Fuel-rich methane oxidation in a high-pressure flow reactor studied by optical-fiber laser-induced fluorescence, multi-species sampling profile measurements and detailed kinetic simulations

• Published in: Combustion and flame 2014-07, Vol.161 (7), p.1688-1700
• Main Authors: Schwarz, Heiner, Geske, Michael, Franklin Goldsmith, C., Schlögl, Robert, Horn, Raimund
• Format: Article
• Language: English
• Subjects: Applied sciences; Combustion of gaseous fuels; Combustion. Flame; Computational fluid dynamics (CFD); Detailed kinetics; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fiber optics; Fluorescence; Laser-induced fluorescence (LIF); Methane; Navier-Stokes equations; Optical fibers; Oxidative coupling of methane (OCM); Profile reactor; Reaction kinetics; Reactor modeling; Reactors; Sampling; Theoretical studies. Data and constants. Metering
• ISSN: 0010-2180; 1556-2921
• DOI: 10.1016/j.combustflame.2014.01.007

A versatile flow-reactor design is presented that permits multi-species profile measurements under industrially relevant temperatures and pressures. The reactor combines a capillary sampling technique with a novel fiber-optic Laser-Induced Fluorescence (LIF) method. The gas sampling provides quantitative analysis of stable species by means of gas chromatography (i.e. CH4, O2,CO,CO2, H2O,H2, C2H6, C2H4), and the fiber-optic probe enables in situ detection of transient LIF-active species, demonstrated here for CH2O. A thorough analysis of the LIF correction terms for the temperature-dependent Boltzmann fraction and collisional quenching are presented. The laminar flow reactor is modeled by solving the two-dimensional Navier–Stokes equations in conjunction with a detailed kinetic mechanism. Experimental and simulated profiles are compared. The experimental profiles provide much needed data for the continued validation of the kinetic mechanism with respect to C1 and C2 chemistry; additionally, the results provide mechanistic insight into the reaction network of fuel-rich gas-phase methane oxidation, thus allowing optimization of the industrial process.