OCR Text |
Show -6- This testing demonstrated the ability to achieve low NOx emissions at high excess air levels. At >90% excess air, NOx measurements were less than 25 ppmv even after correction to 3% 02· At 100% excess air, NOx levels were below 10 ppmv (corrected to 3% 02). Total hydrocarbons (THC) were non detectable for all tests. Carbon monoxide levels were less than 20 ppmv even at 100% excess air. A graph of ULN burner NOx levels versus excess air are shown on Figure 4. The NOx values are corrected to 3% oxygen. There is basically a linear correlation between excess air and NOx. The NOx equivalent in units of Ibs/MM BTU are also presented. Analysis of the data over the full range of burner firing (1.25 - 6 MM BTUjhr) indicated that NOx emissions were independent of firing rate. NOx measurements were confirmed by both Chemiluminescent and Electrochemical techniques. In addition to the excellent emissions performance, these tests demonstrated stable operation over the full range of conditions tested. The ability of a standard UV scanner to detect the burner flame was also verified. Burner flashback did not occur at any of the 46 test point$ or during the transition to these test points. SUMMARY This test program has demonstrated the ability of this design ULN burner to achieve state-ofthe- art NOx emissions below even the most stringent, existing environmental limits. The burner prototype tested represents the basic module which can be assembled into multiple units for heat release requirements ranging from 6 to 50 MM BTU/hr. This burner meets all of the criteria established for a commercially viable product. It is ideally suited to meet the requirements set forth by the Southern California Air Quality Management District (SCAQMD). Applications are expected to expand as rules of this type proliferate throughout the United States, stimulated in part by the 1990 Clean Air Act Amendments. REFERENCES (1) Air Pollution Consultant, January/February, 1992. (2) "Chemical and Engineering Aspects of Low NOx Concentration," P. B. Nutcher and W. H. Wheeler, Presented at "International Symposium on Industrial Process Combustion Technology," October 27,1980. (3) Gas Engineers Handbook, Fifth Edition. (4) Chemical Engineering, 77(12), pp. 103-105, June, 1971. |