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Scaling of Pulverized-Fuel Jet Flames That Apply Large Amounts of Excess Air—Implications for NOx Formation

Division of Energy Technology, Chalmers University of Technology, 41296 Göteborg, Sweden
Luossavaara-Kiirunavaara Aktiebolag, Box 952, 97127 Luleå, Sweden
Author to whom correspondence should be addressed.
Energies 2019, 12(14), 2680;
Received: 21 May 2019 / Revised: 2 July 2019 / Accepted: 10 July 2019 / Published: 12 July 2019
(This article belongs to the Section Energy and Environment)
PDF [5060 KB, uploaded 12 July 2019]


Measures to reduce nitrogen oxides (NOx) formation in industrial combustion processes often require up-scaling through pilot-scale facilities prior to being implemented in commercial scale, and scaling is therefore an important aspect of achieving lower NOx emissions. The current paper is a combined experimental and modelling study that aims to expand the understanding of constant velocity scaling for industrial jet flames applying high amounts of excess air. These types of flames are found in e.g., rotary kilns for production of iron ore pellets. The results show that, even if the combustion settings, velocity, and temperature profiles are correctly scaled, the concentration of oxygen experienced by the fuel during char combustion will scale differently. As the NO formation from the char combustion is important in these flames, the differences induced by the scaling has important impacts on the efficiencies of the applied primary measures. Increasing the rate of char combustion (to increase the Damköhler number), by using, for example, smaller-sized particles, in the pilot-scale is recommended to improve scaling. View Full-Text
Keywords: combustion; pollution; NOx; scaling; flame; rotary kiln combustion; pollution; NOx; scaling; flame; rotary kiln

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Edland, R.; Normann, F.; Allgurén, T.; Fredriksson, C.; Andersson, K. Scaling of Pulverized-Fuel Jet Flames That Apply Large Amounts of Excess Air—Implications for NOx Formation. Energies 2019, 12, 2680.

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