A simplified model of nitric oxide emission from a circulating fluidized bed combustor

Analysis of environmental benefits of CFB combustors via one-dimensional model

“…In the dense phase, due to high char concentration especially at the bottom zone fuel related NO formation is higher than the dilute phase. A smaller mean size of char in the combustor will result in a lower emission of NO if other parameters are kept unchanged [25] as clearly seen from Fig. 9a.…”

“…For CFB only 106 reactions with 28 species were used to model the NO x emission. However, a detailed review shows that all N-related reactions have not the same importance [25]. So instead of considering all N-related reactions, one could use only the important reactions for the development of a predictive procedure for the overall NO emission from a CFB combustor.…”

“…They also offer new useful insights into the oxidation reactions of carbons, generally [13]. A large literature concerning these reactions has developed, as evidenced in three reviews [14][15][16] and by the recent publication of many papers in the area [17][18][19][20][21][22][23][24][25]. These works have suggested considerable complexity in the mechanisms of NO reduction and a large variability in reported kinetics.…”

“…However, the maximum deviation is about 5% for SO 2 and NO emissions at the bed height of 36 cm, the secondary air inlet point. Both the release and combustion of volatiles are influencing factors for the production of NO and SO 2 emissions [15,25,56]. In the model, it is assumed that a great amount of the volatile matters is released at the feed point in the combustor [1,5,8] and sulphur and nitrogen are oxidized to SO 2 and NO immediately.…”

“…There are great differences in the hydrodynamics between the dense bed and the dilute region. However, most of the models in the literature do not completely take account of the performance of the dense bed, consider the dense bed as well-mixed distributed flow with constant voidage, and use generally lumped formulation [1][2][3][4][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Experimental evidence has been reported by Svensson et al [29], and Werther and Wein [30] that, the fluid-dynamical behavior of the dense bed is similar to that of bubbling fluidized beds.…”