OCR Text |
Show MODELLING NOx FORMATION IN COMMERCIAL SWIRL AND LOW NOx BURNERS ABSTRACT S.P. Visona B.Singh W.L. Rowland Austa Electric Process and Combustion Branch Murarrie. 4172 Brisbane B.R. Stanmore Department of Chemical Engineering University of Queensland St Lucia. 4072 Brisbane Australia A wall-fired 350 MW(e) boiler firing pulverised coal was operated with low NOx burners in one portion of the furnace and standard swirl burners in the other portion. Axial in-flame measurements of temperature, oxygen and nitric oxide were obtained for the two types of 35 MW (thermal) bumer at the same relative locations. Computational modelling of the burners was carried out using simplified nitrogen chemistry, with HCN and NH3 considered to be the NOx precursors. Coal moisture with associated in-flame drying of partides and subsequent ignition delay is considered. The partide trajectories, flow patterns and volatile release paterns for the two types burners were compared. In partidular the influence on NOx reduction of partide penetration into the internal recirculation zone was explored. The hydrocarbon rebuming effec1 of volatiles was investigated and found to have particular relevance to the low NOx bumer. Overall the predictions of NO concentrations are in good agreement with the measurements, and it is conduded that simplified NOx chemistry has been successfully applied to both high and low NOx pf coal flames. To be presented to the 1995 American Flame Research Committee International Symposium, October 15-18, 1995, Doubletree Hotel, Monterey, California |