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Energies 2016, 9(11), 940;

Effect of Air Staging Ratios on the Burning Rate and Emissions in an Underfeed Fixed-Bed Biomass Combustor

Industrial Engineering School, University of Vigo, Campus Lagoas-Marcosende, s/n, 36310 Vigo, Spain
Author to whom correspondence should be addressed.
Academic Editor: Tariq Al-Shemmeri
Received: 8 September 2016 / Revised: 31 October 2016 / Accepted: 4 November 2016 / Published: 11 November 2016
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This experimental work studies a small-scale biomass combustor (5–12 kW) with an underfed fixed bed using low air staging ratios (15%–30%). This document focuses on the influence of the operative parameters on the combustion process, so gaseous emissions and the distribution and concentration of particulate matter have also been recorded. The facility shows good stability and test repeatability. For the studied airflow ranges, the results show that increasing the total airflow rate does not increase the overall air excess ratio because the burning rate is proportionally enhanced (with some slight differences that depend on the air staging ratio). Consequently, the heterogeneous reactions at the bed remain in the so-called oxygen-limited region, and thus the entire bed operates under sub-stoichiometric conditions with regards of the char content of the biomass. In addition, tests using only primary air (no staging) may increase the fuel consumption, but in a highly incomplete way, approaching a gasification regime. Some measured burning rates are almost 40% higher than previous results obtained in batch combustors due to the fixed position of the ignition front. The recorded concentration of particulate matter varies between 15 and 75 mg/Nm3, with a main characteristic diameter between 50 and 100 nm. View Full-Text
Keywords: biomass combustion; fixed-bed; air staging; bed stoichiometry; burning rate biomass combustion; fixed-bed; air staging; bed stoichiometry; burning rate

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Regueiro, A.; Patiño, D.; Porteiro, J.; Granada, E.; Míguez, J.L. Effect of Air Staging Ratios on the Burning Rate and Emissions in an Underfeed Fixed-Bed Biomass Combustor. Energies 2016, 9, 940.

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