OCR Text |
Show As shown in the figure , the NOx production rate decreases with an increase of NO recycle rate. All the data fall in a straight line which can be described by an equation R * = l-aF* . It can be derived that the parameter "a", which is the slope of the line, represents the average N Ox reduction efficiency. In Figure 4, the value of "a" is 0.66. This means the N Ox reduction efficiency in the combustor is 66 %, which is not affected by the exit O2 concentration and the furnace load in the experimental conditions. Nonnalized NOx Production Rate, R* Exit 02=2% R*=1"{).53F* Exit 0*2= 3% R*=1"{).41F* o ~ Exit 02=4% R*=1"{).34F* ..{).5 Load = 6 MMBtulhr e Normalized NOx Recycle Rate, F* Figure 5. NO recycle into secondary air stream NO Recycle into Secondary Air Stream Experimental results for NO recycle into the secondary air stream at one furnace load and three different exit O2 concentrations are displayed in Figure 5. It shows that the NOx reduction efficiency is varied with the exit O2 concentrations. The average reduction efficiencies are about 53 %, 41 % and 34 % corresponding to the exit O2 concentration of 2 %, 3 % and 4 % respectively, which are lower than that of the NO 9 |