OCR Text |
Show Existing OFA port designs were found to be as effective as the venturi arches in isolating the upperllower furnace combustion zones. In addition, standard design procedures were found to be effective in achieving combustion zone temperatures that were acceptable. The results of these evaluations, in addition to other practical design concerns for the venturi, led to the elimination of the venturi concept. As a result, a straight wall furnace configuration was selected for the design basis of the commercial generating unit. Modeling was used to evaluate the burner arrangement, and to begin optimization of the OF A port sizing and locations in the upper furnace. This optimization was based on predictions of furnace mixing, carbon loss, and pollutant emissions. A typical model prediction of the Phase I concept is shown in Figure 9. It was recommended that due to the uncertainty of the advanced 10w-NOx burner that would be developed in Phase II, the furnace design should be re-evaluated after burner development to assess the impact of the new burner on the furnace performance. Furthermore, the overfire air system was only partially optimized in Phase I. Therefore, further OFA system optimization should be conducted in Phase II after the burner has been selected and the burner operating conditions have been defined. FIGURE 9 0 , Concentr8t1on In ,,"YOI / PREDICTED TEMPERATURE AND OXYGEN CONCENTRATIONS FOR THE PHASE I COMMERCIAL GENERATING UNIT 11 |