OCR Text |
Show were intended to separate the individual effects of stoichiometric ratio, post flame oxygen flow, and post flame oxygen partial pressure. By varying the natural gas load to the kiln, experiments were designed in which these three parameters vary independently. The purpose was to determine the relative importance of the molar flow rate of oxygen to the waste charge (proportional to post flame oxygen flow) and the volumetric oxygen concentration available to the waste charge (equal to the post flame oxygen partial pressure). Two-dimensional plots of post flame oxygen flow and post flame oxygen partial pressure versus the response variables were prepared at constant stoichiometric ratio (SR=2.0). Additionally, similar plots of stoichiometric ratio and post flame oxygen partial pressure versus the response variables were prepared at constant post flame oxygen flow (F02=14.4 m3/hr, 510 scfh). These data were all corrected for dilution by normalization to a standard total flow of 113 m3/hr (4000 scfh). These plots showed the data to be scattered, and no consistent trend existed between all of the response variables. A likely explanation for these inconsistent results is that, in addition to the effects of changes in the post flame oxygen flow and partial pressure, confounding influences due to large changes in kiln temperature are included. By changing the kiln load, necessary to effect changes in post flame oxygen flow and partial pressure, measured kiln exit temperatures vary over a wide range (320 K, 576 OF). It has been shown previouslyl,2 that the effect of increased kiln temperature is increased transient emissions and that this is likely due to increased volatility. Data have also shown that for toluene, a known soot precursor, soot formation is disproportionately promoted over volatile hydrocarbon emissions with increasing temperature.2 Due to the confounding influences of temperature, no conclusions can be drawn that separate the individual effects of post flame oxygen flow and partial pressure. However, 14 |