OCR Text |
Show Oxygen Enriched Combustion DOE's involvement with oxygen enriched combustion started with the development of improved oxygen separation systems in 1979. Original emphasis was on increasing the oxygen level of combustion air through the use of membranes. Typically, the oxygen concentration of air was enriched to the 30-35% level. One commercial product resulted from this sponsorship. More recently, emphasis has shifted to oxyfuel firing in which a nominal level of 100% oxygen is used. The technology is applicable to energy intensive ferrous, non-ferrous and glass industries. The enrichment or replacement of air with oxygen produces a higher flame temperature to increase heat transfer. Also, oxygen enrichment reduces the sensible heat loss. There is less/no nitrogen to heat up and throwaway. This also results in requirements for smaller fans and damper~ and may make impractical heat exchange equipment such as regenerators. The fuel savings can be significant but the energy required to separate oxygen must be considered. The environmental benefits can be substantial. With the use of 100% oxygen and special burners designed for oxy-fuel firing, the emissions of NOx, CO and particulates will be reduced. The economics of using OEC are determined by the size and condition of the furnace and its heat recovery equipment, the oxygen source, reduction in electric boost and reduction in capital requirements such as those for heat recovery and emissions control equipment. DOE has sponsored industrial demonstrations of oxygen enriched combustion equipment at three installations: Wolverine Tube Co. plant in Alabama; Carr-Lowery in Baltimore and the current demonstration at Gallo Glass in Modesto, CA. Current DOE contract activities in OEC are being conducted by Praxair, formerly Union Carbide Industrial Gases. At Modesto, Gallo runs the nation's largest container glass plant with four gas-fired and one electric furnace. Gallo Glass Company's melter #1 producers glass for wine bottle manufacture. Gallo's primarY objective in converting this melter to 100% OEC was reduction of NOx emissions. The melter was rebuilt in the spring of 1991, and the regenerator was removed. An oxy-fuel combustion system designed and built by Corning, Incorporated was installed for permanent commercial operation. Startup of the melter with nominal 100% OEC occurred in July, 1991. The use of OEC at Gallo resulted in significant declines in emissions as well as a reduction in energy consumption (see Table). The NOx level measured is 1/5 of the California standard which will become effective late this year. |