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Show INTRODUCTION "Robust, Optimal Control of a Natural Gas-Fired Burner for the Control of Oxides of Nitrogen (NOx)" While combustion of fossil fuels provides most of the world's energy, it also produces most of the world's air pollution. One straightforward technique to reduce these emissions from stationary combustion systems is to switch the fuel being burned, substituting a cleaner-burning fuel where a more polluting type is being used (i.e., switching from coal to oil or from oil to natural gas). Although natural gas combustion generates significantly lower emissions of sulfur oxides and soot than coal or oil, reducing the emission of oxides of nitrogen (NO and N02, collectively referred to as NOx) , a major contributor to photochemical oxidant ("smog"), remains a challenge. Many techniques are employed in the task of controlling NOx emissions from stationary combustion applications. Some controls seek to prevent NOx formation during combustion, such as staged combustion, flue gas recirculation, catalytic combustion, etc. Other control processes destroy NOx in a post-combustion reaction; these include selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR), and non-selective catalytic reduction (NSCR). In any of these processes, a set of static input parameters (fuel load, equivalence ratio, etc.) will correspond to particular values for each of a set of output parameters (NOx emission, heat loading, combustion efficiency, etc.). For a given combustion process there will be at least .'... ." , one set of input parameters that produces an optimum set of output parameters. Identifying the input parameters that produce this optimum condition is not trivial. Furthermore, these optimum input parameters will change as boundary conditions vary due to changes in load, fuel type, inlet air properties, or even subtle changes due to equipment degradation. : Using a natural gas-fired, 100,000 BtuIhr, model industrial burner research at the University of California, Irvine, has shown that certain values of swirl intensity and excess air (equivalence ratio) can significantly reduce NOx concentration in the exhaust gases without reducing combustion efficiency [St. John and Samuelsen, 1994]. The present work explores the potential of applying a robust, on-line, active optimization scheme to a combustion process for the control of the emission of nitrogen oxides, over a range 1 |