OXY-COMBUSTION PROPERTIES OF INTERACTING SEPARATED JETS

Abstract

The use of oxy-combustion in separated-jet burners opens interesting possibilities in pollutant and flame control, and has very important impacts on flame stability. An experimental study of the combustion characteristics and flame structures has been conducted on a simplified version of a separated-jet burner that includes a central natural gas jet surrounded by two pure-oxygen jets. The flame stability and its structural properties are analyzed by the chemiluminescence of OH. Liftoff positions, flame front, flame length, and the concentrations of CO₂, CO, O₂ and NOx have been measured. The effects of jet exit velocities, jet diameters and separation distance between jets on flame characteristics have been examined. The results quantify the increase of central jet velocity and the distance between the jets makes possible to control and reduce appreciably the NOx emission. The liftoff height and the flame length depend strongly on the spacing between the jets and the jet exit velocities. The flame front spreads noticeably with the distance between the jets; however, the effect of jet exit velocities is lower, especially if the distance between the jets is high.

Keywords:

• flame length
• flame stabilization
• liftoff flame
• OH chemiluminescence
• oxy-fuel flame
• separated jets

Notes

Subscripts j and ox are relative to the natural gas and the oxygen jets, respectively. U ⁰: jet exit velocity. Re: Reynolds number. λ: initial velocity ratio. R: initial momentum ratio by unit of surface.