OCR Text |
Show 1:a bI e 1 C omponentof natura l gas component of gas volume % CH4 88.5 C2H6 4.6 C3H8 5.4 C4H 1O 1.5 N2 0 calorific value 46.05 MJ/m] Conventional flue gas analysis ( 02' CO, CO2, NOx ) was taken in the flue. Ceramic sheathed, type R , thennocouples were used to measure furnace wall temperature and flue gas temperature. In addition to the above mentioned conventional measurements, heat flux distributions at the furnace heath were measured by heat flux meter. 4. EFFECT OF PROCESS PARAMETERS ON NOx EMISSION 4.1 EFFECf OF AIR DISTRIBUTION INTO FDI MODE As stated in Section 2.1, two firing modes can be generated for the FDI burner, preheat mode which creates a typical stabilized flame, and FDI mode with the air directly injected into the furnace. The combustion air could be distributed into the two air ducts by adjusting a switching valve at the burner air inlet as shown in Fig. 1. The effect of the distribution ratio (e.g. the ratio of the combustion air delivered into FDI mode) on NOx was investigated (heat input 1.7MW air ratio 1.05 furnace temperature I300t preheated air 650t ). In Fig. 5, behavior of NOx versus the distribution ratio, or FDI air distribution ratio has been shown. 100 210 - o Ua 120m/s ~ - 0 ~ T""" 0 T""" 80 168 0 II II N N -0- 0 126 -- E 60 aa.. Ea. I a. x 40 Heat Input: 150 X10'4kcal/h 84 x 0 I (tTMW') 0 Z Air Temp.: 6500 C Z Furnace Temp. : 1300°C 20 42 0 20 40 60 80 100 FDI ratio; % Fig. 5 ~ffect of FDI ratio on NOx emission 6 |