EFFECT OF COMBUSTION AIR DILUTION BY WATER VAPOR OR NITROGEN ON NO_X EMISSION IN A PREMIXED TURBULENT NATURAL GAS FLAME: AN EXPERIMENTAL STUDY

ABSTRACT

A study of the effects of combustion air dilution by water vapor or nitrogen on NO_x emission in a premixed turbulent natural gas flame was performed for lean conditions. NO_x concentrations were measured with dry air, water vapor dilution or nitrogen dilution of the combustion air at varying air factor at three different power/pressure settings. Results showed for all cases a significant reduction in NO_x emission as an effect of combustion air dilution by water vapor and nitrogen for constant T_ad. The results also showed that the reducing effect of water vapor dilution is larger than the reducing effect of nitrogen dilution. It is therefore concluded that water vapor dilution of the combustion air not only reduces NO_x emission in premixed turbulent flames by lowering flame temperature and oxygen deficiency, but also by chemical action.

Keywords:

• NO_x emission
• MAST cycle
• steam dilution

This work was supported by the Nederlandse Organisatie Voor Energie en Milieu (NOVEM) and carried out in cooperation with Winnox Combution Systems b.v. The authors would like to thank Dr. Guus Witteveen for supplying the burner and for the helpful discussions.

Notes

∗Values are calculated for 1000/T_ad < 0.5.