Simulation of a syngas counter-flow diffusion flame structure and NO emissions in the pressure range 1-10 atm

• Published in: Fuel processing technology Vol. 123; pp. 149 - 158
• Main Authors: SAFER, K, TABET, F, OUADHA, A, SAFER, M, GÖKALP, I
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 01.07.2014
• Subjects: Applied sciences; Carbon monoxide; Combustion; Combustion. Flame; Dissipation; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Flame structure; Flame temperature; Fuels; Mathematical analysis; Scalars; Theoretical studies; Theoretical studies. Data and constants. Metering; Gas emission; Radiation; Theoretical study; Synthesis gas; Modeling; Pressure; Counterflow system; Syngas; Diffusion flame; Simulation; Nitric oxide; Flame structure; Counter-flow diffusion flame; Mathematical model; NO emissions
• ISSN: 0378-3820; 1873-7188
• DOI: 10.1016/j.fuproc.2013.10.019

This paper reports a numerical investigation of syngas flame structure and NO reaction pathways over a wide range of operating conditions (H sub(2)/CO ratio between 0.4 and 2.4, scalar dissipation rate from equilibrium to extinction and ambient pressure from 1 to 10 atm) in mixture fraction space. An analysis of optimal operation conditions for syngas combustion in regard to NO index emissions is also provided. Flame structure is characterized by solving flamelet equations with the consideration of radiation. The chemical reaction mechanism adopted is GRI-Mech 3.0. The computational predictions showed that flame temperature exhibits a peak at an intermediate scalar dissipation rate for a given value of H sub(2)/CO ratio. From hydrogen-lean syngas to hydrogen-rich syngas fuels, maximum flame temperature increases for scalar dissipation rate values lower than the intermediate value whereas decreases at higher values. Zeldovich route is found to be the main NO formation route and its contribution to the NO production continually increases with the increase of hydrogen content and pressure. Hydrogen-rich syngas flames produce more NO at lower scalar dissipation rates while NO levels increase towards hydrogen-lean syngas flames at higher scalar dissipation rates.