| OCR Text |
Show valen~ of 7% of the waste heat input, as long as sUitable reburning conditions were maintained, such as proper combustion and sufficient mixing and swirling inside furnace by recirculating gas. Plans are underway to gather more data for future research. 5.4 The influence of O2 density Fig ure 5 compiles the test result as the correlation between the O~ density at the primary combustion chamber exit, and NOx reduction efficiency. At the test, 0 : density was measured at two locations, front and rear of the furnace. We have discovered that if it is maintained below several percentage points at both locations, NOx reduction effect can be improved. By injecting natural gas from the rear of the furnace, we have managed to accomplish this at the test. Also, by reducing the Ozdensity at the furnace exit, 0 : content in the recirculating gas can be lowered, decreasing the amount of natural gas necessary for reburning. We have secured a data at this test that NOx can be cut by more than 509'6 with no increase in CO content when the 0 : density at furnace exit was lowered to the level of 4%. 5.5 Reduction of Dioxins The latest test has proven that CO density can be lowered by means of reburning process. Since CO density is said to be a function of dioxin density, analysis of this toxin was also carried out. Table 7 illustrates the exhaust gas condition at time of sampling, and the analysis of the dioxins. The analyses have all been conducted manually. ~ c5 *~ E a a )( 0 z 140 120 6 :- 100 0 * ~ E 80 Cl Cl X •••• 0 2 60 ' .. 40 20 X X X 6!. !. IIfl 6 •• • 6 X Baseline 6 FGR only • Front Side • Rear-.Slde !. Both Side • a 20 40 60 80 100 120 140 COl ppm 12% Ih ) Figure 4 Effect of I nject ion Nozzle Locations 120~------------------------~ • 100 80 60 • • • 40 20 o 2 o~ (%) Figure 5 Effect of Q Concentration at the Combustion Chamber Outlet 8 12 |
