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Show VIStA Combustor for Very Low N O x Emissions in Furnaces and Boilers Dr. Ronald W . Breault, Kailash Shukla, Fred Becker, and Andrew W. McCIaine of Thermo Power Corporation Dr. Jay Karan of John Zink Company ABSTRACT The objective of the work reported on within is to optimize the low N O x combustion capabilities of the Vortex Inertial Staged Air (VIStA) combustor. The goal is to demonstrate ultra-low N O x production of less than 9 p p m with C O emissions of less than 50 p p m (both at 3 % 02) while maintaining high efficiency, productivity, and ease of operation and maintenance. The VIStA combustor addresses both prompt and thermal N O x production. It reduces prompt N O x by partially reforming the premixed natural gas fuel and air in the first stage of the combustor to C O and H2. By operating the first stage of the combustor at optimum conditions, natural gas can be reformed to species which will not contribute to the formation of prompt N O x . The inertial combustion system is ideal for this purpose because it promotes very stable combustion over a wide range of stoichiometry and firing rates and aids in the reformation of the fuel. The VIStA combustor reduces thermal N O x production by providing a thoroughly mixed gas/oxidant composition in the first stage as a result of using premixed natural gas and air, and utilizing low excess air and high internal recirculation of furnace gases in the second stage. Laboratory tests of a non-optimized VIStA combustor have demonstrated that the VIStA combustion approach is capable of very low N O x levels. The subtask, upon which Thermo Power, John Zink and D O E have embarked, will optimize the combustor and demonstrate the technology at a 2 - 3 MMBtu/hr scale. The first prototype of the VIStA combustor's first stage has been assembled and testing is underway to verify design models. Computational Fluid Dynamic modeling of the combustor using Fluent (a product of Fluent, Inc.) is being performed to evaluate those design elements not easily modified on the prototype. Kinetic modeling is being performed by Reaction Engineering Incorporated (RED to determine the optimum first and second stage conditions. This paper describes the market needs for the burner, the objectives of the burner design effort, the features of the design, the subscale and pilot scale test apparatus and results, and some Computational Fluid Dynamic modeling results. INTRODUCTION The market for industrial combustion equipment in the United States in the latter part of the 1990's and beyond will be shaped by the 1990 Clean Air Act Amendments (CAAA). Title I of the C A A A is designed to bring ambient air quality into attainment with the National Ambient Air Quality Standards ( N A A Q S ) and requires that industrial expansion in non-attainment areas is accompanied by a net decrease in emissions. Some parts of Los Angeles are in "non-attainment" and do not meet the N O ? N A A Q S . "New sources" in N O x non-attainment areas must use emission offsets and a tight level of control known as "lowest achievable emission rate" (LAER). 1 |