OCR Text |
Show ••• i and SRO will be used to denote the stoichiometric ratio in the main burner zone, in the region following secondary air injection, and in the final burnout/stack, respectively. The fuels analysis (table 1) indicate the need for 5-6.5 kg fuel/hr at stoichiometric ratio (SRO=l) at the desir~~ burner firing rate (100 kwth). Combustion tests were performed with secondary air injected axially at a distance of 1.39 m from the burner. Exhaust NO, CO, CO2 and 02 emissions were measured at a distance of 3.365 m downstream from the top of the furnace. The stoichiometric ratio SRO has been hold constant at about 10-20% excess air for all runs. Carbon monoxide emission levels were 50 ppm or less for each test point indicating nearly 100% combustion efficiency. For all results presented the secondary air was injected axially at a distance of 1.39 m from burner, and the 02 concentration was between 2.5-3.5% at a distance of 3.365 m downstream from the top of the furnace. First stage stoichiometry A series of tests was performed to establish the influence of zone 1 stoichometric ratio on the NO concentration while holding SRO constant at about 10-20% excess air. Data from these tests are presented in Figure 2 for all fuels. As shown, the NO level falls rapidly as the primary zone becomes fuel rich. Results in Figure 2 indicate a minimum in NO emission up to an SRI of approximately 0.8. 4)()0 soo D 01 D hit NO • T 400 • 01. NO D 3000 • 10NT i • OI~ • 30NT • • OI.HCH • SONT .•.., 300 2000 o lOON • ~ D fit' 200 0 0 z: 1000 • i' 100 0 0 •• 0.6 0.11 1.0 1.2 1'" 0 0 .• 0.6 0.11 1.0 1.2 SAl sal Figure 2. Influence of Figure 3. Nitrogeneous-zone 1 stoichiometry. species, oil. coo o 30 NT.NO \iUW • 30 NT.MC .i.••., JOOO • 3ONT)O 15000 e lOON I. • ¥ fit' z: • j' 2000 1000 0 0.. 0.6 0.11 1.0 1.2 SAl Figure 4. Nitrogeneousspecies, 30% NT. 'i :! z !J! fit' z: z i 1'" 4 . 100 NJK1 12000 • lOON)O 9000 6000 3000 0 0 •• 0.6 0.11 1.0 1.2 SRI Figure 5. Nitrogeneousspecies, 100% N. I •• |