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- Feng, Bo, et al.
(author)
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Mechanisms of N2O Formation from Char Combustion
- 1996
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In: Energy & Fuels. - 1520-5029 .- 0887-0624. ; 10:1, s. 203-208
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Journal article (peer-reviewed)abstract
- This paper describes an experimental study on N2O and NOx emission from char combustion. Experiments have been carried out in a fixed bed reactor in the temperature range of 973−1323 K. Oxygen concentrations for combustion, temperature, and char type have been found to have strong effects on both N2O and NOx emissions. With an increasing temperature, N2O reaches a peak at 1073 K and then decreases with temperature. At the same time NOx remains nearly the same. When oxygen concentration increases, the concentration of N2O increases and NOx first increases and then decreases. The char with higher nitrogen content emits more N2O, indicating that nitrogen oxides come from char-N. When NO is included in the inlet gases, much more N2O is produced from char combustion. This suggests that the reaction of NO + O2 + char is the main pathway for N2O formation. Another pathway, i.e., the homogeneous oxidation of HCN from the gasfication of char, seems to be important as well.
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- Feng, Bo, et al.
(author)
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Nitrogen oxides emission from a circulating fluidized bed combustor
- 1998
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In: International Journal of Energy Research. - 1099-114X .- 0363-907X. ; 20:11, s. 1015-1025
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Journal article (peer-reviewed)abstract
- Experiments were carried out in a pilot-scale circulating fluidized bed (CFB) coal combustor to investigate the mechanism of N,O formation, nitrogen oxides (including NO, and N,O) emission and the effect of temperature, excess air ratio, recirculation ratio, etc. The concentrations of nitrous oxide and nitric oxide were measured along the height of the CFB furnace. N,O concentration increased with height, and in the exit of the combustor N,O reached the highest level. NO,, however, decreased with height, showing the inverse trend compared with N,O. The N,O emission decreased sharply with the rise of temperature at the bottom of the combustor; at the same time, the NO, concentration increased.
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- Peirano, Eric, 1966, et al.
(author)
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Estimates of turbulence mechanisms in circulating fluidized bed combustors
- 1998
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In: Powder Technology. - 1873-328X .- 0032-5910. ; 96:2, s. 90-105
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Journal article (peer-reviewed)abstract
- Estimates of the characteristic time scales (particle relaxation time, eddy-particle interaction time, interparticle collision time), and the energy dissipation mechanisms are performed together with a turbulent kinetic energy budget, for a simple equilibrium shear flow with conditions similar to those of a circulating fluidized bed (CFB) combustor. Based on dimensional analysis, the influence of five parameters is investigated: the Eulerian integral length scale in the gas phase, the gas-particle density ratio, the mean velocity gradient, the particle diameter, and the particle volume fraction. The results show significant differences between particles of Geldart groups A and B regarding response to gas phase turbulence, transition from dense to dilute suspensions, pressure and temperature dependence, and also energy dissipation mechanisms.
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