Performance Analysis of Novel Flue Gas Self-Circulated Burner Based on Low-NOx Combustion

Abstract

A new type self-circulating structure for flue gas was designed, with a corresponding low-nitrogen oxides (NOx) burner developed. A three-dimensional finite element model was established, and independent grid study and model verification were carried out to guarantee the accuracy. The temperature distribution and gas composition of different cross-sections along the axial direction were measured at different air–gas speed ratios. The influences of nozzle diameter and composition of the mixed gas on combustion and NOx emissions were compared and studied in depth. The results show that as the gas jet speed decreased, the gas permeability decreased, and the degree of mixing of the air and gas was aggravated, which caused the maximum temperature to rise and a large amount of NOx was generated. However, the higher air jet aggravated the airflow disturbance, which improved the low oxygen and low combustible atmosphere, and temperature uniformity was better. Increasing the proportion of blast furnace gas improved the low-oxygen atmosphere. The maximum temperature and temperature difference decreased accordingly, and the NOx emissions were greatly reduced. When the fuel was changed from coke oven gas to blast furnace gas, the NOx concentration at the outlet was reduced from 188.08 to 1.09 ppm.