Numerical Simulation of Low NO_x Combustion Technology in a 100 MW_e Bituminous Coal-Fired Wall Boiler

Abstract

Computational fluid dynamics (CFD) has been applied to evaluate two NO _x reducing schemes in a 100 MW_e per hour (p/h) boiler that uses double volute burners without over-fire-air (OFA). The new schemes involve: a) changing the double volute burners for centrally fuel rich (CFR) burners, and b) using the OFA system in conjunction with a). In analyzing the results of these two schemes, various conclusions were drawn: 1) gas temperatures and related rise rates in the central zone of burners were higher, O₂ and NO _x concentrations were lower; and 2) cross-sectional gas temperature distributions through the burner centers in scheme employing b) is higher than that of original furnace set-up, and lower than that of scheme employing a). Comparing the b) scheme with those of the a) scheme and the original set-up, which is 277 mg/m³ (at 6% O₂) at the furnace outlet, the peak value of NO _x concentration has decreased 571 mg/m³ (67.4%) and 436 mg/m³ (61.2%), respectively.

This work was supported by the Hi-Tech Research and Development Program of China (Contract No.: 2007AA05Z301), the Post-doctoral Foundation of Heilongjiang Province (LRB07-216), Heilongjiang Province via 2005 Key Projects (Contract No.: GC05A314), Key Project of the National Eleventh-Five Year Research Program of China (Contract No.: 2006BAA01B01), and the National Basic Research Program of China (Contract No.: 2006CB200303).