Experimental investigation of NOx emission reduction and efficiency improvement in a reheating furnace using multiple fuel-flow-pulsed burners

This study experimentally investigated NOx emission reduction and thermal efficiency improvement using fuelflow-pulsed combustion in a facility designed to model a partial zone of a continuous reheating furnace. Six 20 kWth burners were installed: two on the top front and four on the bottom side (two on the right and two on the left). The fuel flow was periodically controlled by a high-frequency solenoid valve. Following the zonal combustion control concept of a continuous reheating furnace, pulsating combustion was applied to both the top and bottom burners, only the top burner zone, or only the bottom burner zone. Without pulsation, NOx emissions were recorded at 76.1 ppm (O2 vol. 11 %). Pulsating combustion applied to both the upper and lower burners achieved a 77.1 % reduction in NOx emissions compared to the baseline. When applied only to the lower burners, the reduction was 61.9 %, and when applied only to the upper burners, it was 11.4 %. These results indicate that applying pulsation to all burners in the furnace is most effective for NOx reduction. To evaluate heat transfer efficiency with and without pulsating combustion, a 308 kg carbon steel object was placed in the furnace, and the time to reach 1000 degrees C, along with natural gas fuel consumption, was measured. During pulsating combustion, the target temperature was achieved more quickly with lower fuel consumption, demonstrating improved efficiency. These findings highlight the potential of pulsating combustion technology to enhance efficiency and reduce NOx emissions, offering significant promise for industrial applications.