Characteristics of ultra-fine particles formation in the silica particle spheroidization using methane/oxygen coaxial non-premixed flame

Abstract

Particle spheroidization with flame is an effective procedure to produce spheroidized particles. Ultra-fine particles are formed and attached on the surface of spheroidized particles. Since those ultra-fine particles may affect the fluidity and filling fraction of spheroidized particles, a controllability of the ultra-fine particles formation on the spheroidized particles is important. To understand the effects of pressure and the component of fuel on the spheroidization and formation of ultra-fine particles, the particle spherodization tests of SiO2 using non-premixed flame were carried out under elevated pressure. In this study, SEM photographs, particle size distribution and the specific surface area were measured with BET method for evaluating the effects of pressure on particle spheroidization and ultra-fine particles. Results showed that the ultra-fine particles attached on the spheroidized particles were reduced with increasing pressure of the combustion field. This is because that the forming reaction of SiO2 is inhibited with the decrease of molar fractions of carbon monoxide and hydrogen with increasing pressure. In addition, it is found that the ultra-fine particles can be formed where there is carbon monoxide molecular and high temperature at the same time.

Keywords

• ultra-fine particle
• particle spheroidization
• elevated pressure
• silica particle
• pure-oxygen flame