OCR Text |
Show area and peak height responses at high air and oxygen flows (upper right corners) are approximately nine and five times less, respectively, than at low flows (lower left corners). Filter weight response decreases by a factor of four over the same region, and peak CO by a factor of six. It is important to note, however, that a portion (but not all) of these response reductions can be explained by simple dilution. Total flow changes by a factor of 1.8 over this experimental region, but due to the fact that we are trying to characterize the inlet conditions to which an afterburner system must be able to respond, we have not corrected these data for dilution. The response curves in Figure 3 can be compared with the contours of constant stoichiometric ratio, post flame oxygen flow, and post flame oxygen partial pressure, presented in Figure 2. It is not surprising that puff intensities should be reduced at higher oxidant levels and higher total flows. In addition to the effect of dilution, providing higher oxygen flows and higher oxygen partial pressures to the vaporizing waste cause fuel rich regions to be more difficult to achieve. However, without oxygen enrichment, it is often difficult in practice to operate at high stoichiometric ratios while maintaining kiln temperatures and flame stability due to the quenching effect of nitrogen. Also evident from Figure 3 is the fact that all three responses are more sensitive to changes in oxygen flow than to changes in air flow. Small changes in oxygen flow cause large changes in stoichiometric ratio, post flame oxygen flow, and post flame oxygen partial pressure, without significantly affecting the adiabatic flame temperature or gas-phase residence time. Conversely, large changes in air flow are necessary to effect changes in stoichiometric ratio or post flame oxygen flow. Without oxygen enrichment, oxygen partial pressure is limited by atmospheric conditions. Additionally, increasing air flow also significantly decreases the adiabatic flame 10 |