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Show LASER DIAGNOSTICS AND COMPUTER MODELS OF NOx FORMATION CHEMISTRY IN NATURAL GAS COMBUSTION David R. Crosley, Gregory P. Smith, Jorge Luque, and Norbert H. Heberle Molecular Physics Laboratory SRI International Menlo Park, California 94025 ABSTRACT The reduction of nitric oxide pollutant emissions is a major goal of the natural gas and burner industries. A combination of laser measurements of chemically reactive species together with computer models of detailed combustion chemistry provides the understanding of the chemical mechanisms by which nitric oxide is fonned in flames, and forms the foundation for the selection of the best strategy and design for its abatement in practical systems. This paper describes these methods, as applied in the laboratory to flames burning at both low and atmospheric pressure. INTRODUCTION Natural gas is generally considered a clean burning fueL Nonetheless, one of the major challenges facing the natural gas industry today is the need to conform to environmental regulations concerning emissions of nitrogen oxides, referred to generally as NOx' These requirements are becoming increasingly stringent and pose limitations on cmrent and projected applications of natural gas combustion. Depending on the mode of formation of NOx' and the configuration of the bwner system under consideration, different strategies for its abatement can be chosen. Scrubbers, special control strategies such as reburn or staged burning, or alterations in burner design itself are all possibilities. Two important tools in combustion science, laser diagnostics and detailed computer chemistry modeling, have undergone significant development over the last twenty years. These have important applications to the problem of NOx emissions in natural gas combustion, ranging from fundamental studies of flame chemistry to mapping of NO production zones in real commercial burners. In this paper we describe two such studies in our laboratory, low pressure premixed flames in which a detailed one-dimensional model of flame chemistry can be fully and carefully tested, and an atmospheric pressure Bunsen flame which is a test bed for two-dimensional models, often with less detailed chemistry. |