microscope and 2D dynamic imaging analysis were compared and it showed that the data on particle width, measured by these two techniques, were identical. Indeed, 2D dynamic imaging was found to be the most convenient particle characterization method, providing information on both the shape and the external surface area. Importantly, a way to quantify all three dimensions of biomass particles has been established. It was recommended to represent a biomass particle in combustion models as an infinite cylinder with the volume-to-surface ratio (V/A) measured using 2D dynamic imaging.

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Burnout of pulverized biomass particles in large scale boiler – Single particle model approach

Cited by 42 publications

References 22 publications

Single particle flame-combustion studies on solid biomass fuels

Single particle flame-combustion studies on solid biomass fuels

Release Profile of Volatiles in Fluidised Bed Combustion of Biomass

One way of representing the size and shape of biomass particles in combustion modeling

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