Oxygen-enriched combustion studies with the low NOx CGRI burner

This paper described a study involving an oxygen-enriched-natural gas combustion system with a modified low nitrogen oxide (NOx) Canadian Gas Research Institute (CGRI) burner. The authors examined the effects of oxygen enrichment at various stack oxygen levels and a single furnace operating temperature, on NOx and carbon dioxide (CO2) emissions, fuel efficiency and furnace temperature distribution. In addition, a study of the combined effects of oxygen enrichment and air infiltration was conducted. A single sidewall mounted burner was used in the pilot scale furnace at the Centre for Advanced Gas Combustion Technology (CAGCT). There was a linear decrease of the firing rate needed to maintain the furnace temperature at 1100 Celsius with increasing oxygen enrichment. A reduction in the 40 to 45 per cent range was required in the firing rate to maintain constant furnace temperature at full oxygen enrichment. Changes in oxygen enrichment (up to 60 per cent) had a minimal effect on NOx emissions, which remained relatively constant. Higher oxygen enrichment decreased NOx emissions. Increasing stack oxygen concentration at all oxygen enrichment levels resulted in increased NOx emissions. NOx emissions similar to those observed with no air infiltration but with similar stack oxygen concentrations resulted from air infiltration. The standard deviation of the temperature distribution with no oxygen enrichment fell in the 19 to 27 Celsius range, while the range for 90 per cent oxygen enrichment was 31 to 34 Celsius. 8 refs., 2 tabs., 9 figs.