Planar Heat Pipe Preheater/Substrate for Low NOx Catalytic Combustion

Various techniques have been developed to achieve reliable and cost-effective NOx reductions. Among these techniques, catalytic combustion has been shown to offer the most NOx reduction. In a catalytic combustor, the main combustion occurs at reduced temperatures in a catalytic reaction zone, resulting in substantially reduced NOx formation. A preheating burner is required to heat the compressed air to a temperature that is acceptable to the catalytic reaction. To achieve maximum NOx reductions, the combustion in the preheating burner must be precisely controlled according to the main combustor conditions. This is technically challenging, especially during startups and fast transients, because both combustors have vast differences in size, mass, and transient response time. Sophisticated and expensive control schemes thus are required to coordinate between the preheating burner and the main combustor. This becomes one of the major obstacles to commercialization of catalytic combustion technology. Advanced mechanisms and devices that effectively can reduce or eliminate the combustor mismatch problem will reduce the cost of catalytic combustors, and improve the marketability of low NOx catalytic combustion technology. Developing such advanced mechanisms and devices will improve the United States' technological competitiveness in the energy sector and contribute to a cleaner environment. Although preheating the incoming air/fuel mixture for the catalyst is a major concern for both combustor performance and NOx reduction, cooling of the catalyst bed also is largely beneficial. According to information provided by Siemens Westinghouse Power Corporation, the amount of fuel conversion in the catalyst is limited by the material properties of the catalyst substrate. If the reaction rate is too great, the temperature of the substrate gets too high, resulting in the breakdown of the catalyst bed.