International Scientific Journal

Thermal Science - Online First

online first only

A kinetic evaluation on no2 formation in the post-flame region of pressurized oxy-combustion process

Pressurized oxy-combustion is a promising technology that can significantly reduce the energy penalty associated with first generation oxy-combustion for CO2 capture in coal-fired power plants. However, higher pressure enhances the production of strong acid gases, including NO2 and SO3, aggravating the corrosion threat during flue gas recirculation. In the flame region, high temperature NOx exists mainly as NO, while conversion from NO to NO2 happened in post-flame region. In this study, the conversion of NO → NO2 has been kinetically evaluated under representative post-flame conditions of pressurized oxy-combustion after validating the mechanism (80 species and 464 reactions), which includes nitrogen and sulfur chemistry based on GRI-Mech 3.0. The effects of residence time, temperature, pressure, major species (O2/H2O), and minor or trace species (CO/SOx) on NO2 formation are studied. The calculation results show that when pressure is increased from 1 to 15 bar, NO2 is increased from 1 to 60 ppm, and the acid dew point increases by over 80ºC. Higher pressure and temperature greatly reduce the time required to reach equilibrium, e.g., at 15 bar and 1300ºC, equilibrium is reached in 1 millisecond and the NO2/NO is about 0.8%. The formation and destruction of NO2 is generally through the reversible reactions: NO+O+M=NO2+M, HO2+NO=NO2+OH, and NO+O2=NO2+O. With increasing pressure and decreasing temperature, O plays a much more important role than HO2 in the oxidation of NO. A higher water vapor content accelerates NO2 formation in all cases by providing more O and HO2 radicals. The addition of CO or SO2 also promotes the formation of NO2. Finally, NO2 formation in a Pressurized oxy-combustion furnace is compared with that in a practical atmospheric air-combustion furnace and the comparison show that NO2 formation in a Pressurized oxy-combustion furnace can be over 10 times that of an atmospheric air-combustion furnace.
PAPER REVISED: 2020-07-31
PAPER ACCEPTED: 2020-08-02
  1. Axelbaum, R.L., et al., Advances in Pressurized Oxy-Combustion for Carbon Capture, CornerStone. 4. (2016), 2, pp. 52-56
  2. Gopan, A., et al., Process design and performance analysis of a Staged, Pressurized Oxy-Combustion (SPOC) power plant for carbon capture, Applied Energy, 125. (2014), 125, pp. 179-188
  3. Gopan, A., et al., Effect of operating pressure and fuel moisture on net plant efficiency of a staged, pressurized oxy-combustion power plant, International Journal of Greenhouse Gas Control, 39. (2015), pp. 390-396
  4. Murciano, L.T., et al., Sour compression process for the removal of SOx and NOx from oxyfuel-derived CO2, Energy Procedia, 4. (2011), pp. 908-916
  5. Ting, T., et al., Laboratory investigation of high pressure NO oxidation to NO2 and capture with liquid and gaseous water under oxy-fuel CO2 compression conditions, International Journal of Greenhouse Gas Control, 18. (2013), pp. 15-22
  6. Normann, F., et al., Nitrogen and sulphur chemistry in pressurised flue gas systems: A comparison of modelling and experiments, International Journal of Greenhouse Gas Control, 12. (2013), pp. 26-34
  7. Morrison, M., et al., Rate and mechanism of gas-phase oxidation of parts-per-million concentrations of nitric oxide, Industrial & Engineering Chemistry Fundamentals, 5. (1966), 2, pp. 175-181
  8. Atkinson, R., et al., Evaluated kinetic and photochemical data for atmospheric chemistry: Part 1-gas phase reactions of O x, HO x, NO x and SO x species, Atmospheric Chemistry and Physics Discussions, 3. (2003), 6, pp. 6179-6699
  9. Greig, J.,P. Hall, Thermal oxidation of nitric oxide at low concentrations, Transactions of the Faraday Society, 63. (1967), pp. 655-661
