Oxy-fuel combustion of coal and biomass, the effect on radiative and convective heat transfer and burnout

Smart, J. P.; Patel, Rajeshriben; Riley, Gerry

doi:10.1016/j.combustflame.2010.07.013

Cited by 79 publications

(39 citation statements)

References 13 publications

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“…Smart et al [21] also observed an improvement in burnout by co-firing coal and biomass (shea meal and sawdust) under both oxy-fuel and air firing conditions. Previous studies on the co-combustion of coal/biomass blends have also shown that the addition of biomass to coal can improve the burnout efficiency of coal to a certain degree [22].…”

Section: Burnoutmentioning

confidence: 93%

“…On the other hand, since biomass has a lower calorific value and higher moisture content than coal, the flame temperature may be reduced and the radiative heat flux impeded if the concentration of biomass in the blend is too high. This would then reduce the oxidation rate as Smart et al [21] suggested. However, these authors have shown that the positive effect of co-firing with biomass on burnout is dependent on the type of biomass and have observed significant improvements in burnout value when biomass with a high reactivity is used.…”

Section: Burnoutmentioning

confidence: 99%

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Oxy-fuel combustion of coal and biomass blends

Riaza

Gil

Álvarez

et al. 2012

Energy

153

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The ignition temperature, burnout and NO emissions of blends of a semi-anthracite and a high-volatile bituminous coal with 10 and 20 wt.% of olive waste were studied under oxy-fuel combustion conditions in an entrained flow reactor (EFR). The results obtained under several oxy-fuel atmospheres (21%O 2 -79%CO 2 , 30%O 2 -70% CO 2 and 35%O 2 -65%CO 2 ) were compared with those attained in air. The results indicated that replacing N 2 by CO 2 in the combustion atmosphere with 21% of O 2 caused an increase in the temperature of ignition and a decrease in the burnout value. When the O 2 concentration was increased to 30 and 35%, the temperature of ignition was lower and the burnout value was higher than in air conditions. A significant reduction in ignition temperature and a slight increase in the burnout value was observed after the addition of biomass, this trend becoming more noticeable as the biomass concentration was increased. The emissions of NO during oxy-fuel combustion were lower than under air-firing. However, they remained similar under all the oxy-fuel atmospheres with increasing O 2 concentrations. Emissions of NO were significantly reduced by the addition of biomass to the bituminous coal, although this effect was less noticeable in the case of the semianthracite.

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Section: Burnoutmentioning

confidence: 93%

Section: Burnoutmentioning

confidence: 99%

Oxy-fuel combustion of coal and biomass blends

Riaza

Gil

Álvarez

et al. 2012

Energy

153

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“…Co-firing biomass with fossil fuels in existing utility boilers is also a feasible technology which can not only significantly reduce CO 2 emissions but also increase the share of renewable energy sources in energy co-firing under oxy-fuel is likely to bring up more uncertainties. Biomass co-firing under oxy-fuel conditions is an attractive option to simultaneously increase the use of renewable energy sources, exploit the favorable synergy effects of biomass/coal cofiring and achieve below-zero CO 2 emissions, which has been very little investigated so far [9][10][11][12]. For instance Smart et al [11] evaluated the impact of co-firing biomass on pollutant formation, burnout and heat transfer under oxy-fuel conditions in a 0.5 MWt combustion test facility.…”

Section: Introductionmentioning

confidence: 99%

“…Biomass co-firing under oxy-fuel conditions is an attractive option to simultaneously increase the use of renewable energy sources, exploit the favorable synergy effects of biomass/coal cofiring and achieve below-zero CO 2 emissions, which has been very little investigated so far [9][10][11][12]. For instance Smart et al [11] evaluated the impact of co-firing biomass on pollutant formation, burnout and heat transfer under oxy-fuel conditions in a 0.5 MWt combustion test facility. Experiments at laboratory scale have been focused on the effects of different co-firing ratios on burnout and NO emissions [12].…”

Section: Introductionmentioning

confidence: 99%

Biomass co-firing under oxy-fuel conditions: A computational fluid dynamics modelling study and experimental validation

Álvarez

Yin

Riaza

et al. 2014

Fuel Processing Technology

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This paper presents an experimental and numerical study on co-firing olive waste (0, 10%, 20% on mass basis) with two coals in an entrained flow reactor under three oxyfuel conditions (21%O 2 /79%CO 2 , 30%O 2 /70%CO 2 and 35%O 2 /65%CO 2 ) and air-fuel condition. Co-firing biomass with coal was found to have favorable synergy effects in all the cases: it significantly improves the burnout while remarkably lowers NO x emissions. The reduced peak temperatures during co-firing can also help to mitigate deposition formation in real furnaces. Co-firing CO 2 -neutral biomass with coals under oxy-fuel conditions can achieve a below-zero CO 2 emission if the released CO 2 is captured and sequestered. The model-predicted burnout and gaseous emissions were compared against the experimental results. A very good agreement was observed, the differences in a range of ±5-10% of the experimental values, which indicates the model can be used to aid in design and optimization of large-scale biomass co-firing under oxy-fuel conditions.

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“…However, the thermal histories of coal particles in the experimental facilities can be different from that in the actual large scale boilers because the scale of flame can affect the heat transfer mechanism of the coal particles. Experimental apparatus with various sizes, e. g., the drop tube furnace (8-60 g-coal/h) [21,22], the small coal jet burner (0.5 kg-coal/h) [11,23], the triple stream burner (0.36-2.16 kg-coal/h) [24,25], the RWTH furnace (6-7 kg-coal/h) [26,27], the RWEn Combustion Test Facility (70 kg-coal/h) [28], the BEACH furnace (100 kg-coal/h) [13,29,30,31], the IFRF furnace No. 1 (260 kg-coal/h) [32] and the MARINE furnace (300 kg-coal/h) [19,33], have been used to investigate the coal combustion phenomena or to evaluate the combustion characteristics of various coal brands by some researchers.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis on effect of furnace scale on heat transfer mechanism of coal particles in pulverized coal combustion field

Hashimoto

Watanabe

2016

Fuel Processing Technology

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To investigate the effect of the furnace scale on the heat transfer mechanism of coal particles, numerical simulations of coal combustion fields in three different scale furnaces (915 MW th actual large scale boiler, 2.4 MW th and 0.76 MW th test furnaces) were conducted. High accuracy of simulation methods was validated with the measured data. From the comparison of numerical simulations between three different scale furnaces, it was clarified that the particle residence time with high particle temperature for a small scale furnace is shorter than that for a large scale furnace even if the particle residence time passing the high temperature gas is the same. This is caused by the insufficient heat gain of particles for a small scale furnace due to the lower radiation heat transfer because of the thinner flame thickness in the small furnace. The sphericity of ash particles from small scale furnaces is lower than that for large scale furnaces due to the shorter particle residence time with high particle temperature. These findings should be considered when the usability of coal brands for actual large scale boilers is evaluated by the fly ash properties from a small scale experimental furnace.

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Oxy-fuel combustion of coal and biomass, the effect on radiative and convective heat transfer and burnout

Cited by 79 publications

References 13 publications

Oxy-fuel combustion of coal and biomass blends

Oxy-fuel combustion of coal and biomass blends

Biomass co-firing under oxy-fuel conditions: A computational fluid dynamics modelling study and experimental validation

Numerical analysis on effect of furnace scale on heat transfer mechanism of coal particles in pulverized coal combustion field

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