Development of an Advanced Low NOx Landfill Gas Burner for Utility Boiler Application

The biological decomposition of municipal solid waste deposited in a landfill produces a gas that is typically composed of methane with about equal volume in inerts of carbon dioxide and nitrogen. If the landfill gas (LPG) is left unregulated, it eventually migrates to the surface of the landfill and discharges to the atmosphere causing air pollution and major odor problems. Because the City of Glendale (City) is the majority owner of the Scholl Canyon landfill, the City aggressively pursued a technological solution beyond the conventional flaring of the gas to mitigate this public nuisance. The final solution was to develop a low nitric oxides (NOx) burner that could use this noxious gas to produce clean electric power at the City's Grayson generating station. The paper discusses the approach used to develop an advanced low NOx LFG burner. Development phases consist of conceptual design, proof of concept testing in a research furnace, and complete burner retrofit and performance evaluation at Grayson Units 3 and 4. Performance testing at Grayson Units 3 and 4 has demonstrated that the low NOx LFG burner system has achieved a level of NOx reduction as high as 90 percent with excellent flame stability and without CO emissions. Key burner design parameters and operating variables to achieve optimum burner performance are presented. NOx reductions and overall burner performance achieved with and without the use of flue gas recirculation (FGR) are also discussed.