NO emission from high temperature air combustion of natural gas with longitudinal and swirling burner

Thermal nitrogen oxide (NO) emission is the major pollutant from industrial furnace. High temperature air combustion is an advanced technology to control NO emission, which carries out the combustion at highly preheated air and dilute oxygen conditions. The combustion performance of natural gas with highly preheated air was numerically simulated in an industrial furnace with a longitudinal and swirling burner respectively. The probability density function (PDF) combustion model, discrete ordinate (DO) radiation model and the Reynolds stress turbulent model (RM) were adopted for the modeling. Results showed that swirling burner was effective to reduce the final NO emission and improve the fuel burnout. When the longitudinal burner was substituted by a swirling burner with 180° swirling angle, the NO emission decreased from 35.2 ppm to 12.3 ppm, while the maximum and mean temperature in the furnace increased 38K and 58K. The CO emission also decreased from 379 ppm to 29 ppm, which implied a better burnout was achieved.