OxyFuel Combustion of Coal and the Evolution of NOx

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Oxy-Fuel Combustion of Coal and the Evolution of
NOx

• Ph.d. Student Jacob Brix
• Supervisors Anker Degn Jensen
• Peter Arendt Jensen

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Objectives

• Heat release associated with heterogeneous
  combustion are important for the heat flux
  characteristics of the process.
• Fuel conversion at the boiler exit determines the
  utilization efficiency.
• The time required for char consumption determines
  the size of the boiler.
• NOx emissions decrease in oxy-fuel combustion but
  the reason is not fully understood and can not be
  used in boiler design.

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The Reactors
Isothermal Entrained Flow Reactor (Char Kinetics
NOx)
Fixed Bed Reactor (NOx Particle Temperature)
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Results-Entrained Flow Reactor
Conversions vs. oxygen concentrations at 1373 K
for two different sampling residence times.
Char conversion profiles obtained at 1673 K and
1573 K. The calculated profile is found for a
shrinking sphere in zone III. (? 3.1 vol. O2)(?
3.4 vol. O2)(? 3.2 vol. O2)(o 3.7 vol. O2).
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Results-Fixed Bed Reactor
dp 11.3 mm, 30 vol. O2 in CO2
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Results-Fixed Bed Reactor
dp 1.3 12.1 mm, 30 vol. O2

• The effects of particle radius and particle
  concentration are less pronounced in O2/CO2 than
  in O2/N2.

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Ongoing Work

• Master student Leyre Gómez Navascués is working
  on the setup as part of her project NOx
  Formation in Oxy-Fuel Combustion using lignite
  as fuel.
• Project students Jesper Grossmann and Morten
  Storgård Petersen is working with TGA
  experiments on EFR char as part of their project
  Kinetics for Char Conversion in O2 and CO2.
• Additional experiments using the same bituminous
  coal will be conducted during the fall and winter
  with emphasis on NO reduction on char and the
  influence of CO partial pressure.
• Particle modelling will be used to quantify the
  influence of physical parameters in the fixed bed
  and TGA experiments. A complex model describing
  combustion of multiple particle sizes and char
  morphologies are used to interpret EFR results.

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Tak for opmærksomheden/ Thanks for the Attention !