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NOx emission reduction by staged combustion in grate combustion of biomass fuels and fuel mixtures

Abstract

NOx and N2O emissions have been investigated for different pelletized biomass fuels and fuel mixtures thereof both with and without air staging in a grate fired multi-fuel reactor. The fuels investigated are wood, demolition wood and coffee waste, and selected mixtures of these. The multi-fuel reactor was operated at close to constant operating conditions due to impactor (ELPI) measurements, with a total excess air ratio of about 1.6, and a primary excess air ratio of about 0.8 in the air staging experiments. The reactor set point temperature was held constant at 850 °C. NOx emission levels as a function of air supply mode and fuel nitrogen content are reported, showing a large NO x reduction potential, up to 91% and corresponding to less than 20 ppm NO x at 11% O 2 for a fuel containing about 3 wt.% fuel-N, using air staging. The effect on N2O, however, is adverse at the selected set point temperature and optimum primary excess air ratio for NOx reduction. The effect of fuel mixing and fuel nitrogen content on the conversion of fuel nitrogen to NO x is also reported and discussed. Fuel mixing has a positive influence on the NOx emission level, but a negative influence on the overall conversion factor for fuel-N to NOx and N2O. © 2012 Elsevier Ltd. All rights reserved.

Category

Academic article

Client

  • Research Council of Norway (RCN) / 193817

Language

English

Author(s)

Affiliation

  • Norwegian University of Science and Technology
  • SINTEF Energy Research / Termisk energi
  • University of Belgrade
  • SINTEF Energy Research

Year

2012

Published in

Fuel

ISSN

0016-2361

Volume

98

Page(s)

29 - 40

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