Effect of staged combustion on low NOx emission from an industrial-scale fuel oil combustor in South Korea

• Published in: Fuel (Guildford) Vol. 210; pp. 282 - 289
• Main Authors: Kang, Myung Soo, Jeong, Hyo Jae, Massoudi Farid, Massoud, Hwang, Jungho
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15.12.2017; Elsevier BV
• Subjects: Aerodynamics; Catalysis; Combustion; Combustion chambers; Complex systems; Computational fluid dynamics; Computer applications; Computer simulation; Effects; Electric power generation; Electric power plants; Emissions; Equivalence ratio; Flue gas; Fluid dynamics; Fuel oil combustor; Fuel oils; Fuels; Hydrodynamics; Natural gas; Nitrogen oxides; NOx; Oil; Petroleum; Power plants; Schedules; Selective catalytic reduction; Simulation; Staged combustion; Sulfur; Superheaters; Tubes; South Korea; Staged combustion; Computational fluid dynamics; Fuel oil combustor; NOx
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2017.08.065

[Display omitted] •CFD simulation was carried out for an industrial-scale fuel oil combustor.•Ideal operating conditions were determined by using stringent staged combustion.•NOx emission decreased with proposed conditions compared to reference conditions.•The decrease of NOx emissions was mainly caused by thermal NOx formation decrease.•The theoretical CFD results were in good agreement with experimental data. Staged combustion induces the reduction of NO to generate N2 through the formation of a fuel-rich zone upstream of the flue gas and utilizes the unburned gas by supplying sufficient air for combustion downstream of the flue gas. Since power generation schedules are very constrained and only specific and limited tests can be planned and executed, the use of numerical simulations is currently more suitable for analyzing these large and complex systems. In this study, computational fluid dynamics (CFD) simulation was performed for an industrial-scale fuel oil combustor to determine the effect of staged combustion on NOx emissions. The fuel oil combustor is a 400-MWe opposite-wall unit located in Ulsan, South Korea, where high-sulfur fuel oil (Bunker-C with 2.5% sulfur content) is used. The combustor has a height of 56m and a cross-sectional area of 10×12m2. Water wall tubes (evaporator) are located on the wall of the lower part of the combustor and sixteen burners are located at four different axial positions. The system is comprised of two superheaters, two reheaters, and an economizer located in the upper part of the combustor. Staged combustion is realized by changing the equivalence ratio of each burner. Under the initial staged combustion conditions adopted by the Ulsan power plant, the concentration of NOx at the exit of the combustor was calculated to be 362ppm, which was still high even after selective catalytic reduction treatment. However, when more stringent staged combustion conditions were applied, the predicted concentration of NOx decreased to 309ppm, which is lower than the mandated NOx concentration at the combustor exit.