Simulation of NO_xEmission in Circulating Fluidized Beds Burning Low-grade Fuels^†

Abstract

Nitrogen oxides are a major environmental pollutant resulting from combustion. This paper presents a modeling study of pollutant NO x emission resulting from low-grade fuel combustion in a circulating fluidized bed. The simulation model accounts for the axial and radial distribution of NO x emission in a circulating fluidized bed (CFB). The model results are compared with and validated against experimental data both for small-size and industrial-size CFBs that use different types of low-grade fuels given in the literature. The present study proves that CFB combustion demonstrated by both experimental data and model predictions produces low and acceptable levels of NO x emissions resulting from the combustion of low-grade fuels. Developed model can also investigate the effects of different operational parameters on overall NO x emission. As a result of this investigation, both experimental data and model predictions show that NO x emission increases with the bed temperature but decreases with excess air if other parameters are kept unchanged.

Data Analysis and Symbolic Regression Models for Predicting CO and NOx Emissions from Gas Turbines

“…The issue of the relationship between CO and NO x emissions was mentioned in [19,20]. We calculated the correlation coefficients between CO and NO x emissions for the testing sets and the predictions of the obtained models.…”

Experimental Research on the Conversion of Fuel Nitrogen in the Postcombustion Chamber of the Circulating Fluidized Bed

“…The circulating fluidized bed (CFB) boiler has a de-NO x advantage over the pulverized coal boiler. − Traditional CFB combustion has difficulty reaching ultralow NO x emission standards. − Tourunen et al . found that NO x emissions from CFB were even more sensitive to oxygen concentration rather than combustion temperature.…”

Study on the combustion and NOx emission characteristics of low rank coal in a circulating fluidized bed with post‐combustion

“…[1][2][3][4][5] Compared to other combustion methods, CFB boilers are advantageous for combusting low rank coal, owing to their high combustion efficiency, lower abrasion to heating surface, limited ash deposition, and high desulphurization efficiency. [6][7][8][9][10][11][12] Neimeng coals mainly occur in the Early Cretaceous and Paleogene strata, [13] and belong to the category of low rank coal. In northeastern China, Neimeng coals are the dominant fuel for a large number of CFB boilers, which emit NO x at 200-300 mg/m 3 , significantly higher than the specified 100 mg/m 3 limit in China.…”

“…Circulating fluidized bed (CFB) technology has emerged as a highly utilized steam generation technology owing to its attractive features of fuel flexibility, and the number of CFB boiler installations has been growing exponentially in the last decades . Compared to other combustion methods, CFB boilers are advantageous for combusting low rank coal, owing to their high combustion efficiency, lower abrasion to heating surface, limited ash deposition, and high desulphurization efficiency . Neimeng coals mainly occur in the Early Cretaceous and Paleogene strata, and belong to the category of low rank coal.…”