Ilmenite as alternative bed material for the combustion of coal and biomass blends in a fluidised bed combustor to improve combustion performance and reduce agglomeration tendency

Co-firing coal and biomass has the potential to reduce GHG emissions. However, high levels of alkali and alkaline metals in biomass ash can bring additional issues to the operation of coal-fired boilers. This study investigates the effects of ilmenite as the bed material on CO and NOx emissions and...

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Vydané v:	Energy (Oxford) Ročník 239; s. 121913
Hlavní autori:	Garcia, Eduardo, Liu, Hao
Médium:	Journal Article
Jazyk:	English
Vydavateľské údaje:	Oxford Elsevier Ltd 15.01.2022 Elsevier BV
Predmet:	Agglomerates Agglomeration air Alkali metals Ash Ashes Bed material Biomass Biomass burning Bituminous coal Co-combustion of coal and biomass Coal Combustion Combustion chambers Combustion efficiency Combustion performance Cyclones Emissions Emissions control energy Fluidised bed combustion Fluidized bed combustion Fluidized beds Greenhouse gases Ilmenite Metals Nitrogen oxides quartz Sand Silica Silicon dioxide Wheat straw Fluidised bed combustion Co-combustion of coal and biomass Agglomeration Combustion performance Ilmenite
ISSN:	0360-5442, 1873-6785
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Shrnutí:	Co-firing coal and biomass has the potential to reduce GHG emissions. However, high levels of alkali and alkaline metals in biomass ash can bring additional issues to the operation of coal-fired boilers. This study investigates the effects of ilmenite as the bed material on CO and NOx emissions and combustion efficiency of a coal and biomass blend, and the agglomeration tendency of the bed material with a pilot-scale (30 kWth) bubbling fluidised bed combustor. The experiments were carried out at 900 °C using a bituminous coal blended with wheat straw pellets at 40 wt% as the fuel and silica sand as the baseline bed material. Samples of agglomerates collected from the combustor and cyclone ash were characterised by SEM-EDS, XRD, and XRF. The results revealed that ilmenite could reduce the level of excess air required to achieve complete combustion due to lower CO emissions and less efficiency loss compared to silica sand. However, ilmenite increased NOx emissions. Furthermore, the characterisation of the obtained agglomerates and cyclone ash showed that ilmenite could hinder the K-rich molten substance attachment to the bed material, leading to significantly smaller agglomerates and hence less tendency towards defluidisation in comparison to silica sand. •Coal and biomass co-combusted in a pilot-scale (30 kWth) bubbling fluidised bed.•Ilmenite as bed material led to lower CO emissions and less efficiency loss.•Less and smaller agglomerates were found when ilmenite was used as the bed material.•Ilmenite could reduce the tendency of agglomeration and defluidisation.•Ilmenite improves combustion performance of coal and biomass blends.
Bibliografia:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 content type line 23
ISSN:	0360-5442 1873-6785
DOI:	10.1016/j.energy.2021.121913