  10. Hori, M., et al. An experimental and kinetic calculation of the promotion effect of hydrocarbons on the NO-NO2 conversion in a flow reactor,Symposium (International) on Combustion,1998,27, pp. 389-396
  11. Rasmussen, C.L., et al., Sensitizing effects of NO x on CH 4 oxidation at high pressure, Combustion and Flame, 154. (2008), 3, pp. 529-545
  12. Glarborg, P., et al., Interactions of CO, NOx and H2O under post-flame conditions, Combustion science and technology, 110. (1995), 1, pp. 461-485
  13. Rasmussen, C.L., et al., Experimental measurements and kinetic modeling of CO/H2/O2/NOx conversion at high pressure, International Journal of Chemical Kinetics, 40. (2008), 8, pp. 454-480
  14. Mueller, M., et al., Flow reactor studies and kinetic modeling of the H2/O2/NOx and CO/H2O/O2/NOx reactions, International Journal of Chemical Kinetics, 31. (1999), 10, pp. 705-724
  15. Gersen, S., et al., Ignition-promoting effect of NO 2 on methane, ethane and methane/ethane mixtures in a rapid compression machine, Proceedings of the Combustion Institute, 33. (2011), 1, pp. 433-440
  16. Krzywanski, J.,W. Nowak, Neurocomputing approach for the prediction of NOx emissions from CFBC in air-fired and oxygen-enriched atmospheres, Journal of Power Technologies, 97. (2017), pp. 75-84
  17. Liu, H.,B.M. Gibbs, The influence of limestone addition at different positions on gaseous emissions from a coal-fired circulating fluidized bed combustor, Fuel, 77. (1998), 14, pp. 1569-1577
  18. Mueller, M., et al., Kinetic modeling of the CO/H2O/O2/NO/SO2 system: Implications for high‐pressure fall‐off in the SO2+ O (+ M)= SO3 (+ M) reaction, International Journal of Chemical Kinetics, 32. (2000), 6, pp. 317-339
  19. Pang, L., et al., Experimental Investigation of Oxy-coal Combustion in a 15 kWth Pressurized Fluidized Bed Combustor, Energy and Fuels, 33. (2019), 3, pp. 1694-1703
  20. Duan, Y., et al., Observation of simultaneously low CO, NOx and SO2 emission during oxycoal combustion in a pressurized fluidized bed, Fuel, 242. (2019), pp. 374-381
  21. Dayma, G.,P. Dagaut, Effects of air contamination on the combustion of hydrogen—effect of NO and NO2 addition on hydrogen ignition and oxidation kinetics, Combustion science and technology, 178. (2006), 10-11, pp. 1999-2024
  22. Dagaut, P., et al., A jet-stirred reactor for kinetic studies of homogeneous gas-phase reactions at pressures up to ten atmospheres (≈1 MPa), Journal of Physics E Scientific Instruments, 19. (1986), 3, p. 207
  23. Allen, M.T., et al., The decomposition of nitrous oxide at 1.5 P 10.5 atm and 1103 T 1173 K, International Journal of Chemical Kinetics, 27. (1995), 9, pp. 883-909
  24. Smith, G.P., et al., GRI-Mech 3.0, 1999, URL (2011),
  25. Glarborg, P., et al., Impact of SO2 and NO on CO oxidation under post‐flame conditions, International Journal of Chemical Kinetics, 28. (1996), 10, pp. 773-790
  26. Kee, R.J., et al., CHEMKIN-III: A FORTRAN chemical kinetics package for the analysis of gas-phase chemical and plasma kinetics, 'Report, United States, 1996.
  27. Wang, X., et al., Kinetic investigation of the SO2 influence on NO reduction processes during methane reburning, Asia‐Pacific Journal of Chemical Engineering, 5. (2010), pp. 902-908
  28. Bendtsen, A.B., et al., Visualization methods in analysis of detailed chemical kinetics modelling, Computers & Chemistry, 25. (2001), 2, pp. 161-170
  29. Wang, X., et al., Synergistic SOx/NOx chemistry leading to enhanced SO3 and NO2 formation during pressurized oxy-combustion, Reaction Kinetics Mechanisms and Catalysis, 123. (2018), 2, pp. 313-322
  30. Senior, C.L., et al., Gas-phase transformations of mercury in coal-fired power plants, Fuel Processing Technology, 63. (2000), 2, pp. 197-213
  31. Tan, Y., et al., Combustion characteristics of coal in a mixture of oxygen and recycled flue gas, Fuel, 85. (2006), 4, pp. 507-512
  32. Gao, Z., et al., Heat Transfer Characteristics of Boiler Convective Heating Surface Under Pressurized Oxygen-fuel Combustion Conditions