| OCR Text |
Show 6 Measurement Equipment Far from the burner, the gas stream composition is determined by drawing samples of the gases into a cooled cylindrical pipe for analysis. The pipe is 50.8 rom in diameter and 1.5 m long and has a 11.0 mm hole in the end. The sampled gases are carried to continuous analyzers to measure the concentrations of O2 , CO2 , CO and NOx • Quenching of the sampled gas is provided by convective cooling on the sample line wall. This is not a very efficient way to stop reactions in the sampled gas. Because of this and the size and temperature of the probe it cannot be used in the near burner region of the furnace. The near burner chemistry is of paramount importance in this study. In particular, the major species involved in the formation of NOx must be measured. To this end, a special sampling probe manufactured at the IFRF was used in the near burner region. A schematic of the probe tip is shown in Figure 4. This probe allows for the collection of reaction intermediates and the rapid quenching of any reactions which may be occurring in the gases sampled. The sampled gases then provide a frozen view of the distribution of the species concentrations in the vicinity of the probe entrance. As can be seen in Figure 4, the entry for the sample probe is on the side of the tip. This is to prevent the blockage of the entry of the sample probe by coal particles. The sampled gases are carried to continuous analyzers to determine the concentration of the conventional combustion gases (02 , CO2 , CO and NOx ). This probe has the added capability of collecting other, nonstandard gases using a trapper solution. This solution is an aqueous mixture which will chemically bond to the species of interest and hold it in solution for future analysis. As can be seen in Figure 4, the trapper solution is carried to the probe tip and is drawn back with the sampled gases to a reservoir where it will be recycled to the probe tip. A schematic of the sample system |
