Combustion characteristics of Mg−CO2 counterflow diffusion flames

• Published in: Symposium, International, on Combustion Vol. 26; no. 2; pp. 1945 - 1951
• Main Authors: Fukuchi, Aporo, Kawashima, Masaru, Yuasa, Saburo
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 1996
• ISSN: 0082-0784
• DOI: 10.1016/S0082-0784(96)80017-8

To examine the details of the Mg−CO2 combustion consisting of the gas-phase reactions and the surface reactions, we tried to separate the Mg−CO2 flame from the surface reactions. For this purpose, we formed a stable Mg−CO2 counterflow diffusion flame between the Mg vapor and a CO2 stream by using a Mg vaporizer with many small ejection holes. The Mg−CO2 counterflow diffusion flames contained two types of flames: the luminous flame and the dark flame. In the luminous flame, the homogeneous reaction of Mg with CO2 forming gaseous MgO and CO occurred, as well as the condensation of MgO. The dark flame was observed when the Mg ejection velocity was small. The heterogeneous reaction of Mg with CO2 forming condensed MgO and C occurred. The change from the luminous flame to the dark flame was caused by the heat loss to the Mg vaporizer. The flame stability limits diagram of Mg−CO2 counterflow diffusion flame was obtained, in which the Mg ejection velocity is plotted against the stagnation stream velocity gradients. There exists a critical value of the Mg ejection velocities, below which the flame can never be stabilized. This limit is due to the thermal quenching of the flame near the Mg vaporizer. Also, the critical value of the stagnation stream velocity gradients exists and is due to the chemical limitations on the combustion rate in the flame zone. This flame stability limits diagram was similar to those of the ordinary gaseous fuel-oxidizer counterflow diffusion flames.