OCR Text |
Show CONCLUSIONS The most recent testing of the 6.0 MMBtu/hr VIStA burner has verified the potential of this technology to achieve very low N O x emissions. With first stage stoichiometrics of 0.55-0.60, N O emissions entering the main furnace can realistically be as low as one ppmv. However, combustion stability is very sensitive at this level, and further design modifications are planned to alleviate this problem. The major area of development work now needs to concentrate on the second stage burnout. It is in this region that minimizing thermal N O x formation is very critical. While the present secondary air mixer design was not successful in achieving final N O x levels below 20 ppmv, C O levels were generally well below 25 ppmv at 3 % 02. Temporary design modifications to the secondary air injection approach in which the air was introduced further downstream of the nozzle, nevertheless, were successful in reducing final N O x levels to less than 15 ppmv. However, C O emissions were excessive due to non-uniform mixing. A new secondary air mixer that induces a greater fraction of the furnace gas into the secondary air will thus be required. Following further testing of this design, work is scheduled to progress towards the design, construction and testing of a 30 MMBtu/hr system at the John Zink facility in Tulsa, Oklahoma. At the completion of the test program at John Zink's test facility, the development team will design a 60 MMBtu/hr burner. This burner will first be tested at the John Zink test facility and then installed in a Koch Industry boiler at the Koch refinery at Pine Bend, Minnesota. There, it will be operated to confirm the long-term performance, reliability and commercial attractiveness of the VIStA burner. 10 |