Effect of Syngas Composition and CO2-Diluted Oxygen on Performance of a Premixed Swirl-Stabilized Combustor

• Published in: Combustion science and technology 2008-01, Vol.180 (1), p.64-88
• Main Authors: Williams, Timothy C., Shaddix, Christopher R., Schefer, Robert W.
• Format: Article
• Language: English
• Subjects: Applied sciences; Carbon dioxide; Carbon monoxide; Combustion. Flame; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Premixed combustion; Swirl; Syngas; Theoretical studies. Data and constants. Metering
• ISSN: 0010-2202; 1563-521X
• DOI: 10.1080/00102200701487061

Future energy systems based on gasification of coal or biomass for co-production of electrical power and fuels may require gas turbine operation on unusual gaseous fuel mixtures. In addition, global climate change concerns may dictate the generation of a CO 2 product stream for end-use or sequestration, with potential impacts on the oxidizer used in the gas turbine. In this study the operation at atmospheric pressure of a small, optically accessible swirl-stabilized premixed combustor, burning fuels ranging from pure methane to conventional and H 2 -rich and H 2 -lean syngas mixtures is investigated. Both air and CO 2 -diluted oxygen are used as oxidizers. CO and NO x emissions for these flames have been determined from the lean blowout limit to slightly rich conditions (ϕ ∼ 1.03). In practice, CO 2 -diluted oxygen systems will likely be operated close to stoichiometric conditions to minimize oxygen consumption while achieving acceptable NO x performance. The presence of hydrogen in the syngas fuel mixtures results in more compact, higher temperature flames, resulting in increased flame stability and higher NO x emissions. Consistent with previous experience, the stoichiometry of lean blowout decreases with increasing H 2 content in the syngas. Similarly, the lean stoichiometry at which CO emissions become significant decreases with increasing H 2 content. For the mixtures investigated, CO emissions near the stoichiometric point do not become significant until ϕ > 0.95. At this stoichiometric limit, CO emissions rise more rapidly for combustion in O 2 -CO 2 mixtures than for combustion in air.