| OCR Text |
Show Figure 10 shows the ultra low NOx burner applied to paper mill waste gases. There are many sources of waste gas in a paper mill ranging from digesters to strippers. Some contain significant quantities of organics (usually sulfur compounds) while others are lightly contaminated air streams. As shown on Figure 10, the dilute gas stream is used as the combustion air source for the burner while the concentrated gas(es) are injected downstream. The excess air from the burner supplies the oxygen requirement for combustion of the organics injected downstream. Thus, there is no thermal penalty for operating the burner at 100 % excess air since the dilute gas must also be treated before emission to the atmosphere. The final example is shown on Figure 11. Here vent gases manifolded from the vents of several large compressors are thermally oxidizer to destroy the VOC's. In this case, the VOC concentration produce a rich gas with a heating value in excess of 500 Btu/scf. This gas can be used as the fuel for the thermal oxidation process. The thermal oxidizer operating temperature is limited to 2200 F using air quench so that inexpensive refractory materials can be used. Again, the high excess air requirement of the ultra low NOx burner does not constitute a thermal penalty since excess air is required to limit the temperature rise from the oxidation reactions. These five examples demonstrate real applications of an integrated ultra low NOx burner/thermal oxidizer design. These are just a few of the many applications which could be cited. Despite operating with high excess air levels, these five real-life examples demonstrate that there is no thermal efficiency penalty in many applications. A range of ultra low NOx burners, "ULNEX", is commercially available today. With continuing emphasis on low NOx emissions from waste gas thermal oxidation systems, applications are expected to proliferate. Integrated burner/thermal oxidizer designs are state-of-the-art in controlling NOx emissions from waste gas thermal oxidation and represent Maximum Achievable Control Technology (MACT). V-30 7 |
