OCR Text |
Show 5 instead of the oil atomizer, after the completion of the warming-up. Two(2) types of the injection nozzle were prepared. A single hole type 02 nozzle and a multi-hole (6-holes) nozzle were selected. The detail of each nozzle is also shown in Fig.5. An annulus type coal nozzle was adopted and the swirler was also equipped in the coal nozzle to generate appropriate swirl intensity. The flue gas was sampled at the 'inlet of the heat exchanger (air preheater), and NOx, 02' CO, CO2 and 502 were continuously analyzed by a chemi-luminescence. a paramagnitism and three(3) non-dispersive infra-red type analyzers. respectively. N2 conc. was also analyzed by a gas-chromatogram. Fly ash was sampled at the same location and analyzed to estimate unburnt carbon loss and residual sulfur content. On fir ing test. air was used as an oxidant from light-off to warming up. When the facilities was sufficiently warmed up on oil firing, fuel was firstly substituted from oil to pulverized coal. Then, the air was gradually exchanged into the mixture of 02/recycling flue gas. From the viewpoint of safety operation. a part of recycle flue gas was only used as the primary stream on 02/flue gas recycle combustion. An excessive supply of pure 02 and/or GRF stopping will cause dangerous condition, resul ting in possible explosion. due to rapid increase of 02 cone. in the secondary stream. Similar dangerous state may always occur due to the flame lost. We installed. therefore. the safety interlock system so that the oxygen supply system and fuel feed process could be rapidly shut down, in cases of the flame lost and excessive 02 cone. in the secondary stream. The interlock value for the excessive 02 cone. in the secondary stream was decided to be 38%, according to the limited 02 cone. in the 02/N2 mixture, discussed below in details. |