Evaluation of NOx-Reduction Measures for Iron-Ore Rotary Kilns
| Autor: | Christian Fredriksson, Rikard Edland, Jacob Frandsen, Denver Haycock, Colson Johnson, Klas Andersson, Fredrik Normann, Thomas Allgurén, N.L. Smith, Thomas H. Fletcher |
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| Rok vydání: | 2020 |
| Předmět: |
Kiln
020209 energy General Chemical Engineering Pellets Energy Engineering and Power Technology Biomass chemistry.chemical_element 02 engineering and technology engineering.material law.invention 020401 chemical engineering law 0202 electrical engineering electronic engineering information engineering Coal 0204 chemical engineering Rotary kiln NOx business.industry Pulp and paper industry Nitrogen Fuel Technology chemistry Iron ore engineering Environmental science business |
| Zdroj: | Energy & Fuels. 34:4934-4948 |
| ISSN: | 1520-5029 0887-0624 |
| DOI: | 10.1021/acs.energyfuels.9b04091 |
| Popis: | The grate-kiln process is employed for sintering and oxidation of iron-ore pellets. In this process, a fuel (typically coal) is combusted with a large amount of excess air in a rotary kiln, and the high air-to-fuel ratio leads to significant NOx formation. The current Article is an assessment of NOx reduction measures that have been tested in pilot-scale and in full-scale by the Swedish iron-ore company Luossavaara-Kiirunavaara Aktiebolag (LKAB). The results show that the scaling between the full-scale kiln and the pilot-scale kiln is crucial, and several primary measures that reduce NOx significantly in pilot-scale achieve negligible reduction in full-scale. In the investigated full-scale kiln, thermal NOx formation is efficiently suppressed and low compared with the NO formation from the fuel-bound nitrogen (especially char-bound nitrogen). Suppressing the NO formation from the char-bound nitrogen is difficult due to the high amounts of excess air, and all measures tested to alter mixing patterns have shown limited effect. Switching to a fuel with a lower nitrogen content is efficient and probably necessary to achieve low NOx emissions without secondary measures. Simulations show that replacing the reference coal with a biomass that contains 0.1% nitrogen can reduce NOx emissions by 90%. |
| Databáze: | OpenAIRE |
